Hi all,
These are the break down that we may need to consider when deploying
Composite Application and when starting an ApplicationMonitor. I have
integrated the earlier subscription model with Composite Application.
Please see below and provide you thoughts on this. So that we can finalize
the things before the implementation. Sorry for the bit long mail..
*As discussed in the previous mail by Martin and Isuruh, now that the
service group definitions are deployed independently and Composite
Application will use a reference to pre-deployed service Group with
autoscaling policy, deployment policy and etc.
- service group definition is deployed and persisted in SM
- Composite Application Deployment
+ This will be parsed by SM to get the already deployed service
Group definition to validate and to load the information.
+ SM needs to validate the deployment policy and autoscale policy
against cartridge Type by calling Autoscaler.
+ SM needs to perform any other validation as required or any
logical validation
+ Once all validation are done, SM needs to extract subscription
related information from Composite Application and persist in it.
+ SM needs to build the payload or pass relevant information to CC
to build the payload.
+ SM invokes service call to CC to deploy the Composite Application
with all data.
+ CC will persist any required data from Composite Application and
build the Topology with Composite Application. In that case, it should even
create a Cluster with Composite Application and build the data model. Then
only, it should send the ApplicationCreatedEvent. If we don't build Cluster
object with ApplicationCreatedEvent, then autoscaler has to wait for each
ClusterCreatedEvent to perform the actions. In that case, autoscaler won't
aware of how many ClusterCreatedEvents it should receive before starts
monitoring on a Composite Application. If all the Cluster is available with
Composite Application as part of ApplicationCreatedEvent, then autoscaler
can start monitor and evaluate dependencies to spin the instances.
* New events to the Topology
-ApplicationCreatedEvent
Sent after the composite Application got deployed successfully
-ApplicationTerminatedEvent
when composite application undeployed
-GroupStartEvent
After cluster/clusters in a groups gets started with an instance
-GroupActivatedEvent
After all the clusters in the group becomes active with the minimum
member count
-GroupterminatedEvent
After a group terminated
-GroupInMaintenanceModeEvent
After a group trying to restart on of it's internal cartridge cluster
or group.
*Application Monitor in autoscaler
- has to find out the dependencies, get the least dependent cartridge
type/s or group/s and start minimum rule for them individually or in
parallel according to the start up order specified.
- CC has to send InstanceSpawned/GroupStartedEvent. Once instance/s
activated, CC has to check the minimum no of instance count available in
the Cluster from Topology, and send the GroupActivatedEvent or CC has to
follow any other approach to send GroupActivatedEvent.
- In the member activation or Group activation start the next least
dependent cartridge type/s or group/s
* Find an optimized algorithm to traverse the relation data model for the
Composite Application. I assume, it will be a tree structure..Will
autoscaler or LB or anyone who subscribes to Topology require this at any
point?
* We need to revise our relational data model according to the current
Composite Application Definition. I believe, the same group with different
alias may present in the relational data model more than one time. Eg:
App1
|
-------------------------------------------------------------------------------
|
|
Group1(myapp)
Group2(myapp2)
|
|
-------------------------
------------------------
|
| |
|
Group2(myapp3) cartridge1(mycar1) cartirdge2(mycar2)
cartridge3(mycar3)
Eg: Group1(myapp) - Group1 is the group name and myapp is the alias
Where Group2 is getting used twice in the data model. So, we need to keep
reference of Group2 more than one place. If we already did so, please
ignore this.
Please do add, if there is any missing items to be considered to the list.
Thanks,
Reka
--
Reka Thirunavukkarasu
Senior Software Engineer,
WSO2, Inc.:http://wso2.com,
Mobile: +94776442007
