.Net Foundation Design Reviews, 23 Oct 2018

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From YouTube: .NET Design Reviews: Xamarin Essentials

Description

We'll take a look at Xamarin Essentials today

A

All right so we know life. We have our friends over from the xamarin team. They are not in the room, unfortunately, but we have Stephen in the room. Who is normally on the court of call Stephen? Can you hear me? Okay, great.

B

Can you see the screen awesome.

A

So then James we want to give us an overview of what Zeeman essentials is yeah.

C

Absolutely so so I'm James about two Magnum of principle p.m. on our mobile dev tools. Over in Boston office. We have John dick who works heavily on this, along with Joshua Bell was in the room, John we've.

D

Got a few other people on my team, the components xamarin team, matthew, Leibowitz who's done some work on essentials, David Humphries, who works on some other things and Mel who works on Android support and plays services in Israel who works on mostly iOS bindings, but a good mix, everyone's kind of familiar with essentials, and then a little bit of work here. There all.

C

Right thanks John yeah, so xamarin essentials is a new library for mobile Don that developers now, if anyone's not aware of xamarin.

D

C

The kind of perks and advantages that we have for mobile native development is that we offer 100% API surface for the underlying iOS and Android API s in c-sharp. So if you want to access location on iOS, you have access for location api's. We create these bindings in c-sharp and, as you char features like async await lambdas events and delegates. We do the same thing for android and, of course, if you are writing uwp or other WPF applications, there's those dotnet it kind of equivalent SDK level API.

C

So you just have all of this Fitness now at a high level, though. Well, it's amazing that we offer all these API is for developers. We find that a lot of our developers, majority of our developers, are writing a bulk, if not all, of their application.

C

Inside of a dotnet, sandrov libraries, so all shared code cuz, we have xamarin forms which is share native the user interface all in sam'l. So when you're writing your models or view models, you want to access these core underlying EP eyes of iOS.

D

Android and Windows from your shared code.

C

So traditionally what developers would have to do is they have to learn three different api's? They would create an abstraction, they would have to go, implement it three times over and over so examine essentials. Attempts to do is it abstracts.

C

All of the platform API is into a single cross-platform Donette API for developers, so we attempted to look at what are the most important hardware features that developers are trying to get access to from their shared code and give them a consistent library and API that they can use of a single, immediate library that they can pull in so their iOS, Android or Windows projects and the.net standard is, is basically the API surface and that's what we're looking at here. So we use kind of a bait-and-switch technique.

C

So when a developer calls a method, it's still calling the underlying iOS or Android or Windows implementation, but they don't don't worry about it's one API. So this means for an API like compass, which could be hundreds of lines of codes. It's two lines of code right, just start, stop and add an event handler. So we aim to do that and that's what xamarin essentially is it's a 30-plus platform abstracted api's so when you say Vegas, which basically.

E

I mean you have multiple builds of the same surface area, targeting the different implementation and based on what you deploy to you, get the relative binary. Yes,.

C

Correct so we implement the same API across iOS, Android and Windows. So when a developer adds the library they must add it into their target platform and then a runtime that will choose the IAO favor, the iOS DLL implementation over the dotnet standard version. That just throws exceptional musically, and this was very popular eyes in a lot of different libraries. To do things like this, like our plugins and things like that, so we wouldn't van der dies everything into one library and it's architected- to be very user friendly.

C

So you'll notice that there's a lot of statics there's no interfaces. Everything is trying to be consistent and lowest-common-denominator, but provide a lot of functionality.

E

Is are you able to have a hundred percent? You know behavioral equivalents across all the platforms for the api's you've chosen. Are there any cases where some of these work differently on different levels, yeah.

C

That's a good question. um So when we do an API spec, we take that into consideration for each and every single API. So a good example of how an API would differ. Let's say the compass API is a good one. On Windows and on iOS there is a literal compass API it's get access to now.

C

They offer different information between that, but we picked like heading my magnetic north, for instance, as this is something that all of them represent and what developers are most once now in Android there is no compass ap on you actually have to spin on multiple sensors. Do some math combine them together, so we offer we just hide that from the user, so the end results is expected.

C

So that's there now in our documentation, though, we do sometimes offer some functionality that's available in a single platform that maybe falls back to something graceful and the other ones. So a good example of that in our documentation would be if you were to open the Maps application. So this is our Maps API, so the inside of the documentation.

C

What we do is we reference if there's any setup, any permissions you need to set and then specifically, we have a section called platform, differences and platform implementation, specifics, so platform differences highlights anything that when you're calling a shared API is a little bit different. So, for instance, on this opening Maps, you can request open bicycle driving, walking a default or transit but, for instance, Android doesn't support transit. It does support bicycle, for instance, so developers can take that into consideration.

C

We try to minimize that as much as humanly possible and it so that it's very rare that there is this case, but we do document it if it is, if it is there and what MNO.

E

Sorry, what's the typical fallback at runtime, so in that Android case you request, transit, you get an exception or it falls back to walking or something yeah.

C

It would fall back to the default at that point, so there's a default that would be selected, so it would most likely or what it would do, sorry and almost like what it would do is it would open the location and then have the user select the transportation mechanism instead of selecting one for them. The default is, don't select any and just start navigation on it and let the user decide- and this is the they're very rare cases. So it's not the it's the exception to the rule, not the rule.

C

And you know we try to do things that that make the most sense so for launching the map, application on iOS and Android. There's a specific API to do that on Android. There's, not you have to use the intent system that you pass it a Geo URL. So in this instance we actually have no control over what will happen like what map application will launch, but we document that so we can only do what the API gives us. So we can't force ways or we could.

C

We could force ways and we could force Google Maps, but that's really not what the platform is intended to do. So we don't. We don't do anything, that's not normal for the core underlying iOS Android or Windows API. So we don't. You have basically to make things.

C

D

Also, some cases where we have platforms, specific api's in the platform, specific assembly and there's a few instances like one somebody had requested with secure storage on iOS. You can actually set the keychain data to be available like after the first time that you unlock the device or it's available as soon as the device is booted. So we set a sensible default in that case, but the you know the user really wants to get down to the platform, specific implementation level and kind of override that default.

D

In some cases we actually do compile that into the assembly as well. So.

C

Yeah and in those instances, though, those would be compiled into the iOS or Android specific API level and would not be in the dotnet standard versions, since it's specific to that platform, because this library could also be used not from Adana s, Android library at all, it could just be used from an iOS project, for instance, and then that would be a case where maybe they want a little bit more functionality. I guess those are usually edge cases and we look at those on an API basis and.

A

The reason they would use German essentials over the iOS provided API is because you're so just a much nicer, easier to use or consistent across platform. Well sure. But it's.

D

A

If they already are an iOS app, then they don't care right. There, they're cool, good money. Well,.

D

They can kind of do a mix of it too. Right like they might use the from their nest standard assembly. They might use the secure storage that the same API you know in that shared library, but that can also in their app project their iOS app project, use that specific platform API that we make available to change like when that keychain data is unlocked. So you can kind of have a mix of both as well.

D

You can kind of use that that consistent API as much as you can- and there might be a place up here in there- that you do something platform specific as well a.

C

Good reason why someone.

A

C

Use this, for instance, you know doing like the accelerometer or compass, the iOS API is very elegant. To be honest with you, the Android one is like a hot mess, just as you can look at the code, so I would rather use our API and, for instance, secure storage. Maybe we wrote hundreds of lines of code to abstract it into a simple one-liner. So for me, based on the level of control that I need in my application, I always give this good for a long time. I've always said 8020.

C

So if you can use this API to appease 80% of the use cases, then that's really good. However, I think that xamarin essentials facilitates 95, plus percent of the use cases of a single API. So it's a much more elegant and consistent API across across that.

A

So the typically usage to video all time things like apps using it directly, then you have longer center projects using it directly. Do you have many usages in multi targeted projects as well or what's the other one called the the shared projects which will the old multi-headed approaches is also something that you typically see people using your stuff in.

C

Yeah I think our developers are defaults or Donette standard. Oh, when you create a new project, so I think that is our good, which I don't be usage specifics or could really talk to you, but I do most of our developers that I talk to and even myself we defaulted on that standard. There are something that there are some shared projects out there and then in that instance, you would be falling back to the platform api's that are in there.

C

So you would run into maybe seeing and I am a specific API in there and you have to conditionally compile that what, of course your compiler would catch up, you can do Android, that's what we minimize the specific calls as far as multi targeting for apps would be low. I I've always recommended multi targeting only for library creators, not perhaps developers right in general, at.

D

The current stage, based on tooling yeah yeah, it's not very well supported in Des Moines, Iowa, droid, apps yeah.

C

And and on Visual Studio for Mac yeah.

A

But you wouldn't expect most of your customers to be just a daughter estimate lightly right that.

C

Would be the 80/20 right that makes sense so.

A

The only reason I'm asking is basically so there's a few issues that we recently talked about. One of them was so I, don't know whether you saw them, but we just added reflection emitted on that standard. So we added the capability API groove that so you can actually check whether reflection amid wool. Basically, it's all puffs from one supported and we added another capability API. That indicates how good it is supported. So, like the zevran runtime, people are working on the and I an aisle interpreter.

