[ba-ohs-talk] Fwd: [xml-dev] ANN: Markup Object Events (MOE)
>From: "Simon St.Laurent" <email@example.com>
>I'm happy to report that I've finally published an alpha version of Markup
>Object Events (MOE) . MOE is a Mozilla-licensed Java API and
>supporting set of classes which supports markup processing using both
>events and object trees. MOE programs can work purely with events, purely
>with trees, or with combinations of both, effectively providing a "middle
>way" between SAX and DOM.
>MOE emerged from my work over the past summer on SAX filters, notably
>Regular Fragmentations . I couldn't justify creating DOM trees for the
>relatively tiny changes I've been making to documents, but SAX's streaming
>approach made it difficult to do things like modify the attributes of an
>element based on its contents. I spent a lot of effort building temporary
>containers, and concluded that the "temporary" containers were interesting
>in their own right.
>MOE permits all nodes to have:
>* A three-part namespace-aware name (prefix, local name, URI - QName
>* Unordered content (a set) - think attributes
>* Ordered content (a list) - think child elements, text, etc.
>* Annotations (a map) - any other information you need, largely unconstrained
>MOE's foundation is very abstract (and defined as interfaces for another
>level of useful abstraction), but can be readily applied to XML document
>processing. The abstraction and interface approach make it possible to
>use MOE to represent non-XML content, to preserve lexical information of
>all sorts, to represent content which is not well-formed, and to create
>annotated object models which host information which may not have any
>lexical representation. This alpha release focuses more simply on an
>Infoset-like view of XML - something like the SAX2 view of XML.
>Developers can use MOE as storage for information from SAX events, or they
>can create complete trees built from MOE events. Nodes can listen to
>flows of information, building a tree structure, and report when they
>have "finished" - when an element reaches its end tag, for instance. Those
>nodes can then be reported again as a stream of MOE (or SAX) events,
>converting the tree back into events.
>While it is possible to use MOE in place of SAX or DOM (given a parser),
>it was designed to complement those approaches, not replace them. The
>current API supports only tree-walking navigation, not XPath or similar
>conveniences. For small trees it's fine, but for large trees it won't be
>MOE is still pretty raw. It's had a little bit of review from a few
>people, and has benefited greatly from that, but I suspect there's a lot
>more review to come. I feel reasonably comfortable with the logic of the
>core (hence the alpha relase), but the visitor, adapter, and factory
>classes are still prone to wild gyrations. Namespace support - especially
>declaration management - has also proven trickier than expected, though
>that's not a huge surprise.
>There is also a very simple Swing application - MOEWorkshop - which lets
>you explore MOE trees visually, but it still has a very long way to go to
>become the debugging tool for chains of MOE processing that I want.
>MOE owes a great deal in spirit to various work done by the Python and
>Perl communities. While I work primarily in Java, hearing about the
>various tools for working with partial trees in Python and Perl inspired
>much of this work.
>MOE is deliberately written in what I call "naive Java". Given that I
>expect MOE to change substantially over time, I've opted to focus on
>clarity rather than performance. I've attempted to create a class
>structure which separates particular kinds of processing from the basic
>object model, but I've undoubtedly made some slips as well. I'd also like
>to develop a comprehensive set of unit tests, but haven't yet had time to
>do so. (The tests I have are very simple.)
>I'll be rewriting many of my SAX filters to use MOE over the next few
>months, starting with Regular Fragmentations. I'm hoping that applying
>MOE to a wide variety of general problems will help me evolve it into a
>more powerful toolkit over time. Comments, suggestions, queries, and
>contributions are all welcome. CVS and mailing lists are available
>through the MOE SourceForge project page .
> - http://moe.sourceforge.net/
> - http://simonstl.com/projects/fragment/
> - http://sourceforge.net/projects/moe/
>Associate Editor, O'Reilly & Associates
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