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Posted to commits@servicecomb.apache.org by ni...@apache.org on 2019/12/10 06:17:09 UTC
[servicecomb-website] branch master updated: upload
service-center-client post
This is an automated email from the ASF dual-hosted git repository.
ningjiang pushed a commit to branch master
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The following commit(s) were added to refs/heads/master by this push:
new deb7fe8 upload service-center-client post
deb7fe8 is described below
commit deb7fe895fcab873c9e0dcd9640d88376ce9e47f
Author: zhouzhongyuan <zh...@SERVICECOMB.IO>
AuthorDate: Mon Dec 9 17:15:37 2019 +0800
upload service-center-client post
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assets/images/client/sc-sample-consumer.png | Bin 0 -> 6375 bytes
assets/images/client/sc-sample-provider.png | Bin 0 -> 5405 bytes
5 files changed, 212 insertions(+)
diff --git a/_posts/cn/2019-12-09-servicecomb-service-center-client.md b/_posts/cn/2019-12-09-servicecomb-service-center-client.md
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+---
+lang: cn
+title: "使用ServiceComb客户端轻松调用ServiceCenter"
+ref: servicecomb-service-center-client
+permalink: /cn/docs/servicecomb-service-center-client/
+excerpt: "使用ServiceComb客户端轻松调用ServiceCenter"
+last_modified_at: 2019-12-09T14:00:30+08:00
+author: Zhou Zhongyuan
+tags: [ServiceCenter,Client]
+redirect_from:
+ - /theme-setup/
+---
+
+# 使用ServiceComb客户端轻松调用ServiceCenter
+
+## 1. 问题/背景
+在微服务架构中，服务注册中心是必不可少的组件，提供服务注册与管理的能力。目前使用ServiceComb服用中心的java微服务开发者，不仅需要写微服务业务代码，还要写客户端代码去调用ServiceCenter的openAPI。开发者首先需要熟悉ServiceCenter的openAPI文档，然后代码实现http客户端用于发起请求和接收响应，并绑定ServiceCenter配置参数，最后代码实现对服务中心API的调用，才能使用上ServiceCenter。为了简单化开发者使用ServiceCenter，ServiceCenter客户端实现了上述步骤。开发者只需要添加客户端jar包调用API就能轻松使用ServiceCenter，不需要过多关注openAPI文档、不需要写http客户端层代码。使用ServiceComb客户端，开发者可以轻松调用ServiceCenter，更专注于写微服务业务代码。
+了解更多ServiceComb-Service-Center：[https://docs.servicecomb.io/service-center/zh_CN/index.html](https://docs.servicecomb.io/service-center/zh_CN/index.html)
+了解更多ServiceCenter客户端：[https://github.com/apache/servicecomb-java-chassis/tree/master/clients/service-center-client](https://github.com/apache/servicecomb-java-chassis/tree/master/clients/service-center-client)
+
+
+## 2. 客户端原理及关键代码解读
+2.1 基于httpClient设计ServiceCenter客户端
+ - 客户端发起请求和接收响应。客户端选择httpclient作为底层组件，用于实际发起请求和接收响应，并对请求和响应类进行了封装。代码中get方法对应发起GET请求，调用doRequest方法首先添加服务注册中心信息到封装过的httpRequest请求头部，再基于httpclient组件发起实际的http请求，最后将请求响应结果转化为封装过的httpResponse对象返回。
+
+ ```java
+ //make GET request
+ @Override
+ public HttpResponse get(HttpRequest request) throws IOException {
+ request.setMethod(HttpRequest.GET);
+ return doRequest(request);
+ }
+ ......