A

So if you're, using reflection, Amit, for example, to speed things up, you probably don't want to use it. If you know that the aisle is actually ending up being interpreted, in which case whatever you're doing is probably faster than going to ref emit, and so we basically to capability API is that people use, but the key scenario there is, if you think, I'm a library stamp on you having ap.

A

Is that throw makes a lot more sense than not having the API, because, if you're not having the API, you force everybody to effectively multi target right and having the API and have that just not work. If you read the better approach, but it seems like you're kind of going down the same path because you're basically exposing concepts that may not work everywhere, but if they work in enough places it's still worthwhile having. And then you just deal with the fallout if the API is not available to you. Yeah.

C

Yeah, so in this instance in this, in this Don is standard. If we look at this, secure storage get remove, remove all set those are implemented in every single platform that we support as of today. Now, if you don't install the, if you don't install the new get into your iOS project and you've only put in your done a standard and you call get async that will throw an exception.

C

It's a custom accession assumption that we have, which is that they're not implemented in reference assembly exception, which is a very long name but describes exactly what it is, which is. It's not implemented in a reference assembly, and that throws a helpful they're telling you that you need to install it into your platform project.

C

D

C

There could be, there is no graceful way of detecting is secure storage implemented on the platform today. So as if someone was implement this in or install it into a Mac project, for instance, it would just throw a reference or a WPF project, for instance, because it is not a Sanders I would install right, but it would just throw an exception.

C

A

I think you talked about this I. Don't think you may say you don't have like anything in them. An essential does not have a meaningful, but it's in an implementation right. The only implementations you have are the UWP, ios and android ones right, so you would always throw from the docket senate one. That's.

C

Correct yeah, yeah, okay, so.

A

The one thing may be talked about is probably want to add some notes for the capability API. The question is where to put them and I call that would look like I think when you show me the source code, you have an internal one currently, which I think is on the actual types might see have like browser that is supported or parameter. That is supported and I. Think the question there is that makes sense of it doesn't make sense, I think from a more general like I mean to be fair, we don't have many capability.

A

Api seem to be CL today, because in the past we didn't care that much. We just made it work in all the places, but moving forward I think we have to model this place more often, and the general idea is that you want to put the capability API it's as close to the feature as we can, because it helps people to understand that there is something to you know, think about when they call the API, so I think having it on barometer or whatever would make sense.

A

Now, if you, if, in your case, basically it always returns true, unless you are not incident, in which case it always returns false, that might be a bit of busy. But you set yourself up a bit more for success and I think we talked about having a desktop implementation right, because you currently only have you WP implementation, so moving forward. If you want also support, let's say you know, thought in fabric apps or doing regular, desktop apps. We don't request vo.

A

You might want to extend some of the features and then maybe some things are just not available because they don't exist.

A

A computer like I, don't know you know some of the accelerometer data may not be available, but your money in the regular PC right, while the other ones might be available like secure storage or the browser or a battery information, and so on and so forth, and the other thing that we talked about was the notion of is supported or has implementation, as you call it, and it actually is available to you like, as in you might have a compounds, but your app might lack the permission to actually access it.

A

So then the question is: how do be yeah? How do we model this in the capability? Api? Do we have two of them and, if so like? What would the name be and then also what? What is the expectation for the customer like if it's a property and the check for seeing whether you have the permission is super expensive? The many properties don't make much sense right. I think those are the two things you may want to talk about and then I think.

A

The last thing that we talked about was namespaces right, like whether you want to put this in Zemun essentialist or not, but you can maybe push it a little bit to the end. So.

D

With the capability stuff, I think you know one of the other layers that we get into with. That is, you know yes, first its permissions and whether or not we have permission to access it and then also as the device actually support that capability, but that's kind of got two parts to it as well like one of them is, is the device have a camera and if it does is the is the policy for that device set to allow the camera to be used?

D

So you know it's, not only does the you know does the capability exists, but is it disabled? Is it turned off? Is the GPS turned off so there's a few different layers to that question in itself? Does the developer care.

E

If the device does not have a GPS versus the device, has a GPS, but.

D

C

E

The user has said, no one shall access it period. One of them is you tell them. This feature doesn't work because you turned off GPS and the other. Is you don't tell them, because there's no GPS well.

A

In this, the other thing is next time. Apps have some platforms have to have the ability to prompt the user to analyze.

E

I realized, you might have good out of her app basis. I meant like as a matter of policy if your entire device is just disabled, the GPS system wide. But do we care about exposing that distinction versus you? Don't have a GPS well.

A

That's what I'm saying but like if you, if you, if you expect writing code like if you have a GPS but I, don't have permission from the user for giving me permissions. Yes, it makes no sense to do that if the device doesn't have a GPS or.

E

If, as a matter of policy, GPS is disabled device wide well.

A

I would argue you can have it.

F

You can one of this and one of the inital to manifest that to be out some way, but.

A

F

Mean I slightly noticed just because it's on the most screen here that you have a thing called battery and it very much looks like you're, assuming that a device only ever has one. You know that certainly can be not true for PCs and depending on how different phones model, having extension packs attached that button people true for a phone either yeah yeah.

A

So, like I said just like: let's, let's cover the the capability, API so maybe generally and then just walk the api's and then I think namespaces. We can maybe cover later so I think yeah. The question really is like: what is the model to do that? I? Think the the general idea of capability API says you want to expose. What do you expect customers to actually write code for right? So if, if there's no point in writing an if statement, then exposing that as a capability API may not make a lot of sense, I.

A

Think, generally speaking, the notion of you know if you, if you have, for example, like I, think the in Windows 8 that the same example with the printer API right. So imagine you have a printer API and you want to make sure that you work in data centers where there is no printer right. One way to model is, is to have a property that says, you know, has support for printer or something another. One is to just have an API surface.

A

That kind of implies sort of the battery examples like oh, you may have multiple of those and one correct answer. Is you have none of those right? In which case you have an API that says, get printers and giving an empty array back? It's a completely valid implementation, in which case the API shape itself has a very graceful.

A

If you don't have a printer like what would the return rate is look like a kind of experience, but you don't have to throw right which might be for the camera the same thing if you have more than one camera?

A

Well, if you have either you know, a list of cameras that you can ask for whether maybe have no cameras is also a better return value right, in which case you may not actually actor/model the fact that you know we have an implementation for the platform versus this device, or this particular device doesn't actually have a camera. That might be, you know not useful distinction anymore. Does that make sense, yeah.

D

I think in a bunch of cases it does. You know for something like.

D

For something like GPS, you know, I think there there might be a user desire to be able to kind of differentiate between. There is no GPS and it's disabled, and you know, like you, talked about being able to enable it or guide them on some platforms to enable it yeah.

C

I think that GPS of all of our ApS is the most complex API, especially around Android, and this is a very unique scenario on Android. So Android has the concept of providers so like a Wi-Fi provider, a passive provider, a database provider actual GPS provider. So what we do is based on the parameters that the user gives us. The developer gives us we figure out the best provider to use. No, it's very intriguing here is that if there's no providers, then that means that it's disabled.

C

However, you cannot get a list of providers until the user gives you permission to actually access GPS during this weird catch, where you can't even detect if there is a GPS until your request permission so in a user today, um request geolocation from us, so there's no API on geolocation to say: do I have GPS as it enable like is it available. Is it enabled we had old libraries that did this? When you've got this weird mashup, you have to async of I everything's, you have to handle permissions. Do you let the user handle permissions?

C

Do you handle permissions? So, in this instance, our workflow is pretty simple. When someone requests location, we check to see if they have permission, if they don't, we prompts for permission. If that fails, we throw an exception. Then, if we do get permission, we check to see if geolocation is enabled. So are there any providers that fit our requirements? And there is not the exception, it's a very exception based and then we actually try to get the location and that other passes or fails.

C

So there's multiple tiers there, so even in that instance, which is a an edge case right, but something to be to think about which is it's impossible to know if there is even geolocation enabled until permission is given, so is that a API concern? Is that a documentation concern? Where does that fall? And that's a weird case so for this API is of today we didn't introduce any of those, and we went with this exception based route, but.

F

Taking that one, it sounds effectively like Android can be modeled as having I'll go with rough, counting, six, the different GPS devices, and if you had an enumerate, API well, that would clearly have to ask for permission because you've called it and then now, if they give you the no, you return to the empty set and if they say yes, you can give them all six.

F

And if we have, if you have accelerator API, that handles common cases but doesn't cut someone off from, like you said that you're you're, guessing on their behalf, essentially so like. If all of these api's were just built to handle multiple slash zero, then that would just be a natural flow.

A

Yeah, if it makes sense but I, think for some things, it might not make sense right having multiple omelettes them. Multiple thermometers doesn't seem to be sensible, I just say: well, you either have.

B

Fun that you don't have it I mean it's a question of what.

F

Level of future skate, like you mentioned, desktop desktop. You can plug in unlimited USB devices right or the USB may have some limits somewhere right.

C

F

We start looking at you know, taking an API like this and putting it with. You know the Arduinos and any of those things how many different sensors did you hook up? That will report as being one of these things like, if you think of it, just as a phone yeah, there's, probably only ever gonna, be one temperature sensor in it. But but what is? Is the API really that scoped or does it make sense to.

C

F

Applicable to mobile devices: well, maybe a mobile device itself has multiple different sensors one inside one outside one, as a probe that you stick in your oven. So at.

E

The same time, the complexity of having.

