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From YouTube: Hyperledger Fabric (HLF) - How to use the Node.js SDK? : Hyperledger Sweden Study Circle

Description

A recording of the Study Circle held on July 4th, 2020 hosted by the Hyperledger Sweden meetup group.

Slides are available at: https://samlinux.at/blog/fabric-02/

More details about the event are at: https://www.meetup.com/Hyperledger-Sweden/events/trrdtrybckbgb/

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A

Hello and welcome to my presentation, my name is Roland and I'm very happy to present you this section to you in this topic. I would like to show you how to can access hyper lettre of a weak data with the node.js SDK and last week we have seen how we can install hypertrophy week and we have started a little bit to play with the preinstalled chain code chain.

A

Code example 0, 2 and today I would like to use the same network and the same training code and build a new trails application around cities in the first part of my presentation. I will give you some theoretical basics and especially from the developer pointers of you, so I try to focus really on the developer point of view, and not so much on the administrator point of view and also not on there. I think, identity management, point of view and so on.

A

So, but we are looking a little bit in the identity management world, but not so much and yeah so until in the second part of this presentation, I will show you how you can write an nutrias application, how you can enroll your identities, how you can inspect these identities and I will show you. What do you need to connect to your network and how you can write such such an application yeah?

A

So first yeah. This is the goal of this session, so the in the first part we sure we will see a little bit theoretical thing and then the second part we start to build an application and the first thing what we need is an identity and this identity must be involved or we need an identity for our wallet, and for this we can use also denote realistic, a and we will use this in a sea life command line, form and I will show you how weak use this predefined scripts.

A

All these scripts are in different examples and we will copy this scripts and modify a little bit, so we can use it in a more general way and then we will widen broad West API, with expressed fears to interact with the existing trinkle. So let's add overview this, the first step will be. You need an identity because favorite commercial block, train and everything is based on an identity.

A

So that's an important part to understand what is an identity and how you can get this identity and it's sometimes it's important to see what is in an identity. So we have to inspect these identities. Then, from the developer point of view, it's sometimes not so easy to inspect these identities, and we can also check if this identity is valid and weak. We can, when we can read this identity in a clearer way, then we can look if this identity is valid or if this identity has any problem and so on.

A

So, from the developer point of view, it it's really interesting to see which identity you really use and that's an important part and then the second part is the second important part is to connect through profile. So the connection profile is something like a map from your network and we have to see what is in the connection profile.

A

How can I create this connection or file, and especially in this example, so me use the picture first Network script and this script will create for you, these connection profiles in different ways so and we have to inspect this and we have to see what is in this profile. So so this is an important part and then we are going to develop these wasted by I will paste this on Express chairs.

A

So it's an standard or default West system which we can use very easily to build such an API, and we have to test a little bit our endpoints, and for this we can use mocha in combination with the NPM test environment. But it's shouldn't be we're testing, so we will use it to replace postman or, for example, and yeah to do this. We have some technical, general requirements. So from the developer perspective, of course, we need to run in favorite networks, so we have to start our network again.

A

We have to generate our artificial, we have to generate our Krypton material and then we have to start the network and in this process the chain code is installed and also instantiated, and that that's all basic- and this is a requirement when we don't have a running network and we don't have a chain code. We can't we cannot query something from the nutrients aside and the next thing we need. We need an editor to write our application.

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So Mike's example: I will use literature your code, but you can use every editor of your choice and, in my specific scenario, I will use the same digital ocean droplet for the high poly traffic network, but I locally, with my laptop and I use.

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But all source files should be edited on the drop droplet and on the on the waitress server, and to do this, I will use a visual studio code extension, the remote development extension. So that's a pretty cool thing because I can work remotely. But for me it's like if I work locally in my local environment and yes, of course, we need. We need nutrients for this and Lucia's version.

A

10 and third is supported and, as we have seen in the last session last Saturday, we have installed nutrients 10 forest and we have also the corresponding NPM tool for this. So you saw our technical requirements to do this and then we need an identity. That's really an important part, and we need this identity in our wallet in the local wallet and we need to connect triple file.

A

Here you can see a more general few about the single development steps and, as I have mentioned, we need a connection profile and we need an identity and to get one identity. We have I, think three possibilities and we are here option a this is the case when you have when you have already enrolled a client identity, and then you can add this existing identity to your local wallet with the nutria 15 OGS SDK, and this is provided to you in the fabric.

A

Examples through a script which is called at to Valerius later, we will see where the spirit lives and and the copy this in our seal I directory, and we do some modifications that we can use it in a more general way, and so that's the way which I'm going to show you today and because of the time. So we have to be very quickly because it's not so much time to do to do this.

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And the second option is when you have access rights to the fabrics here and then, and if this the case, then you can enroll an admin and admin identity, and with this at mean identity you can use there, which is the user script. Scripts are located in to the table cards an example. We will copy both files as well and English, which is the user script to processes. The first process is always to register a user, and the second process is to enroll it and that's, that's everything the same for all identities.

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It doesn't matter if it's a client if this appears as the order whatever- and this is all indices in the script. So that's the second option and the third option is a way when you're going to use also a command line tool. Farik see a client, and in this way you also need to have the admin user and the admin credentials for this favor ga, and then you can enroll a new identity from type client, and with this you can use the script from option a to import.

A

This in your local bullet from your nutrias application. In the slides you will find for option B and option. C are the way code code snippet and you- and we can. We can discuss this a little bit later, if it's done so I think that's really interesting and how you can inspect such an identity and what is to do to get an identity into this wallet, and the second step is here to develop the nutrients application, as I've mentioned, and the third step would be.

