The gorge between the X-volution and the real world   Table of contents   Indexes   The Document as Application: Issues and Implications
 

The Reference Browser: Support for Authors in Editing Links
 Dr. Frank-Marcus   Steinmann
  Project Manager
  debis Systemhaus  Magirusstr. 43
 89077 Ulm   Germany
Phone: +49 731 9344 1830
Fax: +49 731 9344 100
Email: fms@debis.com Web: http://www.dtro.e-technik.tu-darmstadt.de/fms/fms.html
 
Biographical notice:
 
Dr. Frank-Marcus Steinmann is a project manager in the debis Systemhaus GEI. Here he has served as a consultant and developer for a number of SGML applications in the automobile industry since 1996. Prior to this, he was scientific assistant in the Department of Computer Engineering in the Darmstadt University of Technology, Germany. There he received a Ph. D. in Computer Engineering in 1996 for his research into text and speech processing.
 
ABSTRACT:
SGML document
XML document
 XSL 
context-dependent
 document 
target
traversion of links
 
The reference browser supports authors in editing links of SGML/XML documents by context-dependent supply of all possible link targets. The author only needs to select the desired target element and does not need to think about the internal representation of the links. Furthermore, presentation and traversion of links are handled. Thus, editing links becomes easier for the user and the error rate will be reduced. The use of a subset of XSL permits a flexible layout design.
 

Introduction
SGML editor
XML editor
creating links
linked documents
modifying links
 
The reference browser is designed for editing systems of linked documents which may belong to one DTD or a known set of different DTDs. Beside the standard referencing mechanisms, every element which can be referenced to should have a designation, for example a content element <name> which will only be used for displaying the link target, not for building the link. By editing these documents, for example in an SGML/XML editor, the reference browser supports the process of creating and modifying links. These links can be internal links in an SGML/XML document or external links to other documents. This support is given by providing a context-dependent list of the names of all possible link targets by using a subset of XSL. The user only needs to select the desired target element and does not need to think about the internal representation of the links.
 CLINK 
 ID/IDREF 
XML links
editing links
nameloc
 reference view 
tree control
 

Editing Links
 
The reference browser supports the user in editing links by providing a context-dependent list of the names of all possible link targets that are available in all relevant documents. For this purpose the reference browser uses a combination of a tree control and a reference view. The tree control can be used to select the target document and the desired type of target element. The reference view can be used to select the target element itself. Reference views can be configured in such a way that, for example, only the names of all targets which are permissible for the reference in question will be listed. By selecting a target in the reference view, the user can create a link without having to think about the internal representation like ID/IDREF attributes or <nameloc> elements. Furthermore, it can be guaranteed that the link will have the desired target element type, since the reference views are listing only the valid target elements.
 
The reference browser supports unidirectional and unambiguous links like:
  •  HyTime CLINK (external)
  •  ID/IDREF (internal)
  •  XML Links
 
 
FigureSTEF-001 shows the process of editing links (referencing elements) by using the reference browser: To select a link target, the following input is needed from the author:
  1.  Selection of a target document (tree control)
  2.  If more than one target element type is allowed in the given context: Selection of the desired target element type (tree control)
  3.  Selection of the target element. The corresponding reference view of the target document will open automatically. In an external configuration file, it can be determined which reference views will be available in which context.
 
In this configuration file, it can be determined for each DTD which elements may link to which target elements of which target DTD. Of course, external links can link to documents of other DTDs.
 
The reference browser keeps all relevant documents where possible link targets shall be listed in a dynamic repository.
 
Another aspect in this context is the traversion of links forward as well as backward. The forward traversion of a link can be used to show the definition of the linked element. To do so, it is necessary to load the referred document. The SGML/XML editor will require the following capability:
  •  Invocation of the appropriate editor and, at the same time,
  •  Opening of the referred document and
  •  Selection of the referred element
 
The backward traversion can be used to find all links to the actual element. Due to the link architecture of CLINKS or ID/IDREF links, additional information is required for this.
 XSL 
layout
 presentation 
 reference view 
 

Presentation of Links
 
To define the presentation of the elements shown in the reference view, a subset of XSL will be used. The presentation of the elements which can be referred can be determined here. FigureSTEF-002 shows an example of the tree control (left pane) and the corresponding reference view defined with the subset of XSL (right pane).
 
 
On the other hand, the presentation of the referencing elements has to be done by the SGML/XML editor used, for example by showing their names. The reference browser offers support here. When a link is created or modified, the reference browser returns values. It also offers these values when there is an enquiry from the SGML/XML editor. In a configuration file it can be determined which values will be returned. These can be parts of the referred elements that shall be used for the presentation of the link (for example a subelement like <name>). Furthermore, the name of the referred document as well as fixed strings can be added to the presentation of the link. It is not important if the SGML/XML editor copies these values internally or requests them when they are needed for presentation. Alternatively, if the presentation of the contents of the target element is not necessary, the presentation can be reduced to the simple information that there is a link, without any information about the target. The reference browser supports all these possibilities.
 JAVA 
platform
 

Conclusion
 
The reference browser has been realized on behalf of the DaimlerChrysler, department FT2/EE, Mr. Rauleder. It is a tool, that does not depend on the used SGML/XML editor or on a DTD. It can be integrated into any editor which allows access to the SGML/XML structure via an API. The realization has been effected with JAVA and C, so that many platforms (for example Windows 95, Windows NT and SUN Solaris) can be used. The users have a favorable opinion of the reference views. Editing links becomes easier for the user, because only the names of the desired target elements are listed. The error rate can thus be reduced. The use of a subset of XSL permits a flexible layout design of the reference views. The performance of JAVA is adequate for building the reference views on-line.
The gorge between the X-volution and the real world   Table of contents   Indexes   The Document as Application: Issues and Implications