E

Number of batteries probably complicates the 99.9% case that most people are using the safety eye for and so I could imagine saying, go with this and then in the future. When it becomes an issue, you have a barometers class that allows you to get instance barometer or whatever, and maybe.

F

It makes me a bad, less nice at that point, but I mean yeah. The problem at that point is barometers which lets you anywhere II can't give you a bra matter, because all of the good names were taking us at hey.

E

So I saw producers awesome, commemorating changes so I'm just I'm saying there are other to me. That seems like less of an issue.

C

I think it's something I didn't necessarily think of because of usually you're right, usually on mobile devices. Only ever gonna be one battery orchid or the API will combine it together and that in sense, but you're correct, you could maybe throw in twenty barometers and then and that gal. The ideas, then, are you subscribing to that specific barometer?

C

And how would you abstract this generic barometer to understand it in an iOS or Android level in general, when there is like on those platforms, there's always a single tin, so I guess you would always pass back the same class barometer so, instead of barometer being a start/stop, it's actually a physical class that represents a physical device right. I.

C

Look at this, as this is an API. That's exposing events, but in kind of the way you're saying we think of the api's are turning like an instance of the device and the capabilities of that device, and it's a different way of looking at a specific API I have.

E

A somewhat related question, but also not exactly so I understand the ease of use of the static API start/stop, but I'm wondering how that works. When you've got maybe multiple libraries in your application that are all communicated, for example, multiple libraries such got a reading changed event. They individually call start and stop, but then after they've called stop, they made still getting events because someone else started it again.

C

Yeah, it's completely possible.

C

She was very honest, but yeah yes, I mean in an instance. Let's say you call start and then, if you call start again, it'll already know that it's monitoring so won't start and trigger new events or when anybody calls stop. Since it is static, it will stop that any readings that are subscribed and if someone you called.

E

Stop and didn't expect to get any more events and then someone else called start. You might get events that you weren't in any way expecting yep.

C

Yeah, that's very yes correct! So.

A

I think that's something we should probably talk about, so the guidance then I think the essentials team has received is the day. You know, as James said, like the typical thing that people have done in the past is that they have an eye sensor and then an eye iOS sensor and an eye that iOS sensor on an android sensor as implementing those interfaces.

A

When you have like dependency injection to get the implementation right and I said, Bessie screw that we just go with bait and switch to make it super super simple and then the next step was. What can you make everything ecstatic?

A

So it's super super super simple, I, think in general that pattern works when I looked over the API of James's I said some other things there are some API is here that seemed to me to maintain state and the general guidelines that we have is the vignette aesthetic type or when you have static members, there are supposed to be thread safe, so meaning you need to be able to have a policy. What happens when multiple people on different threats, calling the same static methods right and I?

A

Think some API that you have like start/stop or having global event handler it's kind of asking for trouble in the sense that you're you're you you basically now subscribing you know on your end, to handle the essential threading issues. If you just make this a class that you can just instantiate well, then you know your policy can sensibly be.

A

I only saw only support one thread if you want multiple threads, whether you use multiple instances of this type right and then it's very clear that well, if you subscribe to events on this type well, you only receive them on this type, but not some other instance that something else abstract you that might actually make your implementation less buggy. But it means that some of the types that are currently static may not be static. Moves forward, but I think from usability standpoint.

A

I think having a type you can just new up is not horrible, like that's still pretty one.

E

Of them is that for like sums for speed like what happens if two different threads all start with two different speeds. Well,.

A

I mean I would say, the underlying api, ios and android clearly has to have a policy of multiple apps are running in different people. Two different things of that right. Whatever that capability is so.

C

I can tell you exactly how this would work so at least in the world of Android, for instance. Let's say you start up an accelerometer, you would get access to that sensor and you could say sensor speed fastest. Then you start listening now. If you create another instance and get that sensor and start another listener at a slower speed that slower speed will take preference over the last call so both of your reading, so you apply listeners which really it basically event, handlers and those listeners.

C

The first one would then be throttled when you apply the second one and you have to roll them back in secession to unsubscribe from those listeners to stop the readings. So there is a certain part of a part of complexity there that is occurring so, for instance, so.

E

I just asked the everything you to subscribed: that's policy at the Android level or that's policy at your library level. So.

C

That's a P and or a level, so our policy as of today is that if you start the barometer at the fastest level- and you hit start again, nothing will change because you have to call stop first, because it's already is monitoring.

C

So if you want to change your sensor speed, you have to stop and then start again as.

F

As part of is monitoring is, are you also capable of detecting the speed and have that'd be reported via property? We.

C

Could yes, we capture it? Yes,.

E

C

Is it? Is it ref counted because otherwise it seems like to libraries start, you know, hook up an event start.

E

Get what they need stop, and one of them would stop it for the other person yeah.

C

That would be the thread safe part of it. So that's not handled is that something.

E

C

Actually ever happens in practice on.

E

Mobile applications, you get a library that uses the wrong I mean or do dessert him to happen at a library level or at the application level. For the most part, I would assume there be libraries that interact with the DEP again yeah, but I would assume it's uncommon for an application to pull in multiple such libraries simultaneously. Yeah.

D

As I said, I think if you're gonna be pulling in a library that lets you helps you work with the barometer you're, probably not going to be accessing it through essentials as well all right, even if that other library access it through extension essentials. So, even though these.

E

Are net standard api's? You expect they're not being consumed by other that standard libraries you expect they're being consumed by the applications. I think.

D

They could be both I'm, just saying like if you, if I install library be that depends on essentials, that interacts with the barometer I'm, probably using library B to access the barometer data and its own gonna be only one accessing the barometer API prep essentials, I'm I'm, probably not gonna, also register my column listener directly through essentials, because I'm already doing it through this other library, I.

C

Mean I think that there may be a you space. Let's say you bring in a 3d game engine that happens to use a mer and essentials and to using our orientation sensor to orient things in the real space, and then you developer come, and you say oh I also want to use the orientation sensor here and I want to do something else in the background for some reason, so you start now on an Android level on a platform level. Let's say you were doing this. Just a job or Kotlin you'd have the same issue.

C

You could create some other third-party library that may be brought in. That's messing around the sensors. Now wouldn't stop yours, though that's the difference, I think on Android you're in pure Kotlin world. You may be interacting with the sensors, and perhaps your sensor speed changes, because another library is changing and subscribing. The difference here is that, if that third-party library with Sam urn essentials, is using that orientation sensor and they call stop, then your events would also be stomping right. So it's like you, don't have a unique instance of that of that orientation sensor there.

C

So that is, it I think that's probably an edge case, but I think that could happen possibly first on my beats. The.

F

Other problem with the static event is Steve mentioned. The you've called stop and now you're surprised when you get more events, because someone else called start, there's not actually a correct time for you to register your event handler, because if you register an event handler pointing at an instance, you might not have finished configuring it, but somebody else has already called starting.

C

F

You start getting events before you before you called start, so you didn't think the sensor should have been active at all. So definitely the ones with events that there's definitely a threat and concern.

C

From a training perspective as well, where are these events raised? Well like.

E

Help whatever, wherever you get a call back from the OS, that's what's involved in the event and.

C

They're, not necessarily so for for these events, it's based on the sensor speed. So if you invoke it, and so the sensor speed itself has three setting four settings. Excuse me.

C

So, if I look at a sensor, they're our fastest game, normal in UI and normal and UI, are guaranteed to be returned on the UI thread and game and facets are not guaranteed to be on the UI thread.

F

Those pulling from your library or those like IO completion, threads.

D

Those it has callbacks from the the native platform depending, however, they implement it. Yeah.

C

We have a, we have a main thread and class and the main thread helps you detect if you're on the main user interface thread and also beginning voting on the UI thread. That's there.

A

The other problem, if you have a static event endlessly, because they point back to the object instance, you have to be very careful that you don't keep your objects around forever. Basically, so typical example here is, you have a user view model summer that subscribes to let's say the barometer event. Well, this guy never unsubscribes. In this view, model will not stick around for all eternity of the app so that gear.

A

Basically, people have to be very careful that they unsubscribe from these guys or bad things will happen, and if you look around in UI code, unfortunately really unsubscribe from anything and then they find out the hard way that they kept their what they thought short-lived objects. You know around for a very long time, so that's why people often ask for you know week event, handlers and I'm, not sure we talked about this. You know a few times.

A

I, don't even have a very good story internally to deal with that right now, you can probably do some crazy messes with weak objects. Also, big big references yourself, but I doubt the double work really well for you, because you will at least leak the underlying element in the linked list. You have, but it's probably better than leaking the entire object reference.

A

Does that make sense. Yeah.

D

A

You basically fire, did you see so I? Don't know like what is your? What does the abstraction seven forms? Look like you have you ones they're disposable is there like? Do people have an easy way to unsubscribe like and I subscribe to a closed event or whatever really I, don't the screen or something? Because that's you read the problem that you have there's no convenient way to register. That's yeah.

D

I mean usually like on you know: different forums has I, can't even stop him, but there is a page. Closing event may be appearing and disappearing. Yes, so typically, especially anything UI related, you know on the disappeared event, he would unregister your handlers and clean up I see. So as long as you been.

A

D

I think you're right and many people don't do that regardless.

F

Again, looking at you know the barometer specifically I'm thinking about threading I'm, also curious. um You know if one library sets up a handler calls start and another library sets if I had learned calls start and, let's assume we're in a sealed room, so the pressure doesn't educate.

