I am developing a business network with hyperledger composer. I have followed the tutorial on composer web site at composer playground and have made the tutorial-network as well. Now I am facing one issue. after finishing defining your business network, how is it possible to get the underlying Fabric code that is generated? I can't think of a reason why it should be necessary to have it directly, but lets say if for any reason, like having to give Fabric code to your customer for whom you have developed a poc, you need to have that. Is Fabric code being saved somewhere? I have looked into the business network folder; there are only subfolders for models, test, the business network itself, and after you generate the archive file there is only one file with .bna extension. Nothing related to Fabric there!
I appreciate your help.
As part of the deployment of your business network, an associated Composer runtime is included that can parse model files, query file and acl files, it is also capable of executing your transaction processor functions. In 0.16.x this was achieved by including a JavaScript VM implementation using Go Chaincode to execute the Composer runtime (written in JavaScript) and the transaction processor functions. In Fabric 1.1, chaincode can be written natively as it now supports Node.js chaincode so with Composer beyond 0.16.x (currently 0.19.x at the time of writing) Composer utilizes this and all Go chaincode it used to contain was removed, along with the Javascript VM. It's the composer runtime that parses the model, query and acl files, and the transaction processor functions run natively inside the node.js fabric chaincode container. Nothing is ever compiled to Go.
The smart contract will be saved in different manner in fabric, as composer is just an abstraction over it. You need to search for the location where the chaincode is present inside the peer. There are some chaincode related commands which can help you in finding out where the chain code is installed. And to the client you can give the .bna file if you are using composer for the development because I am not sure whether the code will be easily readable at fabric level if you are using composer.
Related
I'm studying Hyperledger Fabric with the documentation(https://hyperledger-fabric.readthedocs.io/en/release-1.0/write_first_app.html)
I'm done with two samples, which is "Building Your First network" & "Writing Your First Application"
I'm also done adding 1 extra peer to each organization, by modifying certain files, as well as done trying all commands on "Writing Your Fist Application" session.
Now, I'd like to execute the same commands(e.g. Querying all cars, Adding new cars or whatever) on the first network where I have built up, not on the test Fabcar network.
The thing is that I really have no idea what to do and how to do, even though I know how to handle NodeJS program(by Writing Application webpage)
So I'd like to ask you some questions.
Should I modify some files in order to "move" all necessary things to my network? if so, which file should I modify?
By any chance, Could you please tell me the correct steps to make it? I feel like I need to install and instantiate the required smart contract on my peers. Am I right?
I really appreciate your help in advance.
To answer your question, you would need to read some documentation online that will help you understand the architecture and how you can build up the packages as hyperledger fabric provided freedom to users to create use case specific configurations.
To start with.
Make sure you have have understood the concept of peer, orderer, couchdb, ca authority. Those 4 things you need to play with most of the times.
Assuming you have installed nodejs and able to run node through terminal, Read through the following example
Tuna Fish example, it help you to understand the concept of injecting, updating, querying blockchin ledger. Also, It will help understand the usage of Nodejs backend and angularjs basic UI. or use the other examples as you have seen on the fabric-samples github repository. Fabric Samples. Balance Transfer will help you understand the channel and chaincode operations using Node JS. Build your first network will help you understand the configuration files(concentrate on docker-compose.yaml, scipt.js and byfn.js)
Then to answer your questions.
you just have to modify the mount drive config variables in docker-componse-cli.yaml. Then you can edit your startup script based on how you want to move chaincode to your peer.
you need to install chaincode on all the peers that are part of that channel. And you only need to instantiate chaincode once per channel.
Installation and instantiation combination is a powerful feature because it allows for a peer to interact with the same chaincode container across multiple channels. The only prerequisite is for the actual chaincode source files to be installed on the peer's file system. As such, if a piece of common chaincode is being used across dozens of channels, a peer would need only a single chaincode container to perform read/writes on all the channel ledgers.
To run the node js files on the fabric network.
welcome to blockchain world :)
I am new to hyperledger and bit confused about hyperledger composer & nodejs api.
