Module com.sun.xml.ws

Package com.sun.xml.ws.api.pipe

Interface Pipe

All Known Implementing Classes:

AbstractFilterPipeImpl, AbstractFilterTubeImpl, AbstractPipeImpl, AbstractSchemaValidationTube, AbstractTubeImpl, AsyncProviderInvokerTube, ClientLogicalHandlerTube, ClientMessageHandlerTube, ClientMUTube, ClientSchemaValidationTube, ClientSOAPHandlerTube, DeferredTransportPipe, DumpTube, HandlerTube, HttpTransportPipe, InvokerTube, InvokerTube, LoggingDumpTube, MemberSubmissionWsaClientTube, MemberSubmissionWsaServerTube, PipeAdapter, ProviderInvokerTube, SEIInvokerTube, ServerLogicalHandlerTube, ServerMessageHandlerTube, ServerMUTube, ServerSchemaValidationTube, ServerSOAPHandlerTube, SyncProviderInvokerTube, W3CWsaClientTube, W3CWsaServerTube, WsaClientTube, WsaServerTube

@Deprecated
public interface Pipe

Deprecated.

Use Tube.

Abstraction of the intermediate layers in the processing chain and transport.

What is a Pipe?

Transport is a kind of pipe. It sends the Packet through, say, HTTP connection, and receives the data back into another Packet.

More often, a pipe is a filter. It acts on a packet, and then it passes the packet into another pipe. It can do the same on the way back.

For example, XWSS will be a Pipe that delegates to another Pipe, and it can wrap a Packet into another Packet to encrypt the body and add a header, for example.

Yet another kind of filter pipe is those that wraps LogicalHandler and SOAPHandler. These pipes are heavy-weight; they often consume a message in a packet and create a new one, and then pass it to the next pipe. For performance reason it probably makes sense to have one Pipe instance that invokes a series of LogicalHandlers, another one for SOAPHandler.

There would be a Pipe implementation that invokes Provider. There would be a Pipe implementation that invokes a service method on the user's code. There would be a Dispatch implementation that invokes a Pipe.

WS-MEX can be implemented as a Pipe that looks for Message.getPayloadNamespaceURI() and serves the request.

Pipe Lifecycle

Pipeline is expensive to set up, so once it's created it will be reused. A Pipeline is not reentrant; one pipeline is used to process one request/response at at time. The same pipeline instance may serve request/response for different threads, if one comes after another and they don't overlap.

Where a need arises to process multiple requests concurrently, a pipeline gets cloned through PipeCloner. Note that this need may happen on both server (because it quite often serves multiple requests concurrently) and client (because it needs to support asynchronous method invocations.)

Created pipelines (including cloned ones and the original) may be discarded and GCed at any time at the discretion of whoever owns pipelines. Pipes can, however, expect at least one copy (or original) of pipeline to live at any given time while a pipeline owner is interested in the given pipeline configuration (in more concerete terms, for example, as long as a dispatch object lives, it's going to keep at least one copy of a pipeline alive.)

Before a pipeline owner dies, it may invoke preDestroy() on the last remaining pipeline. It is "may" for pipeline owners that live in the client-side of JAX-WS (such as dispatches and proxies), but it is a "must" for pipeline owners that live in the server-side of JAX-WS.

This last invocation gives a chance for some pipes to clean up any state/resource acquired (such as WS-RM's sequence, WS-Trust's SecurityToken), although as stated above, this is not required for clients.

Pipe and State

The lifecycle of pipelines is designed to allow a Pipe to store various state in easily accessible fashion.

Per-packet state

Any information that changes from a packet to packet should be stored in Packet. This includes information like transport-specific headers.

Per-thread state

Any expensive objects that are non-reentrant can be stored in instance variables of a Pipe, since process(Packet) is non reentrant. When a pipe is copied, new instances should be allocated so that two Pipe instances don't share thread-unsafe resources. This includes things like canonicalizers, JAXB unmarshallers, buffers, and so on.

Per-proxy/per-endpoint state

Information that is tied to a particular proxy/dispatch can be stored in a separate object that is referenced from a pipe. When a new pipe is copied, you can simply hand out a reference to the newly created one, so that all copied pipes refer to the same instance. See the following code as an example:

 class PipeImpl {
   // this object stores per-proxy state
   class DataStore {
     int counter;
   }

   private DataStore ds;

   // create a fresh new pipe
   public PipeImpl(...) {
     ....
     ds = new DataStore();
   }

   // copy constructor
   private PipeImpl(PipeImpl that, PipeCloner cloner) {
     cloner.add(that,this);
     ...
     this.ds = that.ds;
   }

   public PipeImpl copy(PipeCloner pc) {
     return new PipeImpl(this,pc);
   }
 }
 

Note that access to such resource often needs to be synchronized, since multiple copies of pipelines may execute concurrently.

If such information is read-only, it can be stored as instance variables of a pipe, and its reference copied as pipes get copied. (The only difference between this and per-thread state is that you just won't allocate new things when pipes get copied here.)

