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Saturday, September 27, 2003 |
Let me tell you about.... Bill Clementson posts that although
a lot of people are interested in the use of continuations for web
applications programming, nobody has yet come up with an elevator pitch
explanation of their benefits. My pitch usually goes something like
this: "Continuations bring precisely the same benefits to traditional
web development that subroutines bring to GOTOs". Julian Fitzell and I
had to expand on this for a tutorial we gave at Smalltalk Solutions. Here's the first part of the abstract:
Dijkstra may have taught us 45 years ago that GOTO was a bad idea, but
web development has barely caught up. In the CGI model of web
applications, each link that is followed triggers an entirely new
execution of the program. Building complex control flow out of these
abrupt transitions can lead to a tangled and brittle mess of
interdependent pages. Modern frameworks such as WebObjects and Struts
may remove many of the difficulties of CGI scripting, but they do not
escape the web's inherent GOTO: moving from one page to the next,
whether through anchors, actions, forms, or forwards, is still a simple
one-way jump.
Seaside is a framework for developing web-based applications that
insulates the developer from the HTTP request/response loop, presenting
the illusion of a continuous interactive session with the user. Each
page or form acts much like a subroutine, which returns a value to its
caller based on user input. Complex, conditional or looping workflows
can be described in a single piece of straightforward Smalltalk code as
a sequence of calls to individual pages. The benefits this brings to
the reusability and maintainability of web applications closely mimick
the advances made by structured programming long ago.
[Avi Bryant]
9:14:14 AM 
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© Copyright 2003 Clarence Westberg.
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