F

The second library never gets the initial reading, the I presume, because the reading never changed unless reading change doesn't actually changed its reading provided, but in which case there's a different problem. Yeah.

C

Correct I mean there are in yeah, so it's for sensors. It is reading provided for certain things. It is actually changed so, for instance, a battery. We guarantee that all the properties, at least one of them, has changed inside of it accelerometer we don't. We provide just reading triggered in general, and the underlying systems from our findings are only when they actually change.

C

So if it's sitting still, it doesn't trigger it, but that's not necessarily guarantee, but the underlying platform basically guarantees that, but I do think that you may run into that scenario that you described I. Think any of these scenarios, a start-stop from multiple callers could run into this scenario, is.

E

C

There, the concept in these.

E

Devices of polling like is there, is there I, walk up to the barometer on iOS and say what is the current reading.

C

On some of them, yes on another's new, so on Android, for instance, no, you cannot, you have to apply a listener and then the moment that you apply a listener, you will get an immediate call. That will tell you on iOS, for instance, you can just say give that to me. The iOS apos are very beautiful. That will did a great job, but for most of them I would say not all them they're.

C

Definitely not some non beautiful APSU, but in general you can say give me yes give me this this reading for the barometer, for instance, an overturned into you, but since all platforms don't do that. We don't expose that property, because.

F

I mean on platforms that don't you could theoretically just do a subscribe, ask for this and you know depending on if they let you know that they're already running, and so you don't to configure polling speeds in my life, but right like theoretically that could be. You know you can you can provide the polling API on platforms that don't have it.

F

If you want yeah yeah yeah so I as you then have objection to the verb changed if change is not implied in the callback.

C

And I think we could guarantee that I think it would make sense to only be changed if it's changed. I, don't wanna be right back.

E

C

E

C

E

Also, looking at like the accelerometer stuff like that on iOS, and they, as was much earlier, they use Singleton's for everything. So you it's completely unexpected that you might have two different libraries within a single application, both independently trying to use the accelerometer like apples. Documentation clearly calls out. Do you not do that? You who.

A

Are you drawing no.

E

It's like there's, it's a singleton object right. If, if one person calls stopped on a singleton, it's going to affect everyone listening to it right.

A

I mean I mean it kind of makes sense in the sense that all there is Hardware I did there really only is one of them, so we do so much I'm.

F

Just you know wondering what it means for.

F

E

I should say it's it's a per application basis right like if app a call, stop app. You still gonna get data right, but.

D

I think the interesting in line with that too, is that, like, if you you know, even if we kind of build that protection Central's itself, it doesn't stops amended library from stopping or changing the sensor speed on us. You.

F

D

That application, it's still affecting essentials, the same way I mean.

F

If we think that simply the you know being in a xamarin base, namespace implies you know, phone level device and not you know a Raspberry, Pi or an Arduino or anything like that. Then then, maybe some of these assumptions make sense I'm just raising the issue so that they thought about yeah.

A

I think in general, yet you know the other week we did the review of the GPIO stuff right and you know Jana is the point there that maybe the API will not last super long, given that this market is evolving very quickly. So if you may find ourselves having to rewrite the API so anyway, so in that sense, given how mobile works, I would say the same applies. Probably here we can try really hard to make it.

A

You know, go to API, but I think similar to HP net, where something you just have to have making changes, because the ecosystem has just changed. It seems reasonable to so. I would I would generally say, like the goal of the library clearly, is to make users life easier and drive convergence between the platforms. From our point of view, so I would I would say that in general, proving ApS is a good thing, but it does conflict with e. Let's have a simple API right, and so we should probably focus on that.

A

You know at the expense that maybe in a year from now two years from now, we'd find ourselves wanting to change the API surface. But you know, usually you can make the things edit it by just having a new type name and obviously the other one I mean if you think that'll be.

F

Degenerative over time, then it means- maybe maybe you take the second best name for your namespace right now, so that you leave the better name for later so.

E

F

E

These types have units on them like acceleration barometer stuff, like that, are we normalizing those between operating systems, interesting and so, like I was looking at apples. Documentation of acceleration on all three axes is listed as G's I, don't know if it just straight up meters per second square on other platforms, I, don't know yeah.

C

So we normalized every single one of these. We document what they are, for instance, and there are some instances we tend to normalize towards the windows API. To be honest with you, the uwd api, because it's the more dotnet ii api of them. So, for instance, if it is meters per second square, then we will normalize on that yeah. That's of a key objective, I would say in instead of learning three EPs.

C

It give you three different results that no matter what is coming from us as a normalized result for the excel of Celoron or, for instance, and then we will document that they are reported back in G's, and we even will tell you that that you know exactly what. That means that it's a gravitational force, bla, bla bla, you know, 9.8 blah blah blah except accelerate- is that we did you do that they.

E

Vote desert do we tend to specify units in things like property names, or is that mainly adult concern? Well.

A

We I mean we generally try to avoid it. If you can I mean if you have a bunch of clients that have you know like timespan right other than you know, in milliseconds, right, yeah.

G

A

We have pushed back on api's when somebody had an in time and it's like okay Quay, which would unit. Do you take we're like time since Miriam videos so like? If, if there is a type I would prefer the time, but there is no time but is mainly what the metrics are, but for things like I, don't know how would you name the accelerometer result like Bay ug, like I mean? How do you see force well.

E

So the you get back a vector3, it's a vector of three floats acceleration right.

C

Yeah in the beginning of this API, we were returning an XY and Z, and what we decided was that vector3 itself provides. This is from our documentation team, provided me back when they were using the guy that if we were to use a vector3, especially for the orientation sensor, that provides a lot of helper functions to actually iterate on it. So we take a dependency on the system, numeric ambassador package in the inside of here, but maybe it's implemented on every single system.

C

Besides a standard one which we do have a sim compatibility for just for the sake of doing it, so so we do bring down in. So that's why it's a vector3 compared to previously it was acceleration X, acceleration, Y, acceleration, Z or XYZ, just in general yeah, which we thought was not great, but that was what I thought there: okay yeah.

A

All right, maybe we should just walk the api's top to bottom. No, no! Let me actually talking about the generics quite a bit pun intended there, all right, so don't worry doing it! Some of this, if you have, is monitoring which I guess means at least somebody was calling start at some point: correct and then you're the event and then so starting to stop is no traffic on that right. So last one wins right. Last.

F

One wins and start UI, followed by start fastest, is UI or fastest there's a fastest game normal. Why I mean what? What so can you change the start, speed or the sensor speed without calling stop and okay now can you pull the speed? No.

C

It's not available so there's um to to change the sensor speed you would on some platforms. You would have to stop anyways so on Android, for instance. To do it properly, you have to unsubscribe a listener. Andrey subscribed a listener. Of course we could do that for you under the, so it wouldn't really matter, but I, don't know if we document this use case of calling start twice and what would happen. We mostly document call is monitoring first and then start hell. Stop you know, type of thing. Okay,.

A

So I'm wondering when that may be start to roll, if you're already monitoring.

F

Presumably, from.

E

The library's daughter from the hardware statement know.

A

From thank the implementation of accelerometer that we have here like if you call start and it's monitoring returns. True, you just throw it say you know I'm already running what.

E

Are you doing? Did we decide that having two different components calling into the accelerometer was a compelling story? If.

F

It's static, it's dangerous, so, having start throw would be better.

A

Because the reason I'm saying that is because, if you, if you ever hit this case, it needs to know all maybe I should check its monitoring before and then maybe you start thinking about your own logic. Well, what and what happens if it's true like what? What am I supposed to do with that information right, it means probably an error somewhere in your code.

A

Yeah yeah yeah well also like hold your greatest of the event like when you do that, like oh now, I can receive events, even though I'm not ready yet like I think this is some games. You happen that okay and.

F

You know we sneak the feedback on this. One applies to all of them to me. If the verb on the event has changed, I should not get equivalent data in two successive readings, yeah yeah, very.

F

And if that's the case, then that's fine and if it's simply that you're getting periodic updates that then maybe changes on the right, verb, I think.

C

That we can I think it should be changed, because that's when you would want to actually get those reading changes and since every single one of our data structures implement I equate able, we should be able to guaran guarantee that so I think it's just to make sure that if we are calling a reading change, which we believe what it is, then we should guarantee that it's only when the rain changes and I think that makes valid sense right is.

E

Change like do you consider two numbers of differ by point: zero: zero, zero, zero, zero one to be change.

C

F

You have escaped you a different answer. Maybe someone needs to know that they're slowing hold.

E

The OS the OS is pulling right, like LS, is pushing touching yes, but it's doing it periodically. The OS doesn't have a concept of this. Data has changed.

E

Accelerometer data: do you not expect anybody to ever instantiate that cloud or that struct? Aside from you,.

C

As of today, now,.

E

Does you know ever the only complaint and a turnover list?

E

Sorry guys I will be the only constructor on this parameter list. That's one.

C

Yes and I believe we, let me look at the day that site and our share code.

C

Yeah, all of our instructors are internal, so we have accelerometer data that takes in doubles and floats, and then we normalize correctly based on that to create the vector three just the make.

E

C

In there and really difficult.

E

Is vector Muta vectors I donated earlier those.

F

Noodles and the default value this beautiful, so this.