A

Did you develop a front-end application which consumes the rest, API data, and for this you can use angular, mooches PHP, also no choice or whatever, but this part is not part of the session today, because it's a little off topic and also there is no time to do this knowledge. So some general points to note. So this is basically the same. I have a self here.

A

You find in my slides, always links to the official documentation and but one important point is the first point, so you have to install how the application, the favorite application work, how how this process is going, and this is important point where we should look a little bit deeper in this and for this I have created the short diagram where we can see how our small application sent and transaction proposal and what what how how this works- and this is a very high-level overview of this- and you see here- we are here now as an odious developer.

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We develop patent application and when we try to submit a proposal to the blockchain, that means that we are going to use to store something in the blockchain. We are going to change the state of an item or of an asset of whatever you, you name it. Then this process happened and the first thing. What we, what be no trails application, be, is the wallet and the connection profile.

A

So these are really two important parts, so the wallet is nothing else, then, in a folder and in this folder you have different identities and the identity is something like credentials. So a database username and password. When you come from the web development side, then you have also to use credentials for the connection to database or any other server, and the connection profile is also important, because the connection profile is something like a map and the note rias SDK will use this connection profile to find the peers to find the organization's and so on.

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So we will see it a little bit later. So these are both our important parts for the node.js application and when the no chance application sends an request, then he sends this is done through the nutrious SDK and the noches SDK did the heavy work for you.

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So when we submit something, then they know Trias sent date transaction to the endorsement peers and the endorsement peers check the transaction sign with transaction and sent, and if the transaction is ok, the endorsement peers sent their response back to the no GS appreciation and, depending on the chain code policy to the endorsement policy. The noches SDK knows how many peers have to sign this replica. Has this has to sign this transaction and if all transactions signed which should be signed, then the note rest SDK sense.

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This request to the Ottawa and the order on put it in a queue and checks again and then, when everything is fine, then distributed to all peers and as we know, the peers are divided into two different peer types. So the first one is the endorsement peer. This is something like when you install chain code and then your installed instance where the chain code on a beer.

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This is that is called endorsement peer and the second type is the committing peer, a commitment peers- and this is a clear- they only hold the letter data, but they don't has a chain code installed, and you cannot clearly also and commenting here and when Wendy's step is done, the peers will notify also the nutrients SDK and when everything is fine, the notice SDK sent and responds back to the noches application and okay, everything is fine and the transaction is done.

A

So all the heavy lifting here now is done through Dino gsst care and in the light of slides, I will show you how how less you need to do. A query to evaluate certain section are to submit a transaction proposal to the blockchain and all this cryptographic material, designing process, and so on wasn't done. Food is not sure, that's the case. So that's really a cool thing to know and and then this slide is when we're going to develop an application in the in the pelvic work.

A

So we are a little bit a couple through the chain code into the network. So we have to know our network and you have to know which chain code which context we are going to use. What is there, what are the functions from this contract and what are the organization's? Do we have a certified authority? Do we have peers? Do we have a culture to be invoiced and so on? So it's from the developer perspective.

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It's important to know what is the chain code for and in our example, we have used the pre used, pre installed train code, and this is called chain code example under line 2, and this has a simple functionality. He has a an extra a and an extra beef, and both can sent a certain amount of mass units between these actors and this. Basically, they the functionality from the strain code and important here is also the investment policy, and the endorsement policy in this example is with the and parameter mr. Andrew beretta.

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So it means that at least one clear of the organization- one and one tier of the organization to have to sign and endorse the transaction, and then the transaction is Israeli.

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So when we shall town organization to room for example, then we cannot send it transaction to this network because of the fact that their organization to doesn't have any endorsement clear, well II, but we when we change this to a or operator and then it would be okay when organization true would be done so, but this is only for you overview, so we have to know a little bit about the network and then the connector profile. So, as I've mentioned, the connection profile is something like in that. So we will see.

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I will show you what is in the connector over and we see this is we can find years we can find otherwise we combined certified authorities and so on. So this is a information which the SDKs need to find the peers to find the organization, because in the connection when we, when we printed a connection in the script, we will see the data discovery, sellers and 34 just discover.

A

Services turned to true, and that means that, based on the connection profile, the notice SDK knows where the peers are variable, where the fabric CR is which TLS certificate is used and so on so and you can do a little bit on modification and you can control a little bit. What super nutrias sdk use for the network connector, and this is important inverse for myself.

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So when we use the beta first network example, then it's that we have to generate, then you cook the material and every time when we we create the script or material, then also the certificates will be created, new and also the TLS certificates will be created and when we will later see that into the connection profile is the TLS certificate in a pastry on salty base64-encoded way as a text style. So when we copy this connection profile, then- and we later when we create a new one, then the copied version is wrong.

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So in this case it's better to link to the to the file in the project directory where we start the perfect network, because the names are always the same, but only the certificates. The in in this file will change, but we will see this a little bit later and yeah.

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The wallet is a simple thing from the development side, so we can think of the wallet it's simple and folder in this way, and in this folder we can have different identities and that's pretty cool, so we can import different identities and then we can, you can play with this identities and we can say: okay, we will try connection with the identity Atman and we will try connection with the identity, user, one or I will say use or anything it doesn't matter.

A

So in this wallet we can manage, we can organize different identities and also two different networks so and how we can inspect this. We will see a little bit later, but so from the two particular aspect, there are different types of wallets, so in our example, we will use the file system wallet, so this is basically a before we go as we have seen, and this is according to the documentation. This is the most common place to store keyboards, but there are also others.

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So there are different scenarios and for different scenarios you can have different wallet types, so you can happen in memory type. You can have a hardware security model here and you can also use code to be to store.

