d10087-micro-multi-rpc-calls.md

Micro, Multi Rpc Calls

From this chapter the picture will ignore the service details ( Sender/Consumer/EventBus ), show the service communication only.

1. Services

Here are four projects in this demo:

Http Port	Ipc Port	Ipc Service Name	Project	Role
6100	--	--	up-athena	Api Gateway
6201	--	--	up-atlas	Common Service
6401	6411	ipc-coeus	up-coeus	Coordinator A
6402	6412	ipc-crius	up-crius	Coordinator B

2. Source Code

2.1. MultiApi ( service: up-atlas )

package up.god.micro.multi;

import io.vertx.up.annotations.Address;
import io.vertx.up.annotations.EndPoint;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;

@EndPoint
@Path("/api")
public interface MultiApi {
    @Path("ipc/multi/{name}")
    @GET
    @Address("ZERO://RPC/MULTI")
    String sayHello(@PathParam("name") String name);
}

2.2. MultiWorker ( service: up-atlas )

package up.god.micro.multi;

import io.vertx.core.Future;
import io.vertx.core.json.JsonObject;
import io.vertx.up.unity.Ux;
import io.vertx.up.annotations.Address;
import io.vertx.up.annotations.Queue;
import io.vertx.up.commune.Envelop;

@Queue
public class MultiWorker {
    @Address("ZERO://RPC/MULTI")
    @SuppressWarnings("unchecked")
    public Future<JsonObject> sayHello(final Envelop envelop) {
        final String name = Ux.getString(envelop);
        final JsonObject params = new JsonObject().put("name", name);
        return Ux.thenParallelJson(
                Ux.thenRpc("ipc-crius", "RPC://SAY/MULTI", params),
                Ux.thenRpc("ipc-coeus", "RPC://SAY/MULTI", params)
        );
    }
}

2.3. MultiInsider ( service: up-crius )

package up.god.ipc;

import io.vertx.core.Future;
import io.vertx.core.json.JsonObject;
import io.vertx.up.annotations.Ipc;
import io.vertx.up.commune.Envelop;

public class MultiInsider {
    @Ipc("RPC://SAY/MULTI")
    public Future<JsonObject> sayMulti(final Envelop envelop) {
        final JsonObject data = envelop.data();
        data.put("service", "up-crius");
        return Future.succeededFuture(data);
    }
}

2.4. MultiInsider ( service: up-coeus )

package up.god.ipc;

import io.vertx.core.Future;
import io.vertx.core.json.JsonObject;
import io.vertx.up.annotations.Ipc;
import io.vertx.up.commune.Envelop;

public class MultiInsider {
    @Ipc("RPC://SAY/MULTI")
    public Future<JsonObject> sayMulti(final Envelop envelop) {
        final JsonObject data = envelop.data();
        data.put("service", "up-coeus");
        return Future.succeededFuture(data);
    }
}

3. Testing

When you started all above services, you can see more information in console, and then testing with Postman

URL : http://localhost:6100/api/ipc/multi/lang.huan

Method : GET

Response :

{
    "data": {
        "0": {
            "name": "lang.huan",
            "service": "up-crius"
        },
        "1": {
            "name": "lang.huan",
            "service": "up-coeus"
        }
    }
}

4. Summary

This chapter show that one service connect to two rpc services scenarios, you can check more details of this example. Here you can use Ux.thenParallelJson method to merge one or more Future<JsonObject> type, also you can modify the worker as following:

    @Address("ZERO://RPC/MULTI")
    @SuppressWarnings("unchecked")
    public Future<JsonObject> sayHello(final Envelop envelop) {
        final String name = Ux.getString(envelop);
        final JsonObject params = new JsonObject().put("name", name);
        return Ux.thenParallelJson(
                Ux.thenRpc("ipc-crius", "RPC://SAY/MULTI", params),
                Ux.thenRpc("ipc-coeus", "RPC://SAY/MULTI", params)
        ).compose(item -> {
            final JsonObject crius = item.getJsonObject("0");
            final JsonObject coeus = item.getJsonObject("1");
            return Future.succeededFuture(new JsonObject()
                    .put("name", crius.getValue("name"))
                    .put("first", crius.getValue("service"))
                    .put("second", coeus.getValue("service"))
            );
        });
    }

Then you should get following response instead of original:

{
    "data": {
        "name": "lang.huan",
        "first": "up-crius",
        "second": "up-coeus"
    }
}

You can do your own calculation based on response from different rpc services, then you can provide correct response to client.