Re: [sop] SOP Requirements

Vishwas Manral <vishwas.ietf@gmail.com> Fri, 02 March 2012 18:48 UTC

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Date: Fri, 2 Mar 2012 10:48:33 -0800
Message-ID: <CAOyVPHTgfyEDM5Xq9GF+zxcLCY6AAzTdn2s9c1z7529rDO8LGQ@mail.gmail.com>
From: Vishwas Manral <vishwas.ietf@gmail.com>
To: "Ashish Dalela (adalela)" <adalela@cisco.com>
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Cc: sop@ietf.org, Michael Hammer <mphmmr@gmail.com>
Subject: Re: [sop] SOP Requirements
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Hi Ashish,

My point was very simple.

You had talked about cases where protocol is more flexible than an API, and
I was trying to help you understand that anything that can be done in an
East West manner (with protocols), can be done in North-South manner with
API's. If you say we can do something with protocols with only X packets,
we can do the same with just X API's too. That was my point and not the
fact that we have only 1 API or more.

Also API's on which base services sit and ones which end users use could be
different.

Am I missing the point altogether?

Thanks,
Vishwas

On Wed, Feb 29, 2012 at 6:51 PM, Ashish Dalela (adalela)
<adalela@cisco.com>wrote:

> Hi Vishwas,****
>
> ** **
>
> What everyone calls API today uses a protocol – HTTP. APIs survive on the
> interoperability provided by that protocol, and I don’t think anyone can
> get away from that. The real question is – what is the right protocol on
> top of which to build APIs? That’s the question SOP is raising. Once you do
> that, then we can talk of one or many APIs.****
>
> ** **
>
> Limitations of using HTTP as the underlying protocol for any API have been
> described in detail in the requirements draft. I would like to hear your
> comments on that. That section describes what APIs can’t do. Some of the
> limitations are because API is always unicast, and there are many things
> for which you need a manycast and broadcast. Other limitations because APIs
> are synchronous and you need to be asynchronous in some cases. Yet other
> issues because APIs are single complete transaction, but some transactions
> will spread over multiple such APIs. ****
>
> ** **
>
> The total amount of information in a message is unchanged whether you put
> it inside a protocol header or the content body. Putting some things in the
> protocol header saves you having to reinvent them in the content for every
> type of service. In other words, a protocol saves you from increasing
> information across various services. As an example in SIP, we put From and
> To in the protocol header. Could we not put it in the body? Sure we could.
> In that case we would be repeating that for voice and video and chat
> content. ****
>
> ** **
>
> To your point, you can have a single API for doing anything. As the
> service evolves and complexity grows, the number of parameters to that API
> increases. And yes, you can make that backward compatible in terms of
> implementation. But, nobody does that – especially when the interface is
> end-user facing. If this was an acceptable design, then we would not have
> object inheritance and there won’t be hundreds of APIs being opened up by
> cloud providers today. You might want to suggest one API to Amazon or other
> cloud providers. ****
>
> ** **
>
> A practical operational issue with APIs is that users don’t understand all
> the details. A user understands a server memory and CPU, but don’t
> understand VLAN and LUN, and zillions of other complicated things. Exposing
> them through APIs is useless because they can’t use it. Why would a user
> buy an expensive TV when they can’t use most of the features, because the
> remote is too complicated? The need is to reduce complexity through
> automation, not expose it all to the user via APIs. In other words, you
> need a more sophisticated policy engine not a sophisticated API system. **
> **
>
> ** **
>
> For any problem there is a cure and there is a prevention. Building API
> bridges is a cure to diverse APIs, it’s not a prevention. Once you
> recognize a problem, you build a short-term cure and a long-term prevention
> (at least ideally). Then, a single API is neither a cure nor prevention;
> its side-effects are so severe that we might be living with the original
> problem as well. ****
>
> ** **
>
> APIs have always existed and will continue to exist. The goal is to
> interoperate diverse APIs without a translation bridge. That happens all
> the time with network protocols, when one vendor’s APIs works with another
> vendor’s APIs without a translation bridge. I think not having a bridge is
> always better than having a bridge. Agree?****
>
> ** **
>
> Thanks, Ashish****
>
> ** **
>
> ** **
>
> *From:* Vishwas Manral [mailto:vishwas.ietf@gmail.com]
> *Sent:* Wednesday, February 29, 2012 10:45 PM
> *To:* Ashish Dalela (adalela)
> *Cc:* Michael Hammer; sop@ietf.org
>
> *Subject:* Re: [sop] SOP Requirements****
>
> ** **
>
> Hi Ashish,****
>
>  ****
>
> As the number of services increase or the complexity in a given service
> grows, this becomes very hard. Assume there is a service with N tunable
