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Provider Networks extension advice (was Re: [Openstack] question on get_network_details api call)

 

 

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rkukura at redhat

Jun 8, 2012, 8:19 AM

Post #1 of 4 (290 views)
Permalink
Provider Networks extension advice (was Re: [Openstack] question on get_network_details api call)

Dan, Netstackers,

I need some advice ASAP so I can proceed with the provider-networks BP
(https://blueprints.launchpad.net/quantum/+spec/provider-networks)
implementation. This BP will be implemented using a "provider" extension
that adds a number of optional attributes (eg. vlan tags) to the core
network resource. These attributes will be settable by and visible to
those with admin rights.

The main decision I'm looking for advice on is whether to implement this
extension as a RequestExtension or as a ResourceExtension. See the email
quoted below for details.

If implemented as a RequestExtension, these provider attributes would be
returned along with the core attributes from "GET
/tenants/{tenant_id}/networks/{network_id}.json", and potentially from
all API actions that return the core attributes.

If implemented as a ResourceExtension, the provider attributes would be
accessed from a separate sub-resource, such as "GET
/tenants/{tenant_id}/networks/{network_id}/provider.json".

As Dan suggested below, I think it would be preferable to extend the
core resource itself rather than define a new sub-resource. This would
mean using the RequestExtension approach. The issue with this is that I
see no way to support XML with this approach, but the ResourceExtension
approach can support both JSON and XML.

Is the RequestExtension approach preferable? Is it acceptable even if it
cannot (currently) support XML? Or is there a way to extend the XML
using a RequestExtension that I'm missing?

Thanks,

-Bob


On 06/07/2012 05:19 PM, Robert Kukura wrote:
> On 06/02/2012 01:56 PM, Dan Wendlandt wrote:
>> Hi Irena, Bob, Salvatore,
>>
>> Just catching up the thread, and looping the netstack and openstack
>> lists in as well, as this info is general useful in my opinion.
>>
>> Our model with Quantum, like Nova, is that it is definitely ok to extend
>> the content of a core object with additional attributes. These
>> attributes should be formatted properly as extended attribute, so that
>> the "key" of the attribute is <extension-alias>:<attribute-name>
>>
>> This is done pretty commonly within Nova. Two simple examples are:
>> - nova/api/openstack/compute/contrib/scheduler_hints.py
>> - nova/api/openstack/compute/contrib/extended_status.py
>>
>> I do not believe you need to (or should) modify the view-builder code
>> for the core object when you want to add an extended attribute to it.
>
> Thanks Dan! I've now had some success implementing an extension that
> creates a RequestExtension that adds extended attributes to the response
> for a core resource. At least with JSON - I have not been able to figure
> out how to do this for XML, if that is even possible in quantum.
>
>> Instead, the extension framework has you write a wsgi controller
>> specific to the extension that is inserted as its own stage into the
>> wsgi request and response processing pipeline. Thus, when the request
>> is passed in, your code gets a chance to parse the data, and the the
>> response is passed back, your code gets a chance to add data to it.
>
> The above description sounds more like a ResourceExtension than a
> RequestExtension. A ResourceExtension introduces a new Controller,
> whereas a RequestExtension just adds a handler function called by the
> core's RequestExtensionController. All examples and descriptions I've
> seen use ResourceExtension to introduce a new type of resource. Are you
> suggesting this mechanism can also be used to extend an existing core
> resource? Would this have any advantage over using a RequestExtension? I
> still don't see any way a ResourceExtension could add extended
> attributes into an XML response.
>
>>
>> Using the Nova code as example is probably the best bet if you can find
>> a good example within quantum. Quantum's extension framework (and
>> several other openstack projects) all use essentially the same model.
>
> The nova and quantum code seem to have diverged significantly. The nova
> examples use a nova.api.openstack.wsgi.extends decorator on methods of
> an extension-implemented Controller to do "request extensions", but
> quantum doesn't have this decorator. Also, nova uses XML templates that
> are extensible, whereas the _serialization_metadata in quantum core
> resources does not seem to be extensible.
>
> At this point, quantum's RequestExtension mechanism seems able to do the
> job for the provider-networks BP, assuming that a JSON-only solution is
> acceptable. If both JSON and XML support are needed, then, unless I am
> missing something, creating a new (sub-)resource using a
> ResourceExtension (similar to the portstats extension) seems like the
> only straightforward option.
>
> -Bob
>
>>
>> Dan
>>
>>
>> On Sat, Jun 2, 2012 at 8:43 AM, Robert Kukura <rkukura [at] redhat
>> <mailto:rkukura [at] redhat>> wrote:
>>
>> On 06/02/2012 05:02 AM, Irena Berezovsky wrote:
>> > Hi,
>> > Bob, Dan,
>> > I ran into following wiki page:
>> >
>> http://wiki.openstack.org/QuantumAPIExtensionsaction=AttachFile&do=view&target=quantum_api_extension.pdf
>> <http://wiki.openstack.org/QuantumAPIExtensionsaction=AttachFile&do=view&target=quantum_api_extension.pdf>
>> > 'port profile' is exactly what I was looking for to expose in the
>> plugin.
>> > I would like to add the port profile retrieval capability and
>> contribute the implementation.
>> >
>> > Can you please advise if there is any disagreement on getting it
>> into core API? Shall I do it via extension?
>> > Bob, seems that you are dealing with similar issues.
>> > What do you suggest?
>> >
>> > Thanks a lot,
>> > Irena
>>
>> Irena,
>>
>> I'm not sure there is any consensus around using a "network profile" for
>> this. I did see that document as well as archived discussion about
>> defining "port profile" and "network profile" as extensible collections
>> of attributes. But the existing "port profile" extension looks to be
>> Cisco-specific, and seems to serve a somewhat different purpose.
>>
>> My current thinking is that we'd be better off long term following the
>> lead of Nova and other projects in supporting "extension data" within
>> the existing resources instead of requiring introduction of a new
>> resource just to hold plugin-specific attributes.
>>
>> But, in the short term, it might make the most sense for each extension
>> just to provide its own resource extension with its attributes. That's
>> what I'm tentatively planning to do for the provider-network blueprint,
>> but would reconsider if there was consensus that either the "extension
>> data" support or a more general "network profile" should be added now.
>>
>> -Bob
>>
>>
>>
>>
>> --
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> Dan Wendlandt
>> Nicira, Inc: www.nicira.com <http://www.nicira.com>
>> twitter: danwendlandt
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>
>
> _______________________________________________
> Mailing list: https://launchpad.net/~openstack
> Post to : openstack [at] lists
> Unsubscribe : https://launchpad.net/~openstack
> More help : https://help.launchpad.net/ListHelp


