Here is the test code:

const mixin HelloService : Service {
  Str hello(Str name) { "Hello, $name!" }
}

const class HelloServiceImpl : HelloService {
}

class ServiceTest {

  Bool install := false
  Bool clear := false

  Void main() {
    if (install) {
      HelloService hs := HelloServiceImpl()
      hs.install()
    }
    echo("Services by API:")
    Service.findAll(HelloService#).each {
      echo("$it")
    }
    echo("Services by implementation:")
    Service.findAll(HelloServiceImpl#).each {
      echo("$it")
    }
    echo("All services:")
    Service.list.each {
      echo("$it")
      if (clear) {
        uninstall
      }
    }
    version := Pod.find("sys", false)?.version ?: "undefined"
    echo("Fantom version: $version")
  }
}

To reproduce do:

Step 1) Change install field value to true. And run. Here is my output:

Services by API:
fan.04e28e5aa6ebebc0dc107f0000018c31.HelloServiceImpl@132bfeb
Services by implementation:
fan.04e28e5aa6ebebc0dc107f0000018c31.HelloServiceImpl@132bfeb
All services:
fan.04e28e5aa6ebebc0dc107f0000018c31.HelloServiceImpl@132bfeb
Fantom version: 1.0.57

Step 2) Change install field value to false. And run. Here is another output:

Services by API:
Services by implementation:
All services:
fan.04e28e5aa6ebebc0dc107f0000018c31.HelloServiceImpl@132bfeb
Fantom version: 1.0.57

The problem is that Fantom fails to find services that were installed earlier.

Notice: I used http://www.fanzy.net/ (thanks to kaushik). On fanzy environment stays the same for every script. Don't forget to uninstall all installed services (set clear to true in the test code).

I don't think there's any bug with what you have here. Putting fanzy aside for a second (because it may complicate what's really going on), your sample works fine for me locally:

First run (install == true):

Martins-MacBook-Pro:~ martin$ fan HelloService.fan
Services by API:
fan.HelloService_0.HelloServiceImpl@7f033a6f
Services by implementation:
fan.HelloService_0.HelloServiceImpl@7f033a6f
All services:
fan.HelloService_0.HelloServiceImpl@7f033a6f
Fantom version: 1.0.57

Second run (install == false):

Martins-MacBook-Pro:~ martin$ fan HelloService.fan
Services by API:
Services by implementation:
All services:
Fantom version: 1.0.57

I suspect if you're seeing services listed on fanzy, they've stuck around from other people playing around (perhaps Kaushik can comment further on how things are sandboxed (or not))?

M

Well, there are two reasons to this. First, app engine sometimes spins off new jvms per request, sometimes dosen't. So there's a possibility either way of finding the service, and sometimes not.

But a more interesting thing about paul's code is this. In the event that the next request goes to the same JVM, why does

Service.list 

return some value while this doesn't

Service.findAll(HelloService#)

The story is, every time you run a script, fanzy creates a new transient pod to enclose the classes. So first time you run the script, HelloService# is actually pod1::HelloService#, and the next time pod2::HelloService#.

Now it's clear to me. Thanks for the replies.