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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}.

      */

     Pipe copy(PipeCloner cloner);

 }