electing a UML tool for your development organization is, in some ways, similar to buying an automobile for your family. Once you've gotten past some of the basic features that any road-worthy UML tool should have—like, say, decent code generation or support for a wide range of UML diagrams—your choice of a UML tool will most likely reflect the style and character of your development team.
If architecture and modeling aren't necessarily a fundamental part of your current development practice yet, your team might be well suited with more mainstream "Ford" or "Chevy" modeling tools like Rational Rose or Togethersoft, which are plenty adequate to bring code-based teams up to speed in the brave new world of architectural software development. But if your organization isn't constrained by past approaches to development and open to the idea of exploring new and different ways of doing software engineering (for example, re-engineering your processes around UML tools that feature built-in decision support or real-time, Web-based collaboration capabilities), you ought to look more closely at tools like Gentleware's Poseidon for UML or CanyonBlue's Cittera. Integrating one of these next-generation UML modeling tools into your development organization may not be as simple and straightforward as with some of the more mainstream CASE products, but both of these innovative tools will offer your organization some unique competitive advantages.
Down to the Sea in Ships
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Figure 1 | Click here to get a close-up view of the Poseidon application.
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Poseidon for UML is based on the open-source ArgoUML project that was originally started as part of Jason Robbins's doctoral research on the usability of software engineering tools at the University of California, Irvine. Like the ArgoUML tool, Poseidon has a number of built-in cognitive support features that work somewhat akin to the "Intelli-Sense" code completion syntax checkers found in Microsoft and Borland IDEs. Auditors, or "critiques," in the tool constantly analyze your design as you model, displaying little yellow notes and squiggly red underlines where there may be potential problems.
So, for example, when you right-click on an element in your diagram, you're shown a menu that flags incorrect or problematical places in your design, such as classes without operations or instance variables or maybe a class with too many associations. Items on this menu are prioritized (High, Medium or Low) in another list in the Critics Pane in the bottom left corner of the working area, which, in turn, is further explained in a different pane by help text that describes the auditing rule that made the To-Do-Item come up (see Figure 1).
In many instances, a wizard will then walk you through the appropriate choices you need to make to resolve the issue. You also have the option of sorting your To-Do list by priority, decision, goal, offender, poster (that is, someone who posts a specific modeling criticism) and knowledge-type. Knowledge-type refers to issues such as correctness, completeness, optimization, or knowledge specific to your organization or a particular designer.
As you can imagine, with its open source roots, Poseidon offers strong support for a variety of open standards such as XMI, Scalable Vector Graphics (SVG) file format, and OCL. XML Metadata Interchange (XMI) is the mechanism standardized by the Object Management Group for the exchange of models between different UML tools. Unlike many other commercial tools that just import or export XMI, Poseidon uses XMI as its default file format. Object Constraint Language (OCL) is the textual expression language that's defined as part of the UML standard. OCL can be used to specify all kinds of constraints, pre- and post-conditions, guards, and so forth, over objects in different models. Since OCL is a formal language where all constructs have a formally defined meaning, it's very important that syntax and semantics in OCL are used correctly. Fortunately, Poseidon's Constraints panel (on the Details pane) has an OCL editor, which comes with its own syntax assistance mode. This will be especially appreciated by modelers who need to add precise and unambiguous specifications (when defining business rules, for example) to their graphical models.
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Germany's Gentleware Challenging Market Leaders 
