Interoperability

[Daniel Huss <tosca@unentscheidbar.de>]

Hi,

I'm doing some research on cloud interoperability for a seminar and TOSCA is among the open, vendor-neutral standards that I'm going to address in my paper. I was hoping that someone who is already somewhat familiar with the spec could help me build an understanding of the following paragraph:
 
"TOSCA Version 1.0 Committee Specification Draft 02 05 April 2012" chapter 3.2.2 Portability of Service Templates states:

"Note that portability of a service does not imply portability of its encompassed components. Portability of a service means that its definition can be understood in an interoperable manner, i.e. the topology model and corresponding plans are understood by standard compliant vendors. Portability of the individual components themselves making up a particular service has to be ensured by other means – if it is important for the service. "

The definition of "components {...} making up a particular service" appears to be as follows:

(line 274-275) "A Node Template specifies the occurrence of a Node Type as a component of a service"

How can interoperability be achieved if some vendor V must understand the topology model and plans of a service template issued by vendor V', but does not have to understand its node templates? Does understanding the plans imply understanding the node templates/types and their interfaces, since plans may use those interfaces?  What exactly is the meaning of "understand" in this context? Does "has to be ensured by other means" mean MUST/SHALL/REQUIRED or SHOULD? Could you give a few example scenarios that illustrate how iteroperability is ensured? How will service templates facilitate interoperability when there are no standard node types and relationship types that must be understood by everyone? Will the spec define extensive/formal processing semantics for services that handle service template instantiation? Lots of questions, please feel free to comment on any subset of those!


I'm eagerly anticipating being educated on the topic :)

Best Regards,
Daniel