On 20 Nov 2010, at 10:30 , Rickard Öberg wrote: > On 2010-11-20 05.37, Niclas Hedhman wrote: >> 1. A lacking 'layer' on top of the top layer, OR >> 2. A Visibility type of 'external' >> >> The former seems more 'accurate' if one sees the entire Qi4j >> application as a "layer", and the latter gives the ability to expose >> services anywhere, which then seems to be contradictory to our meme >> "only layers directly above can access"... > > Agree. I would definitely prefer nr 1). You could always have a layer that > "uses" all the layers where you have services you want to expose, if it is > not only the top layer you want to expose (for whatever reason). > > Is there any particular reason you don't only want to expose the top layer? > Normally it would only make sense to expose the application layer (through a > UI layer), so do you have an exception to that?
Obviously depends on how you define your architecture and layers, but for example manageability and monitoring can be drawn as a vertical column, accessing components from various layers (depending on how "low level" you want your monitoring to be). Another example could be when scaling your application in such a way that you're actually partitioning components in a cluster (because they're too big to all fit on a single node). Hooking up different components across nodes could be done through externally visible services. Greetings, Marcel _______________________________________________ qi4j-dev mailing list [email protected] http://lists.ops4j.org/mailman/listinfo/qi4j-dev
