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13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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15   * accompanied this code).
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25  
26  package org.omg.CORBA;
27  
28  /**
29   * An object containing the information necessary for
30   * invoking a method.  This class is
31   * the cornerstone of the ORB Dynamic
32   * Invocation Interface (DII), which allows dynamic creation and
33   * invocation of requests.
34   * A server cannot tell the difference between a client
35   * invocation using a client stub and a request using the DII.
36   * <P>
37   * A <code>Request</code> object consists of:
38   * <UL>
39   * <LI>the name of the operation to be invoked
40   * <LI>an <code>NVList</code> containing arguments for the operation.<BR>
41   * Each item in the list is a <code>NamedValue</code> object, which has three
42   * parts:
43   *  <OL>
44   *    <LI>the name of the argument
45   *    <LI>the value of the argument (as an <code>Any</code> object)
46   *    <LI>the argument mode flag indicating whether the argument is
47   *        for input, output, or both
48   *  </OL>
49   * </UL>
50   * <P>
51   * <code>Request</code> objects may also contain additional information,
52   * depending on how an operation was defined in the original IDL
53   * interface definition.  For example, where appropriate, they may contain
54   * a <code>NamedValue</code> object to hold the return value or exception,
55   * a context, a list of possible exceptions, and a list of
56   * context strings that need to be resolved.
57   * <P>
58   * New <code>Request</code> objects are created using one of the
59   * <code>create_request</code> methods in the <code>Object</code> class.
60   * In other words, a <code>create_request</code> method is performed on the
61   * object which is to be invoked.
62   *
63   * @see org.omg.CORBA.NamedValue
64   *
65   */
66  
67  public abstract class Request {
68  
69      /**
70       * Retrieves the the target object reference.
71       *
72       * @return                  the object reference that points to the
73       *                    object implementation for the method
74       *                    to be invoked
75       */
76  
77      public abstract org.omg.CORBA.Object target();
78  
79      /**
80       * Retrieves the name of the method to be invoked.
81       *
82       * @return                  the name of the method to be invoked
83       */
84  
85      public abstract String operation();
86  
87      /**
88       * Retrieves the <code>NVList</code> object containing the arguments
89       * to the method being invoked.  The elements in the list are
90       * <code>NamedValue</code> objects, with each one describing an argument
91       * to the method.
92       *
93       * @return  the <code>NVList</code> object containing the arguments
94       *                  for the method
95       *
96       */
97  
98      public abstract NVList arguments();
99  
100     /**
101      * Retrieves the <code>NamedValue</code> object containing the return
102      * value for the method.
103      *
104      * @return          the <code>NamedValue</code> object containing the result
105      *                          of the method
106      */
107 
108     public abstract NamedValue result();
109 
110     /**
111      * Retrieves the <code>Environment</code> object for this request.
112      * It contains the exception that the method being invoked has
113      * thrown (after the invocation returns).
114      *
115      *
116      * @return  the <code>Environment</code> object for this request
117      */
118 
119     public abstract Environment env();
120 
121     /**
122      * Retrieves the <code>ExceptionList</code> object for this request.
123      * This list contains <code>TypeCode</code> objects describing the
124      * exceptions that may be thrown by the method being invoked.
125      *
126      * @return  the <code>ExceptionList</code> object describing the exceptions
127      *            that may be thrown by the method being invoked
128      */
129 
130     public abstract ExceptionList exceptions();
131 
132     /**
133      * Retrieves the <code>ContextList</code> object for this request.
134      * This list contains context <code>String</code>s that need to
135      * be resolved and sent with the invocation.
136      *
137      *
138      * @return                  the list of context strings whose values
139      *                          need to be resolved and sent with the
140      *                          invocation.
141      */
142 
143     public abstract ContextList contexts();
144 
145     /**
146      * Retrieves the <code>Context</code> object for this request.
147      * This is a list of properties giving information about the
148      * client, the environment, or the circumstances of this request.
149      *
150      * @return          the <code>Context</code> object that is to be used
151      *                          to resolve any context strings whose
152      *                          values need to be sent with the invocation
153      */
154 
155     public abstract Context ctx();
156 
157     /**
158      * Sets this request's <code>Context</code> object to the one given.
