Data conversion

Data conversion is the process by which data is transformed from the format recognized by one operating system into the format recognized by a second operating system with different characteristics such as numeric order.

If you are using a network of systems that use different methods for storing numeric values, or you need to communicate between users who view data in different code pages, you must consider how to implement data conversion.

Code page conversions

Code page conversion might be required for one or more of the following reasons:

• ASCII versus EBCDIC
• Code pages that are specific to national language
• Code pages that are specific to operating systems

In WebSphere MQ, these factors are handled by the CCSID field in the MQMD header. For more information about the MQMD header, see "MQMD - Message descriptor" in the Application Programming Reference section of the WebSphere MQ Version 7 product documentation online. For more information about code page support, see "Code page conversion", also in the Application Programming Reference section.

Encoding

Encoding (byte order) conversion might be required for one or both of the following reasons:

• Big endian versus little endian

  Endian is an attribute of data that describes whether it is stored in computer memory or transmitted with the most significant byte first (big endian) or last (little endian).

• Floating point number representations

In WebSphere MQ, these factors are handled by the Encoding field in the MQMD header. For more information about the MQMD header, see "MQMD - Message descriptor" in the Application Programming Reference section of the WebSphere MQ Version 7 product documentation online. For more information about encoding, see "Machine encoding", also in the Application Programming Reference section.

When you use IBM Integration Bus, you can use the data conversion facilities of IBM Integration Bus, WebSphere MQ, or both.

IBM Integration Bus facilities

You can model your messages in the MRM through the IBM Integration Toolkit. Predefined elements of the messages are converted according to their type and physical layer characteristics. For further details, see Message Sets: Configuring physical properties. You can also use self-defining messages. You can then use the Compute, JavaCompute, or PHPCompute node to configure encoding and CCSIDs. You do not need WebSphere MQ data conversion exits.

• String data is converted according to the CCSID setting.
• Decimal integer and float extended decimal types are converted according to the CCSID setting.
• Decimal integer and float (other physical data types) are converted according to the Encoding setting.
• Binary and Boolean data is not converted.

IBM Integration Bus can also convert the WebSphere MQ headers for which parsers are provided.

When you use IBM Integration Bus facilities, the whole message is not converted to the specified encoding and CCSID: you can specify a different encoding, or CCSID, or both, in each header to perform a different conversion for the following part of the message. The encoding and CCSID in the last header defines the values for the message body.

WebSphere MQ facilities

Headers and message body are converted according to the values set in the appropriate MQMD fields, and other header format names. You might need to set up data conversion exits to convert the body of your messages.

When you use WebSphere MQ facilities, the whole message is converted to the specified encoding and CCSID, according to the setting of the format in the WebSphere MQ header.

For more detail about data conversion using WebSphere MQ facilities, see "Data conversion" in the Application Programming Reference section of the WebSphere MQ Version 7 product documentation online.