Hyperledger Foundation Meetups, 12 Feb 2021

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From YouTube: How to use Node.js to develop applications using Hyperledger Fabric

Description

A recording of the Hyperledger Sweden Tech Study Circle on February 12, 2021. In this session the group looks at how to use Node.js to develop applications using #HyperledgerFabric. The group will work through an asset transfer application as a basic example.

More about this event is at: https://www.meetup.com/Hyperledger-Sweden/events/ctplzryccdbqb/

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So, okay, so welcome to this hyperledger sweden meetup. My name is roland and I'm happy to be your guest for today's session, and uh today we will have a session about node.js. So the title is how to use nodejs for hyperledger favorite application development, and in this session I will give you an overview. uh What we can do with nodejs and especially uh regarding the sets hyperledger certified developer exam.

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So this is resumed. This is closed for the moment, but it will be resumed in the middle of march and that's the reason why I have uh chosen this topic that we can see what we what is needed to pass the exam. Maybe so we can go a little bit through this curriculum and I will show you also how you can get started with with node shares on the client side and also on the chain code side and yeah.

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So we can summarize this in with two pillars, so we can say we can use node shares um for application development for the chain code side. So there we have uh different possibilities, so the first one is is: go and then nodejs and java.

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This are, I think these are the stable versions so and on the client side um there is no chairs and I think, also go, but that's not stable. For the moment, however, there was a new version one week or two week ago, and the certification, uh the certified hyperledger uh developer certification is, uh will be resumed and uh but only in the language node.js.

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So there is on this is available in for the chain code in node shares and for the client side on node.js and that's the reason why I have chosen this topic today that we can have a starting point to see how this will work and how and what we have to learn to pass the exam. If someone uh wants to uh take take this exam um in natural in april or to another time and yeah so small overview, then I will give you a guideline.

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uh What is needed and then I have prepared the these domains and competencies, and uh so that can have an overview. What is important and uh in the next and upcoming sessions. I will uh talk a little bit more about this chain code and uh client development. So and then I will pick some special parts today. I will give an overview and I will use. I will use the asset basic transfer example for that, so because that's a good starting point and for the chain code and also for the client side.

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But on the client side uh the example is for me or the official example is for me a little bit uh difficult to understand.

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So I have um splitted this example in a more easier way to understand uh for me, and uh then we can see how we can use this node.js uh example also on the client side and yeah, so the references you can find here in the slides as well, and also all my examples here you can find in the github repository um yeah short overview, so node.js is, can be used for both for the chain code or smart contract development and also for the client side development.

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So for me, is it's a little bit uh difficult? uh I think so. I came from the goal side um on the for the chain code and uh but um I think when you are a beginner and you come from a web development side, then this is a good choice to start and uh in the in the node shares. uh We have this favorite contract api and this is a high level api.

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So you will, you will see a little bit later, that we uh can make a chain code, uh make some chain code operations with very less code. So it's I think it's it's really easy to use this and um yeah it's a little bit surprising for me. That's it's so easy to use this fabric contract api and you have also uh the possibility to use the the old version or the edition or skin version, and this is a little bit low level digger.

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So that means that you need more commands, and but you have more flexibility to do something, and uh for this uh you have to use a node.js version, 12.

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and yeah. Then you have to deploy it on on your ps. The deployment process is the same like for for a gold chain code, but with some options that you have to name the the the type of chain code for golang.

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This is the default, and that's the reason why we normally don't uh do this so, but when we use a nodejs, then we have to use another option to flag this, that the process now that we use in node.js for that and then but the process in the version 2.2 favorite 2.2, is the same so with the installation with the proof process and also with the commit in the end. So and then we can use the nodejs chairs as a chain code and on the other side we can use it more.

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Naturally, I think for the client application development and uh the end here is uh to build in rest api.

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So I think that's the the normal way, but you can also use a command line um or you can create a command line program like we are going uh to do today, so that we can call the commands from there from the terminal and but I think, when you use it in the web environment, then we have to use some rest api and uh then we need an express js server, for example, or something similar to create this api server. And then we have a client on this.

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So and then we can use any front-end application. Angular futures react whatever you want to have an a nice uh front, end for your browser, interface and uh yeah. So but that's uh front side, client, front side, web development. So it's a little bit out of the scope here and uh we have here this day uh to deploy an api and to create an api that can that we can use and that's normally the rest api.

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And for this is this. We have a so-called application, sdk software development kit. So, and uh on the smart controller side, we have an api, so an application program, programming interface, so yeah from from the term to differences, and uh here we have uh also npm packages. So uh we have to use nodejs uses npm uh normally uh for his package management and we need some external dependencies.

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um We need here the fabric chain, code, node uh npm package and on the client side, the ferric network, favorite c8 client, for example- and there are some some others as well, and here we can use uh the version 10 and 12. so from the node.js version, when we, uh when we have to to um deploy or your your compo or create them in environments or in development environment. Then uh it's uh when we, when we make this both the the nodejs, um the chain code and all and also the client application.

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Then I think we should use nodejs12 then, and in this way we don't have to switch between uh 10 and 12 versions. But we can do this on the on the on the client side, but I think it's better when we use the same version, uh it's easier to get a coffin, and with this with this software development kit, we can create um application, a client application which can interact with the uh with the blockchain system and can uh invoke and query some data.

