Changes between Version 10 and Version 11 of GAPI_AM_API_DRAFT


Ignore:
Timestamp:
10/18/11 11:41:46 (8 years ago)
Author:
Aaron Helsinger
Comment:

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  • GAPI_AM_API_DRAFT

    v10 v11  
    406406The ProtoGENI CMV2 API has [http://www.protogeni.net/trac/protogeni/wiki/ComponentManagerAPIV2#UpdateSliver UpdateSliver], which is described as the way to "Request a change of resources for an existing sliver. The new set of resources that are desired are specified in the rspec." At ProtoGENI as at !PlanetLab, this method takes the full RSpec description of resources the experimenter wants, and the server computes the difference with what the experimenter already has. At ProtoGENI though, this method returns a ticket. The experimenter must then redeem the ticket to actually acquire the resources. Then the experimenter manually calls !RestartSliver as needed on nodes that need to be rebooted, when the experimenter is ready to do so. This takes an extra step, but gives the experimenter full control over which nodes are restarted and when.
    407407
    408 Some key properties and differences of this method at those two aggregate code-bases, with a note on the alternatives. The community must discuss the options:
    409  - Takes the full description of what the experimenter wants, and the server computes the difference. Note that 2 experimenters with permissions to modify the slice (say, 2 students of a professor) could issue conflicting update calls on the same aggregate. And alternative would be that experimenters must compute the difference themselves, and would just specify the incremental changes they want in their reservation.
     408Here are some key properties and differences of this method at those two aggregate code-bases, with a note on the alternatives. The community must discuss the options:
     409 - In both these cases, the method takes the full description of what the experimenter wants, and the server computes the difference. Note that 2 experimenters with permissions to modify the slice (say, 2 students of a professor) could issue conflicting update calls on the same aggregate. And alternative would be that experimenters must compute the difference themselves, and would just specify the incremental changes they want in their reservation.
    410410 - Atomic: either the full request succeeds, or it fails. The alternative would be that if the experimenter wanted 5 more nodes and only 3 were available, that the server could give you those 3.
    411411 - The two implementations above differ on whether the changes are immediate or not. ProtoGENI uses tickets, allowing the experimenter to change their mind or coordinate their requests (See below). They also separate out reservation of the resources with restarting nodes. This allows the experimenter to control which nodes get rebooted and when. !PlanetLab in comparison handles all restarting of nodes for the experimenters, giving them a single operation to get their resources. This approach also more closely matches the behavior of !CreateSliver in the AM API V1.
     
    428428}}}
    429429
    430 Proposed semantics:
     430Proposed method semantics:
    431431 - RSpec argument is a complete request RSpec with the desired new end state for the slice at this aggregate. ''Open questions: Does the request schema support specifying sliver_ids or other attributes that were in the manifest RSpec, and which the experimenter might want or need to preserve in this RSpec?''
    432432 - Atomic: the request either succeeds entirely or fails and the slice is not changed at the aggregate at all, with the aggregate returning a message indicating that it failed and why. Aggregates are encouraged to return enough information to allow the experimenter to modify the request such that it can succeed.
    433433 - Resources are allocated and started or restarted immediately, on behalf of the experimenter (no tickets, and no separate call to restart the sliver)
    434 
     434 - The API provides no guarantees about whether existing resources in the slice at the aggregate will be left undisturbed or will be restarted. Aggregates should document any guarantees or the lack thereof for their resources. For example, an aggregate may move virtual machines from one physical rack to another in order to accommodate an experimenter's modified requirements for internal network topology or disk space.
    435435
    436436=== Change Set D: Slivers and Sliver Groups ===