Re: [Engine-devel] Using REST API in web UI - review call summary
Hi guys, I apologize for my extremely late reply in this discussion.. (please find my comments inline) - Original Message - From: Michael Pasternak mpast...@redhat.com To: Vojtech Szocs vsz...@redhat.com Cc: engine-devel engine-devel@ovirt.org Sent: Sunday, December 1, 2013 8:02:12 AM Subject: Re: [Engine-devel] Using REST API in web UI - review call summary On 11/29/2013 11:59 AM, Michael Pasternak wrote: On 11/29/2013 11:45 AM, Michael Pasternak wrote: On 11/28/2013 09:22 PM, Vojtech Szocs wrote: - Original Message - From: Michael Pasternak mpast...@redhat.com To: Vojtech Szocs vsz...@redhat.com Cc: engine-devel engine-devel@ovirt.org Sent: Sunday, November 24, 2013 9:07:01 AM Subject: Re: [Engine-devel] Using REST API in web UI - review call summary Hi Vojtech, First of all it was a good presentation of requirements + suggested solutions - well done!, Thank you :) few comments/questions inline. 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. not sure i buy this one :), this is the purpose of any sdk, including the one you about to write, people that will use it, will be coupling to it ... Of course, but by saying coupling ourselves to Java SDK I meant SDK perspective, not client perspective: of course, but you told something different, that you want js-sdk to be aware of the client, and this is actually why you taking this path. Yes, this SDK targets JavaScript/browser runtime and its code should therefore be as close to it as possible. There are some conceptual gaps between world of Java vs. JavaScript in terms of language, coding practices and patterns, available APIs, etc. (at least) for the first iteration, I wanted to avoid dealing with any sort of discrepancies between Java vs. JavaScript + extra overhead when dealing with Java SDK; my goal is to prototype initial SDK code by hand, verify it in GUI code, then consider code generation, etc. (so-called baby steps, complexity can always be added..) - someone else (you) maintains Java SDK and therefore controls generated sources (JAR or RPM isn't relevant here) - another guy (me) maintains (fictional) Java/GWT SDK that relies on Java SDK + some (supported) customizations - the only way I can impose changes in my SDK is through supported customizations as you control original (Java SDK) sources, i.e. the whole code generation process is driven by your SDK, so my SDK is coupled to your SDK's build/release cycle that's how things working in software, you always depending on the certain version of the component you're working against, as it expose set of features you need, i don't think that having control over framework features, justifying rewriting the framework ... I agree with your point. For me, however, putting Java SDK on starting position for JavaScript SDK in its initial/prototype phase is just unnecessary complexity. I think that lowest common denominator for Java vs. JavaScript SDK is REST API definition, i.e. definition of the interface. On one hand, building JavaScript SDK on top of Java SDK would mean that Java SDK might get improvements over time as JavaScript SDK evolves. On the other hand, it imposes coupling between these two, which might complicate things in certain situations. For now, I'd like to keep things simple. (please note that i'm not against the js-sdk, go ahead, this is a nice initiative indeed, i just can't see the business case for not reusing existent infrastructure cause it works for all your needs and eventually both worlds would benefiting from it UI and java-sdk users cause you where extending it with additional capabilities they may also need) My motivation is avoiding any extra complexity during initial/prototype phase. But I see your point about Java SDK benefiting when used as the base component. For the sake of simplicity, I guess it's best to start with SDK that has no dependencies whatsoever. so why won't you rewrite the engine in Java-script? your js-sdk eventually will be depending on it, this way you'll have control over it (and it's features) as well ;-) No need to rewrite Engine in JavaScript
Re: [Engine-devel] Using REST API in web UI - review call summary
On 11/28/2013 09:37 PM, Vojtech Szocs wrote: - Original Message - From: Michael Pasternak mpast...@redhat.com To: Itamar Heim ih...@redhat.com Cc: Vojtech Szocs vsz...@redhat.com, engine-devel engine-devel@ovirt.org, Einav Cohen eco...@redhat.com Sent: Sunday, November 24, 2013 9:37:22 AM Subject: Re: Using REST API in web UI - review call summary On 11/22/2013 12:00 AM, Itamar Heim wrote: 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 -
Re: [Engine-devel] Using REST API in web UI - review call summary
On 11/29/2013 11:59 AM, Michael Pasternak wrote: On 11/29/2013 11:45 AM, Michael Pasternak wrote: On 11/28/2013 09:22 PM, Vojtech Szocs wrote: - Original Message - From: Michael Pasternak mpast...@redhat.com To: Vojtech Szocs vsz...@redhat.com Cc: engine-devel engine-devel@ovirt.org Sent: Sunday, November 24, 2013 9:07:01 AM Subject: Re: [Engine-devel] Using REST API in web UI - review call summary Hi Vojtech, First of all it was a good presentation of requirements + suggested solutions - well done!, Thank you :) few comments/questions inline. 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. not sure i buy this one :), this is the purpose of any sdk, including the one you about to write, people that will use it, will be coupling to it ... Of course, but by saying coupling ourselves to Java SDK I meant SDK perspective, not client perspective: of course, but you told something different, that you want js-sdk to be aware of the client, and this is actually why you taking this path. - someone else (you) maintains Java SDK and therefore controls generated sources (JAR or RPM isn't relevant here) - another guy (me) maintains (fictional) Java/GWT SDK that relies on Java SDK + some (supported) customizations - the only way I can impose changes in my SDK is through supported customizations as you control original (Java SDK) sources, i.e. the whole code generation process is driven by your SDK, so my SDK is coupled to your SDK's build/release cycle that's how things working in software, you