Appendix 1 - Tools and standards of PLM A.CALS CALS (Continuous Acquisition and Life Cycle Support) is a comprehensive standard for the broad international transfer of technical information between separate IT systems. CALS began from the United States Ministry of Defense, which was looking for ways to develop the electronic transfer of information. The CALS standard was designed to be so broad that every kind of information, including text and graphics, could be moved effectively between different systems. CALS contains several different standards: SGML standard, IGES format for the transfer of CAD files and EDI (Electronic Data Interchange) for the transmission of commercial documentation. In spite of its background, the standard has also gained a foothold in the civilian world, especially among large-scale international enterprises. CALS has been divided into two different stages (figure 36). Traditional paper based communication has also been compared with stages 1 and 2 of CALS in figure 36. In the first stage, data transfer takes place according to neutral transfer standards. In the second stage, a large database is created for the use of different parties within the information network. CALS will never be a finished and static standard. STEP, for example, is likely to replace IGES completely ifthe use of STEP continues to grow. Appendix I 207 :Customer Suppliers CALS stage1 Customer Exchange of L--.---' product data on application level CALS stage 2 Customer Exchange of product data through integrated database Suppliers Figure 41: Traditional data transfer model and stages l and 2 of CALS. B. STEP STEP (Standard for the Exchange of Product model data) is officially titled ISO I 0303 Industrial Automation Systems and Integration Product Data Representation and Exchange. STEP is an international standard, based on the idea of product models, for representing standard product data. The central idea of STEP is to make the transfer of product data possible between various departments within companies, and between separate companies, organizations, and separate users, with different software applications, over the whole life cycle of the product. With STEP, the data transfer takes place through a standard-type neutral product model, and standardized file formats, programming interfaces and application protocols. 208 Product Lifecycle Management The objective of the STEP standard is to offer a neutral - in other words commercially independent - transfer mechanism for product data, which can represent the product data over the whole life cycle of the product, irrespective of system. According to its definition, STEP is suitable not only for neutral data transfer but is also a foundation for the establishment of databases (ISO CD 103031 ). The objective of the standard is to make possible the connection, into a functional totality, of: • Computer aided design (CAD- Computer Aided Design) • Computer aided work and task design (CAPP- Computer Aided Process Planning) • Computer aided manufacturing (CAM - Computer Aided Manufacturing) In other words, the aim is to provide companies with the preconditions for actual integrated production (CIM - Computer Integrated Manufacturing). A further objective is to make the use of common databases possible for different applications and to enable the uninhibited movement of product data through cooperative networks. The aim is also to replace present standards and file-formats meant for the transfer of image information, such as IGES and DXF. As was stated earlier, STEP is not merely a transfer format for CAD information. It contains a whole technology: 1. Means to formally describe product data 2. Implementation methods to transfer, save and supply the information 3. Testing methods to test the conformity of the implementation to the STEP standard STEP gained official status in 1994. It is a fairly broad, and continuously growing, abstract and high-level standard. The idea of the standard is to function as a general foundation when creating a product model utilizing the standard's integrated resources. The integrated resources are used when developing data transfer protocols (AP - Application Protocol) for particular industries, which serve only one particular kind of data transfer need. These AP's are part of STEP and visible in practical data transfer. An example is AP 214: Core Data for Automotive Mechanical Design Process. Appendix 1 209 There are five AP's in preparation for shipbuilding: • AP 215 - Ship Arrangements • AP 216- Ship Molded Forms • AP 217 - Ship Piping • AP 218 - Ship Structures • AP 226 - Ship Mechanical For example these AP's include several ready sections some of which are already in production use. The naval modeling software of Finnish software provider NAPA (Naval Architecture Package) uses AP 216, among other things, in 3D models, for saving surface data. A function model of the application (AAM Application Activity Model) is used to define the area of qualification of the AP. The AAM defines the functions of the application and the data flows in which the product data is moved and handled. The information needs for the application, and delimitations related to the information, are described using the reference model of the application (ARM Application Reference Model). The resources model of the application (AIM Application Interpreted Model) defines the subset of the integrated resources that an AP uses. In addition to all this, the AP describes the relation between AIM and ARM, in other words how the general concepts of AIM are interpreted in the ARM. The purpose of the different models described above is to allow all application areas to utilize common concepts as resources, such as geometric form descriptions. However, these descriptions can also be interpreted differently by each application protocol, or AP. For example, the volume model for a right-angled prism can be used to describe the form of a concrete block in a building application or to describe the form of a simple steel part in mechanical engineering. These form descriptions will then be tested using the testing methods of STEP - which are a part of each AP - to ensure that the description meets the uniformity demands of the standard. 210 Product Lifecycle Management Generic resources Product description Presentation Math Support Product data management Figure 42: TEP standard. C.DXF DXF, or Data Exchange Format is a data transfer standard developed, maintained and patented by AutoDesk Inc, the creator of AutoCAD software. The standard does not have official approval but due to its wide use in 2D CAD, DXF has become a de facto standard for 2D CAD data. It is most used to transfer data between PC-based CAD applications, due to the good functioning of .dxf and the strong market position of AutoCAD. DXF is not suitable for the transfer ofthree-dimensional, solid models. D. IGES IGES (Initial Graphics Exchange Specification) is a standard developed for the transfer of graphic information - drawings and models - in 2D and Appendix 1 211 3D. IGES is a neutral file format, which can be read by nearly all CAD software. Problems may often occur in the transfer of information due to the scope of the qualifiers in IGES. Features can be presented in many different ways, all of which are correct. The newest IGES files can also contain small amounts of product data, together with attribute tables and solid models. E.SGML SGML (Standard Generalized Markup Language), ISO 8879, is the standard general description language for the structure of a document. SGML makes it possible to present information according to a data model. The description of the data model is called DTD (Document Type Definition). However, the instance of the document describes the structure and contents of the document. SGML is widespread within fields of industry that have any kind of publishing activity. The standard is mainly used to describe the contents and structure of documents. SGML makes possible the electronic storage of documents as well as document retrieval, transfers, and revisions, irrespective of the applications or equipment used. It is said to offer to structured documents what SQL has traditionally offered to structured information: a common language, which makes possible cooperation between different systems and software. A good example of SGML from DTD is HTML, which is used in the Internet's WWW, where the language is used to describe Internet pages, among other things. HTML can be used to create documents that include images, text, sound, and links to other documents anywhere on the WWW. So the user can use a PC to browse documents located anywhere on the Internet. The application used to do this - a browser such as Opera, Netscape or MS Internet Explorer - transforms the documents into a form suitable for the screen. F.XML XML (Extensible Markup Language): The deployment of this data transfer standard probably provides the best new opportunities for 212 Product Lifecycle Management cooperation and collaboration between organizations. XML is a simple subset of SGML. The HTML used on the Internet is similar in its way of presenting structured information. In XML, the separate documents or the parts of the information can contain mutual relations so that it is relatively easy to search a large mass of information. XML is a standardized description language for the structured presenting of information. The structured information can contain different types of content, including text and images, as well as descriptions of the contents. XML describes its contents itself. It differentiates data structures from the user interface, so information from separate sources can be brought to the same user interface. The basic idea of XML is to distinguish structure, content and styles from each other and thus to ease the portability of information. The concept of XML can be understood if one thinks of it as a meta-language, which can be re-defined by anyone who wishes to present certain material in a standard way. XML files are classified into two categories: well formed and valid.