I saw using composer we can create assets, transactions, participants and chaincode and in last we have to archive it this all into .bna file and finally we deploy this chaincode into network using admin card
But at other end using NodeJs API we can also write chaincode by overiding init & invoke methods.
How can we relate these all.
The best way to think about this is the following:
1) Hyperledger Fabric v1.1 supports writing chaincode in two languages: Golang and JavaScript via Node.js
If you want to do all of the heavy lifting yourself, you can write straight chaincode.
2) Hyperledger Composer provides a higher-level model-driven language for developing smart contracts. It currently only allows deployment of these artifacts to Hyperledger Fabric. It also happens to support writing functions in JavaScript as well.
So if you want to start from a higher-level model-driven approach, Hyperledger Composer is the way to go. If you want to write all of the plumbing yourself or use very low-level chaincode features, then using chaincode itself is the way to go.
Moving forward, we are looking at a better way to move between the two and not force a decision / direction up front.
There is another option, we develop a framework called Convector to be in the middle of Composer (high abstraction, low control) and raw code (low abstraction, high control, therefore high risk). We open sourced it a few days ago. At WorldSibu we don't like loosing so much control over our code like with Composer but as Gari Singh was saying, doing all the heavy lifting for each project is crazy. It is like a Mongoose for Hyperledger Fabric. It may help to check it out.
It is also worth noting that, according to IBM, Composer is no longer recommended as a production solution, but only for prototyping. In HLF 1.3, chaincode can now be written in Go, Javascript and Java.
I'm wondering how you can get a hyperledger fabric smart contract to read from external API's ?
A service called oraclize (http://www.oraclize.it/) is used to do this operation in Ethereum blockchains - Is there anything similar for hyperledger fabric smart contracts or any workarounds?
In Hyperledger Fabric - smart contracts (the chaincode), could be implemented at the moment with either golang or Java, both of which are Turing complete and provides you with reach set of libraries and frameworks. Among which you can you any network library to get connected with external services, while you need to be extra cautious doing this to make sure your chaincode is deterministic (e.g. two independent executions of the same chaincode calling same external API will get same result back).
Riccardo from Oraclize here.
We are actually working on a Oraclize integration with Hyperledger.
Other than the fact that Composer makes deployment and testing of prototype business networks easier and the fact that we don't have to know golang to develop chaincode, what is the difference in the functionalities that these interfaces provide that may lead one to choose one over the other?
This article can probably provide you with the answers you need:
https://blog.selman.org/2017/07/08/getting-started-with-blockchain-development/
Hyperledger Composer is both an application development framework and set of powerful tools which simplifies and expedites the creation of blockchain applications and smart contracts that are ultimately executed on the Hyperledger Fabric blockchain. Composer has its own runtime, that is generic chaincode and hosts and interprets the business network deployed - so your smart contract need only use Javascript, not chaincode in Go a (which is Fabric's domain) s you mentioned. It also has a modeling facility to create your business network model and to define such controls as Access Control lists and queries to be executed.
This architecture link should help you with further understanding -> https://www.slideshare.net/SimonStone8/hyperledger-composer-architecture
Furthermore see the Hyperledger Composer docs, see here:
https://hyperledger.github.io/composer/
TO see the Hyperledger Fabric docs - see here:
https://hyperledger-fabric.readthedocs.io/en/latest/
I want to know how Fabric Composer works internally by transforming .bna file to chaincode and how key-value pairs are actually stored in the couch db/state db for the given assets, participants and transactions.
Thanks
see the links here.
Composer Architecture: https://www.slideshare.net/SimonStone8/hyperledger-composer-architecture
This architecture deep dive shows the internal workings, in terms of runtime architecture -> https://www.slideshare.net/dselman/hyperleger-composer-architecure-deep-dive
This article will also be useful to see a side-by-side comparison:
https://blog.selman.org/2017/07/08/getting-started-with-blockchain-development/#more-901
On key/value - see here -> What is the relationship between assets created in a composer network to the assets in fabric chaincode?
Finally, do note its now called Hyperledger Composer and no longer called Fabric Composer, just FYI.