David Mertz, Ph.D.
Gnosis Software, Inc.
At A Glance
Creator: SoftQuad Software Price/License: $495. Closed-source. Home Page: http://www.softquad.com/
This review is one in new series by David that cover specialized XML content editors. A review of XML Spy appeared earlier on Webreview.com, and a review of XML Instance is planned for the near future. If readers would like to see other XML editors reviewed, they are encouraged to contact the author or WR's editors.
XMetal is an XML editor that aims for both the ease-of-use a wordprocessor and the generality and power of a structured editor. For the most part, it succeeds at its goals.
XMetal's default editing interface is called the "normal" or "wordprocessing" view, and will appear quite familiar at first to Microsoft Word users especially. Like many tools of late, many of the toolbar icons, menu shortcuts, menus, and so on are copied from MS-Office. The familiarity may be somewhat deceiving, since what XMetal does is actually rather different from what a wordprocessor does. But the familiarity is a good starting point.
In addition to the "normal" view, XMetal offers several others, with most features borrowed from SoftQuad's popular HotMetal HTML editor. You can edit in a "plain text" view, which is just what you would expect in a text editor that knows a little bit about XML: you get some syntax highlighting, line numbers, Windows/CUA clipboard operations, search/replace (including basic regular expressions). Unfortunately, and unnecessarily, some of XMetal's other capabilities are disabled in "plain text" view (i.e. "structure view" and context-sensitive element list).
The view that SoftQuad first invented (AFAIK) is the "tags on" view. This one is interesting, and quite useful. Each tag in the document--opening and closing--is represented by an arrow- like icon that contains the tag name. The words inside the tags are rendered in the style of the "normal" view, i.e. with different fonts, weights, colors, etc. This combination both lets you see without ambiguity what the markup structure of a document is, and also lets you see a good approximation of at least on likely final rendering of an XML document. Obviously, if the particular XML document is being used in a database style rather than in a book/article/documentation style, the rendering has less literal significance (but it can still visually highlight categories of information in the XML). The element rendering is configurable using CSS, as discussed below.
Another optional view is available as a separate pane. The "structure view" is a hierarchical tree representation of the document being edited in the main pane. Navigation is synchronized between the two panes. While "plain text" or "tags on" view will show you the tag information, the "structure view" helps make it more explicit. The structure view itself can take on multiple appearances, some more useful than others, but generally the options involve some helpful nested indentation and/or icons.
Between all the views, and combinations thereof, XMetal is a versatile and comfortable XML editing environment.
One extremely nice feature of XMetal is that you can configure the "default" (and therefore the "tags on" view also) to look however you like. The rendering is determined by Cascading Stylesheets (CSS) attached to the XML document. XMetal gives you a good interface for modifying and creating these CSS documents, such as automatically configuring the appearance of the element at the current cursor. From the look of things, the rendering is probably done by calls to the same DLL's Internet Explorer uses, since IE5.5 renders things the same way given the same stylesheet.
Much as with XML Spy (reviewed previously), XMetal provides you with context-sensitive tag and attribute panes. These panes are naturally optional, but when enabled they show a list of all the valid insertions at the current cursor location. This really helps when working with a complex DTD (validation is also performed dynamically, so there are several layers of assistance in producing valid documents).
Assuming you want to export your XML documents to more traditional viewable formats, you have several options. However, overall, this is a weak point of XMetal. To produce a many formats, you have the option of using a printer driver, which will render the appearance of the current view (presumably the "normal" WYSIWYG view). For example, PostScript and PDF files can be created this way (assuming the right printer drivers are on your system). Exporting to HTML is done via one of a couple separate menus (the "page preview" does this, basically, as does the "preview in browser"). Either one relies on a Microsoft driver, however, which has some problems mentioned below. XSLT is supported only via an external program of your choice. You can add some menu options to XMetal, but SoftQuad themselves do not really provide anything in this regard (Some installations of David's XML Matters column at IBM developerWorks discusses XSLT as a starting point).
The Microsoft XML Parser (MSXML.DLL) has version/compatibility problems with various Windows versions, and is still a beta product. At least such is my experience on several systems (various browsers, Windows versions, service packs, etc); YMMV. These problems are not really SoftQuad's fault, but it was their decision to rely on an external DLL they do not control.
One feature of XMetal is the inclusion of the "Journalist" DTD, which is subset of DocBook. If you use "Journalist" you get a number of preconfigured menus, toolbars and macros to help you in work with this style of document. However, I found the "Journalist" DTD a bit too restricted to use in editing my existing DocBook documents. You can still just use the DocBook DTD itself very well, but minus a lot of the enhancements (unless you want to "roll your own" if anyone does, David would love to have a copy, he was too lazy to do the work of programming one himself).
Generally, XMetal puts functions where you would expect them. But it has a few confusing parts. For example, if an XML document is not valid, XMetal offers to open it in "well- formed" mode. Fair enough. But once as far as I can tell, once you have corrected whatever might be invalid, the only way to enable validation is to close and reopen the document. And even then, if you do not 100% correct thing, you must revert to "well-formed" mode again. This--and a few other little things-- could definitely be handled better.
About The Author
David Mertz wrote this review aboard a great big clipper ship, going from this land here to that (but with no sailor's suit and cap). You can find out copious biographical details by sailing tohttp://gnosis.cx/publish/.