WCF DateTime woes
Regarding your DateTime question, you are right to be concerned about passing around DateTime via WCF. This is just one link of many that gripe about the difficulties...
http://daveonsoftware.blogspot.com/2008/07/wcf-datetime-field-adjusted.html
Regarding Type Equivalence
According to section 3.1.3 of Juval Lowy's book entitled Programming WCF Services, 2nd Edition...
WCF offers implicit data contracts for
the primitive types because there is
an industry standard for the schemas
of those types.
He also points that out in regards to the use of custom types as parameters on Operation Contract methods. I presume this also applies to method return types.
To be able to use a custom type as an
operation parameter, there are two
requirements: first, the type must be
serializable, and second, both the
client and the service need to have a
local definition of that type that
results in the same data schema.
You may also want to check out section F.4. Data Contracts, which is part of his WCF Coding Standard. Bullet #9 applies to your question...
Do not pass .NET-specific types, such
as Type, as operation parameters.
Bindings Establish Expectations
Bindings that are based on WSHttpBindingBase (search in Reflector.NET for its four derivations) are going to be the most interoperable, since they are designed for interoperability.
Book Recommendation
I highly recommend Juval's book: http://www.bookpool.com/sm/0596521308