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irenab at mellanox

Jun 10, 2012, 12:19 PM

Post #2 of 4 (267 views)
Permalink
Re: Provider Networks extension advice (was Re: [Openstack] question on get_network_details api call) [In reply to]

Hi Robert,
May I add to your question also considerations regarding network creation - POST operation?
I may be wrong in my understanding, but it seems to me that in case of RequestExtension it will be possible to create Provider Network via a single call.
In case of ResourceExtension it will require 2 calls; one for network creation and second for "provider" attributes setting for previously created network. Am I right?
In case of ResourceExtension Plugin on network creation should behave differently for "provider" and other(virtual) network, i.e. skip VLAN allocation. Seems that Plugin should be aware about Network type already during network creation.
What do you think?

Thanks,
Irena

-----Original Message-----
From: netstack-bounces+irenab=mellanox.com [at] lists [mailto:netstack-bounces+irenab=mellanox.com [at] lists] On Behalf Of Robert Kukura
Sent: Friday, June 08, 2012 6:21 PM
To: Dan Wendlandt; netstack [at] lists
Subject: [Netstack] Provider Networks extension advice (was Re: [Openstack] question on get_network_details api call)

Dan, Netstackers,

I need some advice ASAP so I can proceed with the provider-networks BP
(https://blueprints.launchpad.net/quantum/+spec/provider-networks)
implementation. This BP will be implemented using a "provider" extension that adds a number of optional attributes (eg. vlan tags) to the core network resource. These attributes will be settable by and visible to those with admin rights.

The main decision I'm looking for advice on is whether to implement this extension as a RequestExtension or as a ResourceExtension. See the email quoted below for details.

If implemented as a RequestExtension, these provider attributes would be returned along with the core attributes from "GET /tenants/{tenant_id}/networks/{network_id}.json", and potentially from all API actions that return the core attributes.

If implemented as a ResourceExtension, the provider attributes would be accessed from a separate sub-resource, such as "GET /tenants/{tenant_id}/networks/{network_id}/provider.json".

As Dan suggested below, I think it would be preferable to extend the core resource itself rather than define a new sub-resource. This would mean using the RequestExtension approach. The issue with this is that I see no way to support XML with this approach, but the ResourceExtension approach can support both JSON and XML.

Is the RequestExtension approach preferable? Is it acceptable even if it cannot (currently) support XML? Or is there a way to extend the XML using a RequestExtension that I'm missing?

