Class diagram and Sequence Diagram -- Connection

[Sridhar Raman]

Is it necessary to have a class defined in the Class diagram to use its instance in the sequence diagram? I believe that some tools enforce this but I don't believe that this is an UML constraint.
In my opinion, Class diagrams have to give the developer a good idea about the entities and the relationships between them. Showing all the specialized classes such as the DAOs, helpers,etc, would only clutter the class diagram and it would be a good idea to show them in the sequence diagram.
Any comments on this? Also, can anyone confirm if this constraint is not UML based but a tool-specific one?
thanks in advance!
Sridhar

[Nishant Anshul]

welcome to forum...Nopes..its not a UML constraint..For seq diag, they just say u to put a colon( in front.. in case u want to show classes in seq diag. If u havent put any colon, assumption is that it is an object..corresponding class may or may not be shown in class diag...
I agree with ur second point.

[Sridhar Raman]

Thanks, Nishant.
I suppose that a smiley would work just as well in the place of the colon : - )