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| <li class="toctree-l2"><a class="reference internal" href="#_1">工作流程</a> |
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| <li class="toctree-l1"><a class="reference internal" href="../using-java-chassis-in-spring-boot/using-java-chassis-in-spring-boot.html">在Spring Boot中使用java chassis</a> |
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| <li class="toctree-l1"><a class="reference internal" href="../config-reference/kie-client.html">ServiceComb Kie Client 配置项</a> |
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| |
| <h1 id="edge-service">使用 Edge Service 做网关</h1> |
| <p>Edge Service 是ServiceComb 提供的JAVA网关服务开发框架。Edge Service作为整个微服务系统对外的接口，向最终用户提供服务，接入RESTful请求，转发给内部微服务。Edge Service以开发框架的形式提供，开发者可以非常简单的搭建一个Edge Service服务，通过简单的配置就可以定义路由转发规则。同时Edge Service支持强大的扩展能力，服务映射、请求解析、加密解密、鉴权等逻辑都可以通过扩展实现。</p> |
| <p>Edge Service 本身也是一个微服务，需遵守所有微服务开发的规则。其本身可以部署为多实例，前端使用负载均衡装置进行负载分发；也可以部署为主备，直接接入用户请求。开发者可以根据Edge Service承载的逻辑和业务访问量、组网情况来规划。</p> |
| <h2 id="edge-service_1">开发 Edge Service 服务</h2> |
| <p>开发 Edge Service 和开发一个普通的微服务步骤差不多，开发者可以从导入<a href="https://github.com/apache/incubator-servicecomb-java-chassis/tree/master/demo/demo-edge">ServiceComb Edge Service Demo</a>入手。从头搭建项目包含如下几个步骤：</p> |
| <ul> |
| <li>配置依赖关系</li> |
| </ul> |
| <p>在项目中加入edge-core的依赖，就可以启动Edge Service的功能。Edge Service在请求转发的时候，会经过处理链，因此还可以加入相关的处理链的模块的依赖，下面的实例增加的负载均衡的处理链，这个是必须的。</p> |
| <pre><code><dependency> |
| <groupId>org.apache.servicecomb</groupId> |
| <artifactId>edge-core</artifactId> |
| </dependency> |
| <dependency> |
| <groupId>org.apache.servicecomb</groupId> |
| <artifactId>handler-loadbalance</artifactId> |
| </dependency> |
| </code></pre> |
| <ul> |
| <li>定义启动类</li> |
| </ul> |
| <p>和开发普通微服务一样，可以通过加载Spring的方式将服务拉起来。</p> |
| <pre><code>public class EdgeMain { |
| public static void main(String[] args) throws Exception { |
| Log4jUtils.init(); |
| BeanUtils.init(); |
| } |
| } |
| </code></pre> |
| <ul> |
| <li>增加配置文件microservie.yaml</li> |
| </ul> |
| <p>Edge Service本身也是一个微服务，遵循微服务查找的规则，自己也会进行注册。注意APPLICAIONT_ID与需要转发的微服务相同。在下面的配置中，指定了Edge Service监听的地址，处理链等信息。其中auth处理链是DEMO项目中自定义的处理链，用于实现认证。同时auth服务本身，不经过这个处理链，相当于不鉴权。</p> |
| <pre><code>APPLICATION_ID: edge |
| service_description: |
| name: edge |
| version: 0.0.1 |
| servicecomb: |
| service: |
| registry: |
| address: http://127.0.0.1:30100 |
| rest: |
| address: 127.0.0.1:18080 |
| handler: |
| chain: |
| Consumer: |
| default: auth,loadbalance |
| service: |
| auth: loadbalance |
| </code></pre> |
| <h2 id="_1">工作流程</h2> |
| <p>Edge Service的工作流程如下，蓝色背景部分在Eventloop线程中执行，黄色背景部分： |