Thanks,

-Bob


On 06/07/2012 05:19 PM, Robert Kukura wrote:
> On 06/02/2012 01:56 PM, Dan Wendlandt wrote:
>> Hi Irena, Bob, Salvatore,
>>
>> Just catching up the thread, and looping the netstack and openstack
>> lists in as well, as this info is general useful in my opinion.
>>
>> Our model with Quantum, like Nova, is that it is definitely ok to
>> extend the content of a core object with additional attributes.
>> These attributes should be formatted properly as extended attribute,
>> so that the "key" of the attribute is
>> <extension-alias>:<attribute-name>
>>
>> This is done pretty commonly within Nova. Two simple examples are:
>> - nova/api/openstack/compute/contrib/scheduler_hints.py
>> - nova/api/openstack/compute/contrib/extended_status.py
>>
>> I do not believe you need to (or should) modify the view-builder code
>> for the core object when you want to add an extended attribute to it.
>
> Thanks Dan! I've now had some success implementing an extension that
> creates a RequestExtension that adds extended attributes to the
> response for a core resource. At least with JSON - I have not been
> able to figure out how to do this for XML, if that is even possible in quantum.
>
>> Instead, the extension framework has you write a wsgi controller
>> specific to the extension that is inserted as its own stage into the
>> wsgi request and response processing pipeline. Thus, when the
>> request is passed in, your code gets a chance to parse the data, and
>> the the response is passed back, your code gets a chance to add data to it.
>
> The above description sounds more like a ResourceExtension than a
> RequestExtension. A ResourceExtension introduces a new Controller,
> whereas a RequestExtension just adds a handler function called by the
> core's RequestExtensionController. All examples and descriptions I've
> seen use ResourceExtension to introduce a new type of resource. Are
> you suggesting this mechanism can also be used to extend an existing
> core resource? Would this have any advantage over using a
> RequestExtension? I still don't see any way a ResourceExtension could
> add extended attributes into an XML response.
>
>>
>> Using the Nova code as example is probably the best bet if you can
>> find a good example within quantum. Quantum's extension framework
>> (and several other openstack projects) all use essentially the same model.
>
> The nova and quantum code seem to have diverged significantly. The
> nova examples use a nova.api.openstack.wsgi.extends decorator on
> methods of an extension-implemented Controller to do "request
> extensions", but quantum doesn't have this decorator. Also, nova uses
> XML templates that are extensible, whereas the _serialization_metadata
> in quantum core resources does not seem to be extensible.
>
> At this point, quantum's RequestExtension mechanism seems able to do
> the job for the provider-networks BP, assuming that a JSON-only
> solution is acceptable. If both JSON and XML support are needed, then,
> unless I am missing something, creating a new (sub-)resource using a
> ResourceExtension (similar to the portstats extension) seems like the
> only straightforward option.
>
> -Bob
>
>>
>> Dan
>>
>>
>> On Sat, Jun 2, 2012 at 8:43 AM, Robert Kukura <rkukura [at] redhat
>> <mailto:rkukura [at] redhat>> wrote:
>>
>> On 06/02/2012 05:02 AM, Irena Berezovsky wrote:
>> > Hi,
>> > Bob, Dan,
>> > I ran into following wiki page:
>> >
>> http://wiki.openstack.org/QuantumAPIExtensionsaction=AttachFile&do=view&target=quantum_api_extension.pdf
>> <http://wiki.openstack.org/QuantumAPIExtensionsaction=AttachFile&do=view&target=quantum_api_extension.pdf>
>> > 'port profile' is exactly what I was looking for to expose in the
>> plugin.
>> > I would like to add the port profile retrieval capability and
>> contribute the implementation.
>> >
>> > Can you please advise if there is any disagreement on getting it
>> into core API? Shall I do it via extension?
>> > Bob, seems that you are dealing with similar issues.
>> > What do you suggest?
>> >
>> > Thanks a lot,
>> > Irena
>>
>> Irena,
>>
>> I'm not sure there is any consensus around using a "network profile" for
>> this. I did see that document as well as archived discussion about
>> defining "port profile" and "network profile" as extensible collections
>> of attributes. But the existing "port profile" extension looks to be
>> Cisco-specific, and seems to serve a somewhat different purpose.
>>
>> My current thinking is that we'd be better off long term following the
>> lead of Nova and other projects in supporting "extension data" within
>> the existing resources instead of requiring introduction of a new
>> resource just to hold plugin-specific attributes.
>>
>> But, in the short term, it might make the most sense for each extension
>> just to provide its own resource extension with its attributes. That's
>> what I'm tentatively planning to do for the provider-network blueprint,
>> but would reconsider if there was consensus that either the "extension
>> data" support or a more general "network profile" should be added now.
>>
>> -Bob
>>
>>
>>
>>
>> --
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> Dan Wendlandt
>> Nicira, Inc: www.nicira.com <http://www.nicira.com>
>> twitter: danwendlandt
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>
>
> _______________________________________________
> Mailing list: https://launchpad.net/~openstack
> Post to : openstack [at] lists
> Unsubscribe : https://launchpad.net/~openstack
> More help : https://help.launchpad.net/ListHelp


