Application Protocols

An Application Protocol consists of the following components:

1. Functional model of the application which is supported by the product data model. The AAM serves the definition of the standard's scope. The AAM is defined using the SADT method, and describes the application through processes. In the AAM, the dataclasses which identify the input, output, method or parameters of the functions in focus are identified.

2. The product data model describes the data classes identified in the AAM and their relationships to each other from a user's point of view. Usually, EXPRESS-G is used for this purpose. Every object of the product data model needs to be defined explicitly, including all its attributes and relationships.

3. The standardized product data model is an information model, which uses the pre-defined building blocks from the Integrated Resources in the context of the specific application. Therefore, a Mapping is specified between the data objects of the ARM and those of the AIM.

Note: From this follows that for an implementation of a STEP Application Protocol (e.g. STEP processors for data exchange), it is not sufficient to merely state the Application Protocol, in fact also the implemented Conformance Class(es) need to be specified.

If during the development of application protocols scopes are defined which are identically mapped in two or more APs, the definition of so-called Application Interpreted Constructs (AIC) is possible. AICs define the overlapping scopes of several APs. They are lodged as the 500-series of the ISO 10303 standard.

The more application-oriented an Application Protocol is, the sooner it will assert itself in practical utilization. The requirement can only be accomplished, if specialists are involved in the whole development process. This happened intensively e.g. during the development of the APs 212 and 214. At the same time, aspects of the standards have been tested in implementations at an early stage.

The Application Protocols AP212 and AP214 represent widespread information models for different process chains. Since they describe all relevant data for the design- and construction processes within the automotive and electrical industry, they can, as a basis for operational information systems, offer significant strategic advantages to the manufacturers and suppliers in these branches. These advantages, which can be transfered to nearly all STEP applications, consist among others of:

		System independence,
		Data continuity throughout the complete product lifecycle,
		Redundance-free product data representation,
		Higher quality of the product data through formal representation following standardized methods,
		Qualitative better product data exchange and
		Feasability of long-term archiving.

These advantages become outstandingly clear when taking into account, that the german automakers and their 900 suppliers alone use about 110 different CAD systems. Due to the heterogeneous system scenery and the currently inadequate interface formats, a costly manual postprocessing of the transferred data is necessary.

The development of an Application Protocol towards an International Standard is very elaborate. This explains why not every proposition to develop an AP came to a successful ending.
The following table shows the current status of the Application Protocols which have been developed resp. still are under development:

IS - International Standard
FDIS - Final Draft International Standard
DIS - Draft International Standard
CD - Committee Draft
WD - Working Draft

Latest status see: http://www.nist.gov/sc5/soap/