Feature request: Provide default launcher - so not required as Application dependency about update4j

[ChrisLMerrill]

I should add - it would not be as bad if update4j was the only dependency, but since it also drags along 3 JAXB dependencies and javax.activation, it is that much uglier.

[mordechaim]

Will think about this; this will require reflection which I despise, but well, simplicity/usability should come first. Re deps, I was thinking of using maven shade plugin to make it all one fat jar. I never did it before and have to figure out how to do it. I'd also point out, for simplicity, don't start out with delegates as it adds an extra layer of complexity. Only after everything runs properly migrate to delegate.

[ChrisLMerrill]

Thanks for considering it.

The app I'm working on uses Reflection heavily to allow end-users to drop a JAR into their project to extend the tool when that project is opened. The power this gives them is a beautiful thing. I need to learn more about module loading because I think that and/or services might be a better alternative.

But I think this specific case makes a good argument for reflection.

And thanks for the tip - I figured out that I didn't really need a Delegate...instead running my own main method.

[mordechaim]

If you have no issue with usign reflection, there's a way to let your launcher reside in the bootstrap jar. As mentioned in the wiki where it discusses access between the bootstrap and business application, you can access every class in the business app by using the 3 arg variant of 'Class.forName' and use 'context.getClassLoader()' as second arg. Now, all you gotta do is load the class that loads the rest of your application, call the entry point method and you're up and running. Note, now the launcher will only be updateable via dropping higher version.

[ChrisLMerrill]

Thanks for that suggestion. I have it working that way, without any dependencies in my app on update4j :)

You can close this issue if you'd like. But I still think it would be nice to provide the ability launch a specific class via main(), as a built-in part of update4j. This seems, to me, like a pretty common use-case -- most apps are already started via a main(). The code itself is simple (mine is 5 lines not including exception handling), but I expect that the design of how to expose/configure that behavior is a little harder.

Thanks again!

[mordechaim]

I'm currently working on a micro-implementation of an xml parser, so to reduce dependecies to zero!

Btw what's your thoughts on #19 ?

[ChrisLMerrill]

That would be nice!

I seem to need stuff like this all the time (usually JSON more than XML). I know why it isn't included in the standard libs, but it pains me when I look at a large dependency tree and see 3 different libs included for reading JSON :(

I will comment on #19.

[mordechaim]

Feature complete