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Context handling is an important technique to map complex scenarios in XI. This weblog introduces the basics of context handling using a simple example.

Message mapping in XI works by means of queues. A queue contains an entire XML instance of the source message. Depending on the hierarchy in the source message, different nodes and elements can be categorised into different contexts. All the nodes and elements that belong to the same parent node are said to be in the same context. Hence, the nodes and elements that belong to different parent nodes have to be separated by a context change.

XI provides various node functions for context handling during message mapping. Let us understand the concept of contexts using a simple example. Consider the source message shown below:

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Elements ItemNumber and MaterialNumber belong to the same parent node OrderItem, and hence are in the same context. Also, node OrderItem and element OrderNumber are under the same parent node OrderHeader, and hence are in the same context. Whereas, as elements ItemNumber and OrderNumber belong to different parent nodes, they fall under different contexts.

Following figure shows the OrderItem context. Context change is inserted after every occurrence of OrderItem. Grey coloured rows correspond to context changes.

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Following figure shows the OrderHeader context. Context change is inserted after every occurrence of OrderHeader.

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Similarly, using the Customer context, inserts a context change after every occurrence of Customer.

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If the Orders context is used, no context changes will be inserted as Orders is at the highest level in the hierarchy.

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We can use explicit context selection as shown above or use the node functions available in the Graphical Mapping Editor.

Let us take an example where the use of contexts can be emphasised. In the source message shown above OrderNumber appears only once while OrderItem can occur multiple times within the OrderHeader node. Suppose we want to map OrderNumber multiple times in the target message, such that it is available under the target node corresponding to every sales order item. To do this, we can use the node function called useOneAsMany as described below:

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  • The first input parameter expects the list of values that we want to propagate to the target message.
  • The second input parameter expects the number of iterations or how many times we want to replicate the value given in the first parameter.
  • The third input parameter is the list of context changes. Depending on this parameter the source values will be propagated to the target after every context change.

Note: For this function to work as expected, the first two parameters must contain the same number of contexts while the last two parameters must contain the same number of values.

In our case, the first parameter is OrderNumber, since we want to assign value of this element to the field in the target structure. Second parameter is OrderItem as it corresponds to the number of times sales order items would occur in the target structure. Note that both these parameters have the same number of contexts (See figure below). The third parameter is ItemNumber, which indicates the number of context changes. ItemNumber uses OrderItem context by default (since, OrderItem is the immediate parent node of ItemNumber). Hence, the value of first parameter will be assigned to the target every time the context change occurs for ItemNumber. Also note that the second and third parameter has the same number of values (See figure below).

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We can see that the value 1100 (first parameter) has been replicated three times (second parameter) at every context change in third parameter.

There are many other node functions available within the Graphical Mapping Editor to aid the context handling in different scenarios. Graphical Mapping Editor also allows you to write your own functions wherein you can use methods of predefined classes to handle contexts.

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10 Comments

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  1. Michal Krawczyk
    Hi,

    Please have a look at previous weblogs
    as useOneAsMany function (with regardt to context handling)
    was discusses at least 2 times:

    Replication of Nodes Using the Graphical Mapping Tool
    Replication of Nodes Using the Graphical Mapping Tool

    Message Mapping Simplified – Part II
    /people/sravya.talanki2/blog/2005/12/08/message-mapping-simplified-150-part-ii

    let’s try not to write the same things

    there are too many other undocumented
    things you can write about 🙂

    Regards,
    michal

    (0) 
    1. Krishna Kishore
      Hi Michal,
      So what… he has given his view on that topic.

      If you see previous topics
      “Replication of Nodes Using the Graphical Mapping Tool”
      “Message Mapping Simplified – Part II”

      They tried to explain the things their best but not perfectly…OK.

      So please don’t discourage others not to give their opinions and their explanations on a particular topic.

      Thanks
      Krish

      (0) 
      1. Michal Krawczyk
        hi,

        >>>>So please don’t discourage others not to give their opinions and their explanations on a particular topic.

        I never do that
        I just try to convince people
        to write something new – trying to maintain
        XI blogs quality – so everyone will want to
        read them and won’t be dissapointed to see
        10 blogs on the same subject

        BTW
        if someone wants to show a view
        he/she can also comment on the already existing
        blos right ?

        Regards,
        michal

        (0) 
        1. Krishna Kishore
          See if a particular blog is simple and perfect then we can ignore duplications. But no blog is 100% perfect on a particular topic. Everybody has his own style of explaining things. May be who knows last person who blogged on a particular topic is the best one among the existing ones.

          BTW commenting is very different from writing an article on a particular topic.

          Regards
          Krish

          (0) 
  2. DeepaK Sharma
    Hi ,
    I have seen other blogs on the same subject .
    The explaination there leaves a lot to be desired for .
    On such blogger talks about how he/she didn’t find  “Collapse Context all that  useful” there by misleading others .
    Seems to me there is a mad rush to earn points .
    That’s all.
    Your’s is by far the best so far on the same subject .Keep up the good work.

    (0) 
  3. Blue L

    Hi Riyaz,

    I’ve been struggling on looking for helpful documents on how useOneAsMany function works, so far your blog is the most helpful one on helping me unstand the function.

    Thanks for your good work!!

    (0) 

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