Information Infrastructure for the Industrial Virtual Enterprise


Martin Hardwick

Professor of Computer Science, RPI

President, STEP Tools, Inc.


The National Industrial Information Infrastructure Protocols (NIIIP) Consortium is a team of organizations that entered into a cooperative agreement with the U.S. Government, in 1994, to develop inter-operation protocols for manufacturers and their suppliers (see


The NIII protocols make it easier for engineering organizations to share technical product data over the Internet. They do this by building on the STEP standard for product data exchange. STEP provides common definitions for product data that can be read and written by many CAD/CAM/CAE and PDM systems.


If engineering organizations can share data using STEP, then suppliers are no longer constrained to own and operate the same systems as their customers. The potential benefit is large. Suppliers are spending a lot of money buying the systems of their customers, more money training people to use those systems, and even more money re-entering data from their preferred systems into the system required by each customer.


The protocols selected and developed by the NIIIP Consortium have been validated in three end-of-cycle demonstrations. In each cycle, a team with expertise in technical product data, object modeling, workflow management, security, and knowledge representation came together and demonstrated how technical barriers to the dynamic creation, operation and dissolution of "virtual enterprises" are overcome by the NIII protocols.


The challenge problem for the NIIIP project was to make it possible for a client program to perform an operation on technical product data over the Internet. In Cycle 1 the operation was "CAD visualization." In Cycle 2 the operation was "engineering change." In Cycle 3 the operation was "create assembly." To enable these operations, the NIIIP protocols had to make it reasonable for the client application to access product data across the Internet, modify product data across the Internet and to integrate product data across the Internet.


STEP defines an integrated suite of information models for the life cycle of a product. The information models are defined in a language named EXPRESS that is similar to other data definition languages, but unique because it can describe the complex data structures and constraints needed for properties such as geometry and topology. Today, STEP information is usually exchanged using files. However, STEP information can also be shared using an EXPRESS-driven programming interface called the STEP Data Access Interface (SDAI). The SDAI lets an application program access STEP data in a repository. When the NIIIP program began, the repository and application program were assumed to be operating in the same process.


Four NIII PD protocols have been layered on the STEP standards. The first two are being made into new ISO STEP standards, and the fourth is being made into an Object Management Group (OMG) standard. An appropriate standardization body has yet to be selected for the third protocol.


  1. SDAI Java and SDAI IDL are programming environments that let applications access and manipulate product data stored in remote repositories over the Internet [1, 2].
  2. EXPRESS-X is a mapping language that creates application-specific objects out of the neutral data defined by STEP [3].
  3. STEP Services is a set of operations for cutting and pasting objects defined by EXPRESS-X between data sets [4].
  4. The OMG Product Data Management (PDM) Enabler defines a programming interface for servers that integrate product assembly information [5].


The SDAI Java binding lets applications manipulate product data using World Wide Web browsers. The SDAI IDL binding lets applications that are written in different programming languages manipulate product data over the Internet. With these two bindings, an application can open a repository, find data, and transfer it to a remote client. The repository can be defined by one of the EXPRESS models defined by STEP or another EXPRESS model.


EXPRESS-X is a language for mapping data between EXPRESS models. It can be used to map data between the application-neutral EXPRESS model that defines a STEP standard, and an application-specific model. The STEP models are designed to support operations that a large range of enterprises might want to perform against a type of product. An application-specific model is one that can handle the more limited range of operations needed by a single application.


The STEP Services protocol defines data transfer and integration operations. With these operations, an application can integrate objects from multiple sources to create a database. The services define how an application can traverse a set of objects, find the ones it needs, copy them to another data set, and integrate those copies with the existing objects in the database.


The PDM Enabler is a protocol that defines programming interfaces for product data management. Part of the PDM Enabler defines a standard programming interface for servers that manage product assemblies. OMG plans to define similar standards in many other areas, including Manufacturing Execution Systems (MES) and Enterprise Resource Planning (ERP). These standards will be useful for servers that need to manage manufacturing execution and planning information.


When the protocols are complete they will make it easier for enterprises to share technical product data over networks. Programs such as the Boeing 777 design project have shown the value of product data sharing using a homogeneous database. The NIIIP protocols should allow teams of enterprises to share product data from distributed, heterogeneous product databases. For more information see



  1. Industrial Automation Systems. Product Data Representation and Exchange. Part 27, Java Binding for the Standard Data Access Interface, ISO 10303-27, (, International Organization for Standardization, Geneva, Switzerland, 1998.
  2. Industrial Automation Systems. Product Data Representation and Exchange. Part 26, IDL Binding for the Standard Data Access Interface, ISO 10303-26, (, International Organization for Standardization, Geneva, Switzerland, 1996.
  3. Industrial Automation Systems. Product Data Representation and Exchange. Part 14, EXPRESS-X Mapping Language, ISO 10303-14 (, International Organization for Standardization, Geneva, Switzerland, 1998.
  4. M. Hardwick, The STEP Services Reference Manual, Tech. Report 96004, Laboratory for Industrial Information Infrastructure, Rensselaer Polytechnic Institute, Troy, New York, 1995 (
  5. White Paper to the OMG in Response to OMG Manufacturing Domain Task Force OMG TC Document 97-09-1, Object Management Group, Framingham, MA, December 1993 (