| * 如果工作于reactive模式，则直接在Eventloop线程执行 |
| * 如果工作于线程池模式，则在线程池的线程中执行 |
| <img alt="" src="../assets/workFlow.png" /></p> |
| <h2 id="header">定制公共转发 Header</h2> |
| <p>Edge Service 在转发请求的时候, 会默认过滤掉 <code>公共请求头</code> 。 也就是除了 <strong>Provider</strong> 端显示 声明需要的 <code>HEADER</code> 外， 其他的 header 在转发的时候都会丢失。用户可以通过配置相关参数保留 公共请求头。</p> |
| <pre><code class="language-yaml">servicecomb: |
| edge: |
| filter: |
| addHeader: |
| # 开启 公共请求头保留功能。默认 false |
| enabled: true |
| # 要保留的公共请求头，以逗号隔开 |
| allowedHeaders: external_1,external_2 |
| </code></pre> |
| <p>如果对接了配置中心， 可以在配置中心动态修改 配置 <code>servicecomb.edge.filter.addHeader.enabled</code> 和 <code>servicecomb.edge.filter.addHeader.allowedHeaders</code> ， 配置动态生效。</p> |
| <h2 id="_2">定制路由规则</h2> |
| <p>使用Edge Service的核心工作是配置路由规则。场景不同，规则也不同。 |
| 路由规则由一系列AbstractEdgeDispatcher组成。Edge Service提供了几个常见的Dispatcher，通过配置即可启用，如果这些Dispatcher不满足业务场景需要，还可以自定义。</p> |
| <h3 id="defaultedgedispatcher">使用 DefaultEdgeDispatcher</h3> |
| <p>DefaultEdgeDispatcher是一个非常简单、容易管理的Dispatcher，使用这个Dispatcher，用户不用动态管理转发规则，应用于实际的业务场景非常方便，这个也是推荐的一种管理机制。它包含如下几个配置项：</p> |
| <pre><code>servicecomb: |
| http: |
| dispatcher: |
| edge: |
| default: |
| enabled: true |
| prefix: rest |
| withVersion: true |
| prefixSegmentCount: 1 |
| </code></pre> |
| <p>常见的这些配置项的示例及含义如下:</p> |
| <ul> |
| <li>[prefix=rest;withVersion=true;prefixSegmentCount=1]微服务xService提供的URL为: /xService/v1/abc，通过Edge访问的地址为/rest/xService/v1/abc，请求只转发到[1.0.0-2.0.0)版本的微服务实例。</li> |
| <li>[prefix=rest;withVersion=true;prefixSegmentCount=2]微服务xService提供的URL为: /v1/abc，通过Edge访问的地址为/rest/xService/v1/abc，请求只转发到[1.0.0-2.0.0)版本的微服务实例。</li> |
| <li>[prefix=rest;withVersion=true;prefixSegmentCount=3]微服务xService提供的URL为: /abc，通过Edge访问的地址为/rest/xService/v1/abc，请求只转发到[1.0.0-2.0.0)版本的微服务实例。</li> |
| <li>[prefix=rest;withVersion=false;prefixSegmentCount=1]微服务xService提供的URL为: /xService/v1/abc，通过Edge访问的地址为/rest/xService/v1/abc，请求可能转发到任意微服务实例。</li> |
| <li>[prefix=rest;withVersion=false;prefixSegmentCount=2]微服务xService提供的URL为: /v1/abc，通过Edge访问的地址为/rest/xService/v1/abc，，请求可能转发到任意微服务实例。</li> |
| <li>[prefix=rest;withVersion=false;prefixSegmentCount=2]微服务xService提供的URL为: /abc，通过Edge访问的地址为/rest/xService/abc，，请求可能转发到任意微服务实例。</li> |
| </ul> |
| <p>withVersion配置项提供了客户端灰度规则，可以让客户端指定访问的服务端版本。Edge Service还包含根据接口兼容性自动路由的功能，请求会转发到包含了该接口的实例。假设某微服务，兼容规划为所有高版本必须兼容低版本，部署了以下版本实例：</p> |
| <ul> |
| <li> |
| <p>1.0.0，提供了operation1</p> |
| </li> |
| <li> |
| <p>1.1.0，提供了operation1、operation2</p> |
| </li> |
| </ul> |
| <p>Edge Service在转发operation1时，会自动使用1.0.0+的规则来过滤实例</p> |
| <p>Edge Service在转发operation2时，会自动使用1.1.0+的规则来过滤实例</p> |
