Hello,

in GWT world, being more specific (e.g. using ArrayList instead of just List) is preferred since the GWT compiler doesn't need to introspect all possible subtypes and include them in the generated JavaScript. Using too "generic" types is one of the main reasons of significant GWT-generated JavaScript size.

I'd like to improve this and I'm wondering what others think.

For example, in BusinessEntity interface, is there any reason why <T extends Serializable> and not e.g. <T extends Guid> ? If the GWT compiler sees a reference to Serializable type and it isn't obvious what's the instance type behind it, it includes all Serializable subtypes into the generated JavaScript. You can probably imagine how many of those are visible to GWT compiler via Java classpath.

Another example is query & action result allowing arbitrary List/Map/Set impl. to be passed through GWT RPC. What about limiting us to ArrayList, HashSet and HashMap for GWT RPC transfer? Please be aware that usual Java performance tips do not apply to GWT world due to Java-to-JS compilation. (And therefore, using LinkedList instead of ArrayList has no practical effect aside from bigger JS footprint.)

I'd like both frontend and backend maintainers to share their thoughts. Alexander's UI redesign efforts [1] are well on their way into the master branch and it's a good opportunity to improve existing GWT frontend, making it smaller & faster for our users.

[1] https://gerrit.ovirt.org/#/c/75669/

Thanks!

Vojtech