Accessing external text files

External text files (XML, ESDF or OIF) require a file description, which is either provided as data type definition in the resource database or as external file description (more details see "Data Exchange"). XML and hierarchical ESDF files may be defined as data types by using references or embedded complex attributes for subordinated elements.

Property handles for accessing external text files can be provided in two different ways. One is to call Property::openExtern(), which provides ad hoc access to external text files. The schema definition for the external file may be provided in the resource dictionary or in an external type description. The file path is passed directly as parameter to the function.

One may also define an extent in the resource database with the access type for the external file. In this case, the file location is passed in an option variable having the same name as the extent.

In order to save data written to a text file properly, property handles opened for text files should be closed calling Property::closeAll(). Other wise, the file may be incomplete after closing the property handle. In worst case, data is written to file when closing the database.