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 Germe  Laurent 
 

Configuration and version management in an SGML-based document management system

 

Introduction

  Many industrial sectors (aviation, automotive, etc.) have realized the importance of rational control of their documentary database. They are therefore in the market for open, effective systems to organize and update the documentation that also have a high degree of flexibility. These systems must meet specific requirements based on the complexity and size of the industrial projects performed.
  There may be many participants in a project, including suppliers and contractors. For the Rafale military fighter project, for instance, the contractors include Dassault, the industrial-architect, Snecma, the jet engine maker, Thomson, the radar supplier, and Matra, the missile supplier. The project also involves several hundred equipment suppliers.
 The main contractors face a delicate problem since they must handle a large flow of documents from the equipment suppliers as well as from the other contractors involved in the project. The job is all the more complex because of the high frequency of document interchanges and the large amount of important data that needs to be handled.
  Each contractor enters these documents, which are needed to produce the final product, in a documentary database. The database input is managed by the design offices which continually enter new data and the system output consists of releases which are the database viewing media for the users..
  The technical writers, translators, part listers, draftsmen, computer operators can all access the documentary database. They can all enter modifications frequently and in any order.
  The data entered in the documentary database are extremely varied, these including both text and illustrations from various sources.
  The documentary databases compiled and managed by each contractor are also used to prepare documentation for the buyers of the final product. The end users expect documentation that meets their needs, both in format and content. The releases are therefore provided in multiple formats (paper, CD-ROM, Internet, Intranet, etc.).
  To meet these diverse requirements, Sogitec has developed Industrial Documentary Systems (IDS) independent of the Document Type Definitions (DTD) handled and which are based on the concept of Data Modules.
  These systems benefit from our dual qualification as a supplier of aircraft documentation and computer system designer. For many years, Sogitec has been handling technical documentation for all Dassault aircraft, including the Mirage and Rafale fighters and the Falcon series of business aircraft.
 The systems can be adapted to different user profiles.
  For equipment suppliers who usually handle no more than several hundred pages of documentation, the entry-level product will run on a single personal compute running a database management system similar to MS Access.
  For contractors who handle more data (up to several Gigabytes) we have designed a larger system, SDI Open. It operates on a client/server basis with a database management system such as Oracle.
  In addition, we have developed viewing and editing tools dedicated to end-users of documentation produced from the documentary databases.
  These systems are completely interoperable and uses the same database, which is of course database, which is of course SGML structured.
 

The Modularity Concept

  The documentary database is broken down into a multitude of units of documentation (UD). The final documents are compiled by concatenating individual units of documentation.
 This strategy has been dictated by the often overwhelming size of documents combined with the need for fine grained control of the system.
 Each unit of documentation has contents, an identifier and an identity card.
  The contents of a unit of documentation is an The contents of a unit of documentation is an SGML-format text based on a DTD. Almost any DTD is possible, but they sometimes use mark-up which needs to be displayed to identify links, effectivity or any other information useful for database management.
  The identifier is often specified in the standard ( ATA, AECMA or other). Of course there is no universal identifier. The system must be able to accept any settings.
  The identity card is also very changeable. For example, in the status requirements of AECMA standard 1000D, there may be dozens of fields to register the quality assurance status, the reason for updates, applicability, etc. In other cases the identity card is very concise.
 The systems handles links between UDs and can browse through the document tree structure or browse using cross-references within the same document.
 

The Advantages of Modularity

  In addition to the conventional requirements of all technical documentation systems, i.e., completeness of data, reliability of contents, durability of the database, control of workflow, etc., the aeronautics industry has a number of specific requirements which Sogitec has satisfied with a modular approach.
 The selling points of its product—the Open Industrial Documentation System—are discussed below.
 
 

Control of Source Data

 The volume, and even more, the variety of data handled by documentalists is compelling. There are several dozen types of source data provided by the design offices, from system specifications to detailed drawings).
 Control of source data will strongly influence the quality and cost of the final documentation.
 Irrespective of type, the source data must be identified and recognized by the system. The author will list the source data used in each UD. The system will then:
 
  • enable the author to assess the potential impact on documentation if source data is updated,
    •  
  • inform other authors involved once an update has been implemented.
    •  The source data available in electronic format are integrated into the author's day-to-day work environment. The use of electronic viewing and of sophisticated search devices get the right information to authors quickly.
     
