Defining and Using Aliases
To allow the reuse of logical file names when validating file names and to make validation more flexible, you can define aliases for logical file names. An alias is itself a logical file name.
Example for Checking a Physical File Name
The user enters the physical file name /usr/sap/PRD_100/tmp/my_file in the program ACCESS_APPLSERVER_FILE. Program ACCESS_APPLSERVER_FILE uses the logical file name PHYS_FILE_VALIDATION for validation, which is not assigned to a physical path in delivery status. You already have another logical file name Z_FILE_TMP in your system that generates the physical file name /usr/sap/PRD_100/tmp/my_file. Instead of generating this assignment for the logical file name PHYS_FILE_VALIDATION again, enter Z_FILE_TMP as an alias for PHYS_FILE_VALIDATION.
Example for Checking Physical File Paths
The user specifies a physical file name in the directory area /usr/sap/PRD_100/tmp/ or /usr/sap/PRD_100/work/ in the program ACCESS_APPLSERVER_FILE2. The program ACCESS_APPLSERVER_FILE2 uses the logical file name PHYS_FILE_VALIDATION2 for validation, which is not assigned to a physical path in delivery status. You define two new logical file names, Z_DIR_TMP and Z_DIR_WORK, that have the data format DIR, and which are assigned the directory paths named above. You enter Z_DIR_TMP and Z_DIR_WORK as aliases for PHYS_FILE_VALIDATION2.
Example for Specifying a Logical File Name to the User Interface
The user is only allowed to enter certain logical file names in the program ACCESS_APPLSERVER_LOGFILE. The program ACCESS_APPLSERVER_LOGFILE uses the logical file name LOG_FILE_VALIDATION for validation, which is not assigned a physical file name in delivery status.
You have already defined the logical file names ZACCESS_APPLSERVER_LOGFILE1 and ZACCESS_APPLSERVER_LOGFILE2 in your system, which create valid physical file names. You now enter the logical file names ZACCESS_APPLSERVER_LOGFILE1 and ZACCESS_APPLSERVER_LOGFILE2 as aliases for LOG_FILE_VALIDATION.
The user can now enter the logical file names ZACCESS_APPLSERVER_LOGFILE1 and ZACCESS_APPLSERVER_LOGFILE2 for the program ACCESS_APPLSERVER_LOGFILE. The logical file name LOG_FILE_VALIDATION cannot be entered in this example because no physical file name has been assigned to this logical file name. However, if the user is to be able to use this logical file name, then you have to assign a physical file name to the logical file name LOG_FILE_VALIDATION.
When checking a logical file name it does not make any sense to assign a logical file name with the data format DIR as an alias. The program needs a logical file name that defines a complete physical file name.
Generalization
If you define an alias for a logical file name, the alias is handled in the same way during the validation of a file name as the delivered logical file name of an application for validation. That is, a file name is valid according to validation if it meets the requirements of the original logical file name or a defined alias.
Maintaining Aliases
You can maintain aliases in the Implementation Guide (IMG) by choosing SAP NetWeaver → Application Server → System Administration → Platform-Independent Filenames → Maintain Aliases for Logical File Names.