dadOpenPipe

f77:  Call dadOpenPipe( Id, Pipename, Dataflow, KeyTable, Split, OpenFlags, err ) 
      integer Id, Split, OpenFlags, err
      character *(*)Pipename
      character *(*)Dataflow
      character *(*)KeyTable
  or
C:    int dadOpenPipe( int *Id, char *Pipename,
                       char *Dataflow, char *KeyTable,
		       int Split, int OpenFlags, int *err );      

• The variable Id returns a handle which will be used in later calls to the Dad library to specify the opened pipe.
• The Pipename can point to a named pipe on the local filesystem which shall be opened for reading/writing. If Split is a number greater than 1 (i.e. the user wants to split the pipe), the filename must contain a substring '%d' where the Dad library will insert the number of the current split branch.
  It is also possible to use unnamed pipes for the ID. In this case one can give the name of a process to be started prepended by a '|' sign when opening a pipe for writing. The so called process must be able to look on its commandline for a sequence of '--dadinputpipe arg'. The arg has then to be passed to the library function dadSetPipehandle. This sets both the internal file handle for the piping and the global variable dad_instance to 0 in the first called process and to 1 in the second and so on. The reading process afterwards has to open the pipe via a call to

  f77:  CALL dadOpenPipe( Id, '-', Dataflow, 1, CAC_READ, err) 
     or
  C:    dadOpenPipe( &Id, "-", Dataflow, 1, CAC_READ, &err)
  

• The Dataflow is the name of the dataflow that is expected to be read/to be written. You may omit this name in reading mode (set it to ' ') if
• The KeyTable (a new parameter with dad 1.30) contains either an empty string or the name of the keytable if CAC_KEYTABLE is specified. Openflags (next argument) contains the flag CAC_GENTABLES.
• The Openflags specify the operation mode for the pipe to be accessed. You use
  • CAC_READ for reading a pipe
  • CAC_WRITE for writing a pipe
  • CAC_GENTABLES (added to CAC_READ) if the metatable information in the pipe shall be used to generate the Adamo tables in the library while opening the pipe.
  • CAC_NDELAY if a writing operation would block dadWrite returns -aEwouldblock and skips the record.
  • CAC_KEYTABLE for access to the keytable. The Keytable will be available in each of the received or written records. See examples on keytable manipulation.
  • CAC_MULTI Open a multi record type file/pipe to be accessed through the functions dadMRead, dadMWrite and dadRewind only.
• The Err is set to 0 if the call was successfull or contains a Dad error number.