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So and these are the global steps we have to do and we look a little bit deeper. What we have to do, then we can say uh for the smart contract.

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We need a development environment for local testing for this, for the creation process of the chain code and there we can and for this we can use the pa dev mode. um This is the environment which we have seen in the last meetup, so we can use also the native version or the binary version or the docker version for this, and then we can deploy the chain code and we upgrade the chain code on the ps. So that's also once the one interesting step.

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So mostly, we see the deployment of a chain code, so we have a chain card and then we deploy it and then you use it. But what is the upgrade process so and that's also an interesting part when we upgrade when we try to upgrade the chain code, so we can develop and then we can deploy the chain code on the piers and then also on the upgrade the chain code and for the client development. It's a little bit different so for the client application.

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So we need, I think, it's better to have a small test network, something like the test network from the fabric samples, because we need them to prepare a connection profile. So does the connection profile is responsible for the connection to the to.

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We need also some identity, so we need a user uh which is allowed to interact with the network and we have to prepare it, and that means that we have to um enroll and we guess, register and enroll a user for this client development, and uh this process uh could also be done with the node shares and in this in this field we have two possibilities, so we can use an existing identity um and then convert this existing identity in the local wallet from the client application, or we can register and enroll a new user.

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But for this we need a running certified authority. So, but the test network will help us with that. So when we install the favorite network the test net network from the user side, uh paddy fold, two users uh in every organization will be created. So we have an admin user.

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This is the user which we normally use for our testing and for the installation of the chain code and for the administrator part, and then we have a user which is called user one, and this is a normal user and we can convert this normal user as well to an wallet to an identity which which we can use in the client application.

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And uh for when we choose this path, then we don't need the ferric ci for testing. But when we want to create a new user or different users, then uh it's uh better to use the certified authority option and that's the good thing I think uh demo in the version 2.2 and then the test network in the net in test network from 2.2, because it's very easy to start a test network with certified authorities, because it's only a flag to do this.

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And and then we have a running network with two certified authorities, uh one for organization, one and one for organization. Two, and this step is a little bit complicated in the version 1.4. So because the test network already built your first network example hasn't. I hasn't this possibility to easy start. Then certified authority and that's the reason why I think it's. uh This is a good improvement, also for the testing and learning and development, and we can easily start and certify the society and then we can in register and enroll some identities.

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But we have to use the node.js sdk for that and we have to write a script or something like that to that. We can do this and then, when we have this in place, then we can write the application so for that means that we cannot start um and say: okay, we write now in favorite application. So we need some preparation and uh I think we should use for that.

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The test network, because uh we can have any configuration what we want so also we can use a couchdb, for example, so when it comes to which queries when we have a chain code where which queries is used uh or some aggregation functions or whatever how hdb uh offers to to use um or we use the the level b as a state database. And in this case we only can use some key queries, key range queries or composite keys, and but it's also okay.

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But it depends on the use case. But we can all we handle all this. um We can handle all these scenarios uh with the test network and that's the reason why it's a good choice and then we have to prepare this connection profile and this connect and uh with this preparation of the connection profile um that that the name I think it's not got. It's 100 uh correct, because the test network has prepared this connection profile.

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But we have to read this connection profile in our application and uh that's the first step we have to do so, and but we have to prepare it for our um no shares application, and then we have to enroll the users or the um identities for this yeah.

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So, and these are the steps we would like to do, we have to do and when it comes to this uh certification, then here I have a copy of the domains and competences and you can see the most part here: 65 percent about the chain code, development- and we can see here the competences we have to have to pass the exam on- and we say here from the client application, identity management, instantiation, a wallet, import identities to a wallet on selected manager entity.

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For my wallet it's it has only seven percent, but I think it's an important step. uh But without this part you will not have a possibility to connect to your favorite network, also, the creation of the network. The connection profile is an important part so um and uh yeah, but the main part here is about the chain code, development and uh yeah, and not so much about the client application development.

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I think so we have only here in this two small parts and the most part is about the chain code development, and here we have 20 for maintenance and testing. So there are some special topics here: uh unit testing, for example, for contracts. So that's an interesting uh part but depends a little bit on the tools. So when you use go for example, then you have a good uh testing environment because go has a good testing features uh in nodejs.

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You can also have good testing features um yeah so, but it depends a little bit then on the language you use and uh travis troubleshooting transaction flow is also, I think, important part, uh because um as a developer, you have to understand um how favorite is working, and that could be a little bit uh difficult uh to understand this.

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How all the single piece fits together, but normally from the whole perspective from the global perspective, I think as a developer, you can use these tools and the the client application and the nodejs replica uh the the chain code, the nodejs and chaincode.

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And in this way you can create an application and you can install this application also on a managed system like an ibm or you can have from google cloud or on other public cloud providers. They offer managed uh favorite networks and then you can use it and uh yeah and install it, and it's not so complicated as if you try to run your own network, but this depends on the use case and what is the aim of your project?

