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Currently we offer support for bundling venin via rollup with support for other bundlers being scheduled, yet not committed.

General considerations​

Venin is delivered in both es-module and common-js formats. The challenge with bundling the library boils down to whether or not you wish to use the SolidityCompiler function in-browser. If you wish in-browser compilation, a web-worker is provided which fetches the appropriate solidity-compiler binary before carring out the compilation itself via calling any of the Contract.newFrom/Contract.allFrom family of functions.

Compiling path variants of the same Contract.newFrom/Contract.allFrom family of functions is made possible via a synthetically injected ContractsInFileStorage class which is basically a dictionary mapping the path of each solidity file from a given folder (default contracts) to its content.


You don't have to manually deal with ContractsInFileStorage in code. The bundler ties everything up for you so that, for example, if you have a file a.sol in a contracts folder situated in the root of your repo, ContractsInFileStorage would be generated holding something approximating:

export default {
"a.sol": <code of a.sol>,

This will, for instance, allow calling Contract.newFrom({ path: "./a.sol" }).

ContractsInFileStorage is not the only class being synthetically generated. ContractRegistry is another one which gets injected regardless if in-browser compilation is being used or not. This one is important since it contains contract names to their ABI mappings which is needed for acquiring LiveContract instances of already deployed Contracts. I'm talking here about the ApiSession.getLiveContract({ id, abi }) method call.


For the same a.sol file situated in the contracts folder described above, if, let's say, it contains a A contract and a B contract inside, ContractRegistry will end up looking something similar to:

export default {
"A": <ABI code for contract A>,
"B": <ABI code for contract B>,

This allows calling ApiSession.getLiveContract({ id, abi: ContractRegistry.A }) to get an instance of an already deployed A LiveContract to interact with.

What about nested solidity files?​

What if you have a A contract defined in a.sol which is situated in a subfolder 'othersincontracts? So basically, contract Ais located somewhere atcontracts/others/a.sol`. How does this work?

We've got you covered!

In this scenario, ContractRegistry will be generated to something approximating:

export default {
"others/A": <ABI code for contract A>,

which will allow you to reference its ABI via ContractRegistry["others/A"].

Besides synthetically generated classes, process.env also needs to be unpacked and injected to make the bundling possible.


If you're using rollup to bundle your app, we have made available a plugin to take care of all the considerations described above. It's being available at @buidlerlabs/rollup-plugin-hashgraph-venin and you can immediately dive into a working demo here.

If you're going down this path, you will need to first install it through something like

npm install --save-dev @buidlerlabs/rollup-plugin-hashgraph-venin

Importing the rollup-plugin gives access to a default-exported function that generates a rollup-behaved object.


You can find more in-depth docs for our rollup-plugin in its dedicated github page. Feel free to scroll around and bash us with any issues you might hit.

Following is just a quick summary of them.

Currently, it accepts the following options object:

contracts?: {
path?: string,
recurse?: boolean,
environment?: NodeJS.ProcessEnv,
includeCompiler?: boolean,
sourceMap?: boolean,


  • contracts.path is the path of the folder holding the contracts to load into ContractRegistry and possibly ContractsInFileStorage (if includeCompiler is true). Defaults to contracts
  • contracts.recurse controls the behavior of navigating the contracts.path files. If set to true, it uses recursion to load everything from contracts.path. false only loads the first level of files. Defaults to false
  • environment is the environment object that gets unpacked and injected in the library. It defaults to process.env
  • includeCompiler allows for in-browser compilation when set to true and throws an error when trying to compile if set to false. Defaults to false
  • sourceMap controls source-map generation. true generates the source-maps, false does not. Defaults to false

If you're changing contracts.path to something non-default, be sure to also change the HEDERAS_CONTRACTS_RELATIVE_PATH config value so that Venin itself knows how to locate and compile your sources and have the synthetically defined classes (eg. ContractRegistry) generated.

For further guidance, please see the demo repo rollup.config.js which makes use of this rollup plugin with in-browser compilation turned on.