Re: [xwiki-dev] [ArchitectureV2] Model proposal

Hi Vincent, Sergiu and all, Some remarks below after having discussed today with Mikhail Kotelnikov (in CC, author of WikiModel, co-founder of Cognium Systems, a partner of Nepomuk that XWiki company is part of [3]). [1] http://nepomuk.semanticdesktop.org/xwiki/bin/view/Components/WikiModel * WikiModel v2 contains an alpha version of a JavaCC grammar for the XWiki syntax. WikiModelv2 is common event model working currently with several wiki syntaxes: creole, gwiki, jspwiki, mediawiki, xwiki. [2] WikiModel v2 source code download: http://nepomuk.semanticdesktop.org/xwiki/bin/download/Components/WikiModel/… [3] http://nepomuk.semanticdesktop.org [4] http://www.cogniumsystems.com The topic is not easy, we are aware several strategies are possible, here's a contribution :-) Sergiu Dumitriu wrote: Couldn't we try to merge the Document, XObject and Attachment classes into a single class, along the lines of the JCR API where there is mainly a Node class that can have various types and various properties? An Attachment would be represented by a Node with a property containing a binary stream and possibly other properties such as the text description, the title etc. The advantage of this approach is to offer a simplified and more flexible model. What would XPropertyMeta stand for? With Mikhail we tried to produce a wiki model that can be easily mapped to the JCR model, and we came up with the following core elements: - Node (Document, XObject, Attachment would then be represented using Node instances) - NodeType (JCR terminology, equivalent to XClass) - ID: our proposal would be to create a top level class for IDs so that (i) can have several URIs for the same ID, (2) all manipulations with IDs (renaming: giving a new URI for an ID) are distinct from Node manipulation, (iii) this will allow the implementation of a service dealing only with IDs and URIs separately from the Node implementation. - Session: similar to the XWikiContext and to the JCR Session class: it's the user's context, giving access to all repository services adapted to that context. In addition to these core elements, we should add to the model a Version class, but its scope remains to be discussed. Just to see where we are on the map, we also drew the comparison below between the XWiki2 and JCR models: Farm <=> JCR engine Wiki <=> Repository Space <=> Node Document <=> Node Attachment <=> Node XClass <=> NodeType XPropertyDefinition <=> PropertyDefinition XProperty <=> Property XObject <=> Node From the discussion we had, it appears that at least Cognium Systems would be interested in designing core wiki libraries that could be then used by their collaborative engine in addition to being used by XWiki. Obviously, other companies and researchers are likely to take part in the design of such libraries, given the importance of wikis. We believe that such libraries would have more impact if they are maintained by a wide community of companies and researchers, avoiding the situation where a given community fears to use some library because it has too tight links with a single company. This has to be assessed, though. What do you think? Within Nepomuk, we're currently designing such core wiki libraries. We will upload a Node API proposal this week, and we plan to implement it on top of Jackrabbit by mid-june. The more we can share efforts toward a sound and flexible implementation of the core services, the better, but obviously the XWiki2 strategy regarding the Nepomuk effort remains to be investigated and discussed. Stéphane and Mikhail -- Stéphane Laurière slauriere(a)xwiki.com XWiki Research http://www.xwiki.com http://concerto.xwiki.com http://nepomuk.semanticdesktop.org