3.3 Component Interoperability

Interoperability of Frame Application and DTM components is shown in the following table:

Table 1. Interoperability between components of different versions (O – optional A – assured)

The FDT specification ensures that DTMs and Frame Applications of the same major version cooperate regardless of minor version, e.g. FDT version 1.2 is compatible to FDT version 1.2.1. In this case the additional functionality defined in the higher FDT version may not be provided.

The situation is different if the major version number changes:

A DTM with a higher major version (than the Frame Application) may not function within a Frame Application with lower major version. Interoperability in this case is optional. In order to function in the ‘old’ Frame Application the DTM needs to behave according to the FDT version provided by the Frame Application.

A Frame Application with a higher major version (than the DTM) may refuse to work with a DTM with lower major version. Interoperability in this case is optional. In order to work with the ‘old’ DTM the Frame Application needs to provide both interface sets (see section ‘Design Rules’). In this situation the Frame Application behaves like an ‘old’ FDT version toward the DTM (old version number, old XML schemas).

To assure that containers detect only compatible installed DTMs for each FDT major version a separate Category ID will be defined within the FDT specification. This assures that a Frame Application is able to detect installed DTMs for a specific FDT major versions. DTMs supporting FDT version 1.2.1 or higher version must implement the IDtm2 interface. A Frame Application supporting FDT version 1.2.1 or higher versions must check after instantiation of a DTM instance if this DTM supports the IDtm2 interface. In this case the Frame Application must use this interface instead of using IDtm.

Version information is provided by the DTM within it’s information document, the version of the Frame Application is set during IDtm2::Environment2(). A DTM supporting FDT version 1.2.1 or higher version called using IDtm::Environment() must assume a Frame Application supporting FDT version 1.2.

The Frame Application will always provide the schemas according to the FDT version it publishes in IDtm2::Environment2(). For example even DTMs based on version 1.2 will find newer schemas in the schema path if the Frame Application supports a newer version of FDT.