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This is an informal document describing what needs to be done in the Velocity code base and the Velocity documentation. If you need more detailed help, or have specific questions, please send mail to the mailing list ( The Todo list that follows is roughly in order of importance.

The List

Directive Interface
Right now there is a very thin interface for directives, but some knowledge of JavaCC is required. The directive interface is not intended to be used outside core Velocity developers (it is not intended to be a public API), but it probably makes sense to shield directive creators from JavaCC.

It would be good to have a discussion about how objects in the context should be cached, how the caching should be specified, and who should control the caching: the designer, by specifying something in the template; the developer, by placing expiry times on objects placed in the context; or a third party, such as a content manager. For example, say an array consisting of a top 10 list of books is placed in the context. This top 10 list might be valid for a 24 hour period: how should that be specified? Say a content manager later decides this list will be valid for a week. Do they tell the designer, who in turn changes the template, or could we provide a mechanism that would allow a content manager to change the default expiry time for that particular context object with the aid of a webapp of some sort? The groundwork has be laid for a flexible caching system in Velocity, but this discussion would be one of usage and policy.

UML Overview
It would great to include a set of comprehensive UML diagrams that describe Velocity. This would allow new developers to get up to speed quickly.

Velocity Profiling
If someone is handy with one of the standard profilers, it would be great to start hunting for bottlenecks. No serious optimization has been started. But in conjuction with the presence of a JUnit test suite, optimization changes could be made with confidence. It would be nice to have a configuration of a setup for a common profiler so that anyone who wanted to do some profiling could do so in a consistent manner.

Syntax Dumper
Right now there is a primitive syntax dumper in the Velocity code base, and it could be improved. This tool is very helpful in debugging, and it is also good for creating directives. It basically has a simple dump method that is used for all the AST node types. It would be good to tailor dump methods for particular AST node types so that the structure produced is a little clearer.

Syntax Checker
It would be good to have a standard syntax checker, something that would find all syntax errors and report them to the designer in some intelligible format. This tool could be hooked into various designer tools like DreamWeaver.

It would be great to have a template compiler. There is a great utility called JavaClass that provides a very clean and simple way to create class files, and there is also some byte code generating code present in the DynamicJava package that could be utilized.

IDE Integration
How could Velocity be integrated into standard IDEs like JBuilder and VisualAge?

Scripting Language Integration
This is something that has been discussed on the Turbine list. Allowing Context building classes to be written in JPython, Rhino or other scripting languages would dramatically improve development time and might allow technically proficient web designers who are familiar JavaScript to create an entire servlet solution with Velocity. As most of these scripting solutions provide a compiler, performance would still remain at an acceptable level.

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