Re: Use Cases

On Jun 9, 2006, at 4:18 AM, Mark Baker wrote:
>
> On 6/7/06, Tim Bray <tbray@textuality.com> wrote:
>> [...] When building a heterogeneous distributed
>> system, I'd like to have a contract that operates at a higher level
>> than a MIME type, so that when things break, you can finger-point
>> constructively.  -Tim
>
> Sorry, I don't understand what you mean by that.
>

Assuming a business context and the use of XSD, I think Tim is saying  
that a MIME type would usually define some set of business object  
types (e.g. person, invoice) including relationship semantics. I  
think he'd expect a resource that accepts data submission via POST to  
explicitly state what the type of the objects is, that it accepts as  
input (e.g. "I'll take XML input that conforms to the person content  
model of the XSD"). This infomation can be used by developers at  
design time to know that they are expected to consruct a person  
object and send it off.

If the resource just says that it accepts the MIME type then you do  
not get that information (that contract), all the client developer  
can know is that it must send that MIME type - but what kind of  
message??

If the resource some time receives an invoice instance, you'd know  
that the contract of "needing a person" has been violated. The same  
applies to the server on day switching to accept invoices, but not  
persons anymore.

Does that clarify?

Jan



> Mark.
>