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new 11fe550 Translate the article dubbo2.js
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commit 11fe55044cb0bb07d25ed897fdbabe63b171824a
Author: Stella0824 <34200550+stella0...@users.noreply.github.com>
AuthorDate: Wed Aug 15 11:43:40 2018 +0800
Translate the article dubbo2.js
* add en blog
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blog/zh-cn/dubbo2-js.md | 4 +-
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+
+# Implementation of cross-language calls by dubbo2.js
+> [dubbo2.js](https://github.com/dubbo/dubbo2.js) is a Dubbo client for
node.js developped by [Qianmiwang](https://www.qianmi.com/). It supports
Dubbo's native protocol, which makes the RPC calls between javascript and java
efficient and agile. This tool has been contributed to Dubbo's community.
+
+## Cross-language calls for micro service
+Nowadays, Internet architecture tends to be micro-service way. The discussions
about micro-service architecture becomes the most mentioned topic in different
technical conferences. In China, most of the companies, such as Qianmiwang,
choose Dubbo as their micro-servie architecture solution. As most of the
internet companies, Qianmiwang uses various of programming languages. Java is
for most of the backend services. Each business based on these backend can
choose its own programming langu [...]
+
+ - Spring cloud. Spring cloud provides a set of components for micro-service
development. It is based on HTTP protocol and is designed in the restful way,
which makes it support cross-language calls. Other languages can call the
services simply by implementing an HTTP interface.
+ - Service mesh. People call service mesh the next generation of
micro-service framework. The core of this solution is SideCar. Even though the
concept of SideCar changes a lot during the revolution of Service mesh, its
main job never changed: providing reliable communication between different
services.
+ - Motan. [Motan](https://github.com/weibocom/motan) is an open source
cross-language service framework developped by Sina Weibo. Its early version
only supports motan-java. However, as the new versions come out, more languages
are supported in order to handle the cross-language problem. Its newest
version(1.1.0) provides motan-go, motan-php, motan-openresty, etc. Similar to
SideCar in Service mesh, Motan forwards messages by mortan-go, which can be
considered as an agent. Meanwhile, mo [...]
+
+ According to the solutions below, there are two ways to solve the
cross-language calls problem:
+
+ - communicating by a common protocol.
+ - implementing an agent as a protocol adapter.
+
+ When a new team is choosing technical solutions, what I mentioned below
could be our candidates. Meanwhile, the old system's compatibility and
migration costs should also be considered. The first trial we did is to work on
RPC protocol.
+
+## Cross-language calls by a common protocol
+
+ ### SpringMVC
+
+ 
+
+ Before achieving the real cross-language calls, the most common solution is
to use the http protocol. We can call Dubbo provider indirectly by
controller/restController provided by springmvc. This is easy to carry out, but
there are lots of inconveniences. firstly, a call will go through too many
nodes. Secondly, an extra communication layer (for http protocol) will be
involved, but it could have been handled simply by the TCP protocol. Thirdly,
we need to implement the RPC interface i [...]
+
+ ### We support some common protocols
+
+ Most of the service management frameworks support multiple protocols, dubbo
as well. Besides its own protocol, the common protocols such as Dangdangwang's
[Rest](https://dangdangdotcom.github.io/dubbox/rest.html) protocol and
Qianmiwang's [json-rpc](https://github.com/apache/incubator-dubbo-rpc-jsonrpc)
protocol are also supported.
+
+ The developers getting used to traditional RPC interfaces might feel
uncomfortable while working on restful RPC interfaces. On the one hand, this is
not good for rebuilding new interfaces. On the other hand, restful style might
make these interfaces incompatible with the other protocols used by old
interfaces. Of course, if there is no old system problems, using Rest protocol
is the easiest implementation of cross-language calls, since most of the
languages support it.
+
+ Even if Dubbo has tried on restful interface, the difference between rest
architecture and RPC architecture should not be ignored. Rest architecture
defines each resources, and it needs basic operations of http protocols such as
GET, POST, DELETE, PUT. In my opinion, a Rest protocol is more for calls
between different systems on the internet, while RPC is suitable for inner
system calls. Similar to Rest protocol, json-rpc is also implemented by text
sequence and http protocol. Using js [...]