| <p>以上过程用户不必做任何干预，全自动完成，以避免将新版本的operation转发到旧版本的实例中去。</p> |
| <h3 id="urlmappededgedispatcher">使用 URLMappedEdgeDispatcher</h3> |
| <p>URLMappedEdgeDispatcher 允许用户配置URL和微服务的映射关系。使用它可以非常灵活的定义哪些URL转发到哪些微服务。它包含如下几个配置项：</p> |
| <pre><code class="language-yaml">servicecomb: |
| http: |
| dispatcher: |
| edge: |
| url: |
| enabled: true |
| pattern: /(.*) ## 默认值，一般不需要配置 |
| mappings: |
| businessV1: |
| prefixSegmentCount: 1 |
| path: "/url/business/v1/.*" |
| microserviceName: business |
| versionRule: 1.0.0-2.0.0 |
| businessV2: |
| prefixSegmentCount: 1 |
| path: "/url/business/v2/.*" |
| microserviceName: business |
| versionRule: 2.0.0-3.0.0 |
| </code></pre> |
| <p>businessV1配置项表示的含义是将请求路径为/usr/business/v1/.<em>的请求，转发到business这个微服务，并且只转发到版本号为1.0.0-2.0.0的实例（不含2.0.0）。转发的时候URL为/business/v1/.</em>。path使用的是JDK的正则表达式，可以查看Pattern类的说明。prefixSegmentCount表示前缀的URL Segment数量，前缀不包含在转发的URL路径中。有三种形式的versionRule可以指定。2.0.0-3.0.0表示版本范围，含2.0.0，但不含3.0.0；2.0.0+表示大于2.0.0的版本，含2.0.0；2.0.0表示只转发到2.0.0版本。2，2.0等价于2.0.0。</p> |
| <p>从上面的配置可以看出，URLMappedEdgeDispatcher也支持客户端灰度。当然配置项会比DefaultEdgeDispatcher多。URLMappedEdgeDispatcher支持通过配置中心动态的修改配置，调整路由规则。</p> |
| <h3 id="commonhttpedgedispatcher">使用 CommonHttpEdgeDispatcher</h3> |
| <p>CommonHttpEdgeDispatcher 能够将请求转发到监听 HTTP 或者 HTTP 2 协议的 Provider， 对于 Provider 的开发框架没有限制，也不 |
| 要求 Provider 注册契约信息。 </p> |
| <pre><code class="language-yaml">servicecomb: |
| http: |
| dispatcher: |
| edge: |
| http: |
| enabled: true |
| pattern: /(.*) ## 默认值，一般不需要配置 |
| mappings: |
| businessV2: |
| prefixSegmentCount: 1 |
| path: "/http/business/v2/.*" |
| microserviceName: business |
| versionRule: 2.0.0 |
| </code></pre> |
| <p>CommonHttpEdgeDispatcher 配置项的含义和 URLMappedEdgeDispatcher 类似。</p> |
| <h3 id="dispatcher">自定义 Dispatcher</h3> |
| <p>自定义Dispatcher包含两个步骤：</p> |
| <ol> |
| <li>实现AbstractEdgeDispatcher</li> |
| <li>通过SPI发布：增加文件META-INF/services/org.apache.servicecomb.transport.rest.vertx.VertxHttpDispatcher，并写入实现类</li> |
| </ol> |
| <p>详细的代码细节可以参考下面的章节"DEMO功能说明"。开发者也可以参考DefaultEdgeDispatcher等代码来定义自己的Dispatcher。</p> |
| <h3 id="_3">进行认证鉴权和其他业务处理</h3> |
| <p>通过Edge Servie工作流程可以看出，可以通过多种方式来扩展Edge Service的功能，包括Dispatcher、HttpServerFilter、Handler、HttpClientFilter等。比较常用和简单的是通过Handler来扩展。DEMO里面展示了如何通过Handler扩展来实现鉴权。详细的代码细节可以参考下面的章节"DEMO功能说明"。</p> |
| <h2 id="_4">部署示例</h2> |
| <p><img alt="" src="../assets/deployment.png" /></p> |
| <h2 id="_5">工作模式</h2> |
| <h3 id="reactive">reactive (默认)</h3> |
| <p>Edge Service默认工作于高性能的reactive模式，此模式要求工作于Edge Service转发流程中的业务代码不能有任何的阻塞操作，包括不限于：</p> |
| <ul> |
| <li> |
| <p>远程同步调用，比如同步查询数据库、同步调用微服务，或是同步查询远程缓存等等</p> |
| </li> |
| <li> |