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But here you can see and some some important parts we will see today and in the next sessions. I will pick some important other parts, for example the event uh the event part. uh This is also interesting to see, register and handle channel based events and, for example, so that we can see what is uh when is a new block is created or we can uh send an email when the transaction is completed or whatever. So there are a lot of possibilities.

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What we can do with that so and yeah and some uh points we will see today here.

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There are some questions.

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Can anyone hear anything yeah all right welcome, let's have a complete.

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Yeah, okay, so um yeah. So that's so for the introduction here- and um I haven't uh here the link for the um for this for this official uh domains and competence sheet. But you can google it and you will find it on a linux foundation, page and and also some other useful informations.

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But I think it's important when you try to learn this, then you can see. This is a small guideline to focus on different aspects here, but because, when you see here import the wallet topic, then when you look at a little bit deeper onto the wallet topic, then you will see that we have three different kind of wallets. So we can have a file wallet and in memory wallet and also a database wallet, and with this we can create different combinations from applications so and uh yeah.

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So we have here a lot of possibilities to do and to develop some uh things. Okay, so.

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Let's start with the practical part, so.

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Make this a little bit larger and here.

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So today I use two terminals for that, so in the first terminal we would like to run the test network and uh we will install the the chain code and then the second uh test in the second terminal. Here we will create, we will test our nodejs application and uh when we try to start this, that's pretty straightforward. So there is no no secret. So we use the test network again and.

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uh Here is the command, so we have here this network uh network script and this network up. We can create the channel so and with the uh c option we can name the channel, and here uh this is new in our session. So with this options ca, we can create um certified authorities and uh for the network so, and this network is, has two organizations and- and we have two certified authorities and.

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We can do this and then you will see you have.

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We have three organizations, we have also the order organization and also for that and set that authority is created, an enormous scenario. You will have also for the tls and an own certified authority, but here is only for the ottawa, the organization, one, the organization two.

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And uh and that's the good thing on this uh favorite 2.2 version so because here we can create any configuration which we need and now it's running so doc appears. And then you see here.

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We have here this is this: is our normal setup, so we have the order and two piers one for each organization, and here we have now two certified authorities uh also running, but for example, we only need the organization ca for organization one, but all three are running and you can create the als you can use it. Also. uh When you make a client application uh for the organization too, for example, then you can register and user also from this, and you can also with this configuration.

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You can also learn a little bit about the favorite ca, so that's also an interesting topic. So how we can um we just enroll and in and delete or remove identities from this ca and also when it comes to actual attribute paste chain codes, so we can, we can set some attributes to an identity, for example, this is the department marketing or sales or whatever, and then we can use this information into the chain code to have permissions uh on the chain code.

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So we can say uh this read process or this function can only use the from a user from the sales department, for example, or whatever. So we can set different properties uh attributes to an identity, and then we can read it and can handle this situation in our a chain code. So and now we have this in place and one so and then yeah so and then we have to use the chain code so and in the favorite samples we find different chain code. Examples, for uh I think the the asset transfer basic so has.

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For all supported languages.

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So- and you see here uh a lot of examples, so all this, which is with the prefix uh application, so that means for the client side. So we can have here the javascript version and the chain code here with the the folder folders with the chain code. They um are for the uh for the chain code, so we have here in javascript, you can type script, one one version. If you go and one for java as well and uh yeah, we would like to look into.

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And here we can see the change, so we can look here. Look in this chain.

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Yeah so and then here you have this chain code structure, so.

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The interesting part here is, uh we need an index.js file and we need here this lib folder in this lib folder. We have the uh chain code in the chain code, for example. So- and you see here, um this is the init function, yeah and here's a create function, so you can close this a little bit so, and that was the interesting part from me. So it's with the chain code it with this con new contract api.

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um It's really easy to create a train call yeah. This is the favorite contract api implementation here and uh with uh this is a high level. So uh when we say the create asset function here and uh that's it so we can have here, you can make here an object, um that's how you can, how you do it in nodejs and then here you have this uh put state and uh the only thing what you have to uh do is that you create uh uh you have to convert this asset here.

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This object here to um to strip to a puffer, to a bite array and and that's it so, and we have two lines of code to create an asset, and I think that's really easy and also you read function here when you read an asset yeah, you can also say: okay, that's the read the get state yeah.

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So this is everything every time the same so and you have a get state, then you have an asset in the json format and then you can convert this. uh This is paid. This is in bi and I think that's wrong here. It's not json, it's it's in its fight and with the true string you convert this buffer uh to uh jason and that's it and and with this I think so. Okay, when you say this is the the error, uh the error handling.

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So we have one two lines of code and with two lines of code you can read an asset uh from your blockchain and I think that's really easy to do and also the update. So the update here is the same like the creation process. So yeah you see here, this is a bootstrap and this is also a bootstrap.

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So in fact there is no difference between the creation and the update process, because um you could you create an asset and the asset uh has an id and has a buffer here and and and that's it and uh when you update, then you update also this id the asset with this id with a new uh information here and then you have a new state of this asset and that's it and that's in the new state is the new world state and the new world state is then available in the uh state database or uh in level b or in the indication, for example, and that's it.

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So I think- and that's really easy to see how you can transfer asset here so, but it is also the same. You have here a boot state and you override the last state of the asset and that's it so, and this is really easy uh to use and also the get all asset method here is uh so that's the history of an asset.

