I'm starting to get back into obix after a summer
of distractions. Lately I've been doing
some brainstorming on our current design and how
it relates to discovery. This process
has led to the following
conclusions:
- The main value of the work we did under the
guise of the PointService is really to normalize
how primitives are represented and
annotated with meta-data (like min, max, range, etc)
- That led me to think that maybe the
PointService is really just the service used to read and
write data primitives
- That led me to think about the DiscoveryService
as a way to read complex structures down
to the primitive level
- That led me to think that maybe Discovery and
Points is really all just one thing...
What I am thinking is that we collapse Discovery
and Points into a single service which I've been
thinking of as the Reflection
service. To me it encapsulates two primary goals:
- to learn the structure of any vendor's
system without needing to know a whole bunch
of types and data structures ahead
of time
- to normalize key data primitives so that
systems can exchange basic data
I've been thinking about the Reflection service
similar to COM's IDispatch or Java/.Net reflection
APIs. It lets me use a small set of wrapper
types to generically describe and interact with the
vendor's native data model without needing to
know all the gory details about the vendor's native
type system.
Plus we would still use the Reflection service as
a discovery and jump point into other more
rigidly
defined services. Thus reflection can be used to interact with a vendor's
system generically using
loose typing, but still let's us jump to strongly
typed services for solving domain specific problems
like history, scheduling, or
alarming.
My thinking is that the reflection service
provides two operations Get and Put. I've haven't given
a lot of thought to the exact XML syntax, but
just to show an example:
<Get>
<Locale>en</Locale>
<Include>
<Facets>true</Facets>
</Include>
<Depth>1</Depth>
<Id>someid</Id>
</Get>
<GetResp>
<!-- root object of the
get request -->
<Object>
<Id>someid</Id>
<Facets>
<Icon>/icons/happyFace.png</Icon>
<!-- child object, string description
-->
<Object>
<Id>description</Id>
<Type>string</Type>
<Value>someid's description</Value>
</Object>
<!-- child object, int counter with
facets -->
<Object>
<Id>counter</Id>
<Type>int</Type>
<Value>73</Value>
<Facets>
<Min>0</Min>
</Object>
</Children>
</Object>
</GetResp>
Does this seem like a sane way to proceed?
Brian