interface/wx/ipc.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        ipc.h
   3 // Purpose:     interface of wxConnection
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10     @class wxConnection
  11
  12     A wxConnection object represents the connection between a client
  13     and a server. It is created by making a connection using a
  14     wxClient object, or by the acceptance of a
  15     connection by a wxServer object. The
  16     bulk of a DDE-like (Dynamic Data Exchange) conversation is
  17     controlled by calling members in a @b wxConnection object or
  18     by overriding its members. The actual DDE-based implementation
  19     using wxDDEConnection is available on Windows only, but a
  20     platform-independent, socket-based version of this API is
  21     available using wxTCPConnection, which has the same API.
  22
  23     An application should normally derive a new connection class from
  24     wxConnection, in order to override the communication event
  25     handlers to do something interesting.
  26
  27     @library{wxbase}
  28     @category{FIXME}
  29
  30     @see wxClient, wxServer, @ref overview_ipcoverview "Interprocess communications
  31     overview"
  32 */
  33 class wxConnection : public wxObject
  34 {
  35 public:
  36     //@{
  37     /**
  38         Constructs a connection object. If no user-defined connection
  39         object is to be derived from wxConnection, then the constructor
  40         should not be called directly, since the default connection
  41         object will be provided on requesting (or accepting) a
  42         connection. However, if the user defines his or her own derived
  43         connection object, the wxServer::OnAcceptConnection
  44         and/or wxClient::OnMakeConnection
  45         members should be replaced by functions which construct the new
  46         connection object.
  47         If the arguments of the wxConnection constructor are void then
  48         the wxConnection object manages its own connection buffer,
  49         allocating memory as needed. A programmer-supplied buffer cannot
  50         be increased if necessary, and the program will assert if it is
  51         not large enough. The programmer-supplied buffer is included
  52         mainly for backwards compatibility.
  53     */
  54     wxConnection();
  55     wxConnection(void* buffer, size_t size);
  56     //@}
  57
  58     //@{
  59     /**
  60         Called by the server application to advise the client of a change
  61         in the data associated with the given item. Causes the client
  62         connection's OnAdvise() member
  63         to be called. Returns @true if successful.
  64     */
  65     bool Advise(const wxString& item, const void* data, size_t size,
  66                 wxIPCFormat format = wxIPC_PRIVATE);
  67     bool Advise(const wxString& item, const char* data);
  68     bool Advise(const wxString& item, const wchar_t* data);
  69     bool Advise(const wxString& item, const wxString data);
  70     //@}
  71
  72     /**
  73         Called by the client or server application to disconnect from the
  74         other program; it causes the OnDisconnect()
  75         message to be sent to the corresponding connection object in the
  76         other program. Returns @true if successful or already disconnected.
  77         The application that calls @b Disconnect must explicitly delete
  78         its side of the connection.
  79     */
  80     bool Disconnect();
  81
  82     //@{
  83     /**
  84         Called by the client application to execute a command on the
  85         server. Can also be used to transfer arbitrary data to the server
  86         (similar to Poke() in
  87         that respect). Causes the server connection's OnExec()
  88         member to be called. Returns @true if successful.
  89     */
  90     bool Execute(const void* data, size_t size,
  91                  wxIPCFormat format = wxIPC_PRIVATE);
  92     bool Execute(const char* data);
  93     bool Execute(const wchar_t* data);
  94     bool Execute(const wxString data);
  95     //@}
  96
  97     /**
  98         Message sent to the client application when the server notifies
  99         it of a change in the data associated with the given item, using
 100         Advise().
 101     */
 102     virtual bool OnAdvise(const wxString& topic,
 103                           const wxString& item,
 104                           const void* data,
 105                           size_t size,
 106                           wxIPCFormat format);
 107
 108     /**
 109         Message sent to the client or server application when the other
 110         application notifies it to end the connection. The default
 111         behaviour is to delete the connection object and return @true, so
 112         applications should generally override @b OnDisconnect
 113         (finally calling the inherited method as well) so that they know
 114         the connection object is no longer available.
 115     */
 116     virtual bool OnDisconnect();
 117
 118     /**
 119         Message sent to the server application when the client notifies
 120         it to execute the given data, using Execute().
 121         Note that there is no item associated with this message.
 122     */
 123     virtual bool OnExec(const wxString& topic, const wxString& data);
 124
 125     /**
 126         Message sent to the server application when the client notifies it to
 127         accept the given data.