E

Is the not have course bacteria? This is the famous vector3? Is.

F

E

F

So accelerometer data through default food.

E

Not acceleration X, no, that.

F

Won't work because.

E

The acceleration property makes a copy of the field because vector3 itself, Sistrunk.

F

So you get to write code that looks like it does something, and then you can end.

D

Up in rapes, you did assignment.

F

Through a struct field or structure property, and why did the cpu slow down, even though nothing happened to us? Well,.

A

I think I, don't think you don't even get to do something you can fight of a per se acceleration dot x equals back in the compiler will actually be narrow and say you're gonna. Do it.

E

Yeah, the acceleration should probably be a read-only field instead of a property. Would that be because the destruct itself is mutable, which means that if someone says my accelerometer data, dot acceleration dot, X plus plus it will look like it works, but nothing will end up happening. Is you it might.

H

Actually, I think.

E

They get a compiler and pretty sure they always go kind of there. So.

C

Second, test tester link back yeah, but.

A

We'd only if he would invite you much because really somebody has to set it. Oh I guess yeah.

H

What is it stay.

A

H

A

It's a bit unusual to have events of private constructors. I would give you that, but I don't think it matters, because I think unit testing. His library is hard already I.

F

Assume Levi's saying that he's writing his application code. He wants to fire different acceleration events added. It's gonna do what he wants. So not the unit testing, this library unit testing the person who wants to consume this yeah.

A

I think that's a that's the sense of the bond way to say it will be nice if we could at least construct the event arc. So you can indeed simulate who's the receiver of that the polymers, though that you know, depend on how you write the code you. It might just be the first thing you do and then the second thing is, you always should subscribe to the static classes and then you're screwed right you're, going to at least split that apart any but yeah I. Think.

H

The journalists wrong that I had with James was the ideas that you expected yourself. If you want to make it unit, testable yeah.

F

Like you would just pass the acceleration so.

C

Let's own this instance, we would, we would open up the Constructors for both the event args and the accelerometer data.

A

Yeah I mean structs always have a constructor anyway, but that's not the one you want. So you want to make the other one public as well yeah or.

F

At least one that takes a vector3 yeah I, see: oh I, see okay, what does app info, not open settings? Who knows what that is it boy? It.

C

Opens the user interface to the settings of your application? Doesn't.

F

Feel very info, like the rest of the things.

D

It's kind of, like you know, on some certain platforms: I got on the Android, especially to it it's kind of where you go to see info about the app as well like to see how much storage it's easy enough to clear the cat cache and that kind of stuff.

C

Yeah that one may be in the wrong place: yeah.

D

C

Wondering if maybe.

D

Maybe settings is not the right word. Does that do I, don't remember up and does that take us to the actual app setting page and in Android, for example, in that it was yes.

C

So that will take us specifically to the application image in the overall settings page for your application, yeah, which.

D

Which is kind of in the realm of I'm, maybe the name is, is not this.

F

Is your reading data about your app and that one is in the phone? Please send me to Settings dot app, slash application, slash my app like that feels like a very different action than reading the build number okay.

C

Yeah so iOS calls this so iOS calls this open settings, URL string, so you give it a URL, you, okay, the URL specifically and is called open settings. Url string and you WP calls this. It's a hard-coded string, that's MS settings, : apps features app, which is obviously very intuitive. Android is very generic, so you give it package and your name and it's the you open up the actions application to detail settings. So that's the action.

C

So settings is in all three of them in the name of the underlying platform, but I would agree that it is and very different from reading information. Yeah like.

F

That wouldn't I don't know what I would call the class that would have that, but it feels different than the rest of the stuff. In a pin, though, because.

D

That one API weren't its own class then well.

A

With it once its own closet, wouldn't go that far I would just I, don't know if you have a different type that might be more suitable for it, for you, I maybe use that one. Instead, if you don't have them, then I would probably need to do a new type. Just for well-connected are.

E

There other places where you open UI that navigates to something like, maybe if that shouldn't be with setting specifically, maybe there's a generic grab bag. If I want to open this or open that do.

D

We have a generic open settings and like a device in from akin I can't recall offhand, and maybe we could group a couple of those together into a different class of so yeah I know. We had talked.

F

About having it, I was thinking, something like you know, device interaction but then it's like, but if you're trying to open your app settings, that's different than saying just go pop like settings not app and but then maybe that would be open, app device, dot, open, app settings or maybe it. This is the right place for it, but again poke around and see if there's something better. So that's just a considered yeah the.

A

Other thing, I would say, is like open settings doesn't imply to me UI shown like give it a name. That implies that I mean show, settings comes to movies or like open settings UI or something where it's cuz open to me also could just mean I, don't know, read the setting, so I can that's. Why.

F

Maybe I have to call this before I access build stays here then show seems a better birth than open or.

D

Even like navigate to settings UI or so yeah.

B

D

Also works here.

F

Open settings UI in fact suggest there's UI involved.

A

So I do like the consistency between accelerator on bar and barometer. That seems pretty sweet.

C

Yeah, all of our sensors implement the same exact he's monitoring start/stop. It makes it very easy to implement with.

F

Pressure I mean I, assume that you, based on your previous thing, that you're normalizing it, but it's now we get the u.s. people expect it's psi. Europeans expect it's passed, gals meters of murky, whatever the tint no well. Yes, so, pilots want millimeters of mercury non-pilot. U.S. citizens want PSI somebody in Europe once whatever 1033 is yeah I think you one bar I, think oh yeah, that might be bar or millibar like somebody.

B

F

Pascal's, so this one might need a unit nominee or most.

E

Of isn't it most of the devices consistent what units they use for things like this, usually.

C

Not now we we return kiloPascals, we usually we take what is the common between them. So what is the you know? What's in most of them provide at that at that level, so Android and you WP, for instance, provide Killough past kiloPascals and we returned that information back. Basically, so.

F

If, if I were proposing, this API I would name it pressure, kPa and then people would argue about that name. But and so that's that's my it's just off the cuff suggestion and.

A

You will put a good system security cryptography, so.

E

Nothing is everything that I do it's a new.

A

C

Pressure type and.

F

E

Be lots of properties off of it. So that's what.

F

E

Do you want, maybe you want it.

F

In in time of, you have to be done by Thanksgiving. Yes, all.

A

Right so I think the other one we have cover.

E

Yeah, for the most part, this all looks like what you would expect. Yes, yes, the consistent, but battery is kind.

D

Of creative, the.

E

Flipside to what Jeremy mentioned earlier, like Jeremy mentioned, there are scenarios like this laptop, for instance, has two batteries in it? I think there might actually be some areas where you have no batteries. Imagine you're on a kiosk right. It's not that difficult to imagine that there might be an iOS or Android device, but that will be the night. You would be connected to power right yeah, but what does charge level return? Well, whatever it does in your yeah.

E

Man, man, it's a double, it's ok charge level returns, works, forms, belong, I mean an, but man for there is no battery I, usually.

F

E

Level between zero one by the way.

C

Charger level is a double between zero and one, and if it, if there is no battery, I, have to look at the code. I.

E

Don't know well so on Android and iOS, like you're, always going to have a battery with current devices on the market. But it's not that hard. To imagine that you know one. Someone will release a lower-cost device that just for kiosk scenarios that is required to be plenty and.

F

And I will just bring this up just one more time of I know that, for at least I OS devices you can buy external battery packs I, don't know if the OS reports that as two separate batteries or merges them into wine- or it isn't even aware that it's there, but that's just a thing to consider.

C

So in this instance, we do have a battery state which is not present, which means that there is no battery, so Windows specifically exposes that, and in that instance, if there is no battery at all, we report a negative one for the charge level, because if the system itself is telling us that there's no battery and cannot report a dollar charge level or we return negative one interesting. That's that's strange and.

A

The question is: how will people use charge level right? That's why I would probably return 1.0, because probably you want to have like a policy like oh I, give a user a warning that the battery level is below some threshold right and if you always return one point: no, it works. If you do minus one, you get these weird apps that start and say sorry, consider plugging in because you have minus 1.0 better. We left right, yeah, I,.

F

Mean yeah at the same time again, while man is normally not a number that gets used much, this literally is a. There is no number I can tell you that answers this, so man might actually be alert, but I mean.

E

If you, if you want to get technical like yes, that's probably the right thing to do, but just considering how people are likely to use this API yeah, why? Why would someone want to call charge level I.

C

Mean you may want to turn it called charge level to understand if you're doing advanced, animations or getting something intense on the battery, for instance, let's say I want to call geolocation and I noticed that my battery is under 5%. I may want to get a very just last known instead of querying the GPS location in general number.

D

That's like 1, so I think from the two examples on that we've heard. In both cases you know, if you don't think you're plugged in you, want to assume that you have enough power to do whatever it is that you need to do like not warm the user or to actually use GPS, so yeah I think charge a level. 1 sounds quite reasonable. Yeah yeah.

C

Good example is, um by the way, is my desktop: computer doesn't have a battery, I mean it has a power supply, it doesn't have a battery right. So in that instance, it has a power supply. So what's the charge level? Is that one I think I guess I'd have power so.

F

You know, presumably, your comment is when, when there is no battery because technically they plugged in it's also wired, but just like we shouldn't say: oh, it's charging battery a hundred percent, yes yeah.