| <p>任何的sleep调用</p> |
| </li> |
| <li> |
| <p>任何的wait调用</p> |
| </li> |
| <li> |
| <p>超大的循环</p> |
| </li> |
| </ul> |
| <p>Edge Service的底层是基于netty的vertx，以上约束即是netty的reactive模式约束。</p> |
| <p><img alt="" src="../assets/reactive.png" /></p> |
| <h3 id="_6">线程池</h3> |
| <p>如果业务模型无法满足reactive要求，则需要使用线程池模式。</p> |
| <p>此时需要在Edge Service的microservice.yaml中配置：</p> |
| <pre><code>servicecomb: |
| executors: |
| default: servicecomb.executor.groupThreadPool |
| </code></pre> |
| <p>这里的servicecomb.executor.groupThreadPool是ServiceComb内置的默认线程池对应的spring bean的beanId；业务可以定制自己的线程池，并声明为一个bean，其beanId也可以配置到这里。</p> |
| <p><img alt="" src="../assets/threadPool.png" /></p> |
| <h2 id="demo">DEMO功能说明</h2> |
| <p>DEMO 源码请参考 <a href="https://github.com/apache/servicecomb-java-chassis/tree/master/demo/demo-edge">edge service demo</a></p> |
| <h3 id="1dispatcher">1.注册Dispatcher</h3> |
| <p>实现接口org.apache.servicecomb.transport.rest.vertx.VertxHttpDispatcher，或从 |
| org.apache.servicecomb.edge.core.AbstractEdgeDispatcher继承，实现自己的dispatcher功能。</p> |
| <p>实现类通过java标准的SPI机制注册到系统中去。</p> |
| <p>Dispatcher需要实现2个方法：</p> |
| <ul> |
| <li> |
| <h3 id="getorder">getOrder</h3> |
| </li> |
| </ul> |
| <p>Dispatcher需要向vertx注入路由规则，路由规则之间是有优先级顺序关系的。</p> |
| <p>系统中所有的Dispatcher按照getOrder的返回值按从小到大的方式排序，按顺序初始化。</p> |
| <p>如果2个Dispatcher的getOrder返回值相同，则2者的顺序不可预知。</p> |
| <ul> |
| <li> |
| <h3 id="init">init</h3> |
| </li> |
| </ul> |
| <p>init方法入参为vertx框架中的io.vertx.ext.web.Router，需要通过该对象实现路由规则的定制。</p> |
| <p>可以指定满足要求的url，是否需要处理cookie、是否需要处理body、使用哪个自定义方法处理收到的请求等等</p> |
| <p>更多路由规则细节请参考vertx官方文档：<a href="http://vertx.io/docs/vertx-web/java/#_routing_by_exact_path">vertx路由机制</a></p> |
| <p><em>提示：</em></p> |
| <p><em>多个Dispatcher可以设置路由规则，覆盖到相同的url。</em></p> |
| <p><em>假设Dispatcher A和B都可以处理同一个url，并且A优先级更高，则：</em></p> |
| <ul> |
| <li> |
| <p><em>如果A处理完，既没应答，也没有调用RoutingContext.next()，则属于bug，本次请求挂死了</em></p> |
| </li> |
| <li> |
| <p><em>如果A处理完，然后调用了RoutingContext.next()，则会将请求转移给B处理</em></p> |
| </li> |
| </ul> |
| <h3 id="2">2.转发请求</h3> |
| <p>注册路由时，指定了使用哪个方法来处理请求（下面使用onRequest来指代该方法），在onRequest中实现转发逻辑。</p> |
| <p>方法原型为：</p> |
| <pre><code>void onRequest(RoutingContext context) |
| </code></pre> |
| <p>系统封装了org.apache.servicecomb.edge.core.EdgeInvocation来实现转发功能，至少需要准备以下参数：</p> |
| <ul> |
| <li> |
| <p>microserviceName，业务自行制定规则，可以在url传入，或是根据url查找等等</p> |
| </li> |
| <li> |
| <p>context，即onRequest的入参</p> |
| </li> |
| <li> |
| <p>path，转发目标的url</p> |
| </li> |
| <li> |
| <p>httpServerFilters，Dispatcher父类已经初始化好的成员变量</p> |
| </li> |
| </ul> |
| <pre><code> EdgeInvocation edgeInvocation = new EdgeInvocation(); |
