Message Data Conversion
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Problems can arise in message queue managers because of differences in the representation of application message data. Typically, a message queue manager will provide conversion of the fixed auxiliary information when a message is passed (asynchronously) between disparate systems; there is no conversion of the application message data itself.
Message Data Conversion
arise in message queue managers because of
differences in the representation of application message data.
Typically, a message queue manager will provide conversion of the
fixed auxiliary information when a message is passed (asynchronously)
between disparate systems; there is no conversion of the application
message data itself.
differences in the data representation of the messages can
occur because the communicating applications are operating on
machines with different architectures, or because they use character
strings in different code pages or CCSIDs. The following
considerations have to be addressed:
o The message data is to be converted only when necessary. For
example, no conversion is needed when the sending and receiving
applications handle the message using the same data
o The above consideration is also to apply in a "multi-hop"
transfer - where the message passes through one or more
intermediate queue managers before it reaches its destination
queue and the server application. There is to be at most one
o Some compilers may generate code for different data
representations on a single platform. Hence the need for data
conversion that can apply to messages between local
as well as those sent across a network.
o The method needs to be able to work where the application runs
a client workstation, and executes the messages calls on a
o A queue manager provided with a message conversion capability
to exchange messages with other queue managers in the family
which do not necessarily have that capability.
described below was developed for the IBM* MQSeries*
queue manager products. These provide the following facilities:
o When an application PUTs a message, it sends auxiliary data as
well. This "header" contains information that describes the
message. An application that GETs the message receives the
descriptive header too.
o Message headers are always converted by MQSeries queue managers.
They have a fixed structure, so the queue managers know
what type of conversion is required. The requirements of the
queue managers can lead to extra conversion being performed
a message passed through an intermediate system.
o Among the contents of the header are the "Representation" and
"Format" of the message it describes. The "Format" is a name
the shape of the application data.
context the addition of the following features deals
effectively with the problem discussed above.
1. The interface to GET a message includes the requi...