Develop applications that process DBCS data

Design your application programs for processing double-byte data in the same way you design application programs for processing alphanumeric data.

Following are the additional considerations:

• Make sure that the double-byte data is always processed in a double-byte unit and does not split a double-byte character.
• Identify double-byte data used in the database files.
• Design display and printer formats that can be used with double-byte data.
• If needed, provide DBCS conversion as a means of entering double-byte data for interactive applications. Use the DDS keyword for DBCS conversion (IGCCNV) to specify DBCS conversion in display files. Because DBCS workstations provide a variety of double-byte data entry methods, you are not required to use the i5/OS™ DBCS conversion function to enter double-byte data.
• Create double-byte messages to be used by the program.
• Specify extended character processing so that the system prints and displays all double-byte data.
• Determine whether additional double-byte characters need to be defined. User-defined characters can be defined and maintained using the character generator utility (CGU). Information about CGU can be found in the ADTS/400: Character Generator Utility, book SC09-1769-00.

• Use of double-byte data
  You can use double-byte data in several ways.
• DBCS coding considerations
  If the application will be used in a DBCS environment, ensure that it is DBCS-enabled. Here are some suggestions to consider when you develop the general product design.
• Process double-byte characters
  Due to the large number of double-byte characters, the system needs more information to identify each double-byte character than is needed to identify each alphanumeric character.
• Display support
  This topic discusses display support for inserting shift-control characters. Also discussed are the number of extended characters and input fields that can be displayed, and the effects of displaying double-byte data on alphanumeric workstations.
• Make printer files DBCS capable
  In many cases, printer files are used by the server to produce data that will eventually be printed or displayed. In these cases, the data is first placed into a spooled file using one of the IBM-supplied printer files. The data is then taken from the spooled file and is displayed or printed based on the request of the user.
• Copy spooled and nonspooled DBCS files
  You can copy both spooled and nonspooled DBCS files.
• Change alphanumeric programs to DBCS programs
  If an alphanumeric application program uses externally described files, you can change that application program to a DBCS application program by changing the externally described files.
• Enter DBCS text in CL commands
  You can use double-byte character data anywhere in a CL command that descriptive text can be used.
• DBCS conversion
  You can enter an alphanumeric entry or DBCS code and convert the entry or code to its related DBCS word. DBCS conversion is intended for Japanese character sets and its use is limited for application to other double-byte character sets.
• SQL and DBCS
  The basic symbols of keywords and operators in the SQL language are single-byte characters that are part of all character sets supported by the IBM^® relational database products. Characters of the language are classified as letters, digits, or special characters.