+
+ Json-rpc is Qianmiwang's early solution for cross-language protocol. They
open-sourced their [dubbo-client-py](https://github.com/dubbo/dubbo-client-py)
and [dubbo-node-client](https://github.com/QianmiOpen/dubbo-node-client), two
clients based on json-rpc protocol. With these tools, we can easily call the
rpc services provided by dubbo-provider-java with while using python or
node.js. The inner system calls for java services are still mainly implemented
by Dubbo protocol. In addition, [...]
+
+ ``` xml
+ <dubbo:protocol name="dubbo" port="20880" />
+ <dubbo:protocol name="jsonrpc" port="8080" />
+ ```
+
+### Customized Protocols for Cross-language Support
+
+The so-called protocol of the microservice framework can be simply interpreted
as: message format and serialization scheme. Generally, the service governance
framework would provide numbers of protocol configuration items for users to
choose from. In addition to the above two common protocols,there exists some
other customized protocols like the dubbo protocol, the default protocol for
the dubbo framework, and Motan2, a cross-language protocol provided by the
motan framework.
+
+#### Motan2 for cross-language support
+
+
+
+
+
+In the original Motan protocol, the protocol message consisted only of the
Header and the Body, making deserialization indispensable for acquiring data
stored in the Body, like path, param and group, which is terribly unfriendly
for cross-language support. Therefore, the content of the protocol was
modifiedin Motan2, Weibo released the open-source projects,
[motan-go](https://github.com/weibocom/motan-go/),
[motan-php](https://github.com/weibocom/motan-php) and
[motan-openresty](https:// [...]
+
+
+
+
+
+
+After observation we find out that there is no big difference between the
configuration of Motan2 and the dual protocol. It’s just that the agent here is
implicit, and it co-exists with the main service. The most obvious difference
is that different languages do not interact directly in agent scheme.
+
+#### Dubbo for cross-language support
+
+Instead of cross-language support, the dubbo protocol was originally designed
only for common rpc requests. However, it’s not always the case that we can
only choose to support it or not. We can always choose to offer different
levels of support. It may be hard to offer cross-language support based on the
dubbo protocol, but not impossible. Actually, Qianmiwang succeeded. It
conquered the front-end cross-language business field built by nodejs with
dubbo2.js. It builds the bridge between [...]
+
+##### Dubbo protocol message format:
+
+
+
+
+
+Details in dubbo protocol header message:
+
+- Magic: similar to magic number in Java bytes code files, which is used to
determine whether it is a data pack of dubbo protocol. The magic number is the
constant, 0xdabb.
+- Flag: contains 8 bits. The lower four bits are used to indicate the type of
serialization tool used for message body data (default hessian). Among the
upper four bits, the 1 at first bit indicates request, the 1 at second bit
indicates dual transfer, 1 at third bits indicates the heartbeat.
+- Status: used toset response status. Dubbo defines some types for response.
Details can be found in <span data-type="color" style="color:rgb(36, 41,
46)"><span data-type="background" style="background-color:rgba(27, 31, 35,
0.05)">com.alibaba.dubbo.remoting.exchange.Response</span></span>
+- Invoke id: Message id,Type long, Unique indentifier for each request (Due to
asynchronous communication, it is used to match the request to the
corresponding returned response)
+- Body length: message body length, type int,record bytes of body content.
+- Body content: request param, where serializedresponse parameters are stored.
+
+Protocol messages will eventually become bytes and be transmitted using TCP.
Any language that supports network modules and has a socket will be able to be
communicatedwith. Then, why cross-language support is difficult? There are two
main obstaclesin calling service in Java using other languages:
+
+1. <span data-type="color" style="color:#24292E">How </span><span
data-type="color" style="color:#212121">can different languages represent
data types in java, especially dynamiclanguages with possible non-strict data
types</span>?
+2. <span data-type="color" style="color:#24292E">How to serialize string
across language?</span>
+
+## How does dubbo2.js solve problems?