C

And obviously, external battery supplies like an anchor. You know, power supply that that is a that's the same as charging it with AC. You know what I mean that that's like the device doesn't.

D

Know that it is yeah a.

C

Battery there's no there's no USB, you know chat and.

E

And honestly, if we want to like you said if we want to expand this to multi battery devices, just like average them or something yeah yeah, it's a good. It's a good and.

C

I would say that the current API today handles that it combines them into one so, for instance, on uwp, where there could be multiple batteries. We we iterate and get the aggregated battery of all batteries connected.

F

So what do you report if somehow one is charging and one's discharging like because they're doing the the memory phase cycle thing whenever Windows tells us? Oh, not you aggregated, you ask windows for the aggregate state windows.

C

Itself has an API to aggregate batteries. Okay,.

F

C

That's what we use.

F

C

Believe Android is the same. To be honest with you, I OS only has one battery ever so Android I believe is the same. I have to double check on it, but their API is literally just give me the battery information, and it's probably whatever is, and it's whatever is displayed to the user on the top right, yeah. Okay, so make sense what.

A

Do people do with unknown like I, known as your on the permission or I mean not gonna be unknown? Os.

F

Get something that wasn't previously documented.

C

That is an accurate statement, usually on Android, because every single battery every single device manufacturer technically these are not eating. These are just you know, integers coming from Java, so we map them. However, like it's kind of impossible for us to know it to sometimes, if someone reports- something that's not in the official documentation anytime, that your wrapping.

F

System thing you should have it on them. Tell you marry them to say, like the system told me something I don't know ya know.

A

Alright browser, so the only question I have you is: why is that acing that seems counterintuitive? What is it that you're awaiting here.

C

So on browser we.

I

C

On you, WPS launcher is an asynchronous API when.

E

Does it go to completed it's done when it's done whenever when.

D

The browser closes or.

E

Once it's open lot like when it's launched, what do I do after I? The task completes nothing. So what yeah I think.

D

C

When it's launched so between.

E

This and open settings what's the term boy.

C

So bin settings, the API, Melissa good question yeah so open settings we. So it is an asynchronous API, but we wrap it in our own watch for air that that gobbles up stuff so.

F

In either the opening settings UI case or opening the browser is there in a then trace to the application of they've, hit the done button and are back in the app like? How does the app know wing to continue, or does it just keep running it.

D

Just keeps running, there's no yeah and you you see lifecycle events like you know your page would appear again when you come back to your page from the browser, so.

E

The main the main purpose of the task is to communicate if the operation to open the browser failed.

D

Yeah I, don't know what you know, I'm, not sure what the expectation is if it fails, if you see an exception at that point, just that we're seen like in the platform api's that they are a sink them selves.

E

Yeah I would just try and I think it's either spine. It's a little weird if the task, what could never fail and then what are you waiting for so I would just be consistent with anything that opens UI like this and either if it's truly fire forget and you're, never gonna get an error back to get to the user, then make it void. If you might get an error back, make a task returning and do that across the board.

C

B

C

Scenario that you could have is so on on Windows. This is asynchronous and the asynchronous operation returns a pool which we don't expose to our users and it returns true as the application if the URI was launched right else, if it don't I mean.

E

You could convert that into a failure. If you want to do, you could turn a bool into an exception that that was desirable. That.

F

Is correct, yeah, yeah, cuz boy doesn't mean you can't throw.

C

E

Yeah, but if it was actually asynchronous you, wouldn't you wouldn't want to block waiting today, synchronous operation to tell you that available.

C

So right now is basically a fire and stop fire and forget, because we are, you know we would bubble up them and it dawned I guess there would be no exception that would occur bit or turn to fall. So in this instance there is no exception that could occur on iOS or Android. From my understanding, looking at my code today, yeah but.

E

There is those come through.

C

E

Windows could fail and that's why this is this sort of at least common denominator: yeah.

C

Yeah correct, so we wintered this assumption, and this was someone that from the community asked us was you know the two of the platforms don't require async, but the third one technically has an asynchronous API. You have to call so what we do for ours is that we say if one of them is asynchronous, we make everything asynchronous right.

J

E

C

That's what we do I think.

E

That's reasonable, especially for something like this. There are cases where that falls down but like if a fourth platform decides to stand up in the future.

E

F

What would the downside there be like what would that do that problematic, well, I'm, saying right now, if it's Oh, everyone is I, don't want.

C

A synchronous everyone is synchronous right now, yeah, so you've.

F

Gone with synchronous- and it's like well this fourth one popped up so now at.

E

That point you introduced an.

F

Asynchronous overload indeed yeah so and then just out of curiosity is there a regular handling between all of the os's. If you give a invalidly formed uri like TTP :, so the.

D

Ttp polandball I think we to detect for a you know at least a valid like system that URI.

F

Fairy-Like yeah so I guess it's I'm just wondering if that's what why Windows is reporting wouldn't report false and if it's unknown so.

E

It also reports false if, for instance, you give it a file URI and the UN C shares unavailable, but that's a network operation, hence async.

C

What's the difference between external and system for version yeah, so X so system preferred? Is the default and system preferred uses on iOS sf Safari view, which is an optimized browser that kind of it's not in your app, but it's more attached to your app. So there's like a done button and that done button will bring you back into your app and on Android uses chrome custom tabs.

C

So it feels more integrated where on external, it basically launches an intent system out so on Android it could launch of different browser prints, and so it's kind of external to your application on Windows. It's always just launches. Whatever your default is. We don't have control over that, but if system.

F

Preferred is your recommended default. It should be zero yeah.

F

B

C

So, for instance, in the open, a sink, if you don't pass it a browser launch mode, it will use this um pervert yeah. So look Jeremy! So that's p0. Are they? Oh.

F

Yeah, if you called them default index turtle, you would assume the defaulted external were the same.

E

Okay, clipboard, why is one of the clipboard API synchronous in the other s? Think.

C

This is another scenario where, in the world of clipboard.

C

There is basically on Windows, get required, is asynchronous and such as not async. Rest like I could be actual so yeah.

E

C

E

You know if you have text, because house text returns bool synchronously, but you don't know what the tux does well. I didn't.

A

Make sense because.

E

A

Had this guideline that says no operation can take longer than 20, milliseconds or so needs to be asynchronous and I guess get text we have to convert formats and actually persist. The text versus said like to always start but yeah.

H

I'm not saying it's okay, this year, possibly.

J

E

Is somebody have any set, would presumably be I.

F

Mean there's a maybe here if we since we're all making fun of what Windows did here. Maybe this one is, it should not be a sink and you should eat the state. You.

A

Know internally.

F

A

There's some more concerns all good. You.

F

Know get text so these things about the Aysen, then it should be good text and it windows that taste sensation I, don't.

E

Know what means something like cloud support? This is a good example. Well,.

F

Cloud clipboard.

E

Just takes place in the background, like your application, isn't aware of the fact that it exists right.

C

E

Not mean that getting and maybe setting could be no getting getting it just automatically synced by the OS. In the background, tell you don't.

C

Do anything yes,.

C

I was gonna, go if.

E

There's a reason that, as a segue visa tech shuttles, that's that's.

F

A

F

Don't know what the uwp app model actually looks like here, but is this Windows likes the notion of having multiple clipboards on your clipboard? Do we know what board or foot boards? This is using sure.

C

So I posted in the chat window, the actual code that we're calling, so you can take a look at it. So inside of this, we are.

G

One thing that let's do with the sick ticks, which is a little different, is that it's not guaranteed to be complete when the method returns. So you could course it takes. It takes tread away and it hasn't actually been sticky and sort of like operating system. You know sickness ticks that into the I'm, leaving it up to you. So I noticed that I think it was will need an order. You WP I would save the pigs and get it right away.

G

A part of my unit is- and it hadn't said yes, I- put a delayed for a couple of milliseconds you're gonna, find that mmm all right, yeah.

E

So Windows does have an async API to get the clipboard history.

F

E

I'm not sure who was just speaking, but that's a good argument for not making set text async, because if you did, you would assume that when it completed completed then again the boys returning I would also assume it completed. So it just seems like a weird OSAP, I, yeah I.

A

Think there's no good waiting.

B

More than that, yeah like.

F

If u WP exposes like the file explorer and you copy a file, what this good spacing.

F

Like just these are questions that I have given that I've learned that clipboards are weird what.

E

Is the failure modes give text pacing like what, if there's no text, does it just return? Nope I'm, just gonna go in there a source.

C

I

Returns a null currently so.

A

Only support text like you, don't have a notion of like arbitrary, bytes or images or whatever, like you. Don't have that not.

C

At this point,.

F

Take your image, convert it to base64, save the base64 text that.

A

Seems completely reasonable yeah.

C

Technically, each API does have text and images and maybe URLs.

D

And, as you say, to even how they handle images might be more like URL stream based then right, yeah, here's an image you.

A

Have no idea what the mode is that mine on Windows I know we have like 500 different flags for the clipboard right and I was just wondering what the again yeah you've, what we don't have much consistency across the platform. That's.

F

My reference to which goods.

C

So the how we do it on on on uwp is just they just have a generic clipboard and it's it gets the current content that is stored in the clipboard object. That's what they think. That's what it is so.

C

Really documentation yeah, as far as I can tell that. There's no there's no way to specifically get like quad clipboard from the clipboard API, for it.

