[OSLC] Minutes of the OSLC Estimation and Measurement Telecon, 2009-07-24, 10AM EST

[Arthur Ryman]

See [1] for logistics.

Attendees: AndrewCanham, AndyBerner, ArthurRyman, LeeFischman, 
MurrayCantor, ScottBosworth
Regrets: SteveAbrams

Agenda
1. Re-estimation use case [2] - AndyBerner
AndyBerner - We completed the discussion of this use case. No additional 
information to discuss at time.

2. Review working draft of EMS 1.0 Part 0: Primer - ArthurRyman

Updates from review at last telecon
ArthurRyman reviewed the updates.
ScottBosworth - the architecture paragraph looks good.

Update on OSLC leads discussion on use of RDF/XML
ArthurRyman reviewed the discussion on how to use RDF/XML in the context 
of REST. Some key points are:
RDF is an appropriate way to model Web information and to specify the 
semantics of queries (since the query needs to refer to the semantics of 
the underlying data model)
However, RDF uses a very fine-grain notion of resources. 
Not all RDF resources have dereferencible URIs, e.g. you'd get a 404 if 
you tried to GET them.
URIs are used to identify resources which may or may not be retreivable 
via GET. 
In our specifications, only the course-grained resources shouls have a 
REST API. 
RDF/XML can be used as a representation of a resource, e.g. when doing a 
GET of a plain URI (no query parameters). We can specify concrete RDF/XML 
formats as representations for our resources.
RDF/XML can also be used to describe information about resources. This is 
a subtle but very important distinction. For example, a GETof a URI with 
query parameters  should be regarded as requesting a description of the 
resource identified by the plain URI, possibly including information about 
related resources. The plain URI + query parameters is a different URI 
whose representations are only related to those of the plain URI.
RDF allows you to describe collection/container resources, but these can 
sometimes be avoided by using multi-value predicates instead, e.g. a 
Project has zero or more Estimate resources, as opposed to having a single 
EstimateContainer resource that contains the actual Estimate resources. 
Only use explicit containers when there are additional semantics, e.g. the 
members are alternates, the order is important, etc.
Resource creation can be handled by POSTing a resource representation to a 
factory resource, e.g. EstimateFactory, assocated with an RDF type, e.g. 
Estimate. The factory is the container of all resources it created 
(refered to in RDF as the extension of the type) and can be queried, e.g. 
to get subsets of its resources, e.g. the Estimate resources associated to 
a given Project resource.
RDF/XML uses a "striped" style of XML where the alternation elements 
identify predicates that relate subjects and objects. The object of a 
top-level predicate can be used as the subject of a nested predicate, and 
so on. RDF/XML allows the object of a predicate to be a value, which may 
be an arbitrarily complex fragment of XML. These are called XMLLiteral 
datatypes.
In our spec, things like probability distributions should be modelled as 
values, not resources.
AndyBerner - Can our QuantileFunction described the situation where I 
specify the probability of schedule completion at say, 25%, 40%, 70%, 90% 
- where this is an arbitrary list of probabilities?
ArthurRyman - In a QuantileFunction the probabilities are equally spaced, 
so in your example the greatest common divisor is 5%. You therefore 
specify numberOfQuantiles = 20 and ignore the values you don't care about.
AndyBerner - Is that acceptable to estimate vendors?
LeeFischman - Yes, that's what we do.
AndrewCanham- Yes.

Review outline of Reestimating scenario
ArthurRyman reviewed the new scenario in the Primer. There was agreement 
on the overall content. The XML examples will reflect the current thinking 
around RDF/XML.
[ACTION] ArthurRyman to complete the XML for the Reestimation scenario in 
the Primer.


3. Other Business - All
AndyBerner - Next week I'd like to discuss how to represent "effort by 
date".
ArthurRyman - Please post a proposal in advance to the workgroup can have 
a productive discussion.
[ACTION] AndyBerner to post a proposal on how to represent effort by data.

[1] http://open-services.net/bin/view/Main/MetricsMeetings
[2] http://open-services.net/bin/view/Main/MetricsReEstimateUseCase
[3] http://open-services.net/bin/view/Main/MetricsEMS10PrimerReestimating


Arthur Ryman, IBM DE
Chief Architect, Rational Project and Portfolio Management
Office: 905-413-3077, Cell: 416-939-5063
Assistant: Nancy Barnes, 905-413-4182 
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