+
+
+We have analyzed two obstacles above. The key to dubbo2.js in solving these
two problems depends on two class libraries:
[js-to-java](https://github.com/node-modules/js-to-java)，[hessian.js](https://github.com/node-modules/hessian.js).
js-to-java, which makes nodejs have the ability to express Java objects.
Hessian.js provides serialization capabilities. With the help of nodejs socket,
and a duplicate set of dubbo protocol message format, we can finally achieve
nodejs call to java-dubbo [...]
+
+
+## Quick Start
+
+
+To give an intuitive feeling to readers interested in dubbo2.js, this section
presents a quick start example that shows how easy it is to call dubbo service
using dubbo2.js.
+
+### 1. Initiate dubbo-java-provider
+Java provides the backend dubbo service. Firstly, let’s define the service
interface:
+```java
+public interface DemoProvider {
+ String sayHello(String name);
+ String echo() ;
+ void test();
+ UserResponse getUserInfo(UserRequest request);
+}
+```
+
+Then we implement the interface:
+```java
+public class DemoProviderImpl implements DemoProvider {
+ public String sayHello(String name) {
+ System.out.println("[" + new SimpleDateFormat("HH:mm:ss").format(new
Date()) + "] Hello " + name + ", request from consumer: " +
RpcContext.getContext().getRemoteAddress());
+ return "Hello " + name + ", response form provider: " +
RpcContext.getContext().getLocalAddress();
+ }
+ @Override
+ public String echo() {
+ System.out.println("receive....");
+ return "pang";
+ }
+ @Override
+ public void test() {
+ System.out.println("test");
+ }
+ @Override
+ public UserResponse getUserInfo(UserRequest request) {
+ System.out.println(request);
+ UserResponse response = new UserResponse();
+ response.setStatus("ok");
+ Map<String, String> map = new HashMap<String, String>();
+ map.put("id", "1");
+ map.put("name", "test");
+ response.setInfo(map);
+ return response;
+ }
+}
+```
+
+After that,<span data-type="color" style="color:#24292E"> we expose the dubbo
service with xml files:</span>
+
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
+ xmlns:dubbo="http://code.alibabatech.com/schema/dubbo";
+ xmlns="http://www.springframework.org/schema/beans";
+ xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
+ http://code.alibabatech.com/schema/dubbo
http://code.alibabatech.com/schema/dubbo/dubbo.xsd";>
+
+ <!-- dubbo provider info, used to compute dependency -->
+ <dubbo:application name="demo-provider"/>
+
+ <dubbo:registry protocol="zookeeper" address="localhost:2181"/>
+
+ <!-- dubbo protocol, used to expose service at port 20880 -->
+ <dubbo:protocol name="dubbo" port="20880"/>
+
+ <!-- realize a service as a local bean -->
+ <bean id="demoProvider"
class="com.alibaba.dubbo.demo.provider.DemoProviderImpl"/>
+
+ <!-- claim for service interfaces to expose -->
+ <dubbo:service interface="com.alibaba.dubbo.demo.DemoProvider"
ref="demoProvider" version="1.0.0"/>
+
+</beans>
+```
+
+After we implemented all the configurations on server side, initiate an object
initiater to register a dubbo service locally:
+
+```java
+public class Provider {
+ public static void main(String[] args) throws Exception {
+ ClassPathXmlApplicationContext context = new
ClassPathXmlApplicationContext(new
String[]{"META-INF/spring/dubbo-demo-provider.xml"});
+ context.start();
+ System.in.read();
+ }
+}
+```
+
+### 2. Implement dubbo client-side for nodejs
+Install dubbo2.js using npm:
+```sh
+npm install dubbo2.js --save
+```
+
+Configure dubboConfig.ts:
+```typescript
+import { Dubbo, java, TDubboCallResult } from 'dubbo2.js'
+
+const dubbo = new Dubbo({
+ application: {name: 'demo-provider'},
+ register: 'localhost:2181',
+ dubboVersion: '2.0.0',
+ interfaces: [
+ 'com.alibaba.dubbo.demo.DemoProvider',
+ ],
+});
+
+interface IDemoService {
+ sayHello(name: string): TDubboCallResult<string>;
+}
+
+export const demoService = dubbo.proxyService<IDemoService>({
+ dubboInterface: 'com.alibaba.dubbo.demo.DemoProvider',
+ version: '1.0.0',
+ methods: {
+ sayHello(name: string) {
+ return [java.String(name)];
+ },
+
+ echo() {},
+
+ test() {},
+
+ getUserInfo() {
+ return [
+ java.combine('com.alibaba.dubbo.demo.UserRequest', {
+ id: 1,
+ name: 'nodejs',
+ email: 'n...@qianmi.com',
+ }),
+ ];
+ },
+ },
+});
+```
+
+> Using typescript brings better coding experience.
