The resource generator creates file-based resources from the component model of a web application. All the information required for mapping components to the file system is contained in the components' generateCode operations which are invoked top-down from aggregation components to atomic components. For components of small grain this operation returns code fragments of file-based resources. For components at the granularity of resources, this operation returns a filename. And for higher-level components, the operation may return a directory path or nil (when it returns nil, the directory tree is not further subdivided).
The resource generator can perform both a complete installation of a web application, and incremental modifications. For a complete installation, the resource generator proceeds top-down through the component hierarchy, top-down making directories, opening files and filling files with code. For incremental code generation, the resource generator makes use of the component store's revision control. In this process, it generates those resources that contain components that have been modified. As resources themselves are represented by components, the dependencies among components can be evaluated to identify those resources that have to be newly generated.
Summary
With WebComposition webs are modelled in terms of components of arbitrary granularity. Components capture web entities for reuse, sharing and localisation of modifications. Components can capture those web entities that are basic units for more complex patterns, but that are hidden in resources in a standard web implementation. One instance of such patterns are hypertext structures which are based on links and anchors that can be made explicit in the WebComposition model. We would propose that based on the object-oriented WebComposition model, object-oriented design patterns as pioneered by the gang-of-four [8] may be used for development of reusable hypertext structures.
References
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4. T. Isakowitz, E.A. Stohr and P. Balasubramaninan. RMM: A Methodology for Structured Hypermedia Design, Communications of the ACM, August 1995.
5. Alicia Diaz, Tomas Isakowitz, Vanesa Maiorana and Gabriel Gilabert. RMC: A Tool to Design WWW Applications, The World Wide Web Journal, Issue One, Dec. 1995.
URL: http://www.w3.org/pub/WWW/Journal/1/isakowitz.187/paper/187.html
6. H.-W. Gellersen, R. Wicke and M. GaedkeWebCompostion: an object-oriented support system for the Web engineering lifecycle, Computer Networks and ISDN Systems 29 (1997), p. 1429-1437.
URL: http://www.teco.edu/~hwg/www6/PAPER232.html
7. D. Ungar and R.B. Smith. Self: The Power of Simplicity, OOPSLA '87 Proceedings, p. 227-242, 1987.
8. E. Gamma, R. Helm, R. Johnson and J. VlissidesDesign Patterns: Elements of Reusable Object-Oriented Software, Addison-Wesley, 1994.
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