----- Original Message ----- > From: "Michael Pasternak" <mpast...@redhat.com> > To: "Vojtech Szocs" <vsz...@redhat.com> > Cc: "Itamar Heim" <ih...@redhat.com>, "engine-devel" > <engine-devel@ovirt.org>, "Einav Cohen" <eco...@redhat.com> > Sent: Sunday, November 24, 2013 9:38:45 AM > Subject: Re: Using REST API in web UI - review call summary > > On 11/22/2013 12:08 AM, Vojtech Szocs wrote: > > > > > > ----- Original Message ----- > >> From: "Itamar Heim" <ih...@redhat.com> > >> To: "Vojtech Szocs" <vsz...@redhat.com> > >> Cc: "engine-devel" <engine-devel@ovirt.org>, "Einav Cohen" > >> <eco...@redhat.com>, "Michael Pasternak" > >> <mpast...@redhat.com> > >> Sent: Thursday, November 21, 2013 11:00:25 PM > >> Subject: Re: Using REST API in web UI - review call summary > >> > >> On 11/21/2013 11:56 PM, Vojtech Szocs wrote: > >>> > >>> > >>> ----- Original Message ----- > >>>> From: "Itamar Heim" <ih...@redhat.com> > >>>> To: "Vojtech Szocs" <vsz...@redhat.com>, "engine-devel" > >>>> <engine-devel@ovirt.org> > >>>> Cc: "Einav Cohen" <eco...@redhat.com> > >>>> Sent: Thursday, November 21, 2013 10:25:04 PM > >>>> Subject: Re: Using REST API in web UI - review call summary > >>>> > >>>> On 11/21/2013 11:18 PM, Vojtech Szocs wrote: > >>>>> Hi guys, > >>>>> > >>>>> this is a summary of yesterday's review call, I'll try to highlight > >>>>> important Q/A and things we agreed on. Feel free to add anything in > >>>>> case > >>>>> I've missed something. > >>>>> > >>>>> -- > >>>>> > >>>>> Q: Why don't we simply try to use existing Java SDK and adapt it for > >>>>> GWT > >>>>> apps? (asked by Michael & Gilad) > >>>>> > >>>>> A: This might be a viable option to consider if we wanted to skip > >>>>> JavaScript-based SDK altogether and target Java/GWT code directly; we > >>>>> could simply take Java SDK and customize its abstractions where > >>>>> necessary, > >>>>> i.e. using HTTP transport layer implementation that works with GWT. In > >>>>> any > >>>>> case, this would mean coupling ourselves to Java SDK (which has its own > >>>>> release cycle) and I think this would complicate things for us. > >>>>> > >>>>> As proposed on the meeting, I think it's best to aim for JavaScript SDK > >>>>> as > >>>>> the lowest common denominator for *any* web application that wants to > >>>>> work > >>>>> with REST API. oVirt GWT-based UI can simply bind to JavaScript SDK, > >>>>> i.e. > >>>>> Java/GWT code that just overlays objects and functions provided by > >>>>> JavaScript SDK. Another reason is ease of maintenance - I'd rather see > >>>>> JavaScript SDK's code generation process to be independent of any other > >>>>> SDK (people responsible for maintaining JavaScript SDK should have full > >>>>> control over generated code). > >>>>> > >>>>> -- > >>>>> > >>>>> Q: What about functionality currently used by oVirt UI but not > >>>>> supported > >>>>> by > >>>>> REST API? (asked by Einav) > >>>>> [For example, fetching VM entity over GWT RPC also returns related > >>>>> data > >>>>> such as Cluster name.] > >>>>> > >>>>> A: Based on discussion I've had with other colleagues after yesterday's > >>>>> review call, I don't think that separate support-like backend layer is > >>>>> a > >>>>> good idea. Instead, this is the kind of functionality that could be > >>>>> placed > >>>>> in oVirt.js library. Logical operations like "get VMs and related data" > >>>>> would be exposed through oVirt.js (callback-based) API and ultimately > >>>>> realized as multiple physical requests to REST API via JavaScript > >>>>> Binding. > >>>>> > >>>>> oVirt.js client would be completely oblivious to the fact that multiple > >>>>> physical requests are dispatched. In fact, since HTTP communication is > >>>>> asynchronous in nature, oVirt.js client wouldn't even notice any > >>>>> difference in terms of API consumption. This assumes JavaScript SDK > >>>>> would > >>>>> use callback-based (non-blocking) API instead of blocking one - after > >>>>> all, > >>>>> blocking API on top of non-blocking implementation sounds pretty much > >>>>> like > >>>>> leaky abstraction [1]. > >>>>> > >>>>> For example: > >>>>> > >>>>> sdk.getVmsWithExtraData( > >>>>> callbackToGetExtraDataForGivenVm, // might cause extra > >>>>> physical > >>>>> requests to REST API > >>>>> callbackFiredWhenAllDataIsReady // update client only when > >>>>> all > >>>>> data is ready > >>>>> ) > >>>> > >>>> would this also resolve RunMultipleActions? > >>> > >>> Yes, I think so. There could be API to pass multiple "actions" and get > >>> notified when they complete. > >>> > >>>> sounds like no reason to have RunMultipleQueries, although i'm still > >>>> sure a single call to engine for multiple keys would be much more > >>>> efficient than multiple async calls? > >>>> (I understand we may not be able to model this). > >>> > >>> Efficiency-wise, yes, single call to get all data seems optimal. > >>> API-wise, > >>> I don't think it really matters from oVirt.js client perspective. > >>> > >>> We can proceed with simple (possibly inefficient) solution and improve as > >>> needed. We're making baby steps now.. > >>> > >>>> > >>>>> > >>>>> [1] http://en.wikipedia.org/wiki/Leaky_abstraction > >>>>> > >>>>> -- > >>>>> > >>>>> Last but not least, where to maintain JavaScript SDK projects: > >>>>> low-level > >>>>> JavaScript Binding + high-level oVirt.js library. > >>>>> > >>>>> I agree that conceptually both above mentioned projects should go into > >>>>> dedicated "ovirt-engine-sdk-js" git repository and have their own > >>>>> build/release process. However, for now, we're just making baby steps > >>>>> so > >>>>> let's keep things simple and prototype these projects as part of > >>>>> "ovirt-engine" git repository. > >>>>> > >>>>> ... we can complicate things anytime, but we should know that any > >>>>> complex > >>>>> system that works has inevitably evolved from simple system that works > >>>>> ... > >>>>> (quote from http://en.wikipedia.org/wiki/Gall%27s_law) > >>>> > >>>> I think the entities should just be generated from the xsd. > >>> > >>> +1 > >>> > >>> The JavaScript Binding (aka low-level SDK) module should follow same > >>> concepts as existing Java SDK - generated entities decorated with > >>> operations to form fluent API. > >>> > >>> Everything Java SDK currently offers should be available in JavaScript > >>> Binding. oVirt.js is our opportunity to build on top of that. > >>> > >>>> for the rsdl, makes sense to start with clean code to see what works > >>>> best, then see about generating it (but you should adhere the rsdl as > >>>> guidlines i guess). > >>> > >>> +1 > >>> > >>> The initial prototype should be written by hand, things will get > >>> generated > >>> as soon as we have better idea how the end result should look like. > >> > >> i can understand that for the methods and maybe for populating the > >> entities for the first few. > >> the entities themselves, no point in hand coding - just generated them > >> from the api.xsd. > >> and once you decide how you want to fill them, not worth hand coding > >> this - either json gives this out of the box, or should be generated as > >> well. > > > > OK, now I get you :) sure, entities aren't too interesting by themselves, > > but populating (decorating) them is something that requires more thought. > > you have Java-SDK that does this already, so it should be relativity easy > to take it from there.
Yes, Java SDK will be our reference when developing JavaScript binding for REST API [1]: "It would contain everything currently offered by existing Java SDK". [1] http://www.ovirt.org/Features/Design/Using_REST_API_In_Web_UI#REST_API_JavaScript_Binding > > > > >> > >>> > >>>> > >>>> lets try to plan for lightweight entities while at it - the API has a > >>>> mechanism for different level of details - maybe we need a custom level > >>>> where the client specifies which fields they want back or something like > >>>> that. > >>> > >>> Good idea! We should definitely think about the granularity of entities. > >>> > >>> I didn't know REST API supports different level of detail per entity, is > >>> there some documentation for this feature? > >>> > >>> Since JavaScript is dynamic, one possible solution would be to let client > >>> define the entity structure (i.e. what data client needs) on the fly, > >>> during runtime :) > >> > >> michael? > >> > >>> > >>>> > >>>> Good luck, > >>>> Itamar > >>>> > >> > >> > > > -- > > Michael Pasternak > RedHat, ENG-Virtualization R&D > _______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