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The identities, but this is the rarest form of what it's starch so for now we will use the the first one and the file system wallet, but keep in mind. They are also other bullets which you can use depends on your scenario and yeah. So and with this we can go, we can switch to the practical time and when we develop an application in this scenario, so we will use to build your first Network script. Then we have to first create the crypto material. In the second step, we have to stop the ferret Network.

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So then we have these three requirements that we have one network and we have an installed chain code and then instantiated chain code which we can use and then the next step that will mean it there.

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We need an identity, so we will see in this step how we can use this predefined, not just scripts, to create an identity in our wallet, and we will also see where the the new created connection profiles live and how we can connect injustice later in the application and for this I have developed on REST API and you you can't have this the source code from this from this project.

A

It's on github, so you can clone it and you can try it and I have maybe I have a small homework homework for you, so one functionality is not implemented in my in my example so and then, when you would like to try it when you, when you try, you can try to implement the missing functionality. But when it comes to this point, I will show you so. Okay, now I have to switch a little bit.

A

So as I as I have mentioned, I for this I use, Visual Studio code and I use this remote extension and that's really pretty good, so I think that's one of the best features I have seen in the last news, because there is a general problem when it comes to develop with fabrics. So you have to edit a lot of configuration files and you have to do is always in the eye or in small editor, with a small few and so on and I have tried different possibilities to come around.

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So I've used samba to share these files fuse other file systems to share those files, but all this come with a little bit files and it's always difficult when they lose the connection bill and so on. So, but and with this I tried. I tried this way since the two months and I think that's really cool and, and it's very easy to use this extension and I can work here in this. In this way, it's like I'm I have installed fabric on my machine and it's not installed remote on any server in deployed.

A

Ok, so, first, when we I will try this now our hand, so on so I will able to show you the step step by step, but it will copy some related source code snippets from the github repo into the in today, which which would you put a door to be a little bit faster so that we can see this in one hour, everything so, okay, so the first step. What we need is we have to check that no favorite network is running, so we can.

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We see, okay, no dhoka, dhoka, countenance warning and also no docker container is exceeded. So this leads some sometimes to a small problem when volumes or something can also track the volumes. So good.

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So volume so no volume is, is available and.

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And then I will copy I will use. The first I will use the first Network.

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So network and copy this, because when we will be something changed in this in this scenario, then we don't lose the original information. So that's also it's a small security step for my side. So and and then we can switch in this folder. This is the hyper Latrell Valley circle, first Network project, and the first thing we do is when we start the favorite Network. We have to generate our material and this can be done in a very easy way.

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So we can use the picture first Network script and to use the generate command to generate this cuto material and there are a lot of default, and but we can override this default and the channel we can override with the see param here and we can, we can gate, gave this Network our own channel name so and I will call this trend. One.

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Is it better now, can you see it better? Yes, okay, thank you and yeah. So now we have generated our crypto material. This photo material lets in a clip to conflict directory, and you can inspect this with two three command.

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So, okay, now you can see this. These are folders yeah, all crypto material you see installed and for us interesting we will see it a little bit later. It's this part here, so these are prints to pre-configure to a prince, told you that users. So when we use this script than an admin and the user, one will be generated per default and we can use these identity this identity, to import it in our wallet and also for the organization to the same so and yeah. So.

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And with this we can start our network, and we can do this also with the.

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Video first Network command and the command up and you've use also the parameter C with the channel one and the parameter a it's important in this position, because this parameter starts also a certified Authority. But if you don't use this parameter, Amica no certified authority will be started and in this way for organization one and forum section, two, the certificate authority will be started and we can use these dispels certified authorities later when we try to enroll in admin identity and we enroll other identities for our client application. So these are important on step.

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You know and then, if everything is okay, the network should start and when this network routes up also the chain could been installed and they build your first Network script has also end-to-end tests. So let's take some moments.

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And now I did a small mistake because I did not start the determinant multiplexer. So now we have to to make one moment.

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But you can skip this, isn't funny. So what we can start the process again remove this clear this up and we can I think I have enough session already mark Silas. We have one terminal, multiplexer section here so I can use it.

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So, okay, so now it will be a little bit easier. So in the same way we should see our have a little study first and then we can. We can generate it again. Oh.

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So this is a good point. So now you see here the timestamp these. This is the collectible files and this connection profiles you will. The script will generate it in a JSON format and any younger phone and with every generation process. This these scripts will be generated new. So when we start, as we will see later, there's a lot of times them to confirm this.

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As you see, the timestamps are different and because of this we should links to this file when we do practice and we try different different configurations and so on. So that's that puts a good point point so and then we can start this again.

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Then my hope it will stop.

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So we are to clean up.

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And it can start the network much.

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So, okay, and with the multiplexer we can switch in there any different panel. And while this network puts up and does his test, we can go ahead and do some basic steps for our application. So, and the first thing we have to do is we have to create a new project directory I will call this your application, it's a solid circle and switch into this application. So this will be our imported directory for the nutrients application and we need some folders. So we need the CLI folder.

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We will copy our scripts for the identity element for the identities and we need a test folder where we can fill in our specs for the nutrias test for the endpoint test and we need a wallet holder where the identities will be stored.

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So all three folders are acquainted now and because that we use NPM. So when we, when we use NPM, we can make a NPM project and we can make usage of such functionality like the tests and like the package JSON document. So we need some dependencies and for this it's very easy to create a new and current project. We can use the defaults for this, and then we will have also the a package.json file and then we can show we should have this direction. So I will open this again.

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And here we can see our project director, CLI, test and wallet all are empty and here's the package choose file and ok. I see the network is ready, so we see everything is okay. That should be fine. So let us check if all containers are running with crunch will be cool and zero. We can switch back in the 1001 and we'll talk appears making sure. Ok, there are some containers running and everything is fine cool one.

