Taking MSN messenger as an example, let' see what's the difference between compatibility testing and interoperability testing. - Software-Testing

Responding to JustStand...

ALas, both 'compatibility' and 'interoperability' have been co-opted by
marketeers so they often mean different things to different people.
FWIW, in my view...

> Taking MSN messenger as an example, let' see what's the difference
> between compatibility testing and interoperability testing
>
> My understanding is that compatibility is testing for the compatible
> among different platforms (i.e. it's for the AUT to run on/with X,Y,Z
> ), while interperability testing is for two similiar
> features/applications can know/understand/workable with each other
> (i.e. it's for the AUT run together with its brothers or cousins).
> Taking MSN messenger for example, MSN on Unix is compatibility, but MSN
> with MSN 7.5 or Yahoo Messenger is interoperability. Am I right?

Interoperability has an implied client/service communication
relationship between applications. There is also an implied shared
understanding of the semantics of any invoked services. IOW, given both
agree on What needs to be done, an application still needs to talk to
other applications. Interoperability testing implies validating that
they can do so properly. Before interoperability standards that meant
one had to know exactly which other applications the application in hand
needed to talk to and each combination was validated in turn.

With the advent of interoperability standards, the application uses the
same interface to talk to any other application. So the bulk of
interoperability testing comes down to ensuring the application can talk
to the given interface. That's because the interoperability standards
abstract the semantics of communication into one-size-fits-all. (Of
course eventually one needs to test in situ to ensure the interface is
properly understood, but <hopefully> that becomes a pro forma test.)

So you are correct that MSN talking to Yahoo Messenger is an
interoperability issue.

However, if the applications have different views of what
interoperability standard to use, then one has a compatibility problem.
For example, in the Early Days if the application chose DCOM as the
communication standard and another application chose CORBA, they often
could not talk to one another even though both were agreed on the
semantics of the service. IOW, the applications have a different view
of the semantics of the interface itself.

The notion of semantics lies at the core of compatibility testing. To
be compatible two applications need to share the same semantic view of
what do. In the case of MSN and Yahoo, both must have some shared
semantics of what a message is. Compatibility testing is about ensuring
they both agree about message semantics.

This is an issue most commonly with different versions of an
application. The user has expectations about the semantics of how
things work _from the user's perspective_ and different versions have to
be consistent about ensuring things work the same way. So I would
regard MSN vs. MSN 7.5 as primarily a compatibility issue.

A similar notion applies to applications vs. platforms. If an
application is to be portable, it must do the same things _from the
user's perspective_ on each platform. So even if the application
invokes different OS system services on each platform, that is
irrelevant to compatibility testing. Compatibility testing ensures that
the application provides the same problem solution results on each platform.

Both notions apply whenever two applications need to communicate. Both
applications need to share the same view of the semantics of the what
the other does. Similarly both applications need to share the same view
of the communications themselves _in the problem space_. Compatibility
testing deals with the first issue while interoperability testing deals
with the second.


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> My understanding is that compatibility is testing for the compatible
> among different platforms (i.e. it's for the AUT to run on/with X,Y,Z
> ), while interoperability testing is for two similiar
> features/applications

The important thing is this: what is the distinction /in the mind of
the person who is using the words/? H.S.'s answer is excellent for
what it is, but as he says, the terms mean different things to
different people. So the distinction is meaningful in terms of two
things: a) who's asking, and why; and b) how it might materially
affect the choices that you make as you're testing.

---Michael B.