159      *
160      * @param c         the new <code>Context</code> object to be used for
161      *                          resolving context strings
162      */
163 
164     public abstract void ctx(Context c);
165 
166 
167     /**
168      * Creates an input argument and adds it to this <code>Request</code>
169      * object.
170      *
171      * @return          an <code>Any</code> object that contains the
172      *                value and typecode for the input argument added
173      */
174 
175     public abstract Any add_in_arg();
176 
177     /**
178      * Creates an input argument with the given name and adds it to
179      * this <code>Request</code> object.
180      *
181      * @param name              the name of the argument being added
182      * @return          an <code>Any</code> object that contains the
183      *                value and typecode for the input argument added
184      */
185 
186     public abstract Any add_named_in_arg(String name);
187 
188     /**
189      * Adds an input/output argument to this <code>Request</code> object.
190      *
191      * @return          an <code>Any</code> object that contains the
192      *                value and typecode for the input/output argument added
193      */
194 
195     public abstract Any add_inout_arg();
196 
197     /**
198      * Adds an input/output argument with the given name to this
199      * <code>Request</code> object.
200      *
201      * @param name              the name of the argument being added
202      * @return          an <code>Any</code> object that contains the
203      *                value and typecode for the input/output argument added
204      */
205 
206     public abstract Any add_named_inout_arg(String name);
207 
208 
209     /**
210      * Adds an output argument to this <code>Request</code> object.
211      *
212      * @return          an <code>Any</code> object that contains the
213      *                value and typecode for the output argument added
214      */
215 
216     public abstract Any add_out_arg();
217 
218     /**
219      * Adds an output argument with the given name to this
220      * <code>Request</code> object.
221      *
222      * @param name              the name of the argument being added
223      * @return          an <code>Any</code> object that contains the
224      *                value and typecode for the output argument added
225      */
226 
227     public abstract Any add_named_out_arg(String name);
228 
229     /**
230      * Sets the typecode for the return
231      * value of the method.
232      *
233      * @param tc                        the <code>TypeCode</code> object containing type information
234      *                   for the return value
235      */
236 
237     public abstract void set_return_type(TypeCode tc);
238 
239     /**
240      * Returns the <code>Any</code> object that contains the value for the
241      * result of the method.
242      *
243      * @return                  an <code>Any</code> object containing the value and
244      *                   typecode for the return value
245      */
246 
247     public abstract Any return_value();
248 
249     /**
250      * Makes a synchronous invocation using the
251      * information in the <code>Request</code> object. Exception information is
252      * placed into the <code>Request</code> object's environment object.
253      */
254 
255     public abstract void invoke();
256 
257     /**
258      * Makes a oneway invocation on the
259      * request. In other words, it does not expect or wait for a
260      * response. Note that this can be used even if the operation was
261      * not declared as oneway in the IDL declaration. No response or
262      * exception information is returned.
263      */
264 
265     public abstract void send_oneway();
266 
267     /**
268      * Makes an asynchronous invocation on
269      * the request. In other words, it does not wait for a response before it
270      * returns to the user. The user can then later use the methods
271      * <code>poll_response</code> and <code>get_response</code> to get
272      * the result or exception information for the invocation.
273      */
274 
275     public abstract void send_deferred();
276 
277     /**
278      * Allows the user to determine
279      * whether a response has been received for the invocation triggered
280      * earlier with the <code>send_deferred</code> method.
281      *
282      * @return          <code>true</code> if the method response has
283      *                          been received; <code>false</code> otherwise
284      */
285 
286     public abstract boolean poll_response();
287 
288     /**
289      * Allows the user to access the
290      * response for the invocation triggered earlier with the
291      * <code>send_deferred</code> method.
292      *
293      * @exception WrongTransaction  if the method <code>get_response</code> was invoked
294      * from a different transaction's scope than the one from which the
295      * request was originally sent. See the OMG Transaction Service specification
296      * for details.
297      */
298 
299     public abstract void get_response() throws WrongTransaction;
300 
301 };