 128     */
 129     virtual bool OnPoke(const wxString& topic, const wxString& item,
 130                         const void* data,
 131                         size_t size,
 132                         wxIPCFormat format);
 133
 134     /**
 135         Message sent to the server application when the client calls
 136         Request(). The
 137         server's OnRequest() method
 138         should respond by returning a character string, or @NULL to
 139         indicate no data, and setting *size. The character string must of
 140         course persist after the call returns.
 141     */
 142     virtual const void* OnRequest(const wxString& topic,
 143                                   const wxString& item,
 144                                   size_t* size,
 145                                   wxIPCFormat format);
 146
 147     /**
 148         Message sent to the server application by the client, when the client
 149         wishes to start an 'advise loop' for the given topic and item. The
 150         server can refuse to participate by returning @false.
 151     */
 152     virtual bool OnStartAdvise(const wxString& topic,
 153                                const wxString& item);
 154
 155     /**
 156         Message sent to the server application by the client, when the client
 157         wishes to stop an 'advise loop' for the given topic and item. The
 158         server can refuse to stop the advise loop by returning @false, although
 159         this doesn't have much meaning in practice.
 160     */
 161     virtual bool OnStopAdvise(const wxString& topic,
 162                               const wxString& item);
 163
 164     //@{
 165     /**
 166         Called by the client application to poke data into the server.
 167         Can be used to transfer arbitrary data to the server. Causes the
 168         server connection's OnPoke() member to
 169         be called. If size is -1 the size is computed from the string
 170         length of data.
 171         Returns @true if successful.
 172     */
 173     bool Poke(const wxString& item, const void* data, size_t size,
 174               wxIPCFormat format = wxIPC_PRIVATE);
 175     bool Poke(const wxString& item, const char* data);
 176     bool Poke(const wxString& item, const wchar_t* data);
 177     bool Poke(const wxString& item, const wxString data);
 178     //@}
 179
 180     /**
 181         Called by the client application to request data from the server.
 182         Causes the server connection's OnRequest()
 183         member to be called. Size may be @NULL or a pointer to a variable
 184         to receive the size of the requested item.
 185         Returns a character string (actually a pointer to the
 186         connection's buffer) if successful, @NULL otherwise. This buffer
 187         does not need to be deleted.
 188     */
 189     const void* Request(const wxString& item, size_t* size,
 190                         wxIPCFormat format = wxIPC_TEXT);
 191
 192     /**
 193         Called by the client application to ask if an advise loop can be
 194         started with the server. Causes the server connection's
 195         OnStartAdvise()
 196         member to be called. Returns @true if the server okays it, @false
 197         otherwise.
 198     */
 199     bool StartAdvise(const wxString& item);
 200
 201     /**
 202         Called by the client application to ask if an advise loop can be
 203         stopped. Causes the server connection's OnStopAdvise()
 204         member to be called. Returns @true if the server okays it, @false
 205         otherwise.
 206     */
 207     bool StopAdvise(const wxString& item);
 208
 209
 210     /**
 211         Returns true if the format is one of the text formats.
 212
 213         The text formats are wxIPC_TEXT, wxIPC_UNICODETEXT and wxIPC_UTF8TEXT.
 214      */
 215     static bool IsTextFormat(wxIPCFormat format);
 216
 217     /**
 218         Returns the data in any of the text formats as string.
 219
 220         @param data
 221             The raw data pointer as used with any of the other methods of this
 222             class.
 223         @param size
 224             The size of the data buffer pointed to by @a data.
 225         @param format
 226             The format of the data. It must be a text one, i.e. such that
 227             IsTextFormat() returns @true for it.
 228         @return
 229             The string representation of the data. If the format is not text,
 230             an assertion failure is triggered and empty string is returned.
 231      */
 232     static wxString
 233     GetTextFromData(const void *data, size_t size, wxIPCFormat format);
 234 };
 235
 236
 237
 238 /**
 239     @class wxClient
 240
 241     A wxClient object represents the client part of a client-server
 242     DDE-like (Dynamic Data Exchange) conversation. The actual
 243     DDE-based implementation using wxDDEClient is available on Windows
 244     only, but a platform-independent, socket-based version of this
 245     API is available using wxTCPClient, which has the same API.
 246
 247     To create a client which can communicate with a suitable server,
 248     you need to derive a class from wxConnection and another from
 249     wxClient. The custom wxConnection class will intercept
 250     communications in a 'conversation' with a server, and the custom
 251     wxClient is required so that a user-overridden
 252     wxClient::OnMakeConnection
 253     member can return a wxConnection of the required class, when a
 254     connection is made. Look at the IPC sample and the
 255     @ref overview_ipcoverview "Interprocess communications overview" for
 256     an example of how to do this.