--
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Unsubscribe : https://launchpad.net/~netstack
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dan at nicira

Jun 10, 2012, 4:44 PM

Post #3 of 4 (274 views)
Permalink
Re: Provider Networks extension advice (was Re: [Openstack] question on get_network_details api call) [In reply to]

Adding main openstack list, as hopefully someone there can common on
implementing Request Extensions using XML.

I personally think that Request Extensions are a cleaner approach, but it
would seem silly to claim support for two serialization types, but expose
some API extension that work only with one of those types.

Dan

On Fri, Jun 8, 2012 at 8:19 AM, Robert Kukura <rkukura [at] redhat> wrote:

> Dan, Netstackers,
>
> I need some advice ASAP so I can proceed with the provider-networks BP
> (https://blueprints.launchpad.net/quantum/+spec/provider-networks)
> implementation. This BP will be implemented using a "provider" extension
> that adds a number of optional attributes (eg. vlan tags) to the core
> network resource. These attributes will be settable by and visible to
> those with admin rights.
>
> The main decision I'm looking for advice on is whether to implement this
> extension as a RequestExtension or as a ResourceExtension. See the email
> quoted below for details.
>
> If implemented as a RequestExtension, these provider attributes would be
> returned along with the core attributes from "GET
> /tenants/{tenant_id}/networks/{network_id}.json", and potentially from
> all API actions that return the core attributes.
>
> If implemented as a ResourceExtension, the provider attributes would be
> accessed from a separate sub-resource, such as "GET
> /tenants/{tenant_id}/networks/{network_id}/provider.json".
>
> As Dan suggested below, I think it would be preferable to extend the
> core resource itself rather than define a new sub-resource. This would
> mean using the RequestExtension approach. The issue with this is that I
> see no way to support XML with this approach, but the ResourceExtension
> approach can support both JSON and XML.
>
> Is the RequestExtension approach preferable? Is it acceptable even if it
> cannot (currently) support XML? Or is there a way to extend the XML
> using a RequestExtension that I'm missing?
>
> Thanks,
>
> -Bob
>
>
> On 06/07/2012 05:19 PM, Robert Kukura wrote:
> > On 06/02/2012 01:56 PM, Dan Wendlandt wrote:
> >> Hi Irena, Bob, Salvatore,
> >>
> >> Just catching up the thread, and looping the netstack and openstack
> >> lists in as well, as this info is general useful in my opinion.
> >>
> >> Our model with Quantum, like Nova, is that it is definitely ok to extend
> >> the content of a core object with additional attributes. These
> >> attributes should be formatted properly as extended attribute, so that
> >> the "key" of the attribute is <extension-alias>:<attribute-name>
> >>
> >> This is done pretty commonly within Nova. Two simple examples are:
> >> - nova/api/openstack/compute/contrib/scheduler_hints.py
> >> - nova/api/openstack/compute/contrib/extended_status.py
> >>
> >> I do not believe you need to (or should) modify the view-builder code
> >> for the core object when you want to add an extended attribute to it.
> >
> > Thanks Dan! I've now had some success implementing an extension that
> > creates a RequestExtension that adds extended attributes to the response
> > for a core resource. At least with JSON - I have not been able to figure
> > out how to do this for XML, if that is even possible in quantum.
> >
> >> Instead, the extension framework has you write a wsgi controller
> >> specific to the extension that is inserted as its own stage into the
> >> wsgi request and response processing pipeline. Thus, when the request
> >> is passed in, your code gets a chance to parse the data, and the the
> >> response is passed back, your code gets a chance to add data to it.
> >
> > The above description sounds more like a ResourceExtension than a
> > RequestExtension. A ResourceExtension introduces a new Controller,
> > whereas a RequestExtension just adds a handler function called by the
> > core's RequestExtensionController. All examples and descriptions I've
> > seen use ResourceExtension to introduce a new type of resource. Are you
> > suggesting this mechanism can also be used to extend an existing core
> > resource? Would this have any advantage over using a RequestExtension? I
> > still don't see any way a ResourceExtension could add extended
> > attributes into an XML response.
> >
> >>
> >> Using the Nova code as example is probably the best bet if you can find
> >> a good example within quantum. Quantum's extension framework (and