always depending on the certain version of the component you're working against, as it expose set of features you need, i don't think that having control over framework features, justifying rewriting the framework ... (please note that i'm not against the js-sdk, go ahead, this is a nice initiative indeed, i just can't see the business case for not reusing existent infrastructure cause it works for all your needs and eventually both worlds would benefiting from it UI and java-sdk users cause you where extending it with additional capabilities they may also need) For the sake of simplicity, I guess it's best to start with SDK that has no dependencies whatsoever. so why won't you rewrite the engine in Java-script? your js-sdk eventually will be depending on it, this way you'll have control over it (and it's features) as well ;-) After all, there's no common dependency (aside from running Engine to provide XSD RSDL) between Java Python SDK too, if I understand correctly. In other words, building on top of something existing (just because we can do that) isn't always appropriate/flexible/efficient, it always depends on given context and requirements. it would be true, if your requirements would make existing infrastructure inappropriate. 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). what do you mean by people should have full control over generated code? It's related to coupling from SDK perspective I mentioned above: the only way I can impose changes in my SDK is through supported customizations as you control original (Java SDK) sources if you need additional functionality in java-sdk, you could do the following: 1. submit a patch to java-sdk 2. build new java-sdk locally and use it along with new feature you've added 3. make UI depending on next version of java-sdk (which includes your new feature) we (and all other SW projects) doing that day by day in engine,api,etc. (as i mentioned this would also benefit java-sdk users with additional features they might find useful as well) (by people I meant JavaScript SDK developers) Full control means ability to change generated sources in whatever way
Re: [Engine-devel] Using REST API in web UI - review call summary
On 11/29/2013 11:45 AM, Michael Pasternak wrote: On 11/28/2013 09:22 PM, Vojtech Szocs wrote: - Original Message - From: Michael Pasternak mpast...@redhat.com To: Vojtech Szocs vsz...@redhat.com Cc: engine-devel engine-devel@ovirt.org Sent: Sunday, November 24, 2013 9:07:01 AM Subject: Re: [Engine-devel] Using REST API in web UI - review call summary Hi Vojtech, First of all it was a good presentation of requirements + suggested solutions - well done!, Thank you :) few comments/questions inline. 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. not sure i buy this one :), this is the purpose of any sdk, including the one you about to write, people that will use it, will be coupling to it ... Of course, but by saying coupling ourselves to Java SDK I meant SDK perspective, not client perspective: of course, but you told something different, that you want js-sdk to be aware of the client, and this is actually why you taking this path. - someone else (you) maintains Java SDK and therefore controls generated sources (JAR or RPM isn't relevant here) - another guy (me) maintains (fictional) Java/GWT SDK that relies on Java SDK + some (supported) customizations - the only way I can impose changes in my SDK is through supported customizations as you control original (Java SDK) sources, i.e. the whole code generation process is driven by your SDK, so my SDK is coupled to your SDK's build/release cycle that's how things working in software, you always depending on the certain version of the component you're working against, as it expose set of features you need, i don't think that having control over framework features, justifying rewriting the framework ... (please note that i'm not against the js-sdk, go ahead, this is a nice initiative indeed, i just can't see the business case for not reusing existent infrastructure cause it works for all your needs and eventually both worlds would benefiting from it UI and java-sdk users cause you where extending it with additional capabilities they may also need) For the sake of simplicity, I guess it's best to start with SDK that has no dependencies whatsoever. so why won't you rewrite the engine in Java-script? your js-sdk eventually will be depending on it, this way you'll have control over it (and it's features) as well ;-) After all, there's no common dependency (aside from running Engine to provide XSD RSDL) between Java Python SDK too, if I understand correctly. In other words, building on top of something existing (just because we can do that) isn't always appropriate/flexible/efficient, it always depends on given context and requirements. it would be true, if your requirements would make existing infrastructure inappropriate. 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). what do you mean by people should have full control over generated code? It's related to coupling from SDK perspective I mentioned above: the only way I can impose changes in my SDK is through supported customizations as you control original (Java SDK) sources if you need additional functionality in java-sdk, you could do the following: 1. submit a patch to java-sdk 2. build new java-sdk locally and use it along with new feature you've added 3. make UI depending on next version of java-sdk (which includes your new feature) we (and all other SW projects) doing that day by day in engine,api,etc. (as i mentioned this would also benefit java-sdk users with additional features they might find useful as well) (by people I meant JavaScript SDK developers) Full control means ability to change generated sources in whatever way desired, but assuming the idea of reusing
Re: [Engine-devel] Using REST API in web UI - review call summary
