ttmedia_load(library call)                       ttmedia_load(library call)




 NAME    [Toc]    [Back]
      ttmedia_load - send a Display, Edit or Compose request

 SYNOPSIS    [Toc]    [Back]
      #include <Tt/tttk.h>
      Tt_message ttmedia_load(
      Tt_message context,
      Ttmedia_load_msg_cb cb,
      void *clientdata,
      Tttk_op op,
      const char *media_type,
      const unsigned char *contents,
      int len,
      const char *file,
      const char *docname,
      int send);

 DESCRIPTION    [Toc]    [Back]
      The ttmedia_load function is used to create and optionally send a
      Media Exchange request to display, edit or compose a document.

      The cb argument will be passed clientdata when the reply is received,
      or when intermediate versions of the document are checkpointed through
      Deposit requests.  The op argument must be one of TTME_DISPLAY,
      TTME_EDIT or TTME_COMPOSE. The media_type argument names the data
      format of the document, and is usually the primary determinant of
      which application will be chosen to handle the request.  The contents
      and len arguments specify the document; if they are NULL and zero,
      respectively, and file is not NULL, then the document is assumed to be
      contained in file. If docname is not NULL, then ttmedia_load uses it
      as the title of the document.  If send is True, the message is sent
      before being returned.

      The context argument describes the environment to use.  If context is
      not zero, messages created by ttmedia_load inherit from context all
      contexts whose slotname begins with the characters ENV_.

      The Ttmedia_load_msg_cb argument is a callback defined as:

      Tt_message (*Ttmedia_load_msg_cb)(Tt_message msg,
              void *clientdata),
              Tttk_op op,
              unsigned char *contents,
              int len,
              char *file);

      The msg argument is the reply to the load request, or a Deposit
      request with a messageID argument naming the identifier (see
      tt_message_id(3)) of the load request.  In the latter case, the client
      program becomes responsible for either failing or replying to the
      request.  In either case, msg should be destroyed after being



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 ttmedia_load(library call)                       ttmedia_load(library call)




      processed.

      The op argument is the op of msg. It must be either TTME_DEPOSIT or
      the op passed to ttmedia_load(3).

      The contents, len and file arguments represent the contents of the
      arriving document.  If len is zero, then the document is contained in
      file. If contents or file are non- NULL, they can be freed using
      tt_free.

      The clientdata argument is the clientdata passed to ttmedia_load.

 RETURN VALUE    [Toc]    [Back]
      Upon successful completion, the ttmedia_load function returns the
      request it was asked to build; otherwise, it returns an error pointer.
      The application can use tt_ptr_error(3) to extract one of the
      following Tt_status values from the returned handle:

      TT_ERR_NOMEM
                There is insufficient memory available to perform the
                function.

      TT_ERR_NOMP
                The ttsession(1) process is not running and the ToolTalk
                service cannot restart it.

      TT_ERR_OVERFLOW
                The ToolTalk service has more active messages than it can
                handle.  (The maximum number of active messages is
                implementation specific, but is at least 2000.)

      TT_ERR_PROCID
                The specified process identifier is out of date or invalid.

 APPLICATION USAGE    [Toc]    [Back]
      After the request created by ttmedia_load is sent, the application
      will probably want to use ttdt_subcontract_manage immediately
      afterwards to manage the standard interactions with the handler of the
      request.

      A Ttmedia_load_msg_cb callback should return NULL if it processes msg
      successfully, or a tt_error_pointer cast to Tt_message if processing
      results in an error.  It should return the msg if it does not consume
      it, in which case the ToolTalk service will pass TT_CALLBACK_CONTINUE
      down the call stack, so that msg will be offered to other callbacks or
      (more likely) be returned from tt_message_receive(3). Applications
      will rarely want msg to get processed by other callbacks or in the
      main event loop.

 EXAMPLES    [Toc]    [Back]




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 ttmedia_load(library call)                       ttmedia_load(library call)




      This is the typical algorithm of a Ttmedia_load_msg_cb:

      Tt_message
      myLoadMsgCB(Tt_message  msg,
              void           *clientData,
              Tttk_op         op,
              unsigned char  *contents,
              int             len,
              char           *file)
      {
              if (len > 0) {
                      /* Replace data with len bytes in contents */
              } else if (file != 0) {
                      /* Replace data with data read from file */
              }
              if (op == TTME_DEPOSIT) {
                      tt_message_reply(msg);
              }
              tttk_message_destroy(msg);
              return 0;
      }

 SEE ALSO    [Toc]    [Back]
      Tt/tttk.h - Tttttk(5), ttmedia_load_reply(3),
      ttmedia_ptype_declare(3), ttmedia_Deposit(3), tt_free(3),
      tt_message_receive(3).


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