Encoding a Series of Messages Using the Stream-Oriented C Encode Functions

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A common application of BER encoding is the repetitive encoding of a series of the same type of message over and over again. For example, a TAP3 batch application might read billing data out of a database table and encode each of the records for a batch transmission.

Encoding a series of messages using the stream-oriented C encode functions is very similar to encoding of one message. All that is necessary is to set up a loop in which the asn1BSE_<name> functions will be called. It is also possible to call different asn1BSE_<name> functions one after another. An example showing how to do this is as follows:

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

 
    int main ()
 
    {
 
        int       stat;
 
        ASN1CTXT  ctxt;
 
        Employee  employee;	/* typedef generated by ASN1C */
 
	  const char* filename = "message.dat";
 

 
        /* Step 1: Initialize the context and stream */
 

 
        if (rtInitContext (&ctxt) != ASN_OK) {
 
           /* initialization failed, could be a license problem */
 
           printf ("context initialization failed (check license)\n");
 
           return -1;
 
        }
 

 
        rtStreamBufInit (&ctxt);	
 
        stat = rtStreamFileOpen (&ctxt, filename, OSRTSTRMF_OUTPUT);
 
        if (stat != ASN_OK) {
 
           xu_perror (&ctxt);
 
           return stat;
 
        }
 

 
        for (;;) {
 
          /* Step 2: Populate the structure to be encoded */
 

 
          employee.name.numocts = 5;
 
          employee.name.data = "SMITH";
 
          ...
 

 
          /* Step 3: Call the generated encode function */
 

 
          stat = asn1BSE_Employee (&ctxt, &employee, ASN1EXPL);
 

 
          /* Step 4: Check the return status and break the loop 
 
              if error occurs */
 

 
          if (stat != ASN_OK) {
 

 
            ...error processing...
 
 
 
            break;
 
          }
 
       }
 

       /* Step 5: Close the stream */
 

 
       rtStreamBufClose (&ctxt);
 
   }