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We can switch back so, and the next step is that we have to install some dependency and we need some dependencies for development and we need some dependencies for the application itself and we can I copy the scene in the spec adjacent file, and you see we need Express for this for this demonstration and we need the ferric see, see a client nutrients model and we need the ferric network module and both in the 1.4 version.

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So when you look to the documentation, you will find two versions, the 1.4 version and also the 2.1 version and I think the III I think that when we use the network 1.4, we have to use also the denote realigned 1.4. So the minor versions are I think it doesn't matter. So our only part fixes.

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But it's important that you have one point before and for independence for the Deaf dependencies we will use mocha to call our to test our application to the endpoints and we will use the typical tests to do the rest, API cards and later we will fill in here the NPM test, the Test section, where we can start our tests, also full district, but this did come a little later. So now we have this where insert and we can store this dependencies. This is this is done by the command, npm install and now all needed.

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Note models will be installed in the project directory, which would take some seconds now.

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When we develop nutrients application, then we can test our running system, but this is supposes. No trace is a process and the server needs to be any running and state.

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So, but when you change your files and you are going to- and you want to see, if your change is perfect, then you have to restart your application so and you have to do it by hand and that's not really funny when you do it every time this so and for this there is a cool NPM project, it's called node moon and we can installed node moon.

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This will do this will do the job for us so in a global way, so that when we use this parameter G, then the impairment models will be stored in globally on your machine and then we can use it in every project. So but when you're come from the noches developer side, you will notice I think so, because that's really known in the community, ok, so I think with that we have installed you has you see here we have the node module file and when you look into this, you will see a lot of ok.

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You will see a lot of files and directories.

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But that's okay, so the next step.

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The next step is to get an identity so and for this we will go in the CLI folder and, as I have mentioned, our scripts are pre-installed on your machine and this scripts are installed in their favorite samples in different projects. So in the commercial paper project you will find a script that is called add to volunteers and we copy the script in our CLI directory and we do the same.

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With the next the annual admin script- and this is located in the fab car example and the second which we now is the richest, a new script, and this script is also located in the top card example.

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So now we are free, JavaScript files, and with these three files we can, we can create an identity or we can import an identity and, as I have mentioned earlier, I would, in the first step, I will use the option a to create an identity with the edge to wallet script, and this.

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This is the predefined script.

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And indeed, with this script, with these simple steps, we can use an existing identity to import this identity in our Oprah wallet and to use it for our project and I.

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Have a I do a little bit modification on this I.

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Will use a config object and with this conflict object, I can configure the key parameters, the key values from this script. So when, when we use this config object, then we can change all relevant part of the identity input on a single point and then we can use this script in a easier way for other identities. Example. So, and here we have to modify a little bit and a trust a little bit.

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So as we can see here, the script is very, you see, you see, we have a short import section and we said here we import the file system wallet so because we are using the file system wallet, as I have mentioned in the in the in the slides before, and that kind and all this comes from their node moral fabric, Network also the the x.509 wallet mixing, which is responsible for the identity creation later so that's the only fabric related part.

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So this part this standard nutrients element here- and this is a it's- the only part which we need, especially for their favorite network- and this is this- is one thing from the script. So this is a fixture so to fully qualify the pass here and we have to correct the part a little bit that will find it so and we have to do gift. We have to correct this pass here and first Network and for our position here we have to check if this path correct, so we can check this a little bit.

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So we have a favor examples and we will see so this should be the current path on this X on this side. So we have to modify this.

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So fix this check, it.

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Again and that doesn't drag.

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So now it works. So this is, this part is not hard. So the second thing what we have to adjust this day of the wallet part. So with the file system wallet class which we have imported here, we have to get, we have to say: well, there should our wallet live and in our scenario or voltage should live one pair in the parent directory.

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So we have to modify this path in this way and we will use this folder and we are you know in the CLI and we are going to use this wallet after and then we have to change for alarm, identity creation. We need some some some things so first we have to set the the path to the to the users directory in the crypto config top. So we can replace this conflict in the path to the user, and then we have to set the correct path to the users sign throat.

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You can place this.

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And also the paths to the keystore so and that's a little bit, that's a point. You have to be aware, so this is the private key from this user. So, but this all these things as you seek different user one. This is you so on. So these are the same names and also the same locations, and also the identity level should be user one or one example comm. This are default values which we can copy and paste. But this part this is the private key.

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In this this we have to check the correct version of this correctly and.

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This we can find.

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Examples: descriptor comfort as sh t. This is crypto config. This is to convert the PS. This is walk one and there should be users. Then we are here and let use a one and we need the membership service provider Florida and the keystore fall down.

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So, and did this sock so and we have to copy this kingdom and replace it on this position, and we have to replace this as well here.

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We can replace the identity labor name, so this is the name from the identity, the labor name so, and we can also make a conflict parameter for the organization.

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But in our scenario we use only the organization and with this we can create, we can import an existing identity to our local wallet and then, when we try to import another existing identity, we can change these parameters and disposition and it will work as well so and when we now try to execute this, we can do this with the node command and note that the wallet and done this is a good time. So because the promise promise is working and now the console log shows that there is no error because of the catch.

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So when the there was the ground error, then we will see here in eros stick and we are here in the run position. So I think everything is fine, and but we can check we can use to treat command on our wallet. And now we see we have now three different files in our wallet and, as you can see here, we have a public files list. West Coast fixed pub and and treat so. This is the public key.

