MRM XML physical format: Relationship to the logical model
The MRM XML physical format generally respects all the settings in the logical model, but shares certain restrictions in common with the other physical formats.
These restrictions are documented in MRM restrictions.
Default values
The MRM XML physical format ignores default and fixed values on elements and attributes. If validation is enabled in IBM® Integration Bus, this can lead to unexpected validation errors for missing elements, even though they have default or fixed values.
Simple types - unions and lists
The XML properties of an element or attribute of a simple type that is a union or list vary depending on the members of the union or the itemType of the list. If the union or list includes a dateTime type (or other date/time related type) the Date Format field is displayed. If the union includes a binary type, the Encoding field is displayed.
Min Occurs and Max Occurs
The logical properties Min Occurs and Max Occurs specify the permitted number of occurrences of an element or group in a message. They are used when validating the content of a message.
When parsing and writing, using the MRM XML physical format, Min Occurs and Max Occurs are effectively ignored. When parsing, the number of occurrences is identified by the tags in the message. When writing, the writer outputs all occurrences in the message tree.
- A varying number of occurrences (Min Occurs <> Max Occurs) is allowed.
- Optional occurrence (Min Occurs = 0) is allowed.
- Always absent (Max Occurs = 0) is allowed
- An unbounded number of occurrences (Max Occurs = -1) is allowed.
When validating, Min Occurs and Max Occurs are both used to check that the content of the message tree matches the model.