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package com.sun.xml.internal.ws.api.pipe;
import com.sun.xml.internal.ws.api.message.Message;
import com.sun.xml.internal.ws.api.message.Packet;
import com.sun.xml.internal.ws.api.pipe.helper.AbstractFilterPipeImpl;
import com.sun.xml.internal.ws.api.pipe.helper.AbstractPipeImpl;
import javax.annotation.PreDestroy;
import javax.xml.ws.Dispatch;
import javax.xml.ws.Provider;
import javax.xml.ws.WebServiceException;
import javax.xml.ws.handler.Handler;
import javax.xml.ws.handler.LogicalHandler;
import javax.xml.ws.handler.MessageContext;
import javax.xml.ws.handler.soap.SOAPHandler;
/**
* Abstraction of the intermediate layers in the processing chain
* and transport.
*
* <h2>What is a {@link Pipe}?</h2>
* <p>
* Transport is a kind of pipe. It sends the {@link Packet}
* through, say, HTTP connection, and receives the data back into another {@link Packet}.
*
* <p>
* 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.
*
* <p>
* For example, XWSS will be a {@link Pipe}
* that delegates to another {@link Pipe}, and it can wrap a {@link Packet} into
* another {@link Packet} to encrypt the body and add a header, for example.
*
* <p>
* Yet another kind of filter pipe is those that wraps {@link LogicalHandler}
* and {@link 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 {@link Pipe}
* instance that invokes a series of {@link LogicalHandler}s, another one
* for {@link SOAPHandler}.
*
* <p>
* There would be a {@link Pipe} implementation that invokes {@link Provider}.
* There would be a {@link Pipe} implementation that invokes a service method
* on the user's code.
* There would be a {@link Dispatch} implementation that invokes a {@link Pipe}.
*
* <p>
* WS-MEX can be implemented as a {@link Pipe} that looks for
* {@link Message#getPayloadNamespaceURI()} and serves the request.
*
*
* <h2>Pipe Lifecycle</h2>
* {@link Pipe}line is expensive to set up, so once it's created it will be reused.
* A {@link Pipe}line 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.
* <p>
* Where a need arises to process multiple requests concurrently, a pipeline
* gets cloned through {@link 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.)
* <p>
* 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.)
* <p>
* Before a pipeline owner dies, it may invoke {@link #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.
* <p>
* 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.
*
*
*
* <h2>Pipe and State</h2>
* <p>
* The lifecycle of pipelines is designed to allow a {@link Pipe} to store various
* state in easily accessible fashion.
*
*
* <h3>Per-packet state</h3>
* <p>
* Any information that changes from a packet to packet should be
* stored in {@link Packet}. This includes information like
* transport-specific headers.
*
* <h3>Per-thread state</h3>
* <p>
* Any expensive objects that are non-reentrant can be stored in
* instance variables of a {@link Pipe}, since {@link #process(Packet)} is
* non reentrant. When a pipe is copied, new instances should be allocated
* so that two {@link Pipe} instances don't share thread-unsafe resources.
* This includes things like canonicalizers, JAXB unmarshallers, buffers,
* and so on.
*
* <h3>Per-proxy/per-endpoint state</h3>
* <p>
* 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:
*
* <pre>
* 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);
* }
* }
* </pre>
*
* <p>
* Note that access to such resource often needs to be synchronized,
* since multiple copies of pipelines may execute concurrently.
*
* <p>
* 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.)
*
*
* <h3>VM-wide state</h3>
* <p>
* <tt>static</tt> is always there for you to use.
*
*
*
* <h2>Pipes and Handlers</h2>
* <p>
* JAX-WS has a notion of {@link LogicalHandler} and {@link SOAPHandler}, and
* we intend to have one {@link Pipe} implementation that invokes all the
* {@link LogicalHandler}s and another {@link Pipe} implementation that invokes
* all the {@link SOAPHandler}s. Those implementations need to convert a {@link Message}
* into an appropriate format, but grouping all the handlers together eliminates
* the intermediate {@link Message} instanciation between such handlers.
* <p>
* This grouping also allows such implementations to follow the event notifications
* to handlers (i.e. {@link Handler#close(MessageContext)} method.
*
*
* <pre>
* 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.
* </pre>
*
* @see AbstractPipeImpl
* @see AbstractFilterPipeImpl
* @deprecated
* Use {@link Tube}.
*/
public interface Pipe {
/**
* Sends a {@link Packet} and returns a response {@link Packet} to it.
*
* @throws 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 {@link Pipe} if it's one-way.)
* This frees each {@link Pipe} from try/catching a
* {@link WebServiceException} in every layer.
*
* Note that this method is also allowed to return a {@link Packet}
* that has a fault as the payload.
*
* <p>
* On the client side, the {@link 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 {@link Pipe}, you must not catch the exception
* that your next {@link Pipe} threw.
*
* @throws 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.)
*
* <p>
* On the server side, this exception should be most likely
* just logged. On the client-side it gets propagated to the
* client application.
*
* <p>
* The consequence of this is that if a pipe calls
* into an user application (such as {@link SOAPHandler}
* or {@link LogicalHandler}), where a {@link RuntimeException}
* is *not* a bug in the JAX-WS implementation, it must be catched
* and wrapped into a {@link WebServiceException}.
*
* @param 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 {@link Message}. This message represents the
* SOAP message to be sent as a request.
* <p>
* The packet is also allowed to carry no message, which indicates
* that this is an output-only request.
* (that's called "solicit", right? - KK)
*
* @return
* 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 {@link Message}. This message represents
* a response to the request message passed as a parameter.
* <p>
* 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.
*/
Packet process( Packet request);
/**
* Invoked before the last copy of the pipeline is about to be discarded,
* to give {@link Pipe}s a chance to clean up any resources.
*
* <p>
* This can be used to invoke {@link PreDestroy} lifecycle methods
* on user handler. The invocation of it is optional on the client side,
* but mandatory on the server side.
*
* <p>
* When multiple copies of pipelines are created, this method is called
* only on one of them.
*
* @throws WebServiceException
* If the clean up fails, {@link WebServiceException} can be thrown.
* This exception will be propagated to users (if this is client),
* or recorded (if this is server.)
*/
void preDestroy();
/**
* Creates an identical clone of this {@link Pipe}.
*
* <p>
* 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.
*
* <h3>Implementation Note</h3>
* <p>
* It is the implementation's responsibility to call
* {@link PipeCloner#add(Pipe,Pipe)} to register the copied pipe
* with the original. This is required before you start copying
* the other {@link Pipe} references you have, or else there's a
* risk of infinite recursion.
* <p>
* For most {@link Pipe} implementations that delegate to another
* {@link Pipe}, this method requires that you also copy the {@link Pipe}
* that you delegate to.
* <p>
* For limited number of {@link Pipe}s that do not maintain any
* thread unsafe resource, it is allowed to simply return <tt>this</tt>
* from this method (notice that even if you are stateless, if you
* got a delegating {@link Pipe} and that one isn't stateless, you
* still have to copy yourself.)
*
* <p>
* Note that this method might be invoked by one thread while another
* thread is executing the {@link #process(Packet)} method. See
* the {@link Codec#copy()} for more discussion about this.
*
* @param cloner
* Use this object (in particular its {@link PipeCloner#copy(Pipe)} method
* to clone other pipe references you have
* in your pipe. See {@link PipeCloner} for more discussion
* about why.
*
* @return
* always non-null {@link Pipe}.
* @param cloner
*/
Pipe copy(PipeCloner cloner);
}