VM-wide state

static is always there for you to use.

Pipes and Handlers

JAX-WS has a notion of LogicalHandler and SOAPHandler, and we intend to have one Pipe implementation that invokes all the LogicalHandlers and another Pipe implementation that invokes all the SOAPHandlers. Those implementations need to convert a Message into an appropriate format, but grouping all the handlers together eliminates the intermediate Message instanciation between such handlers.

This grouping also allows such implementations to follow the event notifications to handlers (i.e. Handler.close(MessageContext) method.

 TODO: Possible types of pipe:
      creator: create message from wire
          to SAAJ SOAP message
          to cached representation
          directly to JAXB beans
      transformer: transform message from one representation to another
          JAXB beans to encoded SOAP message
          StAX writing + JAXB bean to encoded SOAP message
      modifier: modify message
          add SOAP header blocks
          security processing
      header block processor:
          process certain SOAP header blocks
      outbound initiator: input from the client
          Manage input e.g. JAXB beans and associated with parts of the SOAP message
      inbound invoker: invoke the service
         Inkoke SEI, e.g. EJB or SEI in servlet.
 

See Also:

• AbstractPipeImpl
• AbstractFilterPipeImpl

Method Summary

Modifier and Type	Method	Description
Pipe	copy(PipeCloner cloner)	Deprecated. Creates an identical clone of this Pipe.
void	preDestroy()	Deprecated. Invoked before the last copy of the pipeline is about to be discarded, to give Pipes a chance to clean up any resources.
Packet	process(Packet request)	Deprecated. Sends a Packet and returns a response Packet to it.

Method Details

process

Packet process(Packet request)

Deprecated.

Sends a Packet and returns a response Packet to it.

Parameters:

request - The packet that represents a request message. Must not be null. If the packet has a non-null message, it must be a valid unconsumed Message. This message represents the SOAP message to be sent as a request.

The packet is also allowed to carry no message, which indicates that this is an output-only request. (that's called "solicit", right? - KK)

Returns:

The packet that represents a response message. Must not be null. If the packet has a non-null message, it must be a valid unconsumed Message. This message represents a response to the request message passed as a parameter.

The packet is also allowed to carry no message, which indicates that there was no response. This is used for things like one-way message and/or one-way transports.

Throws:

jakarta.xml.ws.WebServiceException - On the server side, this signals an error condition where a fault reply is in order (or the exception gets eaten by the top-most transport Pipe if it's one-way.) This frees each Pipe from try/catching a WebServiceException in every layer. Note that this method is also allowed to return a Packet that has a fault as the payload.

On the client side, the WebServiceException thrown will be propagated all the way back to the calling client applications. (The consequence of that is that if you are a filtering Pipe, you must not catch the exception that your next Pipe threw.

RuntimeException - Other runtime exception thrown by this method must be treated as a bug in the pipe implementation, and therefore should not be converted into a fault. (Otherwise it becomes very difficult to debug implementation problems.)

On the server side, this exception should be most likely just logged. On the client-side it gets propagated to the client application.

The consequence of this is that if a pipe calls into an user application (such as SOAPHandler or LogicalHandler), where a RuntimeException is *not* a bug in the JAX-WS implementation, it must be catched and wrapped into a WebServiceException.

preDestroy

void preDestroy()

Deprecated.

Invoked before the last copy of the pipeline is about to be discarded, to give Pipes a chance to clean up any resources.

This can be used to invoke PreDestroy lifecycle methods on user handler. The invocation of it is optional on the client side, but mandatory on the server side.

When multiple copies of pipelines are created, this method is called only on one of them.

Throws:

jakarta.xml.ws.WebServiceException - If the clean up fails, WebServiceException can be thrown. This exception will be propagated to users (if this is client), or recorded (if this is server.)

copy

Pipe copy(PipeCloner cloner)

Deprecated.

Creates an identical clone of this Pipe.

This method creates an identical pipeline that can be used concurrently with this pipeline. When the caller of a pipeline is multi-threaded and need concurrent use of the same pipeline, it can do so by creating copies through this method.

Implementation Note

It is the implementation's responsibility to call PipeCloner.add(Pipe,Pipe) to register the copied pipe with the original. This is required before you start copying the other Pipe references you have, or else there's a risk of infinite recursion.

For most Pipe implementations that delegate to another Pipe, this method requires that you also copy the Pipe that you delegate to.

For limited number of Pipes that do not maintain any thread unsafe resource, it is allowed to simply return this from this method (notice that even if you are stateless, if you got a delegating Pipe and that one isn't stateless, you still have to copy yourself.)

Note that this method might be invoked by one thread while another thread is executing the process(Packet) method. See the Codec.copy() for more discussion about this.

Parameters:

cloner - Use this object (in particular its PipeCloner.copy(Pipe) method to clone other pipe references you have in your pipe. See PipeCloner for more discussion about why.

Returns:

always non-null Pipe.