Re: Autonomic Computing with Imperius

[Neeraj Joshi <jn...@us.ibm.com>]

Hi Reza,
Thank you for your interest in trying out  SPL your comments are greatly 
appreciated.

> For example bean.attr1 should be translated internally to 
bean.getAttr1(). 

I think this is a good idea and do not think it will be very hard to 
implement.

>anchor classes are kind of dynamically generated classes, and I can not 
specify their class names

This one is a bit tricky because a policy has a 2 phase life-cycle in 
phase 1 the policy is validated syntatically and semantically and an 
*executable* is generated and cached.
In phase 2 the policy is evaluated using the input parameters.

Not knowing the class name in phase 1 will naturally be a problem so we 
would have to be able to support a way to evaluate on the fly...this may 
require some fundamental changes.

We are always looking for folks to participate in our project so if you 
have the cycles you could just provide us with a patch for #1 and I can 
check it in.

I have cc'ed this email to the community for others to comment

Thanks!
Neeraj



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"The light at the end of the tunnel...may be you"

 
Neeraj Joshi
WebSphere XD - Compute Grid
AIM, IBM
Apache Imperius - http://incubator.apache.org/imperius
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



"Reza Asadollahi" <ra...@uwaterloo.ca> 
04/21/2008 04:07 PM

To
David L Kaminsky/Raleigh/IBM@IBMUS, Neeraj Joshi/Durham/IBM@IBMUS
cc

Subject
Autonomic Computing with Imperius






Hi,
I am doing research in the area of autonomic computing in the University 
of Waterloo Canada. As part of my research, I was intending to develop an 
implementation of CIM-SPL, and hopefully, I found that you did it. Thank 
you so much. You did a great job, and I guess Imperius can be the leader 
of policy engines in this area. 
 
I used the current version of Imperius in my project and I found a few 
limitations in the application. I would like to share them with you and 
get your suggestions about them. 
 
1.       A policy can not access the anchor class private attributes via 
their getter and setter methods, and the attributes should be defined 
“public” instead. Yes, I found that it is possible to call a getter method 
in the “condition” section but it is more interesting to read and write 
attributes in an expression-like language. For example bean.attr1 should 
be translated internally to bean.getAttr1().  The idea of Java EE 
Expression Language in terms of using high-level expressions instead of 
java-like code could be helpful in this context as well.
2.       The objects that I pass to the policies as anchor classes are 
kind of dynamically generated classes, and I can not specify their class 
names in the policy file (they don’t extend a specific super class or 
interface). Hence, it is not possible to work with the anchor objects in 
the policies as sensors and effectors. For example, I have a 
dynamically-generated java bean and I know that it would have have an 
attribute named “attr1”, but I don’t know its class (and it is not 
important at all); however, I would like to able to use that java bean in 
the policy. To overcome this problem, I guess it would be enough for 
Imperius to work with the passed java beans by reflection.
 
I believe that addressing the mentioned concerns in Imperius will 
significantly improve its feature set and facilitate its usage in 
different adaptation environments.
 
I would like to thank you for your attention to my points, and I am 
looking forward to hearing from you soon. 
 
 
 
Best Regards,
 
Reza Asadollahi