Re: Unable to obtain reference to plan in distributedenvironment

Question

An interface is just a definition of attributes and methods it contains no
code.
The code is in the class that implements the interface therefore even if you
can pass an objet
reference as an interface you better be sure that the object that will use
it has access to the
implementation. It works when it is not distributed because all of the code
is on the client therefore
is accessible. Once distributed the partition containing PlanSO does not
have the library wich
contains the code for PlanTester therefore it cannot execute code in
PlanTester. If you
want to do this and not put PlanTester in the same Plan as PlanSO I think
you can copy the library wich
contains the code for PlanTester on the server partition and it will not
give you a deserialization error
because now it can find the executable code.
This could also probably happen with inheritance for example you have a
class defined in plan A (ClassA)
and plan B (wich has plan A supplier) contains a sub-class of ClassA
(ClassB). Now in one partition you
create a ClassB then pass it to another partition in a method call of
signature Something( p1 : ClassA ).
ClassB will fit in ClassA so you can do this (it will compile). But if the
partition on wich you are calling
Something() does not have access to the code in plan B then you will get a
deserialization error.
Hope this helps a little.
Christian Boult ([email protected])
Programmeur - Analyste
Influatec inc.
-----Original Message-----
From: [email protected] <[email protected]>
To: [email protected] <[email protected]>
Date: Friday, April 16, 1999 8:25 AM
Subject: Unable to obtain reference to plan in distributed environment
>
Forte Folks,
I have run across a supplier plan problem that I think I can explain, but
would like confirmation and maybe further explanation on.
The scenario:
I have three plans (PlanClasses, PlanSO, and PlanTester).
PlanClasses has classes that PlanSO and PlanTester use, including an
interface called Observer.
PlanSO has the Service Object and the class that the service object
implements. It has PlanClasses as a supplier.
PlanSO has a method called subscribe(Observer client).
PlanTester is a test client. It has PlanClasses as a supplier. It
implements the Observer interface, and calls the subscribe method on the
PlanSO passing itself as an Observer to the SO.
Anybody see the problem yet?
I run this scenario locally and everything is dandy.
I run this scenario distributed and I get a deserialization exception. The
PlanSO cannot deserialize the test client object that I had passed as an
Observer because it cannot find a reference to the PlanTester plan.
If I put the test client class in the PlanSO plan and partition the
application the same way, it works. The service object needed a reference
to the test client class even though it is getting passed as an Observer
interface.
Has anybody run into this before? Can anybody give me further details on
why forte has this problem?
I get the same exception whether the distrubted runtime property on the
client is allowed or not allowed. If it is set to not allowed, shouldn't
only an OID be sent across, and no serialization need take place? If the
object is serialized, I guess it does make sense that you would need the
details of the implementation of the interface (da class) to deserialized
it.
Note: I used this pattern instead of Forte events because I am going to
expose the SO as a CORBA interface. Right now, for the forte clients that
use the SO, I am registering for forte events which are posted by the SO to
get around this problem.
Thanks for any responses,
Chris Henson
www.atgs.com
To unsubscribe, email '[email protected]' with
'unsubscribe forte-users' as the body of the message.
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Answer 1

An interface is just a definition of attributes and methods it contains no
code.
The code is in the class that implements the interface therefore even if you
can pass an objet
reference as an interface you better be sure that the object that will use
it has access to the
implementation. It works when it is not distributed because all of the code
is on the client therefore
is accessible. Once distributed the partition containing PlanSO does not
have the library wich
contains the code for PlanTester therefore it cannot execute code in
PlanTester. If you
want to do this and not put PlanTester in the same Plan as PlanSO I think
you can copy the library wich
contains the code for PlanTester on the server partition and it will not
give you a deserialization error
because now it can find the executable code.
This could also probably happen with inheritance for example you have a
class defined in plan A (ClassA)
and plan B (wich has plan A supplier) contains a sub-class of ClassA
(ClassB). Now in one partition you
create a ClassB then pass it to another partition in a method call of
signature Something( p1 : ClassA ).
ClassB will fit in ClassA so you can do this (it will compile). But if the
partition on wich you are calling
Something() does not have access to the code in plan B then you will get a
deserialization error.
Hope this helps a little.
Christian Boult ([email protected])
Programmeur - Analyste
Influatec inc.
-----Original Message-----
From: [email protected] <[email protected]>
To: [email protected] <[email protected]>
Date: Friday, April 16, 1999 8:25 AM
Subject: Unable to obtain reference to plan in distributed environment
>
Forte Folks,
I have run across a supplier plan problem that I think I can explain, but
would like confirmation and maybe further explanation on.
The scenario:
I have three plans (PlanClasses, PlanSO, and PlanTester).
PlanClasses has classes that PlanSO and PlanTester use, including an
interface called Observer.
PlanSO has the Service Object and the class that the service object
implements. It has PlanClasses as a supplier.
PlanSO has a method called subscribe(Observer client).
PlanTester is a test client. It has PlanClasses as a supplier. It
implements the Observer interface, and calls the subscribe method on the
PlanSO passing itself as an Observer to the SO.
Anybody see the problem yet?
I run this scenario locally and everything is dandy.
I run this scenario distributed and I get a deserialization exception. The
PlanSO cannot deserialize the test client object that I had passed as an
Observer because it cannot find a reference to the PlanTester plan.
If I put the test client class in the PlanSO plan and partition the
application the same way, it works. The service object needed a reference
to the test client class even though it is getting passed as an Observer
interface.
Has anybody run into this before? Can anybody give me further details on
why forte has this problem?
I get the same exception whether the distrubted runtime property on the
client is allowed or not allowed. If it is set to not allowed, shouldn't
only an OID be sent across, and no serialization need take place? If the
object is serialized, I guess it does make sense that you would need the
details of the implementation of the interface (da class) to deserialized
it.
Note: I used this pattern instead of Forte events because I am going to
expose the SO as a CORBA interface. Right now, for the forte clients that
use the SO, I am registering for forte events which are posted by the SO to
get around this problem.
Thanks for any responses,
Chris Henson
www.atgs.com
To unsubscribe, email '[email protected]' with
'unsubscribe forte-users' as the body of the message.
Searchable thread archive <URL:http://pinehurst.sageit.com/listarchive/>
To unsubscribe, email '[email protected]' with
'unsubscribe forte-users' as the body of the message.
Searchable thread archive <URL:http://pinehurst.sageit.com/listarchive/>