express-protocol

Decode protobuf data for express

• With the protobufjs library.
• It's easy to use.

Installation

npm i express-protocol

Usage

For the client example

Include script tag in html

	<script src="https://raw.githubusercontent.com/chenxianming/express-protocol/master/dist/protobuf.min.js"></script>

FE encode data to buffer

  var root = protobuf.parse(`
	syntax = "proto3";
	package awesomepackage;

	message AwesomeMessage {
		optional string stringVal = 1;
		message EmbeddedMessage {
			optional int32 key2 = 1;
			optional string key3 = 2;
		}
		optional EmbeddedMessage embeddedExample1 = 2;
		optional int32 key4 = 3;
		optional string ke5 = 4;
	}
  `).root;

  var AwesomeMessage = root.lookupType("awesomepackage.AwesomeMessage");

  var message = AwesomeMessage.create({
	  stringVal:'123',
	  embeddedExample1:{
		  key2:1,
		  key3:'123'
	  },
	  key4:123,
	  key5:'111'
  });

  var buf = AwesomeMessage.encode(message).finish();
  var arr = buf.toString();

  //Send array string to server
  post( {protoBuf:'['+arr+']' } )

If you completed setup server, try to encode postdata and decode response data.

The post format like this one , or you can submit "application/json" format.

  $.post('/', {protoBuf:'['+arr+']' }, function( data ){

	  var root = protobuf.parse(`
		  syntax = "proto3";
		  package test;

		  message Message {
			optional string msg = 1;
			message ResultMessage {
				required int32 statusCode = 1;
				required int32 count = 2;
				message Listobj {
				  required string key1 = 1;
				  required int32 key2 = 2;
				}
				repeated Listobj list = 3;
			}
			optional ResultMessage result = 2;
		  }
	  `).root;

	  var arr = [];

	  var proto = root.lookupType("test.Message");

	  var buf = new Uint8Array( data.protoBuf );

	  console.log( proto.decode(buf).toJSON() );
  });

You will recived an array to parse.

Log the decode result;

For the node client( Example for post encode only )

let buf = AwesomeMessage.encode(message).finish();

let data = buf.toJSON().data;

let postArr = [];

data.forEach( a => postArr.push( a ) );

let arr = '['+postArr+']';

	//send postdata to server
request( {protoBuf:arr} );

For the server route

const ExpressProtocol = require("express-protocol");

let indexDecode = new ExpressProtocol({
  packName: "awesomepackage.AwesomeMessage",
  parse: `
	  syntax = "proto3";
	  package awesomepackage;

	  message AwesomeMessage {
		  optional string stringVal = 1;
		  message EmbeddedMessage {
			  optional int32 key2 = 1;
			  optional string key3 = 2;
		  }
		  optional EmbeddedMessage embeddedExample1 = 2;
		  optional int32 key4 = 3;
		  optional string ke5 = 4;
	  }
  `,
  sendName: "test.Message",
  send: `
	syntax = "proto3";
	package test;

	message Message {
	  optional string msg = 1;
	  message ResultMessage {
		  required int32 statusCode = 1;
		  required int32 count = 2;
		  message Listobj {
			required string key1 = 1;
			required int32 key2 = 2;
		  }
		  repeated Listobj list = 3;
	  }
	  optional ResultMessage result = 2;
	}
  `
});

router.post("/", indexDecode.decode(), function(req, res, next) {

    //You will recived a json data from req.body.protoData          
    console.log( req.body );

	//And you can see the buffer data in the client response.
	res.json({
		msg: "ok",
		result: {
			statusCode: 200,
			list: [
				{
					key1: "123",
					key2: 456
				},
				{
					key1: "test",
					key2: 789
				}]
		}
	});

});

Config / syntax

let indexDecode = new ExpressProtocol({
	packName:'Index, to get the proto function object',
	parse:'Text, protocol buffer descriptor',
	sendName:'options, like a packName, if you want to response protobuf json to client',
	send:'Text, protocol buffer descriptor for response json.'
});

In the express route

router.post("/", indexDecode.decode(), function(req, res, next) {
	//do something
});