Uml Sketching Tools

16 June 2004

uml

I draw a lot of UML diagrams, but I don't use CASE tools. The reason is that I'm interested in UmlAsSketch, not in all the repository stuff. So far my regular choice has been Visio. Although Visio comes with UML templates I don't use the built in ones - I prefer those of Pavel Hruby.

Visio has worked very well for me, and it's still my first choice. But I'll admit to a wandering eye. Visio only works on Windows - and I also use Macs and Unixen, so it would be nice to have a tool that worked on all (or actually a common data format). I like to collaborate with others, so something open source would allow them to draw diagrams if they don't have access to Visio.

I've played a little with OmniGraffle on my Mac, not enough to really evaluate its capabilities - although it does produce lovely looking anti-aliased output. UMLet is an interesting looking project too.

The biggest thing I would like however is to specify my UML diagrams as text. That may sound strange - after all UML diagrams are diagrams, so why use text? Text has some advantages. Much of diagram layout is tedious to fiddle with in diagrammatic form, and would be much easier to do textually - using the diagrams as a visualization rather than an editing mechanism. Also text formats allow you to easily track changes over time with cvs and diff.

As a result I was intrigued by UmlGraph. The part of this that most grabs me is the sequence diagram editor which uses the venerable pic program. This page shows show the pic macros create a nice textual representation of a sequence diagram. Of course there are some limitations of what you can do in a pic macro and I can imagine a textual representation that's even more compact and clear.

objects 
  thread, t:thread
  tool, :Toolkit
  peer, p:Peer, unborn

trace 
  found: a1:run(3) -> 
    thread: 
      run() -> 
        tool: 
           callbackLoop() -> self
           create -> peer
           handleExpose() -> 
             peer: 
               return      
           delete -> peer

That's just off the top of my head. I don't know how well that would really work in practice. In any case I intend to experiment with UmlGraph as it stands to see how it would work for me. The pic program is so small I could easily tweak it if I wanted some changes.

UmlGraph's class diagram generator is nice in that it can produce stuff from Java source files. However for just a diagram syntax it looks rather awkward - and I would like some control over placement of classes. Enough to say Customer is to the left of Order. So perhaps represent this diagram with something like this:

layout
  row: Controller, EmbeddedAgent, URLStreamHandler, ChannelIterator
  SetTopController below: URLStreamHandler
  PowerManager below: SetTopController

interface URLStreamHander 
  operations 
    OpenConnection()
    parseURL()
    setURL()
    toExternalForm()

class SetTopController
  specializes
    Controller
    EmbeddedAgent
  implements
    URLStreamHandler
  attributes
    authorizationLevel
  operations
    startUp()
    shutDown()
    connect()
  associations
    -> PowerManager

class ChannelIterator
  dependencies
    -> SetTopController keyword:friend

Again this is just off the top of my head. The important thing is that I'm glad to see someone going in this direction - and would like to see more.

Here's some similar sketch-like tools that people have told me about