io.opns.otl.jaxrs.filter

Class TracingClientFilter

java.lang.Object

io.opns.otl.jaxrs.filter.TracingClientFilter

All Implemented Interfaces:

javax.ws.rs.client.ClientRequestFilter, javax.ws.rs.client.ClientResponseFilter

@Provider
public class TracingClientFilter
extends Object
implements javax.ws.rs.client.ClientRequestFilter, javax.ws.rs.client.ClientResponseFilter

Jax-rs Client filters are similar to container request filters.

for any client request invoked from the client API the client request filters ClientRequestFilter are executed that could manipulate the request. If not aborted, the outgoing request is then physically sent over to the server side and once a response is received back from the server the client response filters (ClientResponseFilter) are executed that might again manipulate the returned response. Finally the response is passed back to the code that invoked the request. If the request was aborted in any client request filter then the client/server communication is skipped and the aborted response is used in the response filters.

Note that there is also a concept of Interceptors in jax-rs specification. But they are more connected with the marshalling and unmarshalling of the HTTP message bodies that are contained in the requests and the responses. Note that they are executed after the filters and only if a message body is present. Hence it is decided to use client filter as they are more suitable for this purpose.

The client request filter will always create a new span to pass the newly created span context (namely the traceId, spanId and the baggage items, if any) to the next service on the chain. The same span would then be closed later by the TracingClientFilter once it receives the response from the remote service. User, however, can override the default behavior by specifying the system property -Djax.rs.span as false. In which case, no new span will be created, but only the contextual data will be passed. The filter has to be explicitly registered with the Client first. Example:

 
     .....
     public Client restClient() {
         Client client = ClientBuilder
             .newBuilder()
             .register(new TracingClientFilter())
             .build();
     }
 
     ....
     ....
 
     public void getName() {
         Client client = restClient();
         client.target("url")
             .request()
             .get(String.class)
     }
 
 

You can also register the request filter via ClientConfig as a provider and use it like below:

 
     .....
     public Client restClient() {
         ClientConfig config = new ClientConfig();
         config.register(TracingClientFilter.class);
         return ClientBuilder.newClient(config);
     }
 
     ....
     ....
 
     public void getName() {
         Client client = restClient();
         client.target("url")
             .request()
             .get(String.class)
     }
 
 

Author:

Sudiptasish Chanda

Constructor Summary

Constructors

Constructor and Description
TracingClientFilter()

Method Summary

Modifier and Type	Method and Description
void	filter(javax.ws.rs.client.ClientRequestContext requestCtx)
void	filter(javax.ws.rs.client.ClientRequestContext requestCtx, javax.ws.rs.client.ClientResponseContext responseCtx)

Methods inherited from class java.lang.Object

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

Constructor Detail

TracingClientFilter

public TracingClientFilter()

Method Detail

filter

public void filter(javax.ws.rs.client.ClientRequestContext requestCtx)
            throws IOException

Specified by:

filter in interface javax.ws.rs.client.ClientRequestFilter

Throws:

IOException

filter

public void filter(javax.ws.rs.client.ClientRequestContext requestCtx,
                   javax.ws.rs.client.ClientResponseContext responseCtx)
            throws IOException

Specified by:

filter in interface javax.ws.rs.client.ClientResponseFilter

Throws:

IOException