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This is simple as the private key, and this one is very interesting to us, because this is a JSON file and this is adjacent where there are some meta informations about them about to decide. Entity and I will show you. Okay, the time is running so if it's ok, I will go I, do it again and we need I think we need a half hour a little bit more 20 minutes, so I will I will speed up, and then you and then I will. Then you can see the dhole portrait yeah.

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So and how we inspect this file, so this is this is ehm the really interesting part. So now we go a little bit back to the bullet and this which individual file so- and we see this so and when we make a cut of this yeah, you see. Oh, that's, that's in this file so, but we cannot read this really, so we can. Of course we can use the visual studio code for this, but I think for this.

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There is an really cool client application, which is called try cool and we will use this in the in later exams.

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Maybe when you try to extend the fabric network, you have to also handle with Jason Jason documents, and this is really a cool tool to inspect and to extract files for on the command line with when you work with Jason document- and this is a command line, Jason Prosser and in this simple terms, when you use this one, when you call the j.crew command and then this is a dot syntax, so the dot on the first pushes position symbolized that this is the root I.

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Think, and when you call this, then you see a path tracer file and and in this file you can see the signing identity. So the sister is the key here. It's the same. It's the same key, private and public, and here is this certificate, and this certificate is now what we are going to inspect and we would like to see what is inside this certificate and we can. But we cannot read this.

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So this is Paige films, base64-encoded pen format, and we have to extract this string from this JSON document and then we have to remove the dots, the leading in the end dot, and then we have to replace the backslash n with a new line so that we will happen and we Pam file. And when we have this pan file, we can use a tool open SSL, to convert this contract to a human readable file and how you can do this.

A

I will show it in a minute so and with this trick full partha, we can also inspect a little bit more, so we can environment. We look at this and you'll see only depart from the environment. You see here an object in the tracing notation and you can we can do it a little bit more detailed. We have the identity, and you see this and we see also- and this is the very very quench.

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Inspect file with the trip Jake, who parts are here so, and that is what we need now and the first step.

A

The first step is that we extract this from the original file and.

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We can do this in a very simple way, so in the first command we use here's the command. This is the the dot notation path which we are, which we would like to have. This is our file name, and then we redirect the output from this only to a new file on the coil this with post fixed.

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As you can see, we have now this file extracted so and we look into this file. We will have the same as we have seen on the console Primula and now we have to replace the the dots and for this we can use di trouser I'm VI editor so, and we can place this so black and gray, white and Krita file and.

A

A

Okay, so- and the next step is to replace this backslash n with a real newline and for this I will use a set command, which you can use always on the command line, and this is something like this, so I think. Maybe there are better ways to do this, so that's a workaround I have found for myself and but you can do it also with Visual Studio code and replace all backslash, N and so on.

A

So but sometimes it's important to know how you can do it on determiner and yeah, and with this we create enough another file define a PEM file.

A

And now you see the.

A

Correct version of this pen certificate and from this position we can now convert this certificate in a human with a reformer so and for this we will use the open method as SS l program and because of that the fabric use only x.509 certificate. We can use op methacel with the x.509 algorithm and we want to print out it the text and with the intro ammeter we say in which file we would like to inspect. And here we go, you see the format of the file so, but we cannot read here the whole thing.

A

So that's that's something from the terminal flex multiplexer. We have to scroll with this, so we can control P and the FN key, and then we can scroll and you see here the certificate. So what you can see here is the validity. So you see the default. You will have a certificate which is valid 10 years. You see the different and you see the subtract. So this one- and but not in this case. So when we create a new identity with the fabrics CI a client command was not realistic.

A

We can include some affiliations, so validations are also really cool thing for identities because of this affiliation. We can in the chang-ho development, okay, only identities which belongs to the department. Marketing I can witness this part of the train code or only identities from the department. Accounting can widen the string code, and this is from developer perspective. Interesting when you know your business logic and you you, you have to know what your nutrias application should know or should of can.

A

Then you have to know, do I have the device for this, and in this way this is a way to track what is the identity and how you can inspect this identity?

A

Okay, so this was a small few in the identity management and how you can inspect such bank files, so but I don't want to spend too much time on this, but all the topic favorite CA, and that entity management and membership service provider. This is really a complicated and huge topic, so this must be handled in a session or into session so where you can really focus on this on this kind of, but from the developer perspective, it's it's not so important.

A

How it's only important is the the certificate valid and you can check the validity of certificate, also with other command. So there is a checked property in the SSA in the augmented edit command, and when you use this check command- and here you can a value, you can give them a value, and this value are in seconds. So when you use this one, so these these are the seconds for one year, and now you can check.

A

Is your certification valid for the moment or in one year so and then you will see here, certificate will not expire in this amount of seconds so and with this command you can little bit inspect and a little bit to check bodies what is in identity, okay,.

A

So the next slides are good script. So now we have a identity in our wallet. The next thing. What we need is the connection profile so and the connection profile is also a chase. Nora gamble file, so I will use the trace file and for this I can use the checker tool again and you.

A

A

A

A

A

Okay, so this is the cart path so, and here again this is a Jason right, but this is business.

A

Yeah but I will show you this in a smaller way. So in this in this file, we have I think one two, three four parts. We have a train set second section, and in this client section we have information about declined in general. So we are organizations section.

A

A

And in this intersection we will find informations about the organization so- and this is the connection Porsche from organization one so and obviously we have two peers and we have this set of other side and such an information you can find in this document so can open this here. You can see it a little bit better way.

A

And here see it in a better way and that what I have mentioned earlier, so this certificate is generated in the creation process of state fertile material, and when you change your configuration, then this file will be written new and then you have to use there yeah other. Can you file? So that's that's the reason why it's better to link this file and net copy during the development process. In a real scenario, you will have this information on your own server so and that's the connection profile.

