1.zuul 1.x的架構如下所示：

線程模型：

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其web應用的web.xml

<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"version="2.5"><listener><listener-class>com.netflix.zuul.StartServer</listener-class></listener><servlet><servlet-name>ZuulServlet</servlet-name><servlet-class>com.netflix.zuul.http.ZuulServlet</servlet-class></servlet><servlet-mapping><servlet-name>ZuulServlet</servlet-name><url-pattern>/*</url-pattern></servlet-mapping><filter><filter-name>ContextLifecycleFilter</filter-name><filter-class>com.netflix.zuul.context.ContextLifecycleFilter</filter-class></filter><filter-mapping><filter-name>ContextLifecycleFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping></web-app>

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從上面可以看出，啟動時有三個主類：

1.1.?StartServer

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@Overridepublic void contextInitialized(ServletContextEvent sce) {logger.info("starting server");// mocks monitoring infrastructure as we don't need it for this simple app MonitoringHelper.initMocks();// initializes groovy filesystem poller initGroovyFilterManager();// initializes a few java filter examples initJavaFilters();}

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1.2.?ZuulServlet

@Overridepublic void service(javax.servlet.ServletRequest servletRequest, javax.servlet.ServletResponse servletResponse) throws ServletException, IOException {try {init((HttpServletRequest) servletRequest, (HttpServletResponse) servletResponse);// Marks this request as having passed through the "Zuul engine", as opposed to servlets// explicitly bound in web.xml, for which requests will not have the same data attachedRequestContext context = RequestContext.getCurrentContext();context.setZuulEngineRan();try {preRoute();} catch (ZuulException e) {error(e);postRoute();return;}try {route();} catch (ZuulException e) {error(e);postRoute();return;}try {postRoute();} catch (ZuulException e) {error(e);return;}} catch (Throwable e) {error(new ZuulException(e, 500, "UNHANDLED_EXCEPTION_" + e.getClass().getName()));} finally {RequestContext.getCurrentContext().unset();}}

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1.3.?ContextLifecycleFilter

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public class ContextLifecycleFilter implements Filter {public void destroy() {}public void init(FilterConfig filterConfig) throws ServletException {}public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)throws IOException, ServletException {try {chain.doFilter(req, res);} finally {RequestContext.getCurrentContext().unset();}}}

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2. zuul2的線程模型

其應用的web.xml文件

<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://java.sun.com/xml/ns/javaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://java.sun.com/xml/ns/javaeehttp://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"version="2.5"><filter><filter-name>guiceFilter</filter-name><filter-class>com.google.inject.servlet.GuiceFilter</filter-class></filter><filter-mapping><filter-name>guiceFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping><listener><listener-class>com.netflix.zuul.StartServer</listener-class></listener></web-app>

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2.1.?StartServer

/*** Overridden solely so we can tell how much time is being spent in overall initialization. Without* overriding we can't tell how much time was spent in BaseServer doing its own initialization.** @param sce*/@Overridepublic void contextInitialized(ServletContextEvent sce) {try {server.start();} catch (Exception e) {LOG.error("Error while starting karyon.", e);throw Throwables.propagate(e);}try {initialize();} catch (Exception e) {e.printStackTrace();}super.contextInitialized(sce);}

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2.2.?ZuulServlet

@Overridepublic void service(HttpServletRequest servletRequest, HttpServletResponse servletResponse) throws ServletException, IOException{try {zuulProcessor.process(servletRequest, servletResponse).doOnNext(msg -> {// Store this response as an attribute for any later ServletFilters that may want access to info in it.servletRequest.setAttribute("_zuul_response", msg);}).subscribe();}catch (Throwable e) {LOG.error("Unexpected error running ZuulHttpProcessor for this request.", e);throw new ServletException("Unexpected error running ZuulHttpProcessor for this request.");}}

2.3?ZuulHttpProcessor

/*** The main processing class for Zuul.** 1. Translates the inbound native request (ie. HttpServletRequest, or rxnetty HttpServerRequest) into a zuul HttpRequestMessage.* 2. Builds the filter chain and passes the request through it.* 3. Writes out the HttpResponseMessage to the native response object.*/

處理過程：

public Observable<ZuulMessage> process(final I nativeRequest, final O nativeResponse){// Setup the context for this request.final SessionContext context;// Optionally decorate the context.if (decorator == null) {context = new SessionContext();} else {context = decorator.decorate(new SessionContext());}return Observable.defer((Func0<Observable<ZuulMessage>>) () -> {// Build a ZuulMessage from the netty request.final ZuulMessage request = contextFactory.create(context, nativeRequest, nativeResponse);// Start timing the request. request.getContext().getTimings().getRequest().start();/** Delegate all of the filter application logic to {@link FilterProcessor}.* This work is some combination of synchronous and asynchronous.*/Observable<ZuulMessage> chain = filterProcessor.applyFilterChain(request);return chain.flatMap(msg -> {// Wrap this in a try/catch because we need to ensure no exception stops the observable, as// we need the following doOnNext to always run - as it records metrics.try {// Write out the response.return contextFactory.write(msg, nativeResponse);}catch (Exception e) {LOG.error("Error in writing response! request=" + request.getInfoForLogging(), e);// Generate a default error response to be sent to client.return Observable.just(new HttpResponseMessageImpl(context, ((HttpResponseMessage) msg).getOutboundRequest(), 500));}finally {// End the timing. msg.getContext().getTimings().getRequest().end();}}).doOnError(e -> {LOG.error("Unexpected error in filter chain! request=" + request.getInfoForLogging(), e);}).doOnNext(msg -> {// Notify requestComplete listener if configured.try {if (requestCompleteHandler != null)requestCompleteHandler.handle(((HttpRequestMessage) request).getInboundRequest(), (HttpResponseMessage) msg);}catch (Exception e) {LOG.error("Error in RequestCompleteHandler.", e);}});}).finallyDo(() -> {// Cleanup any resources related to this request/response. sessionCleaner.cleanup(context);});} }

參考文獻：

【1】http://techblog.netflix.com/2013/06/announcing-zuul-edge-service-in-cloud.html

【2】http://techblog.netflix.com/2016/09/zuul-2-netflix-journey-to-asynchronous.html?utm_source=tuicool&utm_medium=referral

轉載于:https://www.cnblogs.com/davidwang456/p/6421025.html

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