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No, it's not in history get all assets. Is uh we don't returns all assets from the world state here so yeah? So it's I think uh you have here uh in in the get here in the get example- and you read the example, we will receive only one element here, yeah and uh here in this get all assets, so we we we receive multiple. So this is another um function.

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Here gets state by range and then here we can have a range and when we don't use a range, when we leave it a blank, then it means all uh efforts, and uh here we receive an, uh we receive uh multiple assets and then we have here um and promise here we can promise and with that next we can uh have uh recite here and about this result we can uh loop and convert every um every line in this in this array, uh to uh yeah to a record here, left record and pass this to json, and then we can uh in this example, it's all pushed to any way uh into an objective way here in this format.

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So we have the key with the key in the in the in the from the blockchain and then they record information as a whole. um Json object here and uh yeah and that's it so and you see also a function like I get all assets or it's create here. A range of assets is really easy to implement here.

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And yeah so, and that's and that's it for this chain code example and what we have to do now that we can install this. So um when we look into this so here we have to when you copy this, when you clone this favorite examples repository, then you have to install the npn packages here, and uh here you see when we do the mbm install. Then all these dependencies here- and we say here these two dependencies- the favorite contract api and this feature npm packages. So these are the dev dependencies.

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uh It's only for testing, so we don't need this for our chain code here. So that means uh we have to. In our example, we have to npm install and npm install, and then we can, uh then all these node modules will be installed and and loaded. So I have I did this in the preparation here and and that's it so these are.

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This is the the same step as we did for the go installation where we use this vendor folder and the one vendor folder indigo um world is also manage, also the external dependencies and here the node modules. This is the same for the in the in the world of node: shares.

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Okay, so and when we have mbm installed, then we can switch back to our desk network and uh we have to configure this environment variable fabric config path, and this config path must link to the config folder and the test network. Has this config folder here and the important part here is the core yaml file here. So that is the file which the config part path here.

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So you can check this with the end command and you see here grab.

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Favorite matches here is your path.

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And is the same like print, it's the same command and then we have to package this chain code, it's the first step, so we can. We have this command, be a life cycle chain code package, so we say this is the and the packages entire entire package at zip tab package, and uh this is the outcome. This is the result and here is with the path option. This is the path to our file from this current location here and then so we can do.

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Something is wrong, ah no, so this is the command, and this is the uh the flag so which I have mentioned earlier. So uh we have to say this is no chairs and we do that with this length option here, and this is what when we use go. This is the default language we don't have to set, but when we use another language, when we use java or uh javascript here, then no chairs here, then we have to use this flag and the label is the same like every time here.

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Okay, so then we should have here a basic tar file here and yeah that we can so uh to work with the test network. We need also to set some environment variables and the test network gives us a script. It's called infra and you find this under the scripts uh folder, and we can uh use this and with this, uh when, when we use the script, then we have the possibility to use a function set globals and uh with global one.

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We can switch or set all environment variables which are needed for organization one in this test network and when we say set global's two, then we switch to the organization too, and we use in both versions the ps0.

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So on the switch too, then we're using organization one and then we can install this with the life cycle chain code installed and then this tar package, so we can install it.

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This takes some seconds and you see here.

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So payload- and we have identifier here and the same for organization true, so we can, we can switch to organization two and then we install the chain code also on the pier null vs0 organization tool.

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Okay, then let us switch back to organization one, and then we have the possibility to check so for the approve process here approve from org.

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We need the package id, so this package id and this package id is this one here this one and we can create this also so, with this query installed a command and when we do this- and we see here, we can query the peer 0 on organization 1, and we see these chain codes are installed here so because we can install different chain codes uh on this peer on on this channel and um yeah. So and we need this. Is this identifier?

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So you see, this is the same identifier. Okay,.

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And we export this, so we can use it a little bit easier and then we have to approve this a group for organization one.

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This is all the same as we have seen in the in the examples uh before so um yeah, so but here important the package id. So we need this particular package ready and we have here the sequence one, because this is the first, the first write for this chain code and uh in version one for example. So, but when we upgrade, for example, then we have to increase this number here so yeah, but it could also be diversion one this chain code, because this is only for you.

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This is an naming convention uh for the human uh and not for the for the blockchain, and the sequence number is for the blockchain. So when we install an upgrade, then we have to here also to uh increase this number, and this version could also could also be version one because maybe we have an uh an error in our chain code and uh in our process we are. We have version 1.1 of 1.0 and from from this chain code, and uh we have to increase the sequence.

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Number on every change on this chain code, so let's do it that's the reason why this number can different to this number here.

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So and then yeah we have the valid here and then we can switch to organization two.

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So and then we do the same.

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And this is not a different to the go chain code or to the java chain code yeah. This is always the same, and then we can use the commit command.

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And we have here two wallets.

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That looks good, and here we can see uh if this there's another command, it's called query committed, and then we see uh what is the result of the approved process here and you see here the approvals and you see okay organization, one msp membership service provider has approved this and the organization true membership provider has also here true. That means this organization has also approved this chain code, but this it could.

