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25  
26  package com.sun.xml.internal.ws.api.pipe;
27  
28  import com.sun.istack.internal.NotNull;
29  import com.sun.xml.internal.ws.api.message.Message;
30  import com.sun.xml.internal.ws.api.message.Packet;
31  import com.sun.xml.internal.ws.api.pipe.helper.AbstractFilterTubeImpl;
32  import com.sun.xml.internal.ws.api.pipe.helper.AbstractTubeImpl;
33  import com.sun.xml.internal.ws.api.server.Adapter;
34  
35  import javax.annotation.PreDestroy;
36  import javax.xml.ws.Dispatch;
37  import javax.xml.ws.Provider;
38  import javax.xml.ws.WebServiceException;
39  import javax.xml.ws.handler.LogicalHandler;
40  import javax.xml.ws.handler.soap.SOAPHandler;
41  import java.text.SimpleDateFormat;
42  
43  /**
44   * Abstraction of the intermediate layers in the processing chain
45   * and transport.
46   *
47   * <h2>What is a {@link Tube}?</h2>
48   * <p>
49   * {@link Tube} is a basic processing unit that represents SOAP-level
50   * protocol handling code. Mutliple tubes are often put together in
51   * a line (it needs not one dimensional &mdash; more later), and act on
52   * {@link Packet}s in a sequential fashion.
53   *
54   * <p>
55   * {@link Tube}s run asynchronously. That is, there is no guarantee that
56   * {@link #processRequest(Packet)} and {@link #processResponse(Packet)} runs
57   * in the same thread, nor is there any guarantee that this tube and next
58   * tube runs in the same thread. Furthermore, one thread may be used to
59   * run multiple pipeline in turn (just like a real CPU runs multiple
60   * threads in turn.)
61   *
62   *
63   * <h2>Tube examples</h2>
64   * <p>
65   * Transport is a kind of tube. It sends the {@link Packet}
66   * through, say, HTTP connection, and receives the data back into another {@link Packet}.
67   *
68   * <p>
69   * More often, a tube works like a filter. It acts on a packet,
70   * and then it tells the JAX-WS that the packet should be passed into another
71   * tube. It can do the same on the way back.
72   *
73   * <p>
74   * For example, XWSS will be a {@link Tube}. It will act on a request
75   * {@link Packet}, then perhaps wrap it into
76   * another {@link Packet} to encrypt the body and add a header, then
77   * the processing will go on to the next tube.
78   *
79   * <p>
80   * Yet another kind of filter tube is those that wraps {@link LogicalHandler}
81   * and {@link SOAPHandler}. These tubes are heavy-weight; they often consume
82   * a message in a packet and create a new one, and then pass it to the next tube.
83   *
84   * <p>
85   * There would be a {@link Tube} implementation that invokes {@link Provider}.
86   * There would be a {@link Tube} implementation that invokes a service method
87   * on the user's code.
88   * There would be a {@link Dispatch} implementation that invokes a {@link Tube}.
89   *
90   * <p>
91   * WS-MEX can be implemented as a {@link Tube} that looks for
92   * {@link Message#getPayloadNamespaceURI()} and serves the request.
93   *
94   *
95   *
96   *
97   * <h2>Tube Lifecycle</h2>
98   * Pipeline is expensive to set up, so once it's created it will be reused.
99   * A pipeline is not reentrant; one pipeline is used to process one request/response
100  * at at time. The same pipeline instance may serve multiple request/response,
101  * if one comes after another and they don't overlap.
102  * <p>
103  * Where a need arises to process multiple requests concurrently, a pipeline
104  * gets cloned through {@link TubeCloner}. Note that this need may happen on
105  * both server (because it quite often serves multiple requests concurrently)
106  * and client (because it needs to support asynchronous method invocations.)
107  * <p>
108  * Created pipelines (including cloned ones and the original) may be discarded and GC-ed
109  * at any time at the discretion of whoever owns pipelines. Tubes can, however, expect
110  * at least one copy (or original) of pipeline to live at any given time while a pipeline
111  * owner is interested in the given pipeline configuration (in more concerete terms,
112  * for example, as long as a dispatch object lives, it's going to keep at least one
113  * copy of a pipeline alive.)
114  * <p>
115  * Before a pipeline owner dies, it may invoke {@link #preDestroy()} on the last
116  * remaining pipeline. It is "may" for pipeline owners that live in the client-side
117  * of JAX-WS (such as dispatches and proxies), but it is a "must" for pipeline owners
118  * that live in the server-side of JAX-WS.
119  * <p>
120  * This last invocation gives a chance for some pipes to clean up any state/resource
121  * acquired (such as WS-RM's sequence, WS-Trust's SecurityToken), although as stated above,
122  * this is not required for clients.
123  *
124  *
125  *
126  * <h2>Tube and state</h2>
127  * <p>
128  * The lifecycle of pipelines is designed to allow a {@link Tube} to store various
129  * state in easily accessible fashion.