> parameters. You need at least N APIs that modify these parameters
> individually. Then permutations and combination of these parameters create
> hundreds of more APIs. That’s just API bloat. And if you have to
> interoperate multiple instances of these APIs through bridges, it’s just
> inviting more complexity. Another limitation is that when APIs have
> semantic incompatibilities, it becomes even harder to interoperate (syntax
> incompatibility is easier).****
>
> Not true at all.For N parameters you can have one API. The API can be made
> forward compatible by using simple things like unions. Having worked in a
> software company, where we have to extend our software without breaking
> previous API's I am well aware of the fact.
>
> If you give an exact example I can try to help you see how we can make an
> extensible API for the same.
>
> Thanks,
> Vishwas ****
>
>  ****
>
> From an operational standpoint, every new API introduction requires
> software upgrades to the controllers. That eventually hinders the rate of
> service creation.****
>
>  ****
>
> >> I know as services proliferate there could be a proliferation of
> distict API's but the same is true of the protocol layer too.
>  ****
>
> That won’t happen if we separate service-independent and service-dependent
> pieces. An example of that is SNMP. SNMP is device/service independent. MIB
> defines the specific service/device. If you have a standard protocol to
> manage a device, then you just have to add a new MIB to start managing it.
> You don’t need to upgrade all the intermediate systems – hardware or
> software. ****
>
>  ****
>
> BTW, I’m not advocating SNMP here because SNMP has many shortcomings in
> terms of network discovery, capability discovery, advertisements,
> transactions, etc. But, we need to keep in mind that API proliferation is
> inevitable as services proliferate. Protocol proliferation is not
> inevitable. Similar separation has been done in the past in SIP/SDP,
> HTTP/HTML, SMTP/MIME. That separation allows anyone to send any content in
> email to anyone. Or download any web-page, or have any type of codec (voice
> or video) use the same protocol.****
>
>  ****
>
> If you compare the success and widespread use of above mentioned protocols
> the value of separation between service-independent and service-dependent
> seems pretty convincing.****
>
>  ****
>
> >> Correct but the draft seems to differ.****
>
>  ****
>
> Service and instance of service are (and can be) interchangeably used. Is
> bandwidth a service or an instance of a service? I think this is more
> semantics.****
>
>  ****
>
> >> The requirement seems contradictory to what we agree. Similar for
> points below.****
>
>  ****
>
> The requirement is really that services are portable across providers. I
> think it is fair to say (as you also agree) that a user must know where
> they are going for a service. After all, they will have to pay for the
> service and they ought to know in advance who are they going to receive a
> monthly check from. ****
>
>  ****
>
> Thanks, Ashish****
>
>  ****
>
>  ****
>
> *From:* sop-bounces@ietf.org [mailto:sop-bounces@ietf.org] *On Behalf Of *Vishwas
> Manral
> *Sent:* Tuesday, February 28, 2012 1:26 AM
> *To:* Michael Hammer
> *Cc:* sop@ietf.org
> *Subject:* Re: [sop] SOP Requirements****
>
>  ****
>
> Hi Michael,
>
> Sounds like we agree on most of the things, though I see the draft
> contradicting what we agree on.****
>
> 1. Do we really see incompatibilities in the API's soar for say IaaS? The
> AWS API's seem to be the default standard adopted by most providers. From
> the little I know OpenStack based API's may be the alternative way and
> companies have built bridging layers to inter-operate between the same.***
> *
>
>  ****
>
>  ****
>
> Seem?  May be?  Bridging layers?  I think you are making the case for us.
> :)****
>
> I'm sure Ashish will have more to say about APIs, but I would prefer there
> be a de jure than a default, which in the long run is likely to change at
> the whim of a single company, and perhaps not in a direction that everyone
> would like.****
>
> What I am saying is we have 2 sets of API's and there are layers used to
> bridge the same. I know as services proliferate there could be a
> proliferation of distict API's but the same is true of the protocol layer
> too.
>  ****
>
>  ****
>
> 2. Instead of the term customer/ user can we instead use the term
> "consumer". Something like "cloud subscriber" etc could be used. All I am
> saying is can we use standard terms here.****
>
>  ****
>
> We can settle on specific terms to use, just so long as we keep the
> distinction between the entity (enterprise?) that provisions the software
> in the cloud, and the user of that software, which could be an employee or
> a user in the general public.  Using a SIP Proxy as a Service, the operator
> of the Proxy provisions it with a CREATE, but the user is the one sending
> INVITEs through it.  Make sense?****
>
> The NIST document uses terms and we should try to use similar terms as far
> as possible.
>  ****
>
>  ****
>
> 3. Is orchestration about creating services (from the cloud providers
> perspective), or an instance of a service (for a particular user)? I think