+
+Implement caller class main.ts：
+
+```typescript
+import {demoService} from './dubboConfig'
+
+demoService.sayHello('kirito').then(({res,err})=>{
+ console.log(res)
+});
+```
+
+### 3. Call main.ts:
+
+Run nodejs client in Debug mode:
+
+```sh
+DEBUG=dubbo* ts-node main.ts
+```
+
+Checkout running results:
+
+```sh
+Hello kirito, response form provider: 172.19.6.151:20880
+```
+
+Congratulations！
+
+## Features
+
+
+- Support zookeeper as register center
+- Support TCP Dubbo Native protocol
+- Support directly Dubbo connection
+- Support link tracing
+- Generate dubbo interface Automatically
+
+## More details
+
+The sample code in this article is available here,
[https://github.com/lexburner/Dubbojs-Learning](https://github.com/lexburner/Dubbojs-Learning).
+If you don't know much about the dubbo protocol and want to understand
how it works, the project provides a sub-moudle: java-socket-consumer, which is
implemented in a process-oriented approach, realizing a process of sending
dubbo protocal message with native socket and making function calls, and then
get response.
+
+
diff --git a/blog/zh-cn/dubbo2-js.md b/blog/zh-cn/dubbo2-js.md
index a1d90b0..39d8413 100644
--- a/blog/zh-cn/dubbo2-js.md
+++ b/blog/zh-cn/dubbo2-js.md
@@ -90,7 +90,7 @@ dubbo协议报文消息头详解：
## dubbo2.js解决方案
-上面我们分析出了两个难点，dubbo2.js
解决这两个问题的关键依赖于两个类库：[js-to-java](https://github.com/node-modules/js-to-java)，[hessian.js](https://github.com/node-modules/hessian.js)
。js-to-java 使得 nodejs 具备 java 对象的表达能力，而 hessian.js 提供了序列化能力。借助于 nodejs 的
socket ，妇科一套 dubbo 协议的报文格式，最终便实现了 nodejs 对 java-dubbo-provider 的调用。
+上面我们分析出了两个难点，dubbo2.js
解决这两个问题的关键依赖于两个类库：[js-to-java](https://github.com/node-modules/js-to-java)，[hessian.js](https://github.com/node-modules/hessian.js)
。js-to-java 使得 nodejs 具备 java 对象的表达能力，而 hessian.js 提供了序列化能力。借助于 nodejs 的
socket ，复制一套 dubbo 协议的报文格式，最终便实现了 nodejs 对 java-dubbo-provider 的调用。
## dubbo2.js快速入门
@@ -268,4 +268,4 @@ Congratulation！
## 更多细节
-本文中的示例代码，提供在此处，<https://github.com/lexburner/Dubbojs-Learning> 。如果你对 dubbo
协议不慎了解，想要理解它的工作原理，项目中提供了一个子 moudle — java-socket-consumer，使用面向过程的思路实现了
java-socket-consumer，完成了原生 socket 发送 dubbo 协议报文，完成方法调用，并获取响应的全流程。
\ No newline at end of file
+本文中的示例代码，提供在此处，<https://github.com/lexburner/Dubbojs-Learning> 。如果你对 dubbo
协议不甚了解，想要理解它的工作原理，项目中提供了一个子 moudle — java-socket-consumer，使用面向过程的思路实现了
java-socket-consumer，完成了原生 socket 发送 dubbo 协议报文，完成方法调用，并获取响应的全流程。
\ No newline at end of file
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