130  *
131  *
132  * <h3>Per-packet state</h3>
133  * <p>
134  * Any information that changes from a packet to packet should be
135  * stored in {@link Packet} (if such informaton is specific to your problem domain,
136  * then most likely {@link Packet#invocationProperties}.)
137  * This includes information like transport-specific headers.
138  *
139  * <h3>Per-thread state</h3>
140  * <p>
141  * Any expensive-to-create objects that are non-reentrant can be stored
142  * either in instance variables of a {@link Tube}, or a static {@link ThreadLocal}.
143  *
144  * <p>
145  * The first approach works, because {@link Tube} is
146  * non reentrant. When a tube is copied, new instances should be allocated
147  * so that two {@link Tube} instances don't share thread-unsafe resources.
148  *
149  * Similarly the second approach works, since {@link ThreadLocal} guarantees
150  * that each thread gets its own private copy.
151  *
152  * <p>
153  * The former is faster to access, and you need not worry about clean up.
154  * On the other hand, because there can be many more concurrent requests
155  * than # of threads, you may end up holding onto more resources than necessary.
156  *
157  * <p>
158  * This includes state like canonicalizers, JAXB unmarshallers,
159  * {@link SimpleDateFormat}, etc.
160  *
161  *
162  * <h3>Per-proxy/per-endpoint state</h3>
163  * <p>
164  * Information that is tied to a particular proxy/dispatch can be stored
165  * in a separate object that is referenced from a tube. When
166  * a new tube is copied, you can simply hand out a reference to the newly
167  * created one, so that all copied tubes refer to the same instance.
168  * See the following code as an example:
169  *
170  * <pre>
171  * class TubeImpl {
172  *   // this object stores per-proxy state
173  *   class DataStore {
174  *     int counter;
175  *   }
176  *
177  *   private DataStore ds;
178  *
179  *   // create a fresh new pipe
180  *   public TubeImpl(...) {
181  *     ....
182  *     ds = new DataStore();
183  *   }
184  *
185  *   // copy constructor
186  *   private TubeImpl(TubeImpl that, PipeCloner cloner) {
187  *     cloner.add(that,this);
188  *     ...
189  *     this.ds = that.ds;
190  *   }
191  *
192  *   public TubeImpl copy(PipeCloner pc) {
193  *     return new TubeImpl(this,pc);
194  *   }
195  * }
196  * </pre>
197  *
198  * <p>
199  * Note that access to such resource may need to be synchronized,
200  * since multiple copies of pipelines may execute concurrently.
201  *
202  *
203  *
204  * <h3>VM-wide state</h3>
205  * <p>
206  * <tt>static</tt> is always there for you to use.
207  *
208  *
209  *
210  * @see AbstractTubeImpl
211  * @see AbstractFilterTubeImpl
212  *
213  * @author Kohsuke Kawaguchi
214  * @author Jitendra Kotamraju
215  */
216 public interface Tube {
217     /**
218      * Acts on a request and perform some protocol specific operation.
219      *
220      * TODO: exception handling semantics need more discussion
221      *
222      * @throws WebServiceException
223      *      On the server side, this signals an error condition where
224      *      a fault reply is in order (or the exception gets eaten by
225      *      the top-most transport {@link Adapter} if it's one-way.)
226      *      This frees each {@link Tube} from try/catching a
227      *      {@link WebServiceException} in every layer.
228      *
229      *      Note that this method is also allowed to return
230      *      {@link NextAction#returnWith(Packet)} with
231      *      a {@link Packet} that has a fault as the payload.
232      *
233      *      <p>
234      *      On the client side, the {@link WebServiceException} thrown
235      *      will be propagated all the way back to the calling client
236      *      applications. (The consequence of that is that if you are
237      *      a filtering {@link Tube}, you must not eat the exception
238      *      that was given to {@link #processException(Throwable)} .
239      *
240      * @throws RuntimeException
241      *      Other runtime exception thrown by this method must
242      *      be treated as a bug in the tube implementation,
243      *      and therefore should not be converted into a fault.
244      *      (Otherwise it becomes very difficult to debug implementation
245      *      problems.)
246      *
247      *      <p>
248      *      On the server side, this exception should be most likely
249      *      just logged. On the client-side it gets propagated to the
250      *      client application.
251      *
252      *      <p>
253      *      The consequence of this is that if a pipe calls
254      *      into an user application (such as {@link SOAPHandler}
255      *      or {@link LogicalHandler}), where a {@link RuntimeException}
256      *      is *not* a bug in the JAX-WS implementation, it must be catched
257      *      and wrapped into a {@link WebServiceException}.
258      *
259      * @param request
260      *      The packet that represents a request message.
261      *      If the packet has a non-null message, it must be a valid
262      *      unconsumed {@link Message}. This message represents the
263      *      SOAP message to be sent as a request.
264      *      <p>
265      *      The packet is also allowed to carry no message, which indicates
266      *      that this is an output-only request.
