Rajith Attapattu wrote:
Hi All,
I have seen some intrest in clustering but I see that there is no
ongoing discussion or any clear requirments on this topic.
What I would like to do is to start some discussion and gather some
momentum around this so we can flush out the requirments/expectations of
clustering for Axis2.
I can volunteer to cordinate the effort, but I really need people to
come out with suggestions and expectations.
To start with I would like to pose a few questions and get the ball
rolling...
1. What is the basic unit of clustering from Axis2 point of view ?
2. Since web services are more xml driven than object driven, can a
object focused clustering solution be used within Axis2 ?
Publishing xml-docs to a tuple space of some form or other is the
alternative, but you can use java serialization to store xml graphs too.
3. What are some of the challengers or limitations we already know ?
4. If we consider a homogenous collection of web services deployed on
several nodes what will be the users expectations on clustering?
a.) Configuration data to be clustered to all nodes vs One time manul
update ???
b.) If a web service fails during a request how intelligent should
axis2 be in determining wether to transparently move the session/request
to another node?
It shouldnt try. Caller gets to ask again. Maybe some load balancer up
front can change this, but since there are so many interesting ways to
fail, and indeterminite state of a failure unless everything is
transaced, you dont want to go there.
c.) What policies are we going to support ??? Sticky sessions vs
no-sticky sessions and several other variations of this.
We should provide an API for people to write there own
policy/impl for clustering stratergy.
Seems to me that Axis2 ought to be ready-to-cluster, inside whatever the
app server provides (e.g jboss, geronimo, whatever I do with Anubis).
d.) we support several transports, therefore how can we generalize
our clustering support to be applicable within all transports ??
Talk to the app server people, would be my guess.
