[tmql-wg] Result set requirements

Rani Pinchuk Rani.Pinchuk@spaceapplications.com
Thu, 19 Feb 2004 10:50:28 +0100

Dear all,

It is obvious that there is a trade off between having the result set
containing more complex structures and between the simplicity of TMQL.

When the syntax of the language provides the ability to get for example
the base name of a topic, next to a topic object, it brings up some
confusing problems:

1. Different columns in the result set have different type - base name
   column probably will be of type 'string', while topic columns will be
   of type 'topic object'. 

2. If there is more then one base name for that topic, and the scope
   was not specified it probably means that a list of base names
   should be supplied. However, it is not clear in which order such a
   list should be provided. Finally that list of base names should
   come next to one topic object (in the same 'row'), so we end up
   with column of type 'list of strings'. 

3. Should the scopes, and the variants of the base name be retrieved
   with the base names, so actually a structure is retrieved, or
   should the base names retrieved by themselves?
   Should we then define different structures for the different
   sub-structures we have in a topic? For example, when retrieving
   base name of a topic we get a structure containing base names,
   their scopes, and their variants.

On the other hand, the TMQL could leave the fetching of the actual
primitives from a topic object to the programing languages or tools
that might use TMQL. In that case the TMQL returns only topic
objects (or their ids), and the APIs of different languages will
define a way to access the different primitives inside the objects.

However, also when TMQL supports retrieving of different primitives
such APIs will be needed, unless we restrict TMQL to return only
simple textual rows (like in SQL) which is for sure not the

So I would like to ask what are the advantages for supplying the
result sets in "different types". 



Rani Pinchuk
Software Engineer
Space Applications Services
Leuvensesteenweg, 325
B-1932 Zaventem

Tel.: + 32 2 721 54 84
Fax.: + 32 2 721 54 44