Product Review:
XML Spy 3.0

David Mertz, Ph.D.
Gnosis Software, Inc.
August 2000

At A Glance

Creator:       Icon Information Systems
Price/License: Starting at $150 for single-user. Multi-user
               licenses at various discounts. Closed-source.
Home Page:
Requirements:  Win32


Icon Information Systems characterizes XML Spy as:

A true Integrated Development Environment (IDE), XML Spy contains features required for many different aspects of XML-related tasks.

XML Spy lives up to its billing, and includes capabilities for most every ad-hoc and manual XML-related task you might be faced with. You can edit, create and validate XML documents, DTD's, Schemas, Stylesheets, and various other filetypes (including some specialized XML types, such Mathematical Markup and BizTalk Schema but links to some of those definitions on the internet are inaccurate).

In general, XML Spy presents a consistent and helpful interface for working with these document types, and a number of helpful tools that automate development tasks. The interface of XML Spy is generally modelled after Microsoft's Visual Studio development environment with a similar dockable paned interface. The layout will be familiar to many developers; but I personally found the default layout to be too busy, and leave too little screen real-estate for your main documents (I feel the same about Visual Studio though). Fortunately, you have many options in selecting what panes, toolbars, etc. are visible in the workspace, and in arranging them.

What XML Spy is not is a programmatic system for processing XML documents and related filetypes. Basic XSL transformations are supported, but do not expect to perform generalized data extraction and manipulation with this tool. You do not, for example, get any access to DOM methods on XML documents. This limitation is not flaw in XML Spy, it is just what the XML Spy does. Basically, what you get is a very specialized and enhanced text editor; that is, there is little XML Spy does that you could not do in principle with Notepad (with a whole lot more work for the latter).

Nice Behaviors

When editing an XML document (or other filetype), XML Spy provides you with two basic views: the Text View (which looks basically like any text editor) and the Enhanced Grid View (which is a structured schematic representation of the document). There is also a Browser View, which is just an external DDE call to Internet Explorer 5.5 or above; you cannot edit in the Browser View.

In both views, you are presented with onscreen prompts and shortcuts for entering valid tags and attributes. If you are usuing a DTD or Schema, there is a lot more help to provide. An information window describes the current context (element versus attribute, model, occurance rule). Addition "Entry Helper" panes show what subtags, attributes and entities are available in a context, and assist you in entering required or allowed elements. These helpers make your work a whole lot easier in trying to conform to a DTD (or in developing one).

One built-in tool of XML Spy that felt like actual magic was its automatic DTD/Schema generation. From a typeless XML document, XML Spy can do a remarkably good job of inferring the underlying DTD (and creating and attaching it). I found that this generation was not perfect--for example it believed I was using an enumerated type where there was really just CDATA--but the "errors" it makes are no worse than those a person would who had only the XML document, and not the underlying design rules. Cleaning up or customizing an XML Spy generated DTD is a lot quicker than writing one from scratch!

Another nice interface device is an option in the Enhanced Grid View. Most of the time, subtags are displayed in a hierarchical tree fashion. However, XML Spy will automatically detect when it thinks some data could better be displayed in a Database/Table View of repeating element sequences. You can also manually force one view or another. For working with what is basically tabular data to start with, using this view makes entering and understanding an XML document much easier.

Bothersome Behaviors

XML Spy will check the well-formedness of an XML document, and will validate it against a DTD/Schema if one exists. However, the compaint messages produced when these checks fail are far less helpful than they could be. In particular, no line numbers are given to identify problems. In a large XML document, finding a problem that is described, but not specifically highlighted, can be a lot of work.

Another "misfeature" in my opinion is XML Spy fairly strict adherance to a tree model in the Enhanced Grid View. The makers do not seem fully to appreciate the distinction between character-level markup and block level markup, and this makes it hard to enter and view the former. For example, if you want to mark one word as "<ital>" in a block of text (PCDATA), the italicized content is shunted to another cell of the grid from its adjacent text. Formally that is accurate, but as an way of editing an XML document, it gets in your way more than it assists you. Using the Table View for the text block improves things a little bit, but only a little. Basically, to really work with marked-up character data blocks, you have to switch to the Text View--but in that case you could have chosen better plain-text editors, which is basically what you have in that view.

The last--or really the first--trouble I had with XML Spy is that tutorial in the online help is going to be available "real soon now." Not every interface feature of XML Spy was immediately obvious to me, and I really wanted to read the tutorial. But as of the current version, you are stuck with either trial-and-error or trying to find help on a specific feature (which you probably don't know the name of yet, or exactly what it is supposed to do). The learning curve is not bad, but a tutorial would have helped.

About The Author

David Mertz will settle for paraphrase where cannot manage periphrasis. You can find out copious biographical details by rooting around at