F

So compass is the low pass filter or something that makes sense to be changing independent of the sensor speed.

F

If yes, it's fine and if no maybe it's this parameter to start.

C

So that is one technically you could change later on with against that correct, it actually only applies to Android, but we did put it in the share code. So there's probably a consistency problem there.

C

The Android compass is very not great, so we apply this. It's a common thing, that's on there, but I would say that most likely it would not be changed later. John yeah.

D

I was gonna say like I, can't imagine users wanting to to not have it if they ever do need it, so maybe it doesn't make sense to move into the the start. Yeah I think it has a.

F

D

F

So that people who don't know what it means don't have to think about it, yeah.

D

Yeah yeah I would imagine where people probably want. It then do nots on Android, correct.

C

D

C

That would be good to change it now, because I would be a change in functionality, so yeah so.

F

Compass data heading magnetic north is this magnetic degrees magnetic radians, so.

C

Yeah, so, okay, so compass, look at the documentation. That's great.

C

It is degree zero to 360 yeah.

C

Weird magnetic babies.

F

You know heading magnetic north just feels weird, unless, unless this is a you know, Australian pride, they like returning orientation pointing to South or something but the. Nor do he feels implied from a compass, so I.

C

Wouldn't say that instead of the there's really two things that you could possibly provide, which is magnetic north and true, north yeah, and obviously we're not going to do True North, because you we need the GPS location. That's not the yeah yeah.

F

I, like magnetic being in the name I, just think that the north is redundant and heading might also be redundant. So that's why I suggest analytic degrees. Oh I,.

C

See gotcha a weave, and so in this instance we actually followed uwp, specifically, which is actually called headache. Petting magnetic north funnily enough iOS calls it magnetic heading.

C

So we put those, but you believe that probably magnetic makes the most sense actually just.

A

The grease also seems fine by me like what else will really kick them.

F

A

Heading towards north right right.

F

I mean so technically, if you're using a compass that is usually implying that it is based on the magnetic heading yeah. There is the difference between magnetic north and true north and, if you're, trying to tell someone where they're going there's a difference. So I know that at least apple's compass app does do the true or does do the GPS integration and can tell you true versus magnetic. But that may be an app feature instead of a composition, yeah great.

A

C

Yeah, the only the only reason I would say that we kept it. This way is just surely for the sake that it's the same name as one eww eww pieces. So we often defaulted to that as somebody on somebody on that team must have thought of the name. That was our thought. I could.

B

Be wrong if you're on very enough all right moving on so connection profile.

F

Other I would probably call unknown and give that one the zero value, and then we get to ask the question about capital. Letters in WiMAX I was.

A

About to say, what is max, is it an acronym? Is it about.

F

C

Wimax is that that is a trademark of WiMAX. It's a communication standard, so I, don't think it's a trademark, but it's a standard and that's just how it spelled like the actual name itself, like a MAC address right.

F

Yeah we have a very interesting love-hate relationship with three letters: capitals, yeah.

C

A

I mean honestly that could should be probably spent like this I mean we did the same thing everywhere else right like the brand is called madam, and we spell it out. It's usually like this. Yes,.

H

But then it's that.

A

H

Capital n, ET capital C's. You know.

A

H

Would really be this one, except that we that one up well.

F

Sometimes it's capital and sometimes authorities yeah.

A

Rows back to we it up, but I, think I mean it was a very simple if it so do that to acronym it's, it's it's! It's caps, thank you and if it's a three or more than its past good cast, unless the word is ID, in which case we treat it as a word, so it's lowercase D yeah. So it's pretty simple.

F

Just from the extension model, I would put other I would read a my hometown note and I would give it 0. So that is more connection profile types come on in the future. You don't have other being in the middle yeah yeah and then, if connection profiles ever used as an input on something, if it would ever be, then the zero value being the other slash unknown, is a clear like I, don't know what you want me to do. Instead of oh, we default at the Bluetooth yeah.

C

That may comes.

C

Yammy shape of that call it on down yeah.

A

Yes, all right did. We do. Metro gets us that directory no I suppose this Boulder comes way down. Yeah.

A

That's right: internet internet, local I know it's constrained.

E

Internet, like behind a uh it's in China, no I like behind a um like a big.

F

Like metered well, is that the when you get like the Wi-Fi antenna with a bang through it of I, don't think I can reach the internet, but I have an IP address. I captive.

E

Portal, that's what I'm looking for! Is there the captive portal yeah.

C

So constrained Internet is limited, interacts access, often behind a captive portal connectivity or where we can detect it. Yeah.

F

But the the I ask for something on the internet. It doesn't seem to be working, but I have an IP address. So I don't know. What's up yeah correct.

C

Yeah exactly yeah, so this means that you may be local and have access to local access to a web portal. But but that's it.

C

And these were copy basically, one day, one from you WPSL what.

A

You return for profiles.

C

Yes, so for profiles we return so.

I

No I mean take the actual instance. Is it an array there's.

C

A I would be actually in sense right, you'll, return.

I

One because people would always don't come and then you're screwed the next time you changes. We.

D

Usually, yield.

I

Return: okay, yeah.

D

That's what it looks like yeah, yeah.

A

J

A

An internal tybor yield, which is basically the same thing, then you're good. Okay, we.

C

A

J

There Pete.

A

Remember raid on empty when you're movin on empty I change.

F

It to an array and.

A

Everything broke well, we moved away from with the way everything both yeah.

F

So I assume that the reason it's a numerable is because, if you're connected to Wi-Fi and cellular you'll get both of those back and then just as a implementation, make sure that you handle being in the middle of the numerating and they turn off. Wi-Fi.

C

Big correct, so we we gather all the profile profile profiles first and then enumerate over them. Okay. So if there's a snap snap shot in time from when you call that okay.

B

A

What in the change event, arts? What does profiles represent the ones that are now available or the ones that have changed this.

C

Is the currents this is the current state? So what it? What it's it's not it is, it is the current state, so it'd be the same as if you called profile. So when it changed, it is the current new ones. So not a dip. B.

F

Both of those should be current profiles or.

A

Available profiles or something you know.

J

E

Didn't quite follow if I get in the event and then I wait ten minutes and then I read profiles from the event. Darks am I, seeing the state of things from ten minutes ago or from now you.

F

C

F

Read the you wait, 10 minutes before reading the event arms you wait, 10 minutes for reading that connectivity, I, wait, 10 minutes for reading event, arms up with us; I think that snapshot it that's less from.

E

C

F

C

Yeah correct we copy we copy over the values cool it was. You said, current I was gonna say we should just get rid of that property. Well, so that's I. Don't think it's really current, because current would be confusing right because it's not the.

F

Current, it is.

C

Over the profiles of that event, right.

F

F

C

Anything you would you like current I.

F

Mean yeah I. Guess any word that we put that there's always the question of, as of when you read it or as of what it's I think milestone and.

C

The reason the reason we don't put active and I'll tell you specifically is because, let's say return to Wi-Fi and cellular. That means most likely that the actual active one is going to be Wi-Fi, not cellular, but they are technically both there's the system could determine based on different demands. What to use yeah. You.

F

Know it's the just making sure that it feels clear to you and your average consumer that that this means the that have IP addresses and not things that could have IP addresses like when Wi-Fi is in searching mode, and it probably doesn't super matter but I'm. Just thinking out loud yeah high data transfer makes no sense to me.

C

So I hate the name, data transfer and again from Windows I used to call this share. So the idea is that this is when I like hit a share button and I'm gonna share it text to another application. So you know I tweet I go to tweet something right, so you make a share, share request and normally that's text or images or something else so you're, literally sharing or transferring data. If you will between one application to another, we went with data transfer. Just because that's the uwp name, I, don't know if share is correct.

C

Share also seems a little bit weird of a name. What does go to Apple and Google calls yeah, so Google doesn't have a semantics. Is it's an intent so yeah you and doesn't the iOS is called share activity. So you open a share activity. I would.

A

Say I mean my personal opinion is maybe that's what the most informed one, but I would go with something. People are likely to look for like I. Think sharing should probably be the name somehow, because if it's sharing I mean they see how the UI refers to it across all platforms, even on Android I, believe it's called sharing. If you actually do that as a user, which is probably better than whatever the underlying talk phone call today, DIYs yeah.

F

A

Data transfer, like anybody, does the same thing with the clipboard. It's under the data transfer namespace, it's brilliant. Like anything, anybody ever uses those as the as the searching like this will be worth you.

F

Know frame things from my head, but the the button that you use to send things to other applications in Safari in for flight. They use that same icon and call it sent to so maybe maybe that makes more sense, but I don't know. If there's the universe agrees on what knee box with an arrow eating out of it means exporting.

J

Let's go to me alright Zaman essentials to seeing you look, submit I love it ship.

E

C

E

Data transfer sharing.

C

Whatever it's yeah.

I

C

Think sharing is better, probably if I was done. I'll.

A

Go back in time, if you call it sharing and people know what it's for of its data transfer like I'm, not sure what its those yeah.

F

Cuz to me that sounds like Network play in and I'm surprised that there's no answer or that I can't route in this case it's weird cuz the data transfer request. Well, that sounds like I want to download, but you're, not giving me the download, and so that was actually my first impression was the data transfers, download or upload.

I

C

Yes, obviously, there's been happen, fo and device, and about is that this is the actual device that you're on.

