[dais-wg] Notes from DAIS2 Session at GGF13

[Susan Malaika]

A second DAIS session was held at GGF13 (known as session DAIS2). Minutes 
have already been posted on the DAIS mailing list. This note constitutes a 
summary that was created and displayed during the meeting, as the 
discussion progressed. Apologies for this late posting. 
 
Here is a summary of the discussion from the second DAIS session
1. A further discussion meeting will be set up in the UK arranged by David 
Snelling 

2. DAIS can be considered to involve three kinds of resource (see notes 
below for what they are):
2.1 Type (1) resources 
this resource can be accessed by a DAIS service (as a conduit to part of, 
or to
one or more database management systems); this resource could be 
represented
using WSRF

2.2 Type (2) resources 
WSRF seems less suitable for resources managed by database management 
systems when accessed in the context of a DAIS service. 

2.3 Type (3) resources 
WSRF seems suitable for result sets managed by DAIS 

3. There is no guaranteed interoperability between WSRF and non-WSRF 
implementations. There appeared to be little value in attempting to ensure 
compatibility across message bodies while allowing variation across 
message headers 

4. The DAIS specification should support the XML projection of the 
relational CIM model as it evolves (so it continues to follow the CIM 
model)

A Special Thank You for all the folk who attended the DAIS2 session and 
that includes the OGSA folk   
........................................................
 
Here are more notes from the session... 

DAIS has three main choices 
(DAIS1) WSRF Solution    
(DAIS2) Non-WSRF Solution 
(DAIS3) WSRF with some Adaptation 


 There are two main WSRF advantages for DAIS: 
+ Agreed way for supporting lifetime 
+ Agreed way for supporting properties

DAIS is a possible use case for service groups (there are varied opinions 
on this) 

There was quite a bit of discussion about resource properties and lifetime 
and the use of EPRs for DBMS managed resources 

There are three kinds of resources in DAIS:
type (1): A resource that describes and provides access to other 
resources. An example of a property this resource might have is DAIS 
version.
 
type (2): Those resources managed by a DBMS (the DBMS is responsible for 
their lifetime - not DAIS - such as databases or tables) 
These are difficult to adapt to WSRF 
Another inhibitor is that we do not expect DAIS implementations to parse 
the incoming request messages and extract resource names    
 
type (3): Those resources managed by a DAIS implementation (e.g., result 
sets that persist for subsequent delivery) - 
(3.1) The persistent result set is created and removed by a DAIS 
implementation 
     These results sets are suitable to be modeled through EPRs, Resource 
Properties and Lifetime 
 
(3.2) The persistent result set is created by a DAIS implementation and 
stored in a DBMS managed table (in other words it will be deleted by the 
DBMS) then it is not so easy to use EPRs etc 

The idea of adopting WSRF resource property formats for resource 
descriptions was considered sensible - However DAIS may devise its own 
resource properties request format for resources not modeled through WSRF 
 
Susan Malaika


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