I recently got a request to import a database schema definition into Enterprise Architect from an OData metadata XML file. OData or Open Data Protocol is an OASIS standard with a definition of best practises for building and consuming RESTful APIs. A metadata document is an XML file with the description of the available entities, properties, etc.

In addition to the file to process and import, I reviewed the content from publicly available OData metadata sample files: 

• services.odata.org/OData/OData.svc/$metadata : Product entity definition.
• services.odata.org/V4/TripPinServiceRW/$metadata : Airport and trip details.

I couldn't use EA XML Schema (XSD) import since it does not support XML files, even when it defines a data structure (here entities and properties). OData metadata XML files use the EDM schema available here: docs.oasis-open.org/odata/odata-csdl-xml/v4.01/cs01/schemas/edm.xsd.

As I had to manipulate XML data and needed a lightweight, easy-to-use solution, I identified the XML Transformation Language (XSLT) as the appropriate solution.

XSLT makes it possible to convert content from an XML and generate a file with a content matching a number of rules, defined in a template (XSL file). My aim here to create a CSV (comma-separated values) file with a list of UML classes and attributes from the OData metadata file. An enhanced version of Geert Bellekens' free Excel VBImporter would then let me run a bulk import of the resulting entities (classes) and their properties (attributes) into EA.

Process:

• I opened the first OData metadata XML file in Notepad++.

• I used the XML Tools plugin to run the XSL Transformation.
• I selected the XSL file that contains the initial set of rules to convert...
  
  • EnumType elements to Enumeration classes,
  • EntityType elements to entityType stereotyped classes,
  • ComplexType elements to classes,
  • EntityContainer elements to entityContainer stereotyped classes.
  • Note: attributes matching the properties are included.

• Notepad++ XSL Transformation function generated a new file with the expected CSV content (note: the XML tag needs to be removed before saving the file)

• I opened the Excel VBImporter to import classes and attributes (note: EA CSV import is limited to elements i.e. Classes).
• I imported the CSV content to populate the VBImporter.

• Finally, having opened EA and a target package, I ran VBImporter Class import.

Note: other tools than Notepad++ can be used to run the XSL Transformation, e.g. Visual Studio, xsltproc in Linux, etc.

I have not yet published the XSL file which contains the relevant rules to use and improve. Please feel free to contact me to get a copy, test it, use it, and improve it!