J

A

A device display you're assuming there's a single device. It's in a display right, I,.

C

Mean yes, I mean single device; yeah I mean you can have multiple devices, no.

A

I meant like this one right: there was device display.

I

Device display.

A

Metrics public, the the would assume the yeah. You basically have one one of them right well,.

F

Ish I assume that they have that because it has an event, because you can do that and now you get the event that you've rotated sideways with the height this changer act, yeah.

C

F

On I know like win8, had this do side by side split, maybe Apple, where the ending writing, what tablets doing.

A

Like a reason, I'm asking is because I can totally see a world where you can connect yukio, iPhone or whatever, to an external projector or rather than the questions like the audio. You have technically.

B

Probably well flew all that way and what.

F

Does the do you just one of these fire on the iPhones that are too big, where you tell it hit my thumb, you know what I'm talking about.

C

Yeah, so this is the device, it's not your applications dimensions. It is the device dimensions so for Windows, for instance, we get the current view. So the current physical review that you're on whatever windows decides I guess at that point of view. So it's a screen, width and the height of the monitor on iOS.

C

It is going to be the bounds of the main screen, so whatever the Apple signifies, as that so on an iPhone both a plus, it will still be that and basically the size will most likely, never change, because it's impossible for it to change, but it could rotate, for instance,.

F

Yeah, so looking down unsupported for idioms and platforms, both feel more like you probably need unknown and I'm gonna use that this is a place where you can use name of.

F

And then, and now we have a branding question on iOS and UW's capitalization.

A

The volume is identify you can't win because they changed their mind way like Nick OS used to be capital and nosed over kids, and it's like well right.

F

Well, I just mean like iOS: do we keep the little I yeah.

A

I mean that's a that's an appointment that gets a if you, if you line with brands, they may change right. If you don't, then what you don't you're in technical.

F

Er pacing rules say that you wpm.

A

F

F

Or that we call the constant Universal Windows platform and then it returns the string you WP honestly, but I, don't Caroline I'm, just yeah.

E

F

With a client forums, capital.

E

I lowercase OS. We look really strange to.

D

Me yep, it looks terrible and and doesn't mean it doesn't make you think like of what it is immediately like you see this. This capitalization, like no I, know that is yeah.

F

Yeah so again, unsupported I feel like what you're probably reporting, if you're returning on supported is that you didn't know how to map it, which sounds more like I've known that unsupported got it, which is just me thinking so.

A

James, like isn't like I, don't know how Apple model is that, but do they really say that things like what did it do for the watch? Isn't better entry under idioms as well yeah.

C

So and even the Chad Damien was asking about this so technically on Android, you can kind of run an Android app on anything.

D

C

By default on Android, we support every single Android device on iOS, TV and watch. Os are completely different platforms, which xamarin essentials does not support, so it would actually say unsupported in that instance, because we don't know what it is I mean. I guess I would actually throw an exception to be honest with you, because you'd be on an Uncle Tom supported platform. But I do think that watch should be added here because technically on Android it could be a watch, and that is a supported platform.

C

um So on iOS and Android like on iOS 9 iOS right technically, it would be a new platform. So here's what becomes interesting. So if you think about this is there's idioms and platforms, so technically, technically winter, there's where OS, which is androids where OS, but the underlying platform is just Android right, but for iOS it's not ILS on TBO, as it's TV OS and watch OS, so they're completely different operating systems. That are there right and you could run a uwp application on an Xbox.

C

So the idiom would be Xbox, I, guess or TV at that point, that wouldn't it would it be Soviet a uwp yeah, so I think that's how we look at it is like at the end of the day what the user is compiling the application into is the platform so I'm compiling a Android wear OS app into a Android application. There's no differential like from our platform, we're idioms are: where is that application running so they're kind of duplicated in a way, but also not really so.

A

With I kind of told the people right that use the idioms, is it literally just something you put in a log file, or is that something that you actually write code? For that says, if I'm on desktop I.

D

Think it's more for like tablet versus phone in a lot of cases for iOS Android, where they might want to make a decision on how to you navigate or display a different UI. You know there's certainly other ways of doing that, but I think that does get used at some points. You.

F

Get to an Xbox and guessing that it would go to TV like if I'm in this and I'm thinking. Maybe this tells me what sort of events I should be expecting expecting things from an xbox controller and a remote control feel slightly different. Like I, don't know if the if the Smart TVs would be a uwp thing or some other OS completely, but that's I just got to thinking of Xbox as sort of TV and sort of not so yeah.

C

I think we we sort of think of what the display is. So what is the display that you're running on form factor wise so for for an Android TV application? It's running on my Nvidia shield, but it's running on the TV and that Nvidia shield does have a game remote. So it is a tricky situation in that instance, so I think we think of idiom as the physical display that the user is looking at.

A

C

Switch is a very complicated one because it can go and get multiple yeah yeah.

D

I think I think that makes sense because it you know you're you're kind of often making UI decisions based on this in a lot of ways. So Xbox generally is gonna, be ten feet away or whatever it lets me display. Maybe.

A

F

You document what idiom means and it's fine, but yes,.

C

This is an interesting case because this idiom, as you can see, is a static class. That's inside of device information, so it's literally locked in to that one, unlike other ones right, but no.

F

But again you said that you're thinking of the idiom is sort of the display factor and I was thinking of it as an input factor and and so clarifying what you mean from idiom, either by documentation or by making the name be self documenting. It seems good and then so are you doing?

F

Are you doing the constants for comparison or because these are input values to something.

G

G

There were two reasons: I think for that decision. First, one was existing things like Samara forms and stuff was like. Oh, what are we used for you to be you iOS for that's what we wrote at the time and things TV was capitalized or whatever reason on one platform, so we would do essentials.

G

We want to be able people to compare backhoes Aaron with the general form stock platform and then, if we're going to do an actual string equals just because someone might do that and then the other one was I think for extensibility, because if we had an enum with month break cause, we had like. The thing is like that: it's like, okay, let's say we're, gonna, add ties in support or something like that.

G

Then in there all we have to do is that the next version library, we'll just have a new platform, or only in case of of the watch, you just edit and then the property, the device info time platform. You know it is just a string and if some custom user- let's just say the bean team, comes out with a new bing device, then the the platform would be bing device and it doesn't have to Adam UI continue the do an email or something they have just returned. They pass some string to Lee, so we.

F

We have a pattern that we've used a bit called strongly type string, which is you have a struct that only has one member which is a string, and then the struct looks like an enum to most people, but it's actually just a accelerator for wrapping a bunch of constant drinks. So if you look at the hash, algorithm name type, this that's an example of this. So it's uses strings for extensibility reasons, but it looks like an enum for program at ability reasons. Yeah.

A

Well, the one that linked here, which is always a platform, yeah same same concept, no I, think the benefit of this is, if you have a property that returns a string. Well, it no returns whatever. The type is right so like it's strongly typed in the sense of people discover that there is a basically human behind that yeah and but you don't lose the accessibility. As you said, when you just passed the US, you get a string, you put it into the in ermand and nothing bad happens in v2. So.

F

Type string and.

F

A

And x are both good and bad I mean what they what they do, is they make the type less discoverable? As that's what you want, it's good. If it that's not what you want, then that's bad right, so I would I would generally suggest that if you make these strongly typed strings, I think having them as nested types is fine, because people would see them in the signature.

A

But in your case the problem, he doesn't turn them as strings people kind of have to know, there's a nested type in idioms that they can basically go over. But like that is effectively you know they I, don't know how you would discover that yeah.

D

That makes a lot of sense also.

A

How do you even all, because idioms I guess that's why it works yeah, so I'm, like their names, seem to conflict but yeah yeah? They don't I, guess yeah the plural and singular of the property kind of ties them together in the intellisense. That might be actually good enough, as it is come up with you making this what I'm thinking about it but yeah, but.

F

It does if you read both of them in your passive into a function. The strongly typed version tell me remind you with one question: yeah.

A

I use that, like I, think it's generally a better way to do it. It doesn't cost you much all right. We are now basically over time, so we can hone over time. We have there. Two minutes left, I, think the so the question that I have is so we you know, look at the scroll by here. We went through what is what 1/3. Maybe we can do one of two things we can.

A

We can either like set up another one and just completed, but I think most of the value that you're getting out of the review you kind of already gotten, because the think the other thing will be very similar, so I would suggest you know I will send you the notes.

A

The most useful ones might be the more high level discussion that we had in the beginning of like capability api's and how to do a static state in the events and then I think you've got a bunch of feedback here on the actual API shape, and you just apply for the rest of the library and then maybe send us the end result, and you also sundown.

E

That's so we can skim the rest. Yes,.

A

So I will basically do the same thing. I did last week. I would just output the whole thing to Hawaii I view repo. They will have the entire API surface. Plus these comments here cool and then we can do it offline. If you want to calm, does it make sense? You guys are planning on shipping in what two weeks, two weeks or something like that.

C

We don't have a firm day, no, no public, firm date. Okay,.

A

So they own that.

C

A

Like that I'm only asking because they're kind of controls like how fast we should be an already.

C

A

C

um I can talk offline about our plans, good.

A

Sounds good, then, all right, if guys, any any money, any more questions.

A

I

Right then, this is really cool.

D

Guys, thanks for sharing it yeah, hey sweet hope, is great yeah. It's.

C

Been great, thank you so much thanks.