267      *      (that's called "solicit", right? - KK)
268      *
269      * @return
270      *      A {@link NextAction} object that represents the next action
271      *      to be taken by the JAX-WS runtime.
272      */
273     @NotNull NextAction processRequest(@NotNull Packet request);
274 
275     /**
276      * Acts on a response and performs some protocol specific operation.
277      *
278      * <p>
279      * Once a {@link #processRequest(Packet)} is invoked, this method
280      * will be always invoked with the response, before this {@link Tube}
281      * processes another request.
282      *
283      * @param response
284      *      If the packet has a non-null message, it must be
285      *      a valid unconsumed {@link Message}. This message represents
286      *      a response to the request message passed to
287      *      {@link #processRequest(Packet)} earlier.
288      *      <p>
289      *      The packet is also allowed to carry no message, which indicates
290      *      that there was no response. This is used for things like
291      *      one-way message and/or one-way transports.
292      *
293      * TODO: exception handling semantics need more discussion
294      *
295      * @return
296      *      A {@link NextAction} object that represents the next action
297      *      to be taken by the JAX-WS runtime.
298      */
299     @NotNull NextAction processResponse(@NotNull Packet response);
300 
301 
302     /**
303      * Acts on a exception and performs some clean up operations.
304      *
305      * <p>
306      * If a {@link #processRequest(Packet)}, {@link #processResponse(Packet)},
307      * {@link #processException(Throwable)} throws an exception, this method
308      * will be always invoked on all the {@link Tube}s in the remaining
309      * {@link NextAction}s.
310      *
311      * <p>
312      * On the server side, the {@link Throwable} thrown will be propagated to the
313      * top-most transport. The transport converts the exception to fault reply or
314      * simply logs in case of one-way MEP. If you are a filtering {@link Tube} like
315      * {@link AbstractTubeImpl}, you don't have to override the implementation). On
316      * the other hand, any intermediate {@link Tube} may want to convert the exception
317      * to a fault message.
318      *
319      * <p>
320      * On the client side, the {@link Throwable} thrown
321      * will be propagated all the way back to the calling client
322      * applications. (The consequence of that is that if you are
323      * a filtering {@link Tube} like {@link AbstractTubeImpl}, you don't have to
324      * override the implementation)
325      *
326      * @param t
327      *
328      * @return
329      *      A {@link NextAction} object that represents the next action
330      *      to be taken by the JAX-WS runtime.
331      */
332     @NotNull NextAction processException(@NotNull Throwable t);
333 
334     /**
335      * Invoked before the last copy of the pipeline is about to be discarded,
336      * to give {@link Tube}s a chance to clean up any resources.
337      *
338      * <p>
339      * This can be used to invoke {@link PreDestroy} lifecycle methods
340      * on user handler. The invocation of it is optional on the client side,
341      * but mandatory on the server side.
342      *
343      * <p>
344      * When multiple copies of pipelines are created, this method is called
345      * only on one of them.
346      *
347      * @throws WebServiceException
348      *      If the clean up fails, {@link WebServiceException} can be thrown.
349      *      This exception will be propagated to users (if this is client),
350      *      or recorded (if this is server.)
351      */
352     void preDestroy();
353 
354     /**
355      * Creates an identical clone of this {@link Tube}.
356      *
357      * <p>
358      * This method creates an identical pipeline that can be used
359      * concurrently with this pipeline. When the caller of a pipeline
360      * is multi-threaded and need concurrent use of the same pipeline,
361      * it can do so by creating copies through this method.
362      *
363      * <h3>Implementation Note</h3>
364      * <p>
365      * It is the implementation's responsibility to call
366      * {@link TubeCloner#add(Tube,Tube)} to register the copied pipe
367      * with the original. This is required before you start copying
368      * the other {@link Tube} references you have, or else there's a
369      * risk of infinite recursion.
370      * <p>
371      * For most {@link Tube} implementations that delegate to another
372      * {@link Tube}, this method requires that you also copy the {@link Tube}
373      * that you delegate to.
374      * <p>
375      * For limited number of {@link Tube}s that do not maintain any
376      * thread unsafe resource, it is allowed to simply return <tt>this</tt>
377      * from this method (notice that even if you are stateless, if you
378      * got a delegating {@link Tube} and that one isn't stateless, you
379      * still have to copy yourself.)
380      *
381      * <p>
382      * Note that this method might be invoked by one thread while another
383      * thread is executing the other process method. See
384      * the {@link Codec#copy()} for more discussion about this.
385      *
386      * @param cloner
387      *      Use this object (in particular its {@link TubeCloner#copy(Tube)} method
388      *      to clone other pipe references you have
389      *      in your pipe. See {@link TubeCloner} for more discussion
390      *      about why.
391      *
392      * @return
393      *      always non-null {@link Tube}.
394      */
395     Tube copy(TubeCloner cloner);
396 }