xmlhack: oXygen adds limited Relax NG-driven editing support

SyncRO Soft has released version 2.0.4 of oXygen XML Editor, adding, among other new features, initial support for validated editing against Relax NG schemas. But that initial support has some shortcomings that make it of limited value in its current state.

The oXygen site provides the following description of the newly added support:

Content completion driven by Relax NG Schemas. When editing documents associated with a Relax NG schema the editor will offer content completion proposals for elements and attributes.

But there are a couple of serious shortcomings in the "content-completion proposals" it provides in its Relax NG-driven mode:

its Relax NG-driven element completion is currently schema-sensitive but not context-sensitive -- meaning that, instead of presenting you with a list of just the elements that the schema says are valid at whatever point you're at in the structure of the document, it gives you list of every element in the schema, so does nothing to help or prevent you from inserting an element that may not be valid at that point in the document structure
in its Relax NG-driven mode, it does not do completion on enumerated attribute values, so does nothing to help you select a valid value, or prevent you from inserting an invalid value

Neither of those limitations exist when using oXygen in its DTD-driven mode, so hopefully there are plans to enhance the Relax NG context-sensitive completion in future releases (hard to know, though, since the oXygen site provides no "TODO" list of potential features planned for upcoming releases).

Excessive memory footprint

Another serious shortcoming in oXygen is its seemingly unbounded appetite for system memory.

To be fair, it should be noted that resource-hogging is a standard trait of just about every Java-based XML editor out there. But oXygen takes it to a whole new level. Its initial memory footprint is huge by any standard, and appears to continue to bloat as long as the application remains open -- it seems to take as much memory as it can get, but rarely gives any of it back to the system.

Features

Outside of those shortcomings, oXygen does provide a number of decent features, including:

search-and-replace support using Perl 5 regular-expression syntax
XML Catalog support
configurable syntax highlighting
configurable indentation of content
integrated XSLT transformation support

If SyncRO Soft can add complete Relax NG support while somehow managing to find a way to prevent oXygen from gobbling up so much system memory, it could eventually prove to be a usable editor. In the mean time, if you want to do Relax NG-driven context-sensitive validated editing, you might give nxml mode for GNU Emacs a try.

A single-user license for oXygen XML Editor is US $48 for academic use, $74 for non-academic use, with some quantity discounts available (see the oXygen license page for more details). A free 30-day evaluation license is also available.