| edgeInvocation.init(microserviceName, context, path, httpServerFilters); |
| edgeInvocation.edgeInvoke(); |
| </code></pre> |
| <p>edgeInvoke调用内部，会作为ServiceComb标准consumer去转发调用。</p> |
| <p>作为标准consumer，意味着ServiceComb所有标准的治理能力在这里都是生效的。</p> |
| <h3 id="3">3.设置兼容规则</h3> |
| <p>不同的业务可能有不同的兼容规划，servicecomb默认的兼容规则，要求所有新版本兼容旧版本。如果满足这个要求，则不必做任何特殊的设置。</p> |
| <p>还有一种典型的规划：</p> |
| <ul> |
| <li> |
| <p>1.0.0-2.0.0内部兼容，url为/microserviceName/v1/….的形式</p> |
| </li> |
| <li> |
| <p>2.0.0-3.0.0内部兼容，url为/microserviceName/v2/….的形式</p> |
| </li> |
| </ul> |
| <p>……</p> |
| <p>各大版本之间不兼容</p> |
| <p>此时，开发人员需要针对EdgeInvocation设置兼容规则：</p> |
| <pre><code>private CompatiblePathVersionMapper versionMapper = new CompatiblePathVersionMapper(); |
| |
| …… |
| |
| edgeInvocation.setVersionRule(versionMapper.getOrCreate(pathVersion).getVersionRule()); |
| </code></pre> |
| <p>versionMapper的作用是将v1或是v2这样的串，转为1.0.0-2.0.0或2.0.0-3.0.0这样的兼容规则。</p> |
| <h3 id="4">4.鉴权</h3> |
| <p>Edge Service是系统的边界，对于很多请求需要执行鉴权逻辑。</p> |
| <p>基于标准的ServiceComb机制，可以通过handler来实现这个功能。</p> |
| <p>最简单的示意代码如下：</p> |
| <pre><code>public class AuthHandler implements Handler { |
| private static Logger LOGGER = LoggerFactory.getLogger(AuthHandler.class); |
| |
| private static Auth auth; |
| |
| static { |
| auth = Invoker.createProxy("auth", "auth", Auth.class); |
| } |
| |
| @Override |
| public void init(MicroserviceMeta microserviceMeta, InvocationType invocationType) { |
| } |
| |
| @Override |
| public void handle(Invocation invocation, AsyncResponse asyncResp) throws Exception { |
| if (invocation.getHandlerContext().get(EdgeConst.ENCRYPT_CONTEXT) != null) { |
| invocation.next(asyncResp); |
| return; |
| } |
| |
| auth.auth("").whenComplete((succ, e) -> doHandle(invocation, asyncResp, succ, e)); |
| } |
| </code></pre> |
| <p>Auth表示是鉴权微服务提供的接口，Invoker.createProxy("auth", "auth", Auth.class)是透明RPC开发模式中consumer的底层api，与@ReferenceRpc是等效，只不过不需要依赖spring bean机制。</p> |
| <p>Auth接口完全由业务定义，这里只是一个示例。</p> |
| <p>Handler开发完成后，配置到edge service的microservice.yaml中：</p> |
| <pre><code>servicecomb: |
| handler: |
| chain: |
| Consumer: |
| default: auth,…… |
| service: |
| auth: …… |
| </code></pre> |
| <p>这个例子，表示转发请求给所有的微服务都必须经过鉴权，但是调用鉴权微服务时不需要鉴权。</p> |
| <p><strong><em>特别注意：</em></strong> edge service 的定制逻辑，包括 Dispatcher, Handler, HttpServerFilter 等，均在 |
| 事件派发线程 event-loop 中执行， 任何定制逻辑必须不能够存在阻塞逻辑，否则会导致 edge service 出现死锁。 |
| 比如上面鉴权的逻辑，必须使用异步接口，而不能够参考 provider 开发的逻辑那样，使用同步接口。 建议业务使用 |
| 定制逻辑的时候，对 edge service 进行并发测试，死锁问题会在并发数大于 event-loop 线程数量的情况下出现。 |
| （event-loop线程数量默认是CPU核数的两倍， 可以通过 jstack 命令查看线程。）</p> |
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