A

So, as you can see, the connection profile is only a thing where, where you can have information about the network organized in basically four sections, the client section, the organization section, then the peers, peer section yeah and the certified authority section here with the PEM file base64-encoded for Monty, okay. So and with this we should have everything to start develop, develop our nutrients application.

A

And for but before we start, I will show you another slide. So the question is: what is the connection between the nutrients and the chain code so from the well per perspective?

A

You cannot create anything in the blockchain, so you need a permission and you need an identity and the identity has access rights has rights to create something to invoke something to delete something or whatever so and because of this for the web developer for the developer of a nutrients application, he has to know what is the business logic logic from the string code and in our example, we will have three free end points here and.

A

The first two inputs are implemented and the second a deferred end point. The delete functionality is not implemented at the moment, so that would read apart when you come in and say: okay I will try your example. I will try this mr. did your first Network and try to build your application again and then I extend your application with this forest delete for the remove state endpoint.

A

So that's not implemented, so you can see, there's a small homework or training whatever and to try and you can try it and you can try this so and when we have an endpoint here, the first endpoint is this: get data and this get data will clearly 1 1 state, so we'll create the devalue, a or the value from the extra a or the value from the extra P.

A

So- and this is represented in the Jain code in the in the in the query- function so debt in the chain code, there's a function called query and the query function. Does this and the nutrients endpoint called this query function directly, and for this we can use a Noches command from the SDK. This is the contract, every transaction Metro which is here used. So this is a method which only is is is for Queen data. So only in the business versus transaction method.

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You cannot sent an submit and transaction because this metric is only used for created and then but such data Ahmet wrote. This is a post, so we sent here we sent the get from a get request, and here we will send post request and this post request use in the no chairs in the contract, submit transaction method, and this Metro does already have a lifting which we have seen in the in the in in the overview picture for you and will give pack value true or false, to say: okay, it's okay! Oh it's, not! Okay!

A

Your turn transaction is submitted or not, and the parameters here you can see query. That's the function name. So in the invoke function in the chain code, we evaluate the function name, and these are the connecting points. So then we call here this this query. Then we have to use the function, name create to come to the function, to the query function in our triangle, and the same is here in the post in the post request we have to okay. This is false, not query. Key, that's mistake.

A

On my side, this is the sent to store to store, to store key value that I will corrected later and here with the submit transaction method, we can call the invoke function, but this caused the invoked function in the controller, and then we evaluate again the function name and then we use the invoke. You see a upper case invoke and use a lower case invoke. So not these are not the same, and you can look into this chain code. Underline example underlined so true file in the, for example.

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These are exactly the same cause, and here we have two problems: the data we will use them.

A

Parameter one in the parameter to and the value so the chain code sent sent from a to P. Ten units are frumpy to a hundred unit. So that's what the train club does here and doesn't make the payment of X units from a to P oil from peach way and they delete State. There is also a delete function and this deletes an entity from this date so and that's not implemented. So maybe that could be your home, but this is only for procreation. This is only did you know.

A

What could what can you create and you have to know what is the business logic and what is the what the chain code does, which parameter you need which function names? You have to call. So that's an important part to understand what is the chain code for okay so and now you can finally start our application and we do it quickly so and the first step is: we create an index GS file.

A

A

So the first step in the creation of the index.js file is the requirement section. I have divided this. This index.js file uses this main file in different sections and to explain four bodies each section. So this requirements are basic standard requirements for every nutrients application, so we need expressed and we need the body Plaza. So we need the powder Passa, because we will send reduce the post request and to have access to the post values we will send and then to have a little bit more overview and to exclude the code.

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I have created for every endpoint and no chess model that we can exclude the source code and to have a little bit more about you what's going on so, but for now we comment this out and also the connection. So in my example. As for this, you can have different approaches to build such an application. So, in my application, I have the approach that I will. First I will connect to the favorite network and when the farik connection is ready, then I will point this.

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This connection to every endpoint I have so I have only one connection and when the application is running, we don't have to connect and reconnect to this favorite network. So that's the reason why I have a separate connection model. Then I have a short config file where we have some conflict config parameters that we can change a little bit and we have a global gateway variable which we can see as a pointer and that's something maybe I need for their development process. So in node moon, it's like that.

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You start your project with not moon, and then you can stop this. Only when you click control C to interrupt us with this signal, and then that happened, then we don't have a disconnect.

A

We cannot call a disconnect function from the Gateway from from you know, trees from the ferry gateway and with this I can show you how you can interrupt the signal and catch this interrupt signal, and then you can call it a disconnect function and then, in the last step you can exit from this process. So this only the way we have this here and the next step is that we need the Express pub on the Express section.

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So we copy the same, and here you can see. Okay, it's an Express application, it's pretty sweet straightforward! So that's how you build an Express application. Then we include the body posture and also that's the will encoding. Think that says, for example, it's not needed, but I think it's standard for every application, and here this is the the part where we use to connect to contract module here and when this is a promise. So when, when this, when we start this function, there is a promise and when this promise is resolved, then we are ready.

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Then they could been. The connection is established and we have a connection device eyelid. This is an object with a gateway and the contract and a gateway.

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We point to this global pointer for for our exit scenario and then the connection to the favorite network is where so and when this, when the connection is ready, I have here the end points defined and in the last step here we have the start command for the rest, API server. So it's also basic for every note: riyals Express application. So that's the internal part, and this is the start command for the seller. Okay, so we.

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Created step Antilla, the last part is the exit scenario and.

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This is fire upon receipt to exit, node moon and that's the reason why I have a global pointer to the Gateway and then we can disconnect from the Gator and we exit finally, the program here so this now the index gs5 should be ready. So what we need is the configuration file and.

