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Message Mapping concepts and introduction to Queues
By Nisheeta Naidu
Mapping is nothing but a set of rules, which are used to
transform the source XML to target XML, based on the business requirements.
To understand the mapping concepts let me first explain the
basics taking a simple example:
A simple mapping in the graphical editor looks as below. The
Age XML tag in the target structure is created for each Age tag in the source
The color indicators for the XML messages has a specific
1.Green color indicates that we can map these XML tags
according to our requirements
2.Red color indicates that these tags are mandatory and
should not be left unmapped.
In Example 2 we can see that Age is an Element. Element is nothing but a simple XML tag. MT_Target is a Node.
Node is a collection of XML tags.
What is Occurrence: Occurrence is nothing but the number of
times a given xml tag appears in the xml document. Occurrences are defined in
the datatype editor and a minimum and maximum occurrence is specified for each
Referring to Example 1 the occurrence of the source Age field
should be similar to the occurrence of target Age field. Occurrence 1:1
indicates a minimum and a maximum occurrence of 1 i.e it should be present once.
For Address field the occurrence is 1: unbounded which means
minimum occurrence should be once but maximum can be n number of times.
and Context Handling:
Context is nothing but the level or the hierarchy at which an
XML tag is present in the xml document with respect to its parent node.
Context Handling can be achieved using Node functions like RemoveContexts
Context Changing can be done to shift the level of the xml
tag during runtime. Example 3 shows this below.
Initially by default the element first was under the node name
and can be seen by right click and context.
The same can be seen in the text view as well
Now I would like to change the context of the first
tag to the root MT_first as
And the text view can be seen as :
In Message Mapping:
works internally using Queues. Queues can be viewed at any step and can be used
for debugging purposes at mapping level.
To see how Queues work let us consider the example below:
<MT_String> <Start 1> <item> A </item> <item> B </item> </Start 1> <Start 2> <item> C </item> <item> D </item> </Start2> </MT_String>
Corresponding Queue Representation
The Queue gets filled as and when the values in the message
arrive. If at any particular level there are no further elements present then a Context
Change is inserted.
The following Scenario explains in depth:
The process flow for the above Fig is given below:
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