Use Continuations to Develop Complex Web Applications

By Abhijit Belapurkar
2005-04-22


Pros and Cons of Continuations
As I've shown in the preceding sections, continuations essentially provide a way to add conversational state to Web applications. The advantages of using continuations are that unusual navigation patterns can be handled easily; it is very simple to use debugging tools to run through the entire application in one shot, instead of having to place breakpoints at multiple places in a scattered code base; and it becomes very easy to understand and communicate the program structure, as well as the possible Web navigation paths in the entire application.

The biggest problem with using continuations for Web development is that not many of the languages, frameworks, and environments commonly used to develop Web applications support them. The concept of continuations and CPS itself is seen to be arcane and not intuitive. A second big hurdle is that of how and where to store continuations. We can store them on the client side, but due to the previously mentioned issue with cookies being shared across all instances of a cloned browser window, the viable option is to store the entire continuation in a serialized form in a hidden form field. This necessitates ensuring the integrity of the continuation. We can also store them on the server side, which is what I did in the sample application, but then we have to worry about issues like garbage collection and replication across cluster nodes. Lastly, there is a lack of clarity around the efficiency (performance-wise) of continuations-based Web applications.

Tutorial Pages:
» A Programming Paradigm to Simplify MVC for the Web
» What is a Continuation, Anyway?
» Problems in Conventional Web development
» The Case for Continuations
» User-Centered Navigation
» You Make the Rules!
» The Continuations Repository
» An Example Application
» Web Continuations in Apache Cocoon
» The Application Sitemap
» The Application Logic
» Understanding the Application Logic
» Resuming the Continuation
» JavaScript vs. the Java language
» Continuations in Java code
» Pros and Cons of Continuations
» Conclusion
» Resources


First published by IBM DeveloperWorks

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