Automatic property extraction (or APE in short) is one of the most powerful and useful features provided by Documentum DFC. One of the most frequent business needs is to automatically set a document's attributes (properties) based on the values set by the content creator in the content template (XML file). Let us understand this through a very simple example.
Imagine a fictitious template that requires users to fill in an Article Title field in the XML template. The requirement is that the value entered by the content creator in this field should be automatically saved in the title attribute (property) of the document as well.
Let's say that the content creator provides the following value for Article Title:
Major breakthrough in financial investments. The value is saved in the <ARTICLETITLE> XML element (for example) in the content file created by the user.
Through its Automatic Property Extraction feature (and if configured correctly), Documentum automatically copies the value specified by the user in the <ARTICLETITLE> field in to the title attribute (property) of the document, whenever the user saves and checks in the document.
Through some other configuration settings, it could even work the other way round. The XML element can also be populated automatically based on the value provided by a user in the attribute for the document.
Property extraction adds value for the business content creators in the following ways:
- It saves the effort of manually entering the same value at two places—the properties page and the content file (template editor).
- It saves the effort (and time) to open Web Publisher editor by allowing them to enter values in the Properties page itself.
Note that Automatic property extraction works with the following Web Publisher widgets only:
- textline
- checkbox
- choice
Internally Documentum uses the following two object types for managing Automatic property extraction for XML elements:
dm_xml_application(supertype:dm_folder):Used for creating a folder under theSystemApplicationsfolder in Docbase to store the XML configuration objects (dm_xml_config).dm_xml_config(supertype:dm_document):Specifies the XML configuration file to be used for the specified XML application.
The property extraction rules need to be specified within the XML configuration file. Once you have created the XML application folder and saved the XML configuration file within it, you need to set the a_category attribute of the content file. DFC queries this attribute and detects the Automatic Property Extraction rules to be applied to the content file based on its XML configuration file. You, however, need to ensure that the dm_xml_application folder and the dm_xml_config application file have exactly the same names, since Documentum Content Server searches for the XML application file based on the exact name that we specify in the content file's a_category attribute.
We are free to not specify any XML Application for the content file. In such cases, the Default XML Application provided by Documentum is used.
Figure 18.1: How XML Application works
Internally, Documentum uses a SAX parser for XML processing of documents against the associated XML Application and DOM for reading the XML configuration file.