Hystrix Request Servlet Filters

This module contains functional examples for a J2EE/Servlet environment that initialize and uses HystrixRequestContext.

You can use this module as is or model your own implementation after it as these classes are very basic.

If using a framework that doesn't use Servlets, or a framework with other lifecycle hooks you may need to implement your own anyways.

Binaries

Binaries and dependency information for Maven, Ivy, Gradle and others can be found at http://search.maven.org.

Example for Maven:

xml

<dependency>
    <groupId>com.netflix.hystrix</groupId>
    <artifactId>hystrix-request-servlet</artifactId>
    <version>1.1.2</version>
</dependency>

and for Ivy:

xml

<dependency org="com.netflix.hystrix" name="hystrix-request-servlet" rev="1.1.2" />

Installation

HystrixRequestContextServletFilter

This initializes the HystrixRequestContext at the beginning of each HTTP request and then cleans it up at the end.

You install it by adding the following to your web.xml:

xml

  <filter>
    <display-name>HystrixRequestContextServletFilter</display-name>
    <filter-name>HystrixRequestContextServletFilter</filter-name>
    <filter-class>com.netflix.hystrix.contrib.requestservlet.HystrixRequestContextServletFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>HystrixRequestContextServletFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

HystrixRequestLogViaLoggerServletFilter

This logs an INFO message with the output from [HystrixRequestLog.getCurrentRequest().getExecutedCommandsAsString()](http://netflix.github.com/Hystrix/javadoc/com/netflix/hystrix/HystrixRequestLog.html#getExecutedCommandsAsString(\)) at the end of each requet.

You install it by adding the following to your web.xml:

xml

  <filter>
    <display-name>HystrixRequestLogViaLoggerServletFilter</display-name>
    <filter-name>HystrixRequestLogViaLoggerServletFilter</filter-name>
    <filter-class>com.netflix.hystrix.contrib.requestservlet.HystrixRequestLogViaLoggerServletFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>HystrixRequestLogViaLoggerServletFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

HystrixRequestLogViaResponseHeaderServletFilter

This adds the output of [HystrixRequestLog.getCurrentRequest().getExecutedCommandsAsString()](http://netflix.github.com/Hystrix/javadoc/com/netflix/hystrix/HystrixRequestLog.html#getExecutedCommandsAsString(\)) to the HTTP response as header "X-HystrixLog".

Note that this will not work if the response has been flushed already (such as on a progressively rendered page).

xml

  <filter>
    <display-name>HystrixRequestLogViaResponseHeaderServletFilter</display-name>
    <filter-name>HystrixRequestLogViaResponseHeaderServletFilter</filter-name>
    <filter-class>com.netflix.hystrix.contrib.requestservlet.HystrixRequestLogViaResponseHeaderServletFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>HystrixRequestLogViaResponseHeaderServletFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>