On Tue, Jun 16, 2009 at 8:02 AM, Felix Meschberger<fmesc...@gmail.com> wrote: > ...Replying to this message, but my response applies to the complete thread. > > Let's step back a second and look at what we really need to know to be > able to decide the system is ready or not. And who is responsible to > provide this knowledge. > > > (1) The most basic criterion for the system to be ready is the available > of certain services.
ok > (2) There must be away to specify which services are required. ok > Now, this is very simple and easy: As Alex Klimetschek proposes we are > using ConfigurationAdmin for this. Each service can be described by a > few properties: > > (a) Service Name > (b) Service Filter > (c) Number of services... And in some case (like script engines), additional properties. Use case is "I want the JSP script engine to be ready" - can we express that with a filter? > ...The system status service itself : > > * requires the ConfigAdmin service to be present > * registers as a ManagedService to receive the configuration > > Thats basically all. Very simple, very lean.... But how do you bootstrap that ConfigAdmin information for the first startup of a Sling instance, where no OSGi state is stored? Use case: 1) I create a variant of the launchpad app with my own set of bundles 2) I define a custom list of services (according to the above syntax) that must be active for my system to be ready 3) I want my SystemStatus configuration to be available from the first startup of the system How can I put 2) in my custom executable jar? Again, I think using sling.properties to define where this info comes from is the most flexible way, going back to yesterday's example from sling.properties: # Values like myServiceA uses the syntax proposed by Felix sling.readyness.check.1 = services:myServiceA, myServiceB # jcr: means look in the repository for additional definitions sling.readyness.check.2 = jcr:/system/sling/status # osgi:ConfigAdmin means use that service to get additional required # services definition. If not present, the ConfigAdmin service is not # required (for super-lean Sling instances) sling.readyness.check.3 = osgi:ConfigAdmin:nameOfTheConfigThatHoldsThisInfo This is easy to implement, flexible, and implementing it is probably faster than spending ages discussing exactly which options we allow ;-) -Bertrand