+
+ //make http request with httpClient component
+ public HttpResponse doRequest(HttpRequest httpRequest) throws IOException {
+ //add cse-serviceregistry-client header to identify client
+ httpRequest.addHeader(HEADER_CONTENT_TYPE, "application/json");
+ httpRequest.addHeader(HEADER_USER_AGENT, "cse-serviceregistry-client/1.0.0");
+
+ if (globalHeaders != null) {
+ globalHeaders.forEach(httpRequest::addHeader);
+ }
+
+ //make http request
+ org.apache.http.HttpResponse response = httpClient.execute(httpRequest.getRealRequest());
+
+ int statusCode = response.getStatusLine().getStatusCode();
+ String messgae = response.getStatusLine().getReasonPhrase();
+ String context = EntityUtils.toString(response.getEntity(), "UTF-8");
+
+ return new HttpResponse(statusCode, messgae, context);
+ }
+ ```
+
+ - 客户端支持定制化服务中心配置参数。代码中看到，客户端支持开发者定制服务中心IP，端口，项目名称，租户名称，导入TLSConfig和新增请求头，并通过客户端的Builder方法注入配置。TLSConfig为客户端TLS认证配置类，给客户端导入TLS证书配置，即可开启客户端双向认证模式。
+
+ ```java
+ /**
+ * Customized host, port, projectName, tenantName, TLSConf, headers and any one parameter can be null.
+ */
+ public ServiceCenterClient(String host, int port, String projectName, String tenantName, TLSConfig tlsConfig,
+ Map<String, String> extraGlobalHeaders) {
+ HttpTransport httpTransport = HttpTransportFactory.getDefaultHttpTransport();
+ if (tlsConfig != null) {
+ httpTransport = new TLSHttpsTransport(tlsConfig);
+ }
+ httpTransport.addHeaders(extraGlobalHeaders);
+
+ //set configuration parameters
+ this.httpClient = new ServiceCenterRawClient.Builder()
+ .setHost(host)
+ .setPort(port)
+ .setProjectName(projectName)
+ .setTenantName(tenantName)
+ .setHttpTransport(httpTransport).build();
+ }
+ ```
+
+2.2 ServiceCenter客户端核心API
+- 服务注册与发现，注册服务和实例到服务注册中心，根据服务ID发现服务实例。registerMicroserviceInstance方法用于注册服务实例，发起httpPOST请求访问服务实例注册URL，并将实例注入到请求body中，返回服务ID字符串; getMicroserviceInstanceList方法用于发现服务的所有实例，根据服务ID，发起httpGET请求访问服务发现URL，返回MicroserviceInstancesResponse对象。
+ ```java
+ //service register
+ public String registerMicroserviceInstance(MicroserviceInstance instance, String serviceId) {
+ try {
+ ObjectMapper mapper = new ObjectMapper();
+ mapper.configure(SerializationFeature.WRAP_ROOT_VALUE, true);
+ HttpResponse response = httpClient.postHttpRequest("/registry/microservices/" + serviceId + "/instances", null,
+ mapper.writeValueAsString(instance));
+ if (response.getStatusCode() == HttpStatus.SC_OK) {
+ return response.getContent();
+ } else {
+ throw new OperationException(
+ "register service instance fails, statusCode = " + response.getStatusCode() + "; message = " + response
+ .getMessage()
+ + "; content = " + response.getContent());
+ }
+ } catch (IOException e) {
+ throw new OperationException(
+ "register service instance fails", e);
+ }
+ }
+ //service discovery
+ public MicroserviceInstancesResponse getMicroserviceInstanceList(String serviceId) {
+ try {
+ HttpResponse response = httpClient
+ .getHttpRequest("/registry/microservices/" + serviceId + "/instances", null, null);
+ if (response.getStatusCode() == HttpStatus.SC_OK) {
+ ObjectMapper mapper = new ObjectMapper();
+ return mapper.readValue(response.getContent(), MicroserviceInstancesResponse.class);
+ } else {
+ throw new OperationException(
+ "get service instances list fails, statusCode = " + response.getStatusCode() + "; message = " + response
+ .getMessage()
+ + "; content = " + response.getContent());
+ }
+ } catch (IOException e) {
+ throw new OperationException(
+ "get service instances list fails", e);
+ }
+ }
+ ```
+- 心跳，服务实例发送心跳告知服务中心。代码中发起httpPUT请求中访问心跳URL，并导入HeartbeatsRequest （包含服务ID和实例ID）到请求body中，响应状态码为200表示心跳成功。
+ ```java