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There could be a situation where, if you have three organizations, for example- and uh you have the the uh train code, lifecycle endorsement or the change lifecycle policy, the default policy and the default policy says, the majority must approve a chain code, then that there could be a situation where, where two organizations has has improved this chain code, but the third organization not- and you can own, but they can also install this uh chain code uh in the network.

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But you can change this with your lifecycle, endorsement policies and you can say: okay, only only all three members has will have to improve, uh have to approve this chain code, but in the default configuration it's, the majority and uh two uh or three are the majority so and that's two and that's the command where you can check how your organization has uh voted on this uh chain code, for example, okay and that's it, uh the chain code is installed and the only difference between the standard way with go is here.

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So when we package the chain code, we have to say language node.

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The rest here is always the same and of course you have to write the chain code in nodejs in javascript, and then you have uh npm installed to do the npm install uh that you can have the uh favorite contact api npm packages or this package, and that's all, but this process is the same uh like in go when you use code, and you also have to use to go vendor to load the dependencies, and here we also have to install the dependencies.

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That's the same, but it's done a little bit different because of the different languages here and but the difference here. This is new, so you have to set language note or language java that you can use this correct at the rest and the rest is the same as you install every other chain code.

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Okay, so then we have this running so and you see this- and you see here, you have here your chain code containers and now you have uh some javascript or nodejs chain code containers run.

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And then you can, inter start interact with this and uh so okay, so okay, so here I have a test command, so we can test it with the clr, with the.

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Command line, so we can. The first uh is that we have to init the ledger, so our lecture doesn't have any uh information now and when we remember to this here.

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Here so now we have to call it in the lecture function and the init lecture function defines here some assets.

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There is a simple loop, a for loop yeah uh over this over this uh assets array here and uh with the with the put state function. The asset will be created in the in the blockchain, and this is the step we have to do. First.

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This command is a little bit long because we have here to set the you see here.

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So on the piers we have here localhost the first localhost here, so we have the low closed from pier 0 organization, 1, yeah and tls from this organization from the spear here and then you have the dp address from the second beer here: localhost 1951 and also the tls project.

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The tls would certificate here the path to the wood certificate so and that's important that, because this is this majority rule, so when we have two, then we need the majority and only one has not the majority to invoke and chain code command here.

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So and that's the reason why we have to use here in when we use the cli command uh all this to appears, but when we use it with the nodejs, then we don't have to do this, so we don't have to because node.js denotes sdk will know how many peers the the system needs to call this function.

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Okay, let us try this and that's it.

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Compose so um we use this locks and follow so, and so you can, you can see the logs here and yeah. You see here validated block six yeah, okay, so and then you can create, for example, okay,.

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Okay, so, and then we switch here to the second camera.

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Okay, now I will only so let me check this and now you see, uh there's an error. Config file not found yeah, favorite config path and that's the config path here so yeah. So that's the reason why we have to set this counting path.

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Of course we need the this environment and then we have to set some environment variables, so we say we are from the organization one and then we can create this, and you see here uh we can use here. When you do this, then you have this as a string on your side and then we we can bite this and you use the jk tool yeah. This is a javascript parser for the command line.

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Then you have a nice output here and you see all the assets we have created.

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Yeah so and then you can create also one asset and so on so uh yeah. So I said one, that's it true! So and uh now this works so now we we can say that we have used the nodejs um as a train code. We have installed this chain code, and now we have tested this chain code in the same way uh as we have they did the mibas with the go language, for example, with the gold chain code, and here you can also for the when updating asset yeah.

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You can try it so um yeah so, but this we will skip, and now we try this with node with the node shares, and uh for this I have created a new folder, my app- and this is basically uh copy and paste from the official uh from the official example, but I have a little bit modified this.

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So that we can understand it a little bit easier so.

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So here this application, javascript folder- and this is the application here so and here you find all the information you need to do this, but it's a little bit difficult to understand how this works together and uh yeah. So, but you can see here all the uh queries uh and on all queries are related to this uh basic transfer example, and you can try it and also the the enrollment process register, android role for user uh android admin and so on also the chain code and so on.

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But it's a little bit uh difficult to understand and that's the reason why I have changed this a little bit.

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And I've created.

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Another example: this is my up here.

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I have divided this. This example in three files- and I have here a helper file.

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Which has here three functions which we need, so we need this build connection profile, so that is the function uh which reads the connection profile, which is created to the to the start process of the network script and that's also an advantage from the network script. This creates this for you and json uh connection profile or yaml connection profile in the json format or in the yummy format. For this uh for organization one and for organization. Two, and with this script um we read the script from this file location here and uh pass it.

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There's a json object and returns it to uh to the usage here yeah. So that's and the connection profile uh contains all the information about our organization one and we can print it out later and then see. We will see what is in this connection profile and yeah. So and in this here we have the build a build wallet function.

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So we need this build wallet, function uh for the enrollment process of the administrator and the user, and also for the uh ledger actions here and then the small functions, uh the pretty json string, so that you can stringify the return string to a json object here. So we have here three functions and the first step is that we have to. We need some identities and to create their entities.

