[rules-users] how to specify classpath dependencies in .drl files.

[Mark Proctor]

Godmar Back wrote:
> I agree that it may not belong into the .drl file, though loading
> bytecode through the classloader via getResourceAsStream() also seems
> a rather ad-hoc solution.
>
>   
I've already told you, that you are mistaken here. You do not need to 
keep bytecode hanging around, and available via getResourceAsStream() 
for any compilation to work.  I can generate a class at runtime, in 
memory, add it to a classloader and have the engine compile against it 
without getResourceAsStream() being able to search for and return the 
.class' bytecode.
> Some module system that allows the bundling of class and rules into
> modules, and the specification of dependencies between them, is
> clearly needed.
>
>   
Yes in the rule agent and the deployment configuration properties system.
>  - Godmar
>
> On 9/26/07, Mark Proctor <mproctor at codehaus.org> wrote:
>   
>>  Godmar Back wrote:
>>  On 9/26/07, Mark Proctor <mproctor at codehaus.org> wrote:
>>
>>
>>  Simple add the class at runtime to a classloader and use that classloader
>> as
>> the root classloader of the packagebuilder.
>>
>>
>>  This would work if the class loader I provide implements
>> getResourceAsStream to match its behavior in loadClass (which most
>> class loaders do) - so you are correct here.
>>
>> The problem, however, is that I don't know which .jar files to include
>> in that class loader's path, *unless* I keep track of these .jar files
>> elsewhere - say in a configuration file, as a command line switch, or
>> by hardwiring it in my code.
>>
>> My proposal is to allow the user to specify the location of these jar
>> files in the .drl file, which a special classloader would then
>> automatically include as it encounters this declaration in the .drl
>> file.
>>
>>  - Godmar
>>
>>
>>  I don't think DRL files should be hard coded to Jars, I would rather see
>> this configuration else where. What you are talking about is deployment
>> configuraiotn issus, which is a difference concern and belongs in something
>> more like the RuleAgent. I beleve there are already plans to allow the
>> RuleAgent to specify locations to lookup classes at runtime.
>>
>>  Mark
>>
>>     
>
>   

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