RE: [Discuss] Defining Cloud Bursting Pattens in Application Policy

[Shaheedur Haque (shahhaqu)]

LGTM....

________________________________
From: Imesh Gunaratne [im...@apache.org]
Sent: 04 March 2015 11:59
To: dev; Shaheedur Haque (shahhaqu); Lakmal Warusawithana
Subject: [Discuss] Defining Cloud Bursting Pattens in Application Policy

Hi Devs,

Shaheed raised an issue related to Application Policy definition where we 
define an attribute called "activeByDefault" to mark the network partitions 
which will be used for initially spawning application instances.

The concern was to either remove this attribute and only send the active by 
default network partitions in the list, or to introduce a capability to define 
an algorithm to traverse among network partitions. I think it would be better 
to go with the second option for this purpose as it provides more flexibility 
for the user. Here the algorithms should be implemented using an interface and 
should be pluggable.

Modification 1:
If we do this I think we can change the application policy definition as 
follows:

{
    "id": "application-policy-1",
    "algorithm":"one-after-another",
    "networkPartitions":[
        "network-partition-1",
        "network-partition-2",
        "network-partition-3",
        "network-partition-4"
    ],
    "properties":[
        {
            "key1" : "value1"
        },
        {
            "key2" : "value2"
        }
    ]
}

The algorithm value ("one-after-another") to its class name mapping can be done 
in autoscaler configuration file. If the algorithm class needs any additional 
values those can be passed via the properties field.

Modification 2:
In addition to this we should be able to manage Application Policies in global 
level. If so we can reuse Application Policies for different applications.

Modification 3:
According to this model the application deployment API method would change as 
follows:

Deploy Application API Method:
POST /api/applications/{application-id}/deploy/{application-policy-id}

UnDeploy Application API method:
POST /api/applications/{application-id}/undeploy

I'm +1 to incorporate these changes for the 4.1.0-beta developer preview. 
Please review and add your thoughts.

Thanks

--
Imesh Gunaratne

Technical Lead, WSO2
Committer & PMC Member, Apache Stratos