> it is the latter, but doesn't sound so from the definition.****
>
>  ****
>
> Orchestration is about the on-demand provisioning of the
> compute/storage/network/XaaS in the cloud by the subscriber/customer.  Once
> provisioned, the service can provide services to the intended user.  We are
> trying to be general here.  Need to keep provisioning and operations
> distinct.  "Service" is occurring in levels.****
>
> Correct but the draft seems to differ.
>  ****
>
>  ****
>
> 4. How is Service Domain Name different from a URI? Aren't they the same?*
> ***
>
>  ****
>
> There is a distinction here between a class of services and running
> instantiations of those services.  Either may be hierarchically named.****
>
> Hmm.
>  ****
>
>  ****
>
> 5. Is Scenario -1 talking about all providers should provide the same
> services? I guess not. I think the idea should be the same set of services
> should be accessible from a cloud provider the same way. It however does
> not mean that all providers need to provide the same services, as it seems
> from the requirement.****
>
>  ****
>
> Agree.  All providers may not provide the same set of services.  ****
>
> But, if two providers offer the same service, it should not require a new
> customer protocol stack to do so.****
>
> And users should not know that they may be going to one provider or the
> other when using the same service.****
>
> The requirement seems contradictory to what we agree. Similar for points
> below.
>
> Thanks,
> Vishwas
>  ****
>
>  ****
>
> 6. It seems for most purposes you are talking about users, but as such a
> user in an enterprise should be unaware of where the service is coming
> from. It is the role of the customer to actually provide clear demarcation
> so a user is unaware of the same. Interoperability with virtual provider is
> how companies achieve the same.****
>
>  ****
>
> Agree, and we would like that to be true for multi-provider cases as well.
> ****
>
> I would go further to say that even a user not in the enterprise should be
> unaware where the service is coming from.****
>
>  ****
>
> 7. I don't think you should mention providers should inter-operate with
> each other. That is a business decision. I think what you mean here is that
> providers should have a clear interoperable means should they wish to
> inter-operate.****
>
>  ****
>
> Yes.  We want them to be able to inter-operate.  Whether they want to is a
> business decision.****
>
>  ****
>
> 8. Is it really a requirement for the Orchestration to allow
> inter-operation for all models? I would have thought we are focusing on the
> IaaS alone.****
>
>  ****
>
> We don't see a reason to limit it to just IaaS.  We are looking several
> years down the road here.****
>
>  ****
>
> 9. S-5 and S-3 sound like similar services to me. How are they different -
> vendor versus provider?****
>
>  ****
>
> We were considering cases where multiple companies are involved in
> providing all the capabilities needed.  One involved coordination within an
> administrative domain, while the other involves independent administrative
> domains.  We didn't want to limit this to single company operations.  Large
> global providers may involve many companies.****
>
>  ****
>
> 10. I think one of the key requirements for SOP, is the ability to work
> across only a sub-set of the base services and allow for extensible
> services on top. There could be so many variants of the SaaS or even PaaS I
> am not sure how you would make every service inter-operate.****
>
>  ****
>
> There needs to be several layers of standards involved.  This is an onion
> not a single layer orange-peel.****
>
> Here we are trying to provide structure that allows easy extension,
> substitution, and innovation at the more service-specific granular levels.
> ****
>
>  ****
>
> 11. I think when a VM is moved the biggest issue is the ability to move
> the storage along with it. All other state is minor and minimal.****
>
>  ****
>
> I would say the networking is the biggest issue, but that is my bias.  :0*
> ***
>
>  ****
>
> 12. Section 6 seems to be relevent within a cloud too and not just between
> clouds.****
>
>  ****
>
> Agree.  Internal to a cloud and from the customer to the cloud are the
> simple cases.  ****
>
> We emphasize the inter-cloud cases to test the architecture for the worst
> cases.****
>
>  ****
>
> 13. Doesn't CDN provide the ability to separate address and ability
> already?****
>
>  ****
>
> Probably needs more discussion.  I see content as a specific scenario.
>  There you don't care which copy of data is accessed so long as you reach
> it.  In other types of services, a lot more control over who accesses what
> is needed.****
>
>  ****
>
> 14. For Service discovery. management we wrote something quite a while
> back
> https://datatracker.ietf.org/doc/draft-yokota-opsawg-virtnw-service-management/
> .****
>
> Will take a look.  Thanks.  Mike****
>
>  ****
>
> Thanks,
> Vishwas
>
> _______________________________________________
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> https://www.ietf.org/mailman/listinfo/sop****
>
>  ****
>
>  ****
>
> ** **
>