Dear all,
  While trying to implement the consensus modeling services we realized
that the POSTed parameters are multivalued while this is not supported
by the current API. In particular, users need to post pairs of
predictive and domain of applicability model URIs as one parameter
instead of two. We examined the possibility of accepting two lists of
parameters, namely one list for DoA models and a list for predictive
ones but this caused various problems in the RDF representation and in
the consistency of the service API. This raises questions about the
efficiency of the efficiency of ot:Parameter in such cases as well as in
cases where one needs to post  an array of parameters of the same type.
So the following cases have to be taken into account:

1. Posting a vector-valued parameter:
curl -X POST -d param1="value1=15,value2=5"
http://someserver.com/service

2. Posting an array of parameters (of the same type), i.e.
posting the array  xyz[] = {1,3,5}
curl -X POST -d  xyz[]=1 -d xyz[]=3 -d xyz[]=5
http://someservice.com/service

3. Posting an array of vector-valued parameters:
Here we need to post an array of two vectors: array[] = {[7,8], [9,10]}
curl -X POST -d prm[]="value1=7,value2=8" -d prm[]="value1=9,value2=10"
http://someserver.com/service

Obviously the problem exists because URL-encoded parameters posted as
application/x-form-url-encoded were not design to support so complex
data, so we either have to adapt to it as we explained above or we have
to find some other (more complex) way to provide these information to
the service such as POST the request as XML or JSON. The latter will be
inevitable if the client has to post a matrix to the service as a
configuration parameter.

>From the RDF point of view, we also need some extensions to be able to
represent the abovementioned data structures. So for arrays of
parameters we suggest to have just an indexing using the ot:index
property. For example:

http://sth.com/algorithm/abc 
  a ot:Algorithm
    rdfs:comment "myParam[]={100,200}"
  ot:Parameter [
        ot:index 1
        dc:title "myParam"
        ot:value "100"^^xsd:int
  ]
  ot:Parameter [
        ot:index 2
        dc:title "myParam"
        ot:value "200"^^xsd:int
  ]

No indices should be skipped.

For vector valued parameters we can make use of ot:Vector. Here is an
illustrative example:

http://sth.com/algorithm/abc 
  a ot:Algorithm
  ot:Parameter [
        dc:title "myParam"
        ot:value [                
                    a ot:Vector
                    dc:title "xyz"
                    rdfs:comment "xyz=[1.274, -4.823]"
                    ot:vectorElement [
                        a ot:VectorElement
                        ot:index "1"^^xsd:int
                        ot:value "1.274"^^xsd:double
                    ]
                    ot:vectorElement [
                        a ot:VectorElement
                        ot:index "2"^^xsd:int
                        ot:value "-4.823"^^xsd:double
                    ]
                ]
  ]

Best Regards,
NTUA Development Team