DSL for Integration

Posted by anton
on Monday, August 20, 2007

this is somewhat of a wide-eyed rant, but i wanted to get it off my chest for a while.

i have worked with Tibco BusinessWorks suite of tools for quite a bit in past few years, and i came to really appreciate it. for those not familiar with it – it is a GUI-based drag-and-drop frontend that allows one to use standard components for quickly building integration scenarios – e.g. get data from source x, transform it, then shove it into destination b.

for the longest time this sort of GUI tools were anathema for me – i learned over time that there is no silver bullet, abstractions leak, and for “general” software development these tools did not succeed in addressing complexity.

at the same time Tibco BusinessWorks was remarkably successful – one could knock out an integration scenario in under an hour and deploy it in full enterprise glory – high availability, load balancing, monitoring, etc, etc.

i think one way to explain that is to talk in terms of brooks’ “silver bullet” essay – the winning approach addresses both accidental complexity (very good tools that make a developer more productive) and essential complexity (focusing on a very narrow problem domain). that is besides plain good engineering, of course.

while accidental complexity is a subject for another post, it is interesting to note how essential complexity was addressed by focusing on the problem domain of integration.

generic “embrace and solve the world” tools have an unmanageable problem domain, and it is impossible to get them right for everyone.

in this particular case it comes down to being able to express your problem domain, define it in terms of higher-level abstractions, and then allowing those to leak gracefully as needed.

Tibco BusinessWorks excels at integration, and the domain is very simple – read the data, transform it, and load it elsewhere. as long as you keep business logic to the minimum and use the tool for what it’s good for – it shines.

at this point GUI is almost nothing to be ashamed of – it is simply a representation of the abstract syntax tree (AST) for your program – it is in a sense your integration language represented through GUI abstractions. in theory one could write a domain specific textual language to work off the same AST, and it will be yet another representation of the same thing.

Fowler’s article on DSL i mentioned before on this blog was very much responsible for this redeeming outlook on GUI tools.

here’s a good example – take a look at rails. it is a DSL for a well-defined problem domain of small web applications where you build the db and the app from scratch. if needed, it leaks abstractions gracefully, falling back on the power of ruby and metaprogramming. although it can be pushed beyond its intended domain, its strength is in its deliberate limitations.

an emergence of the next big language in the nearest future is perhaps just a utopia. instead it looks like the next step is a whole bunch of languages on top of a few existing platforms. these “smaller” languages will become more and more domain-specific, getting us closer to the promised bliss of intentional programming. their rapid adoption will build upon the strengths of a few existing platforms.

another related term that has a nice ring to it is neal’s polyglot programming.

it is really exciting to see all the stuff happening in .net and jvm camps as they port dynamic languages to their platforms. one of the things i am really looking forward to is all the existing “enterprise” stuff being augmented, glued, and morphed together using these smaller, expressive languages resulting in more “living” adaptable systems. hopefully, this will also lead to a culture shift (and not just in the form of apple laptops and steadily increasing enumerators prefixed with “web”).


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