Zope and XML

• Martijn Faassen
• Infrae (Rotterdam, the Netherlands)

Goals

• document-centric XML
• store documents in ZODB
• view, edit, annotate, search XML in Zope

ParsedXML

• Foundation to the rest
• stores XML in the ZODB
• allows DOM access for programmatic manipulation

Changes

• rewrote and sped up ParsedXML's DOM wrappers
• made it rely on PyXML, not carry around own Expat parser
• pretty print
• bugfixes and cleanups

Demo of ParsedXML

• loading an XML document
• viewing and editing
• pretty printing
• DOM access

NodePath

• Currently part of ParsedXML, but just relies on DOM
• allows paths to nodes in URLs
• various path schemes
• can be used for annotations and node event handling

NodePath schemes

• child
• element_id
• robust

Scheme child

• doc/child,3,1
• works for all nodes
• very unstable to changes
• good for annotations of stable documents

Scheme element_id

• doc/element_id,e0,e1
• only works for elements
• more stable to changes, but reparses break it
• good for editor event handling

Scheme robust

• doc/robust,zittingsdag1,resolutie3,p1,text2,23dat5is14de17middelen.*23
• only really works for text nodes with text, heuristic
• robust to all kinds of changes (but needs tuning)
• good for annotations of evolving documents

Demo of NodePath

• getNodePath(scheme)
• resolving URLs

XMLWidgets

• TTW Editors and viewers
• Builds on ParsedXML and NodePath
• Silva is built with it

Model/View/Controller for DOM Nodes

• An XML Widget is a Folder, looked up dynamically
• Model: XML DOM node (usually element node)
• View: PageTemplates in widget folder
• Controller: Python Scripts in widget folder

Demo of XMLWidgets

• Silva document viewer
• Silva document editor

XPathIndex

• uses XPath from PyXML
• catalog-like, but for XML documents and nodes
• XPath to select what to index, NodePath to point to nodes
• can work together with the ZCatalog

Demo of XPathIndex

• filling index, filling catalog
• search with catalog

Problems

• ParsedXML is relatively slow
• DOM not optimal representation for some tasks
• PyXML/ParsedXML incompatibility
• XML really needs unicode, Zope 2 not designed for it

Dreams: XSLT support

• already prototypes available
• needs nurturing and care

Dreams: libxml, libxslt, gdome integration

• libraries in C, very fast in comparison
• libxml and libxslt now have python bindings
• issue: needs to be storable in ZODB (pickleable)

Dreams: storing XML in different way

• store and index XML in non-tree form
• allow fast (XPath) query
• have prototype using ZODB and BTrees

Dreams: Zope 3

• Hide functionality of various systems behind a clear set of interfaces
• Let the system choose adapters to provide the functionalities.
• for instance: DOMAdapter