A

This is something like.

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So in this configuration, I have so all relevant informations for the ferry network, so we have the channel name. We have the chain code. Id. The chain code is not called chain code. Underscore example underscore zero two. So in the in the install install process we use the default name is my channel in this way and we used user name. So that's the label identity which we have seen in the wallet and here's the path to their connection profile.

A

A

And this is the path to the wallet and then we need the connection file.

A

A

So this is the model which is responsible for the connection to the fabric network. Unless you can see here, we are here in Duluth pub and then we are also here. The promise which I have mentioned here so yeah. Then the return and.

A

To find the connection of the beauty collection, it's really easy, so you don't have to do so much so we need the wallet. So we create the object from the filesystem wallet now. First, we have to define the path and.

A

With the conflict parameter here we can import the config values from from the index.js file and here's the the wallet is created, and then we can create the gateway with the gateway class and we have the gateway. And then we can connect to the gateways and for the connection to the Gateway. We need the wallet, we need the identity from the water which should be used, and here this is the discovery.

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So this is what I have said earlier, that the noches sdk needs the connection profile with all relevant informations about the network and with the discovery, the property here, and when this is any word, then it looks for the right, pier and so on. So and this parameter is also important to know this is as localhost.

A

That means, when you call it in my scenario: I have the favorite Network locally installed and in node.js application is also locally, and then we can say as localhost is true, but when we have the scenario that the Tremec network is on a remote server on the other server and the note application is also on other server, which would be in a will case scenario.

A

Then we have to set this to 4, and the next step is here that we get the channel the network, channel and yeah, and with this channel on this channel, we want the chain code. It's the chain code name, and this is the final contract.

A

So and now we have the contract, we have a gateway for exit scenario and we have the contract and both will be in this I will I will do both in as a pointer in this in this object and when it's done, then the promise will resolve it and we will have it here in the connection result and then the connection should be established and the network is wearing, and then this is basically the same as we have to do.

A

In every Express application- and here it starts so now when I have not forgotten, so we can add one point left, so we need to test.

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So then, can be this new file.

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So- and this is the so we have free test of free API calls so I use this, as I said, as a replacement for curl of the postman, and so it's a little bit easier for me to do this and to store also the payload here and can it's it's for development better to test with this kind of setup? So the first call is only if this is this is TPS Arowana and this.

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So we can check if this small work so with the script command. We can skip this test, so we uncomment this. So we will only execute now this test, the first test and see if the API, if the waste area is running and how the connection is established.

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But to do this we need a small modification in the package.json file.

A

Because we want to start our tests through the npm command and we have to replace in the script section with the test name, democra command and we call here or spec file. So let's did the time walk as I started. Developing this example I had different it in my first version they are I connected and we I connected in every endpoint to the favorite network and after I have received my data I disconnected from the network, and this took some time so on this local machine.

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It took five seconds we we'll see a little bit later and and and I I thought. Okay that was too slowly and for and to work around. This I have found a decent solution and a time I connected to the ferric network on the boot time of their noches application and share the connection between all endpoints. And when we do this, we will see that the request and also did submit process will all will take only two seconds a little bit more than two seconds. So with this we can improve the performance a little bit.

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Okay, so and now big moment.

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So and then we can use node, moon and stop index.

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There is a small arrow, okay, so the path to the connection file.

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Now the path is correct and you see.

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The connection network is ready and the API server and started listening on port 3000. So and now we are here so this is the console log print for this, and this is the console log print for it. So no execution so I think the connection is established and the network should work now so one so and then and now we can test the first.

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Endpoint, which team can test command and you see: okay, hello, favorite, API, so, okay. What does this mean? That means that our REST API is vaccine. The connection to the ferric network is also established, but we don't have now a call to the blockchain itself, and for this we have to.

A

Activate our endpoint, so first we try to create something and for this I have now you see this file is missing. We created file, it's called index query tree s.

A

In this file we will copy this part of information and okay, everything works, and here you see the model where we can query the chain code and first, we need to creating be critically in the specs. We will use now this one, so we sent a key yeah, so we have a get request and we this is our path and as a parameter of the sched request, we are the key. The key could be a of- and we have the key be for this moment and.

A

Truly request: object from Express and type Aramis object. We will, we can get Dicky and with this key value, so in my case, I bring it to lower case and yeah. So that's preparation for this, and finally, the only thing you have to do to create this value now is to call this command and that's really really cool. So one single command is used to create the palm, the parameter, a or p value from a or P, and this is in the same way. I if you have shown you to you in the slides.

A

So we have this elevation between section function from from the contract object and we have to say: okay, we will use from the central invoke function, the query function and we want the information from this key, and this is also a from this pirate forward from the SDK. So can you we can use the weight, a keyword to wait until the I think own promise is finished. So when you use the irate here, you have to use your also I.

A

Think so, because that's not really- and this is the result- but the aside will be in a pasta format. So and then you have to convert this Papa to human readable string, but it, but it is done. Food it to Papa, has also add to string method, and you can do this with two string and here I construct. The final return object with the key and the value, and also in the case, when you create maybe C, then we commonly catch fall and then you see there's an error and surely a try and cut.

A

We don't have a. We, don't click the application? Okay, so this is done. So this is activated and now in the specs. We have it also uncommented and now, when we try the test again and you see here, we go the value D key B has this value and now we can play and we look a and you see the restart of the neutrals application here and the a has two key areas.

A

This value- and you see so simple- is it to query a contract and in the same way we can do it with the set.

A

The last step in this demonstration now the index set file.

