RFC - Presentation to application Server

Question

Hi,
    when we call a transaction in SAP R/3  e.g. SE38. , a  RFC is called from presentation server to application server. i wnat to know what exactly happens behind the screen.how a rfc is called? how  the connection is established between presentation server & application server.
please do the needful
Regards
Hemant

Answer 1

Hi,
The following is an example of the Client-Server negotiation
    process.
      Server:   IAC DO TERMINAL-TYPE
      Client:        IAC WILL TERMINAL-TYPE
      Server:   IAC SB TERMINAL-TYPE SEND IAC SE
      Client:        IAC SB TERMINAL-TYPE IS IBM-3287-1 IAC SE
      Note: To request a specific LU the TERMINAL-TYPE string would be:
      IAC SB TERMINAL-TYPE IS IBM-3287-1 @ LUNAME IAC SE
      (The client has specified its terminal type is an IBM-3287-1)
      Server:   IAC DO END-OF-RECORD
      Client:        IAC WILL END-OF-RECORD
      Server:   IAC WILL END-OF-RECORD
      Client:        IAC DO END-OF-RECORD
      (The Server and Client have both agreed to transmit End-Of-Record
      (EOR)).
      Server:   IAC DO TRANSMIT-BINARY
      Client:        IAC WILL TRANSMIT-BINARY
      Server:   IAC WILL TRANSMIT-BINARY
      Client:        IAC DO TRANSMIT-BINARY
      (The Server and Client have both agreed to use binary
      transmission)
      Server:   0x00 (3270 PRINT DATA)
      Client:        (S/S with DEV END) IAC EOR
      Server:   0x00 (3270 PRINT DATA) IAC EOR
      NOTE:  LU 1 type data is prefaced with a 0x00 character. LU 3
      type data is not prefaced with a special character.  This
      character will precede print data in each chain, and should be
      discarded before the print data is processed.   An <IAC EOR> must
      be received before changing to LU 1 or LU 3 type data.
      Client:        (S/S with IR) IAC EOR (This indicates a paper jam
                    at printer.)
      Client:        (S/S with DE) IAC EOR (This indicates the clearing
                    of above condition.)
      Server:  0x00 (3270 PRINT DATA) (This indicates start of LU 1
               data)
      Server:   (3270 PRINT DATA)
      Server:   (3270 PRINT DATA)
      Server:   (3270 PRINT DATA) IAC EOR
      Client:        (S/S with DE) IAC EOR
      Server:   0x00 (LAST 3270 PRINT DATA) IAC EOR
      Client:        (S/S with DE) IAC EOR
      Server:   IAC AO
      (The Abort Output <AO> signifies the end-of-bracket -- end of
      print job)
Thanks,
Shankar