- Original Message - From: Michael Pasternak mpast...@redhat.com To: Vojtech Szocs vsz...@redhat.com Cc: engine-devel engine-devel@ovirt.org Sent: Sunday, November 24, 2013 9:07:01 AM Subject: Re: [Engine-devel] Using REST API in web UI - review call summary Hi Vojtech, First of all it was a good presentation of requirements + suggested solutions - well done!, Thank you :) few comments/questions inline. 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. not sure i buy this one :), this is the purpose of any sdk, including the one you about to write, people that will use it, will be coupling to it ... Of course, but by saying coupling ourselves to Java SDK I meant SDK perspective, not client perspective: - someone else (you) maintains Java SDK and therefore controls generated sources (JAR or RPM isn't relevant here) - another guy (me) maintains (fictional) Java/GWT SDK that relies on Java SDK + some (supported) customizations - the only way I can impose changes in my SDK is through supported customizations as you control original (Java SDK) sources, i.e. the whole code generation process is driven by your SDK, so my SDK is coupled to your SDK's build/release cycle For the sake of simplicity, I guess it's best to start with SDK that has no dependencies whatsoever. After all, there's no common dependency (aside from running Engine to provide XSD RSDL) between Java Python SDK too, if I understand correctly. In other words, building on top of something existing (just because we can do that) isn't always appropriate/flexible/efficient, it always depends on given context and requirements. 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). what do you mean by people should have full control over generated code? It's related to coupling from SDK perspective I mentioned above: the only way I can impose changes in my SDK is through supported customizations as you control original (Java SDK) sources (by people I meant JavaScript SDK developers) Full control means ability to change generated sources in whatever way desired, but assuming the idea of reusing/customizing existing SDK code, aspect of full control is lost in favor of reusing existing code. And of course, this assumes that existing code (Java SDK) provides everything we need, which might or might not be the case. So I just vote for simplicity, generate JavaScript SDK the way like other SDKs (Java/Python) - not trying to reuse anything, just grab XSD RSDL and generate sources. the purpose of code generation is to ease maintenance, i.e you/maintainer should not write the feature once it available in api, just run CodeGen and you'll get it for free, but this is zero control over code. +1 I agree with you on this. -- 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
Re: [Engine-devel] Using REST API in web UI - review call summary
- Original Message - From: Michael Pasternak mpast...@redhat.com To: Itamar Heim ih...@redhat.com Cc: Vojtech Szocs vsz...@redhat.com, engine-devel engine-devel@ovirt.org, Einav Cohen eco...@redhat.com Sent: Sunday, November 24, 2013 9:37:22 AM Subject: Re: Using REST API in web UI - review call summary On 11/22/2013 12:00 AM, Itamar Heim wrote: 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
Re: [Engine-devel] Using REST API in web UI - review call summary
- 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
Re: [Engine-devel] Using REST API in web UI - review call summary
Hi Vojtech, First of all it was a good presentation of requirements + suggested solutions - well done!, few comments/questions inline. 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. not sure i buy this one :), this is the purpose of any sdk, including the one you about to write, people that will use it, will be coupling to it ... 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). what do you mean by people should have full control over generated code? the purpose of code generation is to ease maintenance, i.e you/maintainer should not write the feature once it available in api, just run CodeGen and you'll get it for free, but this is zero control over 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 ) actually this the main bottleneck in moving UI to work on top of REST, and most interesting/complex part of this project, you should think of very wise polling mechanism cause callbacks is a nice thing on paper, but behind the scene it all about polling: - the entity/s till action got accomplished - add to this updating different grids - running multiple actions - showing events - and obviously much more and don't forget that every polled entity should be marshalled from xml to the javascript entity so at the end, callbacks mechanism will be extremely CPU consuming. [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) Regards, Vojtech ___ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel -- Michael Pasternak RedHat, ENG-Virtualization RD ___ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
Re: [Engine-devel] Using REST API in web UI - review call summary
On 11/22/2013 12:00 AM, Itamar Heim wrote: 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
Re: [Engine-devel] 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
Re: [Engine-devel] Using REST API in web UI - review call summary
- Original Message - From: Michael Pasternak mpast...@redhat.com To: Itamar Heim ih...@redhat.com Cc: engine-devel engine-devel@ovirt.org Sent: Sunday, November 24, 2013 9:37:22 AM Subject: Re: [Engine-devel] Using REST API in web UI - review call summary On 11/22/2013 12:00 AM, Itamar Heim wrote: 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
Re: [Engine-devel] Using REST API in web UI - review call summary
- 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
Re: [Engine-devel] Using REST API in web UI - review call summary
- 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
Re: [Engine-devel] 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
[Engine-devel] Using REST API in web UI - review call summary
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 ) [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) Regards, Vojtech ___ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
Re: [Engine-devel] 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? 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). [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. 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). 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 luck, Itamar ___ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
