Simple gRPC javascript client example

EventStoreDB V20.X
1

Hello,
I’m new to gRPC, EventstoreDB API and the whole configuration - gluing it makes me a headache.
Can someone please just give a very, very simple sample of working gRPC Node client, for example with “Append” method? I need something to begin with, official SDK is in TS , complex to read and understand for me, spent already few hours on it.

2

Could you elaborate a bit more on this? TypeScript just adds types, we don’t use classes, the API is based on functions. Also, the example in README is pure JS https://github.com/EventStore/EventStore-Client-NodeJS#example

3

Thanks for your quick reply!
Now I see that I may have been misunderstood. Syntax of NodeJS SDK is clear, readable and I get it to work with my dev env.
What I want to do is to communicate with ES without official SDK, using ‘@grpc/grpc-js’ and ‘@grpc/proto-loader’ - I plan to create Node-RED subflow which will be using gRPC nodes (which operates on .proto files).

I’m using below code:

const protoLoader = require('@grpc/proto-loader');
const grpc = require('@grpc/grpc-js');

const packageDefinition = protoLoader.loadSync("streams.proto");
const es_proto = grpc.loadPackageDefinition(packageDefinition).event_store.client.streams;

function main() {
	//const metadata = new grpc.Metadata();
	//metadata.set("authorization", Buffer.from(`Basic ${user}:${pass}`).toString("base64"));
	let client = new es_proto.Streams("10.0.60.13:2113", grpc.credentials.createInsecure());

	var call = client.Append(function (error, success) {
		if (error) {
			console.log(error);
		} else {
			console.log(success)
		}
	});

	let data = JSON.stringify({"test": "test"})

	call.write({
		content: {
			options: {
				stream_identifier: {
					streamName: Buffer.from("yagtak").toString("base64")
				},
				expected_stream_revision: {
					any: {}
				}
			}
		}
	});

	call.write({
		content: {
			proposed_message: {
				id: {
					value: {
						string: "46412379-2379-2379-2379-160346412379"
					}
				},
				data: Buffer.from(data).toString("base64")
			}
		}
	});
	call.end();

}

main();

and getting error:

{ Error: 2 UNKNOWN: Exception was thrown by handler.
    at Object.callErrorFromStatus (/Users/tomek/Projects/grpc/node_modules/@grpc/grpc-js/build/src/call.js:31:26)
    at Object.onReceiveStatus (/Users/tomek/Projects/grpc/node_modules/@grpc/grpc-js/build/src/client.js:244:52)
    at Object.onReceiveStatus (/Users/tomek/Projects/grpc/node_modules/@grpc/grpc-js/build/src/client-interceptors.js:342:141)
    at Object.onReceiveStatus (/Users/tomek/Projects/grpc/node_modules/@grpc/grpc-js/build/src/client-interceptors.js:305:181)
    at process.nextTick (/Users/tomek/Projects/grpc/node_modules/@grpc/grpc-js/build/src/call-stream.js:124:78)
    at process._tickCallback (internal/process/next_tick.js:61:11)
  code: 2,
  details: 'Exception was thrown by handler.',
  metadata:
   Metadata {
     internalRepr:
      Map {
        'date' => [Array],
        'content-type' => [Array],
        'server' => [Array],
        'content-length' => [Array],
        'grpc-encoding' => [Array] },
     options: {} } }
2020-10-23T19:06:55.331Z | call_stream | [0] HTTP/2 stream closed with code 8

which say me nothing.

I have no idea how proper request body/bodies should looks like.

4

You can see by yourself by looking at the code. Here’s a link where we do a write request: https://github.com/EventStore/EventStore-Client-NodeJS/blob/master/src/command/streams/WriteEventsToStream.ts#L51

We also used “@grpc/grpc-js” and went the code generation route.

5

@yorick.laupa I am trying it out it on ReactJS client but I am getting complaints about http2 and framer packages but even after adding them I am still getting complaints about:

Error: Cannot find module ‘./framer’

6

We haven’t really planned for this client to get used on the UI. We call it the NodeJS client, not JavaScript client. Browser support for gRPC is still very weak and I won’t rely on that at all.

1 Like