[jacorb-developer] terminology

[Phil Mesnier]

Hi Thufir,

> On Mar 11, 2015, at 10:07 AM, thufir <hawat.thufir at gmail.com> wrote:
> 
> In general, and specific to Jacorb, what's the definition for:
> 
> 
> ORB:  Object Request Broker.  Commonly, referrred to as the "broker."  The broker is what I would call the server.  It runs the show.
> 

Don't conflate an ORB with a server. Every process has an ORB, "Client" and "Server" are simply roles played. A client makes requests and a server takes requests. The ORB is responsible for resource management, connection establishment, etc.

> POA:  Portable Object Adapter:  Runs on the broker.  Splits the handler into the Object and the Servant.
> 

The POA is part of server processes. It is used to manage the lifecycle of object references and servants.

> handler:  ???
> 

Handler is not a common term in the CORBA Lexicon. Ignore it.

> Object:  resides in the client?
> 

CORBA "Objects" reside no where. However object references are created by POAs and publicized by some means. A client then uses the reference to make requests of the object.

> Servant:  resides in the broker.
> 

Resides in the server. Written by application developers, the servant implements the object. It conforms to the IDL interface definition of the object by extending the generated skeleton.

> 
> I'm just trying to understand the process a bit.  On localhost, I have no problem writing a small Java program of the hello world variety.  However, I cannot fathom how make a remote connection, nor do I see much specific tutorial or information on making that seemingly small step.  Why is it a hurdle to make a remote connection?
> 

It's a matter of publishing the object reference. If you look at demo/hello, you will see the server converts the object reference to a string and writes that to a file. The client reads the file and converts it back into an object reference. If you do that on separate hosts, you need to copy the generated file to the client machine.

> So far I've been using Glassfish, but have hit a wall with troubleshooting it.  When it comes to Jacorb, assuming a starting point of "hello world" with everything on the same JVM and the same hardware, what's the next step to making a remote connection?  With Jacorb, is it simply a matter of specifying the hostname or address for the broker?

No, as long as you write the IOR (Interoperable Object Reference) to a file and share that, you should be fine. Of course there is a lot more you can do as you gain experience. There are a few excellent CORBA/Java books available that you ought to check out, just google it. There is also a fine reference guide distributed with JacORB, though it is not much of a beginner's tutorial.

Good luck!
-Phil

--
Phil Mesnier
Principal Software Engineer and Partner,   http://www.ociweb.com
Object Computing, Inc.                     +01.314.579.0066 x225