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We need an admin user and uh when we start when this fabric says started, then the admin user has a default. Password uh in in this case is the user admin and this is artbeam password. So when you look into the rocker compose file, there is a separate compose file for for the certified authorities and they are the depart the username and password is set, and this is the default name for this, and here we need the wallet path.

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And then we have here some functions: the build certified authority, client, we need decline and then one function for the in admin, enrollment and one function for the user enrollment here.

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So that user so and.

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So let us try this so and uh one important part we need some dependencies, we need the the spherical client dependency and we need the ferric network dependency here, and so we can so we can remove this and then we can say: okay, the first step is, do an npm install and then these two nodejs models will be installed.

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This you can find this also here so with the npm in it we create an and a node project, uh and here the npm installed with that so and then we have three files, this helper file, this tr actions and the ledger action action here. This is the these three files here, and the first step is that we need here.

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A bullet, so this is a this- is the wallet path here and in this in this folder, the identities from from your users uh are stored so and if and we need the admin identity to register users, engine royal new users and that's the reason why we first has to use this uh this script so with node on cr, ca actions, admin.

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I hope this works.

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Good okay, so I think we have a small problem here, so um why is this not.

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ah Okay, yeah, that's something! That's a small error, so this is my helper script, and so this was because of a small refectory.

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And here the same big wallet.

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So, okay, now it works. So this is a problem from the refactoring and uh so and now you see here a new file admin id and when we look a little bit into this file.

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And you see here the information so and we see here the certificate from this admin from this user, the private key from this user membership service provider and the type and the type is always this format. This is x509, so favorite ca and fabric.

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This is the only type which is accepted here and okay, so and in this ci actions file, I have uh two functions, this get get me function and then they get user function here and uh yeah. This is a small.

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Command here, so I passed the name here: admin the modules- you can say the modules here and then I call I can read this with the process and arc variable here, and then we have here on the second, the second uh position of this array, uh the arguments here. The second argument here this is the second argument and then, if it's admin, then I call the get admin function and then, if it's user, then I call this get user function here with the name on the position.

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Three so and that's the reason why I will say here: uh ci actions, user and uh beta, so we need the user beta, for example.

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um Okay, so and this get admin function, you have it here so- and this is here when you see this connection profile, we call this community connection profile and then we need a cr client, and this cr client is also this. uh Is this build cr client function which we have seen earlier and we need this uh nbn package here: ferrix cr, client.

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And the connection profile and the name of the certified society- and this is organization one and then here we have this- build wallet function which I have splitted in the build in the helper in the helper file, and it needs also two to parameters the wallet and the wallet path here and then we can use this enrollment um function here and with this enrollment function we have here the um you have it here, and you see here. This is the main function for in to enroll an admin, user and uh yeah.

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And then here we see that here's, the enrollment and that's important to know so the admin user is already registered, so this is registered when the favorites here is started, and then we only have to enroll enroll it here in the normal user we have first to uh which is study user, that's here.

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So this is the and then we can enroll it so, and we have first to register a user in this certified authority, and then we can enroll this user and convert this user uh to this wallet identity and put this identity in this wallet here and that's the second part we have to do so.

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The first, the next step is that we use this function uh to co to call this function here. So this get user function. We say we want the user roland.

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And now we have a second identity in our wallet.

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And you'll see here this wall and id and here when you log into that oops, then you see.

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Here the same now we have the certificate informations here yeah and we have his private key to sign the request and the membership service provider and uh yeah, and this is the first step in the preparation so uh already the the two first steps. So we need this um connection profile or the preparation of this connection profile and we need two users, the admin user and also an application user.

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And then we are ready to write our application, and uh this is now and uh to write the application. I did uh the same. I did the same so I created here.

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A script and we have I've implemented here, one two: three functions: they get all asset function with an asset function and create another asset here, and this works in the same way. So because we we need here the helper function. With this to read the connection profile, then we need the information from the wallet also from the helper function, and then we need a gateway. So here we create the new instance of this, of the gateway object. So here this comes from the favorite network.

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So here this is the wallet which we have used, also in the cr ca example, and we need the gateway from this and here's the wallet path. So you know the wallet path, yeah, just in the same folder- and this is the name of the folder, and these some constants here are the name of the user and the user is the name of the identity and then the information about the channel which channel we are going the query and which chain code.

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We are going to query here and then we have to make a connection and that's pretty easy. So there's this connect function comes from the gateway here from the gateway, and we need the connection profile. The information about the wallet then which identity we should use and then the information, how the network, how the sdk should discover the network and uh with the discovery. True then everything is, is done automatically.

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So this then uh the nodejs sdk will use uh the gossip protocol and we will discover all the informations in your network and the only thing what we need in the connection profile is the path to one pier so and then the sdk connects to this particular pier and then collects all the information about the network and uh yeah and as local hoster. That means only the flag is when we use this at low close, and this is this is the connection so, and I think that's also, I think, to enroll and register users.

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That's a little bit complicated because you have to um to look what is needed and how you can query the ca and and register and roll in user yeah. So that's the reason why I have splitted this in a separate file that we have this in another scope.

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And then, when we have this information in place, then we need only less things to connect to the network. So we need this connection profile information. So let's start here in this ccp connection profile. Then we need. uh Okay.

