Hi, I think $subject is very important specially when comes to data cartridges like MySQL, Mongo ..etc. So we need to define these volume requirements in the cartridge definitions. It should support 1 to n number of volumes. (we can define max, say 5?)
Then CC can attached these volumes (witting underling IaaS via jclouds) to the cartridge instance and pass the volume information to instance via payload. Cartridge must configured to get these volume information and configure itself. And also we need to add these volume information to the topology under member information. Let see what is the use case of this. Say that somehow cartridge instance crashed. We can identify this by cartridge health stats not coming to CEP, then it will summaries these info and notifier auto scaler. Then auto scaler should create new instance for this cashed instance. When it notify CC, it should attached previously used volumes (can get from the topology) to newly created instance. With this we can pass persist data to newly created instances. When cartridge un-subscription we can destroy these volumes. WDYT? -- Lakmal Warusawithana Software Architect; WSO2 Inc. Mobile : +94714289692 Blog : http://lakmalsview.blogspot.com/
