DFHTPP (terminal page processor)

The terminal page processor (DFHTPP) directs completed pages to a destination specified in the BMS output request:
  • SEND MAP or SEND TEXT sends to the originating terminal
  • SEND MAP PAGING or SEND TEXT PAGING directs to temporary storage
  • SEND MAP SET or SEND TEXT SET directs to a list of completed pages that are returned to the application program.
Figure 1 shows the relationships between the terminal page processor and other components in response to BMS output requests.
Figure 1. Terminal page processor interfaces
Diagram showing the relationships between the terminal page processor and other components in response to BMS output requests.
Note:
  1. DFHTPP is entered from DFHPBP after processing by 3270 mapping (DFHM32) for 3270s, by LU1 printer with extended attributes mapping (DFHML1) for those LU1 printers, and by data stream build (DFHDSB) for other devices.
  2. DFHTPP communicates with storage control to obtain:
    • The return list (to store the address of completed pages to be returned to the program)
    • Deferred work elements (DWEs), which ensure that message control information is written to disk, even if the program neglects to issue a SEND PAGE request
    • Storage for a list that correlates pages on temporary storage with the logical device codes for which they are destined.
  3. Temporary-storage control is used to store pages and the message control record (MCR) for messages stored on temporary storage.
  4. The terminal type parameter (TTP) controls the formatting of a message for a particular terminal type (for example, an IBM 2741 Communication Terminal). TTPPGBUF contains the address of a completed page.
  5. The terminal output macro (DFHTOM) is issued to provide an open subroutine assembled within DFHTPP that puts a completed page out to the terminal. If the data stream contains extended attributes, and the terminal does not support extended attributes, the extended attributes are deleted.