io.opns.otl.jaxrs.filter

Class TracingContainerFilter

java.lang.Object

io.opns.otl.jaxrs.filter.TracingContainerFilter

All Implemented Interfaces:

javax.ws.rs.container.ContainerRequestFilter, javax.ws.rs.container.ContainerResponseFilter

@Provider
public class TracingContainerFilter
extends Object
implements javax.ws.rs.container.ContainerRequestFilter, javax.ws.rs.container.ContainerResponseFilter

As per jax-rs specification, there are three ways to intercept/filter the incoming request: one by using the standard servlet filter, TracingWebFilter, secondly, by creating a ContainerRequestFilter, and finally, by creating a WriterInterceptor.

Interceptors share a common API for the server and the client side. Whereas filters are primarily intended to manipulate request and response parameters like HTTP headers, URIs and/or HTTP methods, interceptors are intended to manipulate entities, via manipulating entity input/output streams. In case of tracing, the state of the request body is never changed. Therefore, having a request filter makes more sense to intercept incoming request.

The request filter can either be added in the web.xml file, or via Provider annotation. Here we are skipping the provider annotation, in case user wants to use the TracingWebFilter by specifying the same in the web.xml. Note that, Providers are a simply a way of extending and customizing the JAX-RS runtime. You can think of them as plugins that (potentially) alter the behavior of the runtime, in order to accomplish a set of (program defined) goals. If this class is annotated with Provider, and the TracingWebFilter is also added to the web.xml, then multiple span will be created for the same request. Hence, it is recommended to add the TracingContainerFilter in the web.xml.

For example, in Jersey, you can specify the provider as below:

 
 <web-app>
     .....
     <servlet>  
         <servlet-name>Jersey REST Service</servlet-name>  
         <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>  
         <init-param>
             <param-name>com.sun.jersey.spi.container.ContainerRequestFilters</param-name>
             <param-value>io.opns.otl.jaxrs.filter.TracingContainerFilter</param-value>
         </init-param>
         <init-param>
             <param-name>com.sun.jersey.spi.container.ContainerRequestFilters</param-name>
             <param-value>io.opns.otl.jaxrs.filter.TracingContainerFilter</param-value>
         </init-param>
         <init-param>  
             <param-name>jersey.config.server.provider.packages</param-name>  
             <param-value>io.opns.otl.jaxrs.filter,package.name.for.other.rest.classes</param-value>  
         </init-param>  
         <init-param>  
             <param-name>com.sun.jersey.api.json.POJOMappingFeature</param-name>  
             <param-value>true</param-value>  
         </init-param>      
         <load-on-startup>1</load-on-startup>  
     </servlet> 
     .....
     .....
 </web-app>
 
 

Author:

Sudiptasish Chanda

Constructor Summary

Constructors

Constructor and Description
TracingContainerFilter()

Method Summary

Modifier and Type	Method and Description
void	filter(javax.ws.rs.container.ContainerRequestContext requestCtx)
void	filter(javax.ws.rs.container.ContainerRequestContext requestCtx, javax.ws.rs.container.ContainerResponseContext responseCtx)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TracingContainerFilter

public TracingContainerFilter()

Method Detail

filter

public void filter(javax.ws.rs.container.ContainerRequestContext requestCtx)
            throws IOException

Specified by:

filter in interface javax.ws.rs.container.ContainerRequestFilter

Throws:

IOException

filter

public void filter(javax.ws.rs.container.ContainerRequestContext requestCtx,
                   javax.ws.rs.container.ContainerResponseContext responseCtx)
            throws IOException

Specified by:

filter in interface javax.ws.rs.container.ContainerResponseFilter

Throws:

IOException