A

If this content so- and that's basically the same so the structure of such a model is the same, so it's awesome, I think process. We have also in a rage here and the method we are going to use from the contract class. It is submit to transaction and we want the invoke function from the global invoke function and we use the parameters. P, 1, P, 2 and the value so, and these parameters provided from the request, object and the poly object, which is apart from the poly Partha, and so we can with this.

A

We can use it in this variables and we can use in the same way the radio.

A

So then we do the lower case thing yeah and that's it so then we can submit this and we call in both function and that's the Department sequence here is the same as we can do it on the command line when we use the CLI container and when you, when you can do it in this way, then you you can use the same sequence and we can do it also here in an odious application and then vendors, then, if it's done we have here small return, bird and also the exception.

A

So and now you can skip this so so now we try to send ten units from P to a.

A

So, okay and when we call test again- and you see it takes two seconds and you see, transaction has been successfully submitted and we can repeat this so and you see here you have hundred here, 110 and so on.

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Hundred and twenty.

A

Yeah, so I think we are. Finally, in the end of this presentation, I.

A

Will post you every post, the slides later and the Select channel, so you can find here also some useful links. This is the path to the link to the github repo, so you can clone it. You can play with this example. You can try to reproduce it and you can try to extend this. This example with delete functionality.

A

This is the path to the noches SDK release. One point one point four, and there are some points which I have not shown. This button will show you the slides for this No so because these are also very useful informations to this. So this is the. This is a slide where you can see how you can use the favorite, see a client to Ricky's register engineer or a new user, so I think that I can look into it copy and paste. So this will work.

A

The only thing here is that in my example, I I don't know why. But you have to set the local hosts file. They see a the path to the departed, a local see a file and it's down on the pitiful I had so actually what we have seen. So the only thing we we have not seen here is the annual opening and there and we purchased them. So we can have a short find a few on that. So, but it's it's basically the same.

A

So this is the script which you can use to enroll, an admin user so and for every transactions on the fabric. Ca. You have to be an admin of this certificate authority and to to be so, you have to enroll it first and that's the script where you can do this so here the first step is you have to set the path to your connection profile, so that's only other representation to resolve the path. So you can. You can correct this in any way you want.

A

So this should be okay, this work because we are using the CA from one it's the same name, and it's also the same so here you have to create the path to to our wallet in this way, because we only see like fold out beneath the opening, so the admin name is correct. So and this is the track, so it can only involve one at me, so if one identity is already enrolled, so in every script you can find this exists scenario, and then you cannot in order to try.

A

So you have to delete this and when you don't have a problem with the marks in royal parameter in the fabric CA and then you can roll it again, and here you can have, and that's there, the tricky part so to use this, you must be a. You must have the information from the uplink and that's I, don't know if being when you come from a developer perspective when when when when I see the note us develop of you, so I need an identity.

A

So it's the same for me as a developer when I say: okay, I have my secret database or MongoDB or whatever, and for this I need my credentials and my path to this database. So from the developer perspective, I think the option is to use the option a so true that the administrator enroll this identity, with his tools and I, gave you this identity, and you can add this identity with the optional to your local bottom.

A

So, and in this way you don't have to know about the admin name and also not known at the admin credentials, the your secrets, your password and yeah, and then you enroll it so and with this, when you have done this, you can use the seconds book, and this is a two part script I think so because the first is always you have to register a new user, and then you can enroll them in the user and the the part here is so you also you need the admin identity.

A

So to do this, you need the admin identity. This is represented here, and this is their affiliation. You see so this. This is also this would be also interesting part for analyze, because we can write train code and with the chain code we in the chain code. We can say that only members, only identities who belongs to the Department one or two-year department to can read this- can execute. This query can do this functionality and so on. So this is. This is really interesting part to play a little bit with all stitches.

A

Until you see this is the enrollment ID, and this is the client, so that's also important in many online or in tutorials, or you find the type user so and in the ferric see our documentation, you will not find the type user, so the top is client so and that that's really important that this is a client and not the user, and we see fabric doesn't see a use.

A

An identity excited entity sauc. He said as a client and the client could be now the nutrients application. So this is important part. So there is no role user. The role is client peer order, but not user, and this is the secret. So this is the enrollment to adjustable says, and that's also important part to mention that when you work with the fabric CA first, you have to register an identity that could be the client that could be the peer that could be Oregon.

A

And then you will have a secret and this secret is only used for the enrollment.

A

So and then you involved this identity on ten, you have an Android identity, and with this information we can use the creditor entity function and and create a new user identity, and then we can use this user identity to add this to the wallet and gave them the wallet name, jusa, one and yeah I think that's it so yeah. The only thing you have to do here is to correct the paths and yeah and fill in the affiliation, the user, the environment, ID.

A

The type is always client in this in this case and I think that's it, and in this way you can create.

A

A new user and a lot of users and their can some maybe some problems in this way, so yeah that that's also a tricky part. So what happens if you enroll it use again? So then sometimes you can face in this error. Message is already, which is that and to handle this scenario, you can do different things so and it's the last part I am going to show you not on the slides. So when this happened for the development for the testing, then you can connect to the docker container with the exit command.

A

Then you have to install sqlite3, you can do it. It's not pre-installed in the sea like container and then you're switching the new route in the home folder from your favorite CI, and there is a file, it's called Felix. He is already be and that's a SQLite file and if the SQL free command, we can enter this file and we can do.

A

We can administrate this SQLite database and then you have to delete this certificate. You can delete this certificate and you can delete the user and then you can. We register our in gold to use again. So that's this one one way to solve this solution, but I think there are also no kanata way. Okay, so I have to say sorry, it takes a little bit longer than expected, but I think it was a great session. So you have seen a lot. I will publish the slides later in the slack Channel and I I.

A

Thank you for your attention.