Mojom example

README.md

Overview

• math.mojom is the definition of the service
• math.ts is auto-generated code based on Mojo definition: it gives a stub and a type definition of an implementation
• mathImpl.ts is an actual implementation of Math service.
• mathRPC.ts is the necessary code to call a remote implementation of Math service via JSON-RPC (using a RPCPeer). It can be auto-generated as well.

In the best world, dev just have to define math.mojom and implement mathImpl.ts, the logic of the service. The rest is code-generated.

Local usage

import { Math } from './math.ts'
import { MathImpl } from './MathImpl'

const math = new Math(new MathImpl());

const { sum } = await math.add({a: 1, b: 2});
// sum is 3

Remote usage

In process A (server):

import { Math } from './math.ts'
import { MathImpl } from './mathRPC.ts'

const rpcPeer = getRPCPeer();

const math = new Math(new MathImpl(rpcPeer));

const { sum } = await math.add({a: 1, b: 2});
// sum is 3

In process B (usage):

import { MathImpl } from './MathImpl'
import { bindImpl } from './mathRPC.ts'
const rpcPeer = getRPCPeer();

bindImpl(rpcPeer, new MathImpl());

math.mojom

module bx.util;

interface Math {
  Add(int32 a, int32 b) => (uint32 sum);
}

math.ts

export type IMathAddRequest {
  a: int;
  b: int;
}

export type IMathAddResponse {
  sum: int;
}

export interface IMath {
  add: (r: IMathAddRequest) => Promise<IMathAddResponse>;
}

    
// stub
export class Math implements IMath {

  constructor(impl) {
    this.impl = impl;
  }

  async add(r:IMathAddRequest ): Promise<IMathAddResponse> {
    return await this.impl.add(r);
  }
}

mathImpl.ts

import { IMath } from './math.ts';

export class MathImpl implements IMath {
  async add(r) {
    return r.a + r.b;
  }
}

mathRPC.ts

import { IMath } from './math.ts';

export class MathRPCImpl implements IMath {
  static module = 'bx.util';
  static interfaceName = 'Math';

  constructor(rpcPeer: RPCPeer) {
    this.peer = rpcPeer;
  }

  async add(r) {
    return this.peer.request('bx.util.Math.Add', r);
  }
}

export class bindImpl = (rpcPeer: RPCPeer, impl: IMath) => {
  rpcPeer.addHander('bx.util.Math.Add', async (r) => {
    return await impl.add(r);
  })
}