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Hi Johannes,
On 7/31/2012 7:37 AM, Konstantinidis, Johannes wrote:
Hi all,
can you tell me the
difference between the hello.host/consumer and the
hello.host/consumer.rs examples, please?
Of course, I see the
different source code, but to me both examples seem to have
the same result, only reached in two different ways:
The rs example seems to
do the things explicitly, that are done magically by the
non-rs example (I only tried the non-rs example so far and
just looked at the source code).
The same confusion with
the three "getting started" links [1], [2], [3] related to
Remote Services: to me [1] seems like non-rs, [3] like rs
and [2] like something in between. Maybe one or more are
outdated? Can you give me a hint what to use and about the
advantages of the different approaches?
Ok...a brief explanation.
ECF has a 'remote services API'...which provides direct access to
runtime API for interacting with the ECF IContainer,
IRemoteServiceContainerAdapter and other ECF interfaces. This API
is in org.eclipse.ecf.remoteservice and org.eclipse.ecf.core
plugins. It's transport-independent, and allows quite a lot of
customization/extension for the behavior of existing providers (e.g.
generic, r-osgi, restlet, etc)...and, of course, allows the modular
creation and customization of providers.
ECF also has an implementation of the OSGI remote services
specification. The OSGI remote services specification is actually
implemented *on* the ECF remote services API...meaning that new
providers that implement the ECF remote services API will
automatically work as a complete OSGi remote services
implementation. This is kind of nice for those interested in
creating new providers, because it makes it very easy to create new
providers (reuse/extend existing providers)...and then any code that
uses the OSGi remote services will 'just work' with a new provider.
No need for anyone to re-implement the OSGi remote services/RSA
specifications. It can only be done/maintained once (in true
modular fashion :), and we (ECF committers) will do this for you.
This is described graphically...with a layering diagram...on this
page [1].
Historically, the ECF remote services API existed before the OSGi
RS/RSA spec existed...and when the OSGI spec came out it just made
sense to use ECF remote services as the basis of our OSGi remote
services implementation.
Now...back to the examples.
The .rs examples actually expose the ECF remote services API usage
(currently in a simple/trivial way...but nonetheless it's there).
The non-rs examples only use the OSGi remote services API...and ECF
remote service containers are created and used automatically by
RSA. As per the OSGI RSA specification...and ECF's RSA
implementation [2]...RSA's topology manager makes decisions about
how/when to export a remote service as it's registered. The ECF
topology managers create container(s)...if necessary...and export
services...again using the ECF remote service API.
The take away with the examples is that the non-rs example is OSGI
remote services only, while the .rs example exposes the ECF remote
service API at the application level...to allow for deeper
customization. That...and there's no point in deleting/deprecating
example code :-).
Hope this helps. I will take a look at the doc links to check for
whether things are now out of date. There may be...as like I said
the ECF remote service API predated the OSGi specifications...and so
there may be wrong or confusing links at this point.
Thanks,
Scott
[1] http://wiki.eclipse.org/OSGi_4.2_Remote_Services_and_ECF
[2] http://wiki.eclipse.org/Remote_Services_Admin
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