+ //heartBeats
+ public void sendHeartBeats(HeartbeatsRequest heartbeatsRequest) {
+ try {
+ ObjectMapper mapper = new ObjectMapper();
+ HttpResponse response = httpClient
+ .putHttpRequest("/registry/heartbeats", null, mapper.writeValueAsString(heartbeatsRequest));
+
+ if (response.getStatusCode() == HttpStatus.SC_OK) {
+ LOGGER.info("HEARTBEATS SUCCESS");
+ } else {
+ throw new OperationException(
+ "heartbeats fails, statusCode = " + response.getStatusCode() + "; message = " + response.getMessage()
+ + "; content = " + response.getContent());
+ }
+ } catch (IOException e) {
+ throw new OperationException(
+ "heartbeats fails ", e);
+ }
+ }
+ ```
+
+2.3 更多客户端API介绍，参考客户端说明文档 [https://github.com/apache/servicecomb-java-chassis/tree/master/clients/service-center-client](https://github.com/apache/servicecomb-java-chassis/tree/master/clients/service-center-client)
+
+## 3. ServiceCenter客户端实践
+3.1 实践准备
+- 启动ServiceComb服务中心：[http://servicecomb.apache.org/cn/docs/service-center/install/](http://servicecomb.apache.org/cn/docs/service-center/install/)
+- 下载演示代码：[https://github.com/zaneChou1/spring-boot-servicecenter](https://github.com/zaneChou1/spring-boot-servicecenter)
+
+3.2 provider端启动服务，通过客户端注册到ServiceCenter
+运行provider模块，启动helloServer服务，并调用客户端API创建客户端对象、创建helloServer服务和实例对象、注册服务和实例到servicecomb 服务中心，并保持30s一次心跳，代码实现如下。
+ ```java
+ public static void registerMicroservice(){
+ //new ServiceCenterClient object
+ ServiceCenterClient sc = new ServiceCenterClient();
+
+ //new Microservice object and setting properties and serviceName is necessary
+ Microservice microservice = new Microservice();
+ microservice.setServiceId("1111");
+ microservice.setServiceName("HelloServer");
+ //register microservice to service-center
+ sc.registerMicroservice(microservice);
+
+ //new MicroserviceInstance object and bind server IP and port
+ MicroserviceInstance instance = new MicroserviceInstance();
+ List<String> endPoints = new ArrayList<String>();
+ endPoints.add("rest://127.0.0.1:8080/");
+ instance.setEndpoints(endPoints);
+ //setting instance hostName, instanceId and hostName is necessary
+ instance.setHostName("test");
+ instance.setInstanceId("2222");
+ //register microservice instance to service-center
+ sc.registerMicroserviceInstance(instance,microservice.getServiceId());
+
+ //send a heartbeat every 30s
+ HeartbeatsRequest heartbeatsRequest = new HeartbeatsRequest("1111","2222");
+ while(true){
+ sc.sendHeartBeats(heartbeatsRequest);
+ try {
+ Thread.sleep(30000);
+ } catch (InterruptedException e) {
+ e.printStackTrace();
+ }
+ }
+ }
+ ```
+查看service-center的UI显示如下，helloServer服务注册到服务中心成功，且有一个服务实例test。
+
+访问provider服务监听的8080端口，返回“Hello Spring-Boot-ServiceCenter !”。
+
+
+3.3 consumer端通过客户端发现服务实例，发起服务调用
+运行consumer模块，启动consumer服务，调用客户端API新建客户端对象、发现helloServer服务实例、获取服务监听的IP和端口，最后调用provider端helloServer服务返回结果。
+```java
+//find service instance
+ServiceCenterClient sc = new ServiceCenterClient();
+MicroserviceInstancesResponse instances = sc.getMicroserviceInstanceList("1111");
+//get IP and port that service is listening on
+URI endpointURIBuilder = new URIBuilder(instances.getInstances().get(0).getEndpoints().get(0)).build();
+int port = endpointURIBuilder.getPort();
+String host = endpointURIBuilder.getHost();
+
+//call service
+RestTemplate restTemplate = new RestTemplate();
+ResponseEntity<String> result = restTemplate.getForEntity("http://"+host+":"+port,String.class);
+return result.getBody();
+```
+访问consumer端监听的8081端口，返回helloServer的响应结果“Hello Spring-Boot-ServiceCenter !”，consumer端通过ServiceComb服务注册中心调用provider端服务成功。
+
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