Logiweb(TM) Amnesia

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The 'frontend' of lgc(1) translates the lgs source into a Logiweb vector. After that, the Logiweb vector could be written to a file and lgc could quit, leaving further processing to other tools. However, lgc passes the Logiweb vector to its 'codifier' which 'understands' the vector and verifies its 'correctness' as explained in the section on loading. That process has to do with semantics and is outside the scope of the present section. When the codifier is done, lgc passes the output from the codifier to the 'backend' of lgc which renders the page.

When lgc has translated an lgs source into a Logiweb vector, it suffers from voluntary amnesia: it forgets the lgs source and continues with the vector from that point. For that reason, the frontend on the one side is quite separate from the codifier and the backend on the other side. If one has access to a Logiweb vector but the rendering of the vector has been lost, then one can by-pass the frontend of lgc and ask lgc to re-understand, re-verify, and re-render the page based on the vector alone.

The amnesia has the benefit that the codifier and backend only see what everybody can see once the page is published, so one avoids that any dependency on the lgs source sneaks in. The amnesia has the drawback, however, that if the codifier or backend finds an error, then they cannot report which line of the source code the error relates to. They have to relate the position of the error to e.g. the rendering of the page.

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Copyright © 2010 Klaus Grue, GRD-2010-01-05