Hello to everyone! I am trying finalizing the initial draft of the LDAP implementation and have a few questions that need to be resolved before I can finish. Question 1: In the Entity class on page 8 of the GLUE Specification, the Association.End has just one field, Extension.Key, but in the Extension class its unique identifier is LocalId. The Extension.Key should probably not be used as its description is "This identifier is not required to be unique; several instances of this class MAY hold the same value of this attribute". So in the Entity class, should Extension.LocalId be specified instead of Extension.Key? Question 2: The relations in the association end list are always specified with the attribute they have to link with. (E.g. Service.ID). There are several reasons why this may not be a good idea. a) In the Entity-Relationship models, relationships between entities/classes/objects are generally specified without any knowledge of each of the attributes in them. b) To know which attribute you wish to link to from a related object, you will need to to take a look at its definition to get the key field. c) There could be more than one key field and sometimes the key of an entity could be a combination of several fields, which would not work with the current approach As a solution I would suggest just taking out every attribute in all the Association End lists. Question 3:
From the theoretical definition of inheritance, just by pointing to a class we cannot be sure to have access to its subclasses, only to its superclasses. As a solution I would propose to choice one of the following depending on what we are trying to describe:
a) Add ComputingService, StorageService, AdminDomain and UserDomain to the Association End list if we really would like to access attributes exclusively from those in the Location class, which results in more Foreign Key attributes. b) Remove them from the Inherited Association End list if we just want to have access to the attributes of the Service and Domain classes in the Location class. c) Just take out the Inherited Association End list and put in the Association End list all the concrete classes we want to point out. I would personally prefer this last option. In addition to the questions above, I have three proposals on how to implement the relationships and would appreciate some feedback on each of them and which one is prefered. 1) Use an 'EntityFK' attribute (same as GlueForeignKey used in GLUE 1.3) in every entity that has a relationship 2) Differentiate each final object in the relationship from its superclass point of view. E.g. LocationFKService 3) Differentiate each final object in the relationship to the very concrete classes we would like. E.g. LocationFKComputingService. I would personally prefer this last option. Also should we use 'FK' or 'ForeignKey'?. Regards, David -- David Horat Software Engineer specialized in Grid and Web technologies IT Department – Grid Deployment Group CERN – European Organization for Nuclear Research » Where the web was born Phone +41 22 76 77996 http://davidhorat.com/ http://cern.ch/horat http://www.linkedin.com/in/davidhorat