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Where is the wallet located? Because in this wallet is my identity, then we need a gateway, object, yeah and this gateway object makes the connection so, and this is the same process as you uh do it. When you use a database for example, then you need also a username, a password, the host uh database name, for example, and that's similar the same information. So the connection profile is: where is your host information? The wallet is the place. Where is your? uh Where are your identity stored and then what is the username? What is the identity?

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And, uh of course we have no password here, because we use here the um areas, a company component, the certificate and the private key from this user. So we don't need any password here and the discovery here is only how the sdk can find the information about the network and that's it. Then we have a connection here and then the next step is okay.

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When we are connected to the network so to the channel, for example, channel uh to the ps0 from organization one which channel we would like to connect and uh with the get network from the channel, so we say channel one that's our channel, then we have a a connection to the channel and the next information is which chain code we would like to use- and this is done with net network, get contract here and the chain code name. And then we have a contract.

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And at this point here we are ready to use uh our uh chain code and query the information or create and create an asset or whatever we want to do in this chain code and with this contract here we can use two functions. So in this example.

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Basically, you can use this two functions, so one is to evaluate transaction. So that's important because when you use evaluate transaction then you send your create only to your peer to connected peer and when you use the submit transaction, then you use the order so and that's a diff, that's the difference.

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So the submit transaction will always uh try to invoke to and to invoke the chain code, the create asset chain code and uh is sent to the orderer and the other uh does his work and so on so, but this took, uh I think so until two seconds in a normal setup like we use it here and um yeah, it's a little bit too slow, but you can also use and read asset function yeah with the submit transaction. It will also work, but it takes some time it takes two seconds and it's not very efficient.

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So and that's the reason why we have two different uh functions here in the contract class. The evaluate transaction is queue is only your local instance, and this is pretty fast so and uh when you submit something when you create an asset and you update an asset when you transfer an asset every time when you change an asset, then you have to use a submit function and this is called submit transaction and then the process works. So how many?

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How many uh peers have to improve this transaction? And then the sdk sends a broadcasting to all the peers and then the peers have to uh evaluate this transaction have to simulate. This transaction sends the transaction proposal proposal back and then all the transaction proposals are back and the sdk knows. Okay, we have the majority, then we need at least two successful uh transaction proposal.

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Then it then uh the sdk sends the proposal to the order and the order does his work and then, if everything is in place, uh the order are committed, these these transactions to a block. What does the block and so on and then follows the typical uh transaction flow which is done in the favorite system and but you can also call the sweet asset with the submit transaction.

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So this will work, but it takes two seconds and because it runs through the whole process and it's uh of course better when we use this evaluate transaction function for queries. And that's also when we remember to this cli uh example. Then we have also the possibility to call invoke or to query, and the query means that it's created the local beer and and that's important to understand that here we have an a specific query function which creates the local environment.

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So the local beer here, for example, ps0 from this organization and then we have a separate, submit transaction. We took some time uh until everything is in place and uh yeah. That's it so and when we try this here now,.

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So then I have here yeah so and okay. We can call this.

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And you see this one.

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And you see here the same recite like before, but from the client side and also when we're doing the read asset function.

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We just set one.

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Okay, then there's an error, because this is it. The error handling is not good implemented here so and then this can query as 2, 3 and so on, and you can also create an asset here, and here we create a new asset asset 14, with this informations.

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And you see here, then you see here the the informations, the lock from there and then we can click sub 14.

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And you see it works and yeah so, and this is how you can use node.js for your client application.

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So um I think, with with this simple steps here, uh it's very easy to query- to use node.js as a client for your favorite network so and there are only some steps to do, and these steps are similar to maybe a database connection and the important parts only here. So when we we can make here a console log, for example, for this ccp.

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And you see here, this is the connection profile.

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And you see here for the organization, one, the connection profile has some informations about the beers. So what is what are the user and what is the ibrs and the address of the bs?

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What is the tls certificate of the beer and so on so and also for the certified authority, but this is only needed if you uh register and enroll new new users when you use it, uh maybe the user one identity which is automatically generated from the network script from the from the build script from the start strip script, then you only need you don't need this information because you don't need these uh certified authority actions here and uh then you only need this in your connection profile and uh and that's all what you need so yeah, but this informations will be generated in your test network every time new.

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Then, if this, if the system uh starts here- and I think that's all the organizations.

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I don't know: what's the script ah we can look um helper.

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This is on the test network organizations, peer organizations and organization, one example so, and here organizations peer organization of organization, one and then you have here these two files and you can use this as a json file or as a yaml file, and when you look into this file, then you see here all the informations and and this file will be created every time you when you use the uh the network script. This is an the the script to start and stop the network.

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And if you run your own network for example, then you have to create, then you have to create.

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A connection profile in this way.

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So I think the structure is easy to understand, so the only difficult part is how you can do this, so how you can.

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Copy the the content in this in this in a single line file, but uh in I think in the last or in one of my sessions there is a function in my repose, where you can see how you can do this. So that's in one liner to do this.

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It's an, uh I think, a set command.

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So yeah and that's uh that's the connection profile, so yeah there's no magic behind this. Then you need the information about your wallet. You need the wallet, object and the wallet path so, and this.

