Uploading and downloading files from an application server archivfile_server_to_client archivfile_client_to_server

Today i'll illustrate how to read and write files from an applications server on an SAP R/3 systems.

First some pitfalls:

1. If you run a system with multiple application servers be very careful that the file system you are accessing is mounted on the servers your programs or transactions are running on.
• This seems trivial, but it happens very often that programs suddently fail at night, when they run on batch "systems", but they run just fine when run during the day.
2. Be very careful using the "ASC"/"BIN" options in functions and transactions.
• Sometimes someone downloaded a file ( also via FTP ) and put it back by uploading it again. The ascii conversions had destroyed the file structure and the programs reading the file simply went nuts.

Possible methods for file reading and writing

1. Transactions CG3Y and CG3Z
• Just check them out: they are simple and effective, and are the ones used most of the times.
• Combined with AL11 to help us find out the directory structure.
2. ABAP PROGRAMMING:
• OPEN DATASET  / TRANSFER / CLOSE DATASET
• There are plenty of examples with these simple commands in the internet: just look them up in the abap help or google it.
• FUNCTION MODULES for example
•  ARCHIVFILE_SERVER_TO_CLIENT & ARCHIVFILE_CLIENT_TO_SERVER

For example see  the following 2 programs relying on the fact that the transfer is binary by default for the funtion usedExample 1:download a file to application server 

REPORT z_get_srv_file .

PARAMETERS: file TYPE SAPB-SAPPFAD
default '/usr/sap/trans/data/R916228.PD1'.

PARAMETERS: lfile TYPE SAPB-SAPPFAD
default 'c:\R916228.PD1'.


START-OF-SELECTION.
  CALL FUNCTION 'ARCHIVFILE_SERVER_TO_CLIENT'
    EXPORTING
      path             = file
     TARGETPATH        = lfile
 EXCEPTIONS
   ERROR_FILE       = 1
   OTHERS           = 2
            .
  IF sy-subrc <> 0.
* MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*         WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
  ENDIF.

Example 2: upload file to application server

 REPORT z_put_srv_file .

PARAMETERS: file TYPE sapb-sappfad
DEFAULT 'D:\usr\sap\trans\data\R916228.PD1'.

PARAMETERS: lfile TYPE sapb-sappfad
DEFAULT 'E:\R916228.PD1'.

START-OF-SELECTION.
  CALL FUNCTION 'ARCHIVFILE_CLIENT_TO_SERVER'
       EXPORTING
            path       = lfile
            targetpath = file
       EXCEPTIONS
            error_file = 1
            OTHERS     = 2.
  IF sy-subrc <> 0.
* MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*         WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
  ENDIF.

Another important concept is the LOGICAL file : i'll write just a couple of lines to give the reader an idea and provide a code snippet or two.

Because of SAP R/3 running on different OS with different OS path syntax, SAP provided a means of hiding the actual path of a server file from the end user and programmer.

Transaction FILE allows you to customize phisical file names, in a pretty complicated fashion if you like (also specifing different path structures for different operating systems and the like)
Your phisical file name or path is associated to a LOGICAL file name or path.
The function "FILE_GET_NAME" does the dirty work of of creating the physical path using the informastion stored in the tables behind view cluster "FILE"

Here the code snippet:

DATA: FLAG,
      FORMAT(3),
      FNAME(60).
WRITE SY-OPSYS.
CALL FUNCTION 'FILE_GET_NAME'
     EXPORTING
          LOGICAL_FILENAME        = 'MYFILE'
          OPERATING_SYSTEM        = SY-OPSYS
          PARAMETER_1             = '01'
     IMPORTING
          EMERGENCY_FLAG          = FLAG
          FILE_FORMAT             = FORMAT
          FILE_NAME               = FNAME
     EXCEPTIONS
          FILE_NOT_FOUND          = 1
          OTHERS                  = 2.
IF SY-SUBRC = 0.
  WRITE: /  'Flag      :', FLAG,
         / 'Format    :', FORMAT,
         / 'Phys. Name:', FNAME.
ENDIF.

A more real life example is the following:

     parameters:  server like filename-fileintern default 'ZBLA'
    lower case.

    CALL FUNCTION 'FILE_GET_NAME'
      EXPORTING
        logical_filename = server
      IMPORTING
        file_name        = p_file "lth_logic-fileintern
      EXCEPTIONS
        file_not_found   = 1
        OTHERS           = 2.
    IF sy-subrc <> 0.
      MESSAGE 'Errore' TYPE 'E'.
    ENDIF.

    OPEN DATASET p_file FOR OUTPUT IN TEXT MODE ENCODING DEFAULT.

Last thing: reading and writing from a presentation server (the user PC or terminal)

•  HR_99S_UPLOAD ; HR_99S_DOWNLOAD
• GUI_DOWNLOAD ; GUI_UPLOAD.   

Obviously these functions do not work in background.