avro入门之rpc

关于avro的rpc入门使用，官方给的资料实在是太少了，这个链接https://github.com/phunt/avro-rpc-quickstart有具体说明

现在对在java下使用总结如下：

参考：http://www.iteblog.com/archives/1008

http://my.oschina.net/zhzhenqin/blog/151040

http://www.bianceng.cn/Servers/web/201411/46469.htm

我这里没有使用maven，直接在项目中加入使用到的jar包有：avro-1.7.7.jar、avro-tools-1.7.7.jar、 jackson-core-asl-1.8.8.jar、jackson-mapper-asl-1.8.8.jar

当然，如果你需要，你也可以在Avro源码中进行编译，获取avro-1.7.7.jar和avro-tools-1.7.7.jar

Avro协议是以JSON结构性描述文本。协议定义了基本的通信的数据类型，名称。并且还包含可调用的方法等。首先定义协议文件

{
    "namespace":"avro",
    "doc":"This is a message.",
    "protocol":"messageProtocol",
    "name":"HelloWorld",
    "types":[
        {
            "name":"nameMessage",
            "type":"record",
            "fields":[ {"name":"name", "type":"string"} ]
        }
    ],
    "messages":{
        "sayHello":{
            "doc":"say Hello to manbers",
            "request":[ { "name":"name", "type":"string" } ],
            "response":"nameMessage"
        }
    }
}

保存在d盘 a.avro

然后编写服务端代码：

import java.io.File;

import org.apache.avro.Protocol;
import org.apache.avro.Protocol.Message;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.ipc.HttpServer;
import org.apache.avro.ipc.Server;
import org.apache.avro.ipc.generic.GenericResponder;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class AvroHttpServer extends GenericResponder {

    private static Log log = LogFactory.getLog(AvroHttpServer.class);

    public AvroHttpServer(Protocol protocol) {
        super(protocol);
    }

    public Object respond(Message message, Object request) throws Exception {
        GenericRecord req = (GenericRecord) request;
        GenericRecord reMessage = null;
        if (message.getName().equals("sayHello")) {
            Object name = req.get("name");
            //  do something...
            //取得返回值的类型
            reMessage = new GenericData.Record(super.getLocal().getType("nameMessage"));
            //直接构造回复
            reMessage.put("name", "Hello, " + name.toString());
            log.info(reMessage);
        }
        return reMessage;
    }

    public static void main(String[] args) throws Exception {
        int port = 8088;
        try {
            Server server = new HttpServer(
                    new AvroHttpServer(Protocol.parse(
//                            new File("helloword.json"))),
                    		new File("d:/a.avro"))),
                    port);
            server.start();
            server.join();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

接下来编写客户端代码：

import java.io.File;
import java.net.URL;

import org.apache.avro.Protocol;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.ipc.HttpTransceiver;
import org.apache.avro.ipc.Transceiver;
import org.apache.avro.ipc.generic.GenericRequestor;
import org.junit.Before;
import org.junit.Test;

public class b {
	private Protocol protocol;

    private GenericRequestor requestor = null;

    @Before
    public void setUp() throws Exception {
        protocol = Protocol.parse(new File("d:/a.avro"));
        Transceiver t = new HttpTransceiver(new URL("http://localhost:8088"));  //这里如果要在两台机器上运行记得把localhost改成服务端的ip
        requestor = new GenericRequestor(protocol, t);
    }

    @Test
    public void testSendMessage() throws Exception {
        GenericRecord requestData = new GenericData.Record(protocol.getType("nameMessage"));
        // initiate the request data
        requestData.put("name", "zhenqin");

        System.out.println(requestData);
        Object result = requestor.request("sayHello", requestData);
        if (result instanceof GenericData.Record) {
            GenericData.Record record = (GenericData.Record) result;
            System.out.println(record.get("name"));
        }
        System.out.println(result);
    }

}

上面先运行服务端在运行客户端，可以看到客户端收到消息。

{"name": "zhenqin"}
Hello, zhenqin
{"name": "Hello, zhenqin"}

以上参考http://my.oschina.net/zhzhenqin/blog/151040

至于用python编写跨语言的客户端，具体内容还有待研究