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This is this information here in this folder. All your identities are stored. Yeah, then you need the gateway. Okay, this is something an object, and then you have to connect it and to connect it. You need these informations, the connection profile. So what is your network?

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Where is my wallet which user want wants to connect, and is it localhost or not, and should I use the discovery service or not? And then you have a a connection. So the await. That's important that you use this await here, because that's an asynchron uh function and the javascript has has to wait until this.

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uh This function is ready and yeah, and then you need, of course, the channel name and the chain code name and that's it, and then you have the link to the contract and then, when you have the contract, you can do uh your basic functions. You can query all your all your chain code.

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All your chain code, queries with the evaluate transaction function, and the name, and also with the uh here, is there with the options here so get all assets uh doesn't need any options, but read asset has an option yeah, because we have defined this um yeah in there in the in the in the train code and and then you can call and that's it. So I think that's easy in the database uh in the database query sometimes and also for the create asset.

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So when you submit a transaction, then you have to use this function here and send your parameters here and that's it and then you you can disconnect from the gateway and that's it.

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So I think, to query and to center transaction is, is a little bit easier um as uh to understand what is needed to get the user and to enroll and register register and to involve a user here yeah. So, but this is an if this is something you need not so so often and uh yeah, but I think it's not so. The important part to know is that when you want to and when you want to create a new user, the first step is always to register this user.

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Also, when you do it in the with the cli yeah, and then you receive a secret from this and then you can enroll it uh with this secret, so yeah, the user id and the secret is important. So here this is an important step here that you store the secret and then enroll the user with the secret, and then here you put this into the wallet so yeah and with wallet.

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This is the wallet you know, and then you have here: roland id and admin id and whatever it is okay. So I think now we are done with the basic overview, how you can use nodejs as a chain code, and I think that's pretty easy to do so, especially for a simple or for standard youth standard use case, and then you can use nodejs also for your uh for the client- and I think it's also not so complicated to do this.

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So I think it's more complicated to build the rest api around this system, yeah and.

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Yeah and the certified authority actions: uh this could be a little bit uh complicated and difficult difficult to understand.

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What provides the command set globals.

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This is the command set global, so this is the function set globals here.

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And this function, the only thing uh this function does is to set different environment variables within fabric. uh When we use the cli version, we have to to define some environment very variables, so this is the here, the local membership service provider, so that we say: okay, we have someone from organization, we will use organization one and the id from organization. One is organization, one msb and this idea is country, is configured in the conflict txtml file.

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So that's a simple name and id from this organization and then, when we use tls, then we have to define the path to the root certificate and we have to say: okay, we are what is the p address? What is the? Where? Is the membership service provider, config folder, a config user, config folder? And you save here- and this is from the admin user, so this user is is working now in our example.

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So this is here organization one we have for users folder, and this is the admin user and then every user has a membership service provider folder and in this folder are the important credentials for this user and there is another user. As I have mentioned, user one or one example.com, also with a membership service provider, a folder this- this user identity- we could. We could also use for our nodejs example here.

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But then we there's also a script um where we can convert this existing to this wallet and then here the the address, the peer address and that's all so and they said globals function in this test network. We have uh normally two um peers, but there is an extended version where we can extend the network to a second at the third organization and that's the reason why we have here organization, free msp and that's the job from the set globals function here.

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You can do this also without without this function and export this free environment variables. If you.

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Question nobody.

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Okay, if okay, can you elevate on ctx and its method stop? I was explained very well.

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Can you evaluate on ctx it's metabones now, that's in in in nodejs, it's a little bit difficult, because so um personally, I tried to prepare myself for the developer certification and uh I did my preparation uh with go on the notre dame.

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On the chain on the chain code side- and um now I have to switch also to uh no chairs for that, and I think we have to look about this information. That's not not so easy to explain um so from there.

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Let's we have to it's not.

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So I mean this, you mean.

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So I think to understand this uh context and this stop here we have to look into the in not into the favorite contract api.

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We have to look into the favorite shim and because that's this isn't high level. So uh it's very easy to use this, and uh when we look into the week into the into the favorite trim package, then we will see more about this context and throughout this stop implementation here here we have only uh the the the extents from this contract and through this contract. We have access to this.

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To this uh context and to this stop here and yeah, so to evaluate this a little bit more, we have to look into this favorite uh shim package. I think.

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Is there anybody out there who wants to do the developer certification in the near future?.

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Cool, so you have to do it also with node in nodejs, yeah, okay,.

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But now it's uh it's stopped so when you have enrolled it already, uh then I think the certification process is stopped now and.

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I received an email last week this week I received an email last week and in this email there was a date, the 16th of march. There will be the start of the of of the certification, but I don't know if this time is the time where this is open to the public, because they have. The information already gave the information that it will test it with the proctors. So maybe this is only for the test for testing for this exam and and not open for the public, but we will see.

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um Yeah, if no questions, then uh I have to say thank you. I will publish uh the slides later um and also the recording, and then you can. uh Maybe you can try, try to reproduce this example with my script and uh if you have any question to this scripture then feel free to ask me and yeah. So that's from my side, thanks for your attention and your time and stay safe in this time and yeah, we will see you soon.

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