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Subject: [OASIS Issue Tracker] Commented: (CAMP-31) State change mechanism is unclear


    [ http://tools.oasis-open.org/issues/browse/CAMP-31?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=31802#action_31802 ] 

Jacques Durand  commented on CAMP-31:
-------------------------------------


The only potential issues I see with controlling the applications by using "new_state" : "<new-state-value>", is that this might restrict the the way Providers can extend the CAMP state machine. 

While one may see this as a good thing (to Tobias' view), are we so sure that we do not want to handle the following situations:

-  a Provider want s to extend the CAMP basic state machine by providing different ways to get to the same state: e.g. different modes of starting/running an application (yet leading to the same state "started"), while abstracting the details - i.e. by just differentiating these ways using different op names. ( I also believe at the F2F we considered possible to do extensions that create more than 1 edge between 2 states?)

- a Provider wants to add non-state-changing operations to the basic CAMP state machine (other than GET) , that would look like  "loops" (such as "customize" going from Deployed to Deployed in current state machine.). E.g. "is_deployable()",  or "can-be-run-within-SLA-requirements(my_SLA)" or the like.

In both above cases, won't  the Provider want to define "operations" anyway ? 

> State change mechanism is unclear
> ---------------------------------
>
>                 Key: CAMP-31
>                 URL: http://tools.oasis-open.org/issues/browse/CAMP-31
>             Project: OASIS Cloud Application Management for Platforms (CAMP) TC
>          Issue Type: Bug
>          Components: Spec
>            Reporter: Jacques Durand 
>
> (filed jointly with Tom Rutt)
> In CAMP draft there seems to be a confusion in section 6.11 about the name of a state and the name of the operation leading to that state.
> -----"{"new_state" : "<new-state-value>"} 
> Where, new_state specifies the new desired value for the application state. This specification defines two such values: "suspend", and "resume,"..."-----
> But resume/suspend are operations - not "new states".
> In fact, it seems more natural to control lifecycle (state transitions) with operation names (like in CIMI) rather than by stating the "new state". The latter may appear more RESTful but is rather limited for controlling enterprise apps.
> The specification should clarify the state-changinf mechanism. Using operation names in requests instead of "new state" has some advantages:
> (a)	There may be more than one way to get to a new state from a current state (so using state name is not enough).
> (b)	There might be a need for operations that don't change state. E.g. an op that verifies whether or not a PDP is deployable on a platform even before we try to deploy it.
> Unless we are sure (a) and (b) never apply then we can use "new state" names (in which case 6.11 still need to be fixed). But that needs some investigation.

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