## Capturing incoming HTTP requests and outgoing responses

Logback ships with a module called logback-access which integrates with Servlet containers such as Jetty or Tomcat to provide rich and powerful HTTP-access log functionality.

When diagnosing issues in a web-application, it is very helpful to be able to capture incoming HTTP requests and the outgoing response. This is particularly true for a web-applications offering web-services using SOAP. Having access to the "raw" SOAP message makes it much easier to diagnose errors caused by misspelled namespaces or missing fields.

Certain Web-Service stacks can be easily configured to log the SOAP traffic. For instance, with JBoss' Web-services stack, you can set the level of the `org.jboss.ws.core.MessageTrace` logger to `TRACE` in order to enable SOAP message tracing as documented in the Jboss wiki.

If you are using a different Web-Services stack, e.g. Metro, it might not be very convenient to enable SOAP message tracing. In that case, and assuming you application is deployed on Tomcat, you might want to enable RequestDumperFilter. Unfortunately, not only is `RequestDumperFilter` rather hard to install, it does not dump the payload of the incoming request nor the outgoing response.

With help of logback-access and the TeeFilter you can capture the full input and output for each request as explained below.

### Capturing

The `TeeFilter`, as any other servlet filter needs to be declared in your web-application's web.xml file. Here is the decleration to add to your web-application's web.xml file.

    <filter>
      <filter-name>TeeFilter</filter-name>
      <filter-class>ch.qos.logback.access.servlet.TeeFilter</filter-class>
    </filter>

    <filter-mapping>
      <filter-name>TeeFilter</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>

The `TeeFilter` requires the logback-access module to be installed in your web-server. The installation of logback-access is explained elsewhere. Once you have installed logback-access into your Servlet container, e.g. Tomcat or Jetty, you can configure logback-access according to your wishes with the help of a configuration file named logback-access.xml.

Here is a sample logback-access.xml configuration file which will output the full contents of the request and response on the console.

    <configuration>
      <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <layout class="ch.qos.logback.access.PatternLayout">
          <pattern>%fullRequest%n%n%fullResponse</pattern>
        </layout>
      </appender>

      <appender-ref ref="STDOUT" />
    </configuration>

Here is the output generated when accessing the logback-demo application configured as shown above, yields:

GET /logback-demo/index.jsp HTTP/1.1 Host: localhost:8080 User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8) Gecko/20070312 Firefox/1.5.0 Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8 Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive Referer: http://localhost:8080/logback-demo/login.jsp Cookie: JSESSIONID=15c7tqi9ehlwk; OID324nkzcmr=null; OID32862zgoa=null; HTTP/1.1 200 OK Content-Type: text/html; charset=iso-8859-1 Expires: Thu, 01 Jan 1970 00:00:00 GMT Set-Cookie: JSESSIONID=bgebt99ce9om;path=/logback-demo <html> <head> <LINK REL=StyleSheet HREF="css/pk.css" /> </head> <body> <h2>Logback demo center</h2> [snip, so that text is reasonably sized]

### Enabling only in the integration environment

### Filtering captured requests