 257
 258     @library{wxbase}
 259     @category{FIXME}
 260
 261     @see wxServer, wxConnection, @ref overview_ipcoverview "Interprocess
 262     communications overview"
 263 */
 264 class wxClient : public wxObject
 265 {
 266 public:
 267     /**
 268         Constructs a client object.
 269     */
 270     wxClient();
 271
 272     /**
 273         Tries to make a connection with a server by host (machine name
 274         under UNIX - use 'localhost' for same machine; ignored when using
 275         native DDE in Windows), service name and topic string. If the
 276         server allows a connection, a wxConnection object will be
 277         returned. The type of wxConnection returned can be altered by
 278         overriding the
 279         OnMakeConnection()
 280         member to return your own derived connection object.
 281         Under Unix, the service name may be either an integer port
 282         identifier in which case an Internet domain socket will be used
 283         for the communications, or a valid file name (which shouldn't
 284         exist and will be deleted afterwards) in which case a Unix domain
 285         socket is created.
 286         @b SECURITY NOTE: Using Internet domain sockets if extremely
 287         insecure for IPC as there is absolutely no access control for
 288         them, use Unix domain sockets whenever possible!
 289     */
 290     wxConnectionBase* MakeConnection(const wxString& host,
 291                                      const wxString& service,
 292                                      const wxString& topic);
 293
 294     /**
 295         Called by MakeConnection(), by
 296         default this simply returns a new wxConnection object. Override
 297         this method to return a wxConnection descendant customised for the
 298         application.
 299         The advantage of deriving your own connection class is that it
 300         will enable you to intercept messages initiated by the server,
 301         such as wxConnection::OnAdvise. You
 302         may also want to store application-specific data in instances of
 303         the new class.
 304     */
 305     wxConnectionBase* OnMakeConnection();
 306
 307     /**
 308         Returns @true if this is a valid host name, @false otherwise. This always
 309         returns @true under MS Windows.
 310     */
 311     bool ValidHost(const wxString& host);
 312 };
 313
 314
 315
 316 /**
 317     @class wxServer
 318
 319     A wxServer object represents the server part of a client-server
 320     DDE-like (Dynamic Data Exchange) conversation. The actual
 321     DDE-based implementation using wxDDEServer is available on Windows
 322     only, but a platform-independent, socket-based version of this
 323     API is available using wxTCPServer, which has the same API.
 324
 325     To create a server which can communicate with a suitable client,
 326     you need to derive a class from wxConnection and another from
 327     wxServer. The custom wxConnection class will intercept
 328     communications in a 'conversation' with a client, and the custom
 329     wxServer is required so that a user-overridden wxServer::OnAcceptConnection
 330     member can return a wxConnection of the required class, when a
 331     connection is made. Look at the IPC sample and the @ref overview_ipcoverview
 332     "Interprocess communications overview" for
 333     an example of how to do this.
 334
 335     @library{wxbase}
 336     @category{FIXME}
 337
 338     @see wxClient, wxConnection, IPC, overview()
 339 */
 340 class wxServer
 341 {
 342 public:
 343     /**
 344         Constructs a server object.
 345     */
 346     wxServer();
 347
 348     /**
 349         Registers the server using the given service name. Under Unix,
 350         the service name may be either an integer port identifier in
 351         which case an Internet domain socket will be used for the
 352         communications, or a valid file name (which shouldn't exist and
 353         will be deleted afterwards) in which case a Unix domain socket is
 354         created. @false is returned if the call failed (for example, the
 355         port number is already in use).
 356     */
 357     bool Create(const wxString& service);
 358
 359     /**
 360         When a client calls @b MakeConnection, the server receives the
 361         message and this member is called. The application should derive a
 362         member to intercept this message and return a connection object of
 363         either the standard wxConnection type, or (more likely) of a
 364         user-derived type.
 365         If the topic is @b STDIO, the application may wish to refuse the
 366         connection. Under UNIX, when a server is created the
 367         OnAcceptConnection message is always sent for standard input and
 368         output, but in the context of DDE messages it doesn't make a lot
 369         of sense.
 370     */
 371     virtual wxConnectionBase* OnAcceptConnection(const wxString& topic);
 372 };
 373