netflix zuul 1.x与zuul2.x之比较

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davidwang456 2021-07-14 15:07:45

文章标签 netflix zuul 1.x zuul2.x 文章分类 代码人生

1.zuul 1.x的架构如下所示：

netflix zuul 1.x与zuul2.x之比较_zuul2.x

线程模型： netflix zuul 1.x与zuul2.x之比较_zuul2.x_02

其web应用的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>

从上面可以看出，启动时有三个主类：

1.1. StartServer

    @Override    public 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();    }

1.2. ZuulServlet

@Override    public 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 attached            RequestContext 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();        }    }

1.3. ContextLifecycleFilter

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();        }    }
}

2. zuul2的线程模型

netflix zuul 1.x与zuul2.x之比较_zuul2.x_03

其应用的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/javaee          http://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>

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     */    @Override    public 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);    }

2.2. ZuulServlet

   @Override    public 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. */

处理过程：

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);        });    }}