     

    Handling Large Volumes of Data

     A complete set of documentation can often run to several Gigabytes.
     As an example :
     
  • Sogitec has hundreds of GB available space for storing its documentary database.
    •  
  • the documentation for a single Mirage aircraft version contains tens of thousands of pages, and there are currently over thirty versions of the Mirage 2000 fighter in use.
    •  The tools needed to handle such impressive volumes of data must be powerful. and the computer technology must be upward-compatible..
     Client/server technology is particularly well suited to this activity.
      This is because relational databases have excellent performance characteristics while ensuring reliability of data under all circumstances, including hardware crashes, power failures, etc.
      Relational databases facilitate handling of identifiers and identity cards.
     
     

    Database Life Span

      In the aeronautics industry, the life span of a documentary database is several decades, a relatively long period.
     This durability means that the coding standards must remain constant in the long term.
      Organizations such as ATA (for civil aeronautics) and AECMA (military aeronautics) have issued standards in the field. Compliance with these standards guarantees that all participants will produce consistent electronic documents that can be exchanged easily.
     These standards are imposed for all projects, yet industrial contractors must at times adapt them for specific aircraft programs.
     Further more,
     
  • Several dozen DTDs are needed to reflect all the specific requirements of different documentary database components.
    •  
  • The DTDs are adapted for each contract.
    •  This multiplies the number of DTD which must be handled by each company.
     Our document system handles this with customizing capabilities that can be changed rather than requiring new development to handle a new set of DTDs. The diversity of these customizing capabilities must nevertheless remain high enough to permit fine management of the large amount of documentation involved.
     
     

    Eliminating Data Redundancy

     Given the large amount of data to be handled, a reduction in data redundancy provides significant economies of scale.
     Each UD is given an applicability identifier to enable use of the common portions shared by different documents. The applicability may:
     
  • reflect the type of system documented:
     
  • aircraft model
    •  
  • aircraft version
    •  
  • aircraft serial number
    •  
  • equipment
    •  
  • etc.
    •  
  • reflect specific client requirements.
    •  This permits multiple use of the same unit of documentation in different contexts
     Once the applicability identifiers have been inserted, the system must be able to cull information that is pertinent for a given user. This function is used when the final publication is compiled.
      Finally, the system must ensure consistency of applicability marking. To understand the importance of consistency checking, it is important to remember that a documentary database relies on a large number of links between the units of documentation. The links can be:
     
  • Inclusion links—a given chapter UD will contain a section UD which will contain specific paragraphs
    •  
  • Association links—a given text UD will call a given illustration, a given tool, a given spare part, etc.
    •   The two rules that ensure consistency of a documentary database are:
     
  • A documentary object contained in another must have applicability included in the applicability of the parent object (upward compatibility)
    •  
  • Two associated document objects must have intersecting applicabilities.
    •   The document management system must have efficient and automatic link consistency verification functions to manage the huge number of associative and inclusive links.
     
     

    Reactivity

     One of the major trends in recent years has been the need to reduce turnaround times. It requires time savings at every point on the critical path from the system design stage to document update times. In the aeronautics industry document update frequency has jumped by a factor of threefold in just five years.
     The documentary systems used must be designed to permit frequent updating and releases.
     Concurrent engineering is used to perform tasks in parallel that before needed to be performed sequentially. It improves reactivity times but requires more sophisticated tools to keep the documentary system under control.
     Control must be ensured by:
     
  • Handling the links between all the documentary database components
    •  
  • Checking access rights
    •  
  • Predicting the impact of a modification to a documentary unit.
    •  For instance handling the text/illustration link will prompt the author to review the text each time a draftsman changes the illustration to ensure that both are still consistent.
     

    Tailoring Documentary Databases

      Each user of a documentary database has specific requirements and expectations because of their activity. The trend has been to use the same database to compile documents for specific users: flight manuals for pilots, maintenance manuals for mechanics, illustrated parts catalogs for logistics support personnel, etc.
      This means that the appropriate information must be identified and extracted from the database for different purposes.
      The users of documentary databases now expect the latest viewing technology. In the field of aeronautics, the contents of the documentary database must remain the same for several decades but the techniques used to call up the information change much more rapidly (from hard copies to CD-ROM to Intranet and Internet in less than 10 years).
      This means that the database structure must be independent of the viewing support used.
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