I realise this is more of a semantic quest rather than a functionality quest.
I have three types of compile-scope dependencies:
Compile-only scope, not used at run-time.
GWT client-side dev, MVP4G, RestyGWT, Source retention annotation processors. I use REST, so I don't need GWT server side.
Provided - Hibernate jars required for compilation but provided by JBoss.
Compile + runtime jars.
For case 2, we could use provided scope. Case 3, we would use compile scope.
However for case 1, I use provided scope, even though JBoss does not provide those files at all. Nor are they needed at run-time.
Anyway, don't you think Maven should provide for a synonym for "provided" for a scope where the artefacts are not really needed except at compile time? Perhaps, should there be a "compile-only" scope?
If the jars with are not true "runtime" dependencies (only for building) but not for the final artifact, you can exclude them various means:
- Exclusion in the assembly descriptor
- Exclusion in the jar (or war, ear, whatever) plugin configuration
- Shade Plugin minimize jar goal
I agree that shipping unnecessary classes is annoying (I've seen junit and testng jars in production deployments - brrrr...), but for all practical purposes it's a rather minor one.
If you have a dependency conflict (i.e shipping a "all deps" version of a library or framework), that's a different story, but doesn't sound like what you're facing here.
Don't complain that the language does not offer fine distinctions if you only know half its vocabulary.
If a dependency is only used for building, such as an annotation processor, it should be a maven <plugin>, or <dependency> thereof.
Otherwise, if it is in the compilation classpath, it will be necessary for linking the generated class file at runtime. Then, there are two cases:
- It is always necessary to load that class
- the class should be shipped as part of the application:
<scope>compile</scope>
- the class should be provided by the runtime environment:
<scope>provided</scope>
- It is sometimes necessary (because that class will be loaded only under particular circumstances):
<optional>true</optional>
The only option not covered is compiling a Java program, and never running it in a JVM. This is a really obscure use case, and I can't fault the designers of maven for not including a scope just to express this distinction - particularly since it is irrelevant to Maven's core responsibility (building the software).
