Procedure for Using the C++ Control Class Encode Method

---

The procedure to encode a message using the C++ class interface is as follows:

1. Instantiate an XML encode buffer object (OSXMLEncodeBuffer) to describe the buffer into which the message will be encoded. Constructors are available that allow a static message buffer to be specified. The default constructor specifies use of a dynamic encode buffer.

2. Instantiate an ASN1T_<type> object and populate it with data to be encoded.

3. Instantiate an ASN1C_<type> object to associate the message buffer with the data to be encoded.

4. Invoke the ASN1C_<type> object Encode or EncodeTo method.

5. Check the return status. The return value is a status value indicating whether encoding was successful or not. Zero indicates success. If encoding failed, the status value will be a negative number. The encode buffer method printErrorInfo can be invoked to get a textual explanation and stack trace of where the error occurred.

6. If encoding was successful, get the start-of-message pointer and message length. The start-of-message pointer is obtained by calling the getMsgPtr method of the encode buffer object. If static encoding was specified (i.e., a message buffer address and size were specified to the XML Encode Buffer class constructor), the start-of-message pointer is the buffer start address. The message length is obtained by calling the getMsgLen method of the encode buffer object.

A program fragment that could be used to encode an employee record is as follows:

    #include employee.h         // include file generated by ASN1C
 

 
    main ()
 
    {
 
        OSOCTET msgbuf[4096];
 
        int     msglen, stat;
 

 
        // step 1: instantiate an instance of the XML encode 
 
        // buffer class.  This example specifies a static 
 
        // message buffer..
 

 
        OSXMLEncodeBuffer encodeBuffer (msgbuf, sizeof(msgbuf));
 

 
        // step 2: populate msgData with data to be encoded
 

 
        ASN1T_PersonnelRecord msgData;
 
        msgData.name.givenName = "SMITH";
 
        ...
 

 
        // step 3: instantiate an instance of the ASN1C_<ProdName> 
 
        // class to associate the encode buffer and message data..
 

 
        ASN1C_PersonnelRecord employee (encodeBuffer, msgData);
 

 
        // steps 4 and 5: encode and check return status
 

 
        if ((stat = employee.Encode ()) == 0)
 
        {
 
           printf ("encoded XML message:\n");
 
           printf ((const char*)msgbuf);
 
           printf ("\n");
 

 
           // step 6: get start-of-message pointer and message length.
 
           // start-of-message pointer is start of msgbuf 
 
           // call getMsgLen to get message length..
 

 
           msgptr = encodeBuffer.getMsgPtr ();  // will return &msgbuf
 
           len = encodeBuffer.getMsgLen ();
 
        }
 
        else
 
        {
 
           printf ("Encoding failed\n");
 
           encodeBuffer.printErrorInfo ();
 
           exit (0);
 
        }
 

 
        // msgptr and len now describe fully encoded message
 

 
        ...