> >> several other openstack projects) all use essentially the same model.
> >
> > The nova and quantum code seem to have diverged significantly. The nova
> > examples use a nova.api.openstack.wsgi.extends decorator on methods of
> > an extension-implemented Controller to do "request extensions", but
> > quantum doesn't have this decorator. Also, nova uses XML templates that
> > are extensible, whereas the _serialization_metadata in quantum core
> > resources does not seem to be extensible.
> >
> > At this point, quantum's RequestExtension mechanism seems able to do the
> > job for the provider-networks BP, assuming that a JSON-only solution is
> > acceptable. If both JSON and XML support are needed, then, unless I am
> > missing something, creating a new (sub-)resource using a
> > ResourceExtension (similar to the portstats extension) seems like the
> > only straightforward option.
> >
> > -Bob
> >
> >>
> >> Dan
> >>
> >>
> >> On Sat, Jun 2, 2012 at 8:43 AM, Robert Kukura <rkukura [at] redhat
> >> <mailto:rkukura [at] redhat>> wrote:
> >>
> >> On 06/02/2012 05:02 AM, Irena Berezovsky wrote:
> >> > Hi,
> >> > Bob, Dan,
> >> > I ran into following wiki page:
> >> >
> >>
> http://wiki.openstack.org/QuantumAPIExtensionsaction=AttachFile&do=view&target=quantum_api_extension.pdf
> >> <
> http://wiki.openstack.org/QuantumAPIExtensionsaction=AttachFile&do=view&target=quantum_api_extension.pdf
> >
> >> > 'port profile' is exactly what I was looking for to expose in the
> >> plugin.
> >> > I would like to add the port profile retrieval capability and
> >> contribute the implementation.
> >> >
> >> > Can you please advise if there is any disagreement on getting it
> >> into core API? Shall I do it via extension?
> >> > Bob, seems that you are dealing with similar issues.
> >> > What do you suggest?
> >> >
> >> > Thanks a lot,
> >> > Irena
> >>
> >> Irena,
> >>
> >> I'm not sure there is any consensus around using a "network
> profile" for
> >> this. I did see that document as well as archived discussion about
> >> defining "port profile" and "network profile" as extensible
> collections
> >> of attributes. But the existing "port profile" extension looks to be
> >> Cisco-specific, and seems to serve a somewhat different purpose.
> >>
> >> My current thinking is that we'd be better off long term following
> the
> >> lead of Nova and other projects in supporting "extension data"
> within
> >> the existing resources instead of requiring introduction of a new
> >> resource just to hold plugin-specific attributes.
> >>
> >> But, in the short term, it might make the most sense for each
> extension
> >> just to provide its own resource extension with its attributes.
> That's
> >> what I'm tentatively planning to do for the provider-network
> blueprint,
> >> but would reconsider if there was consensus that either the
> "extension
> >> data" support or a more general "network profile" should be added
> now.
> >>
> >> -Bob
> >>
> >>
> >>
> >>
> >> --
> >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> Dan Wendlandt
> >> Nicira, Inc: www.nicira.com <http://www.nicira.com>
> >> twitter: danwendlandt
> >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >>
> >
> >
> > _______________________________________________
> > Mailing list: https://launchpad.net/~openstack
> > Post to : openstack [at] lists
> > Unsubscribe : https://launchpad.net/~openstack
> > More help : https://help.launchpad.net/ListHelp
>
>


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dan Wendlandt
Nicira, Inc: www.nicira.com
twitter: danwendlandt
~~~~~~~~~~~~~~~~~~~~~~~~~~~


rkukura at redhat

Jun 11, 2012, 6:15 AM

Post #4 of 4 (266 views)
Permalink
Re: Provider Networks extension advice (was Re: [Openstack] question on get_network_details api call) [In reply to]

On 06/10/2012 03:19 PM, Irena Berezovsky wrote:
> Hi Robert,
> May I add to your question also considerations regarding network creation - POST operation?
> I may be wrong in my understanding, but it seems to me that in case of RequestExtension it will be possible to create Provider Network via a single call.
> In case of ResourceExtension it will require 2 calls; one for network creation and second for "provider" attributes setting for previously created network. Am I right?
> In case of ResourceExtension Plugin on network creation should behave differently for "provider" and other(virtual) network, i.e. skip VLAN allocation. Seems that Plugin should be aware about Network type already during network creation.
> What do you think?

Hi Irena,

I'd like to avoid this sort of two-step resource creation process.
Adding new optional arguments to the existing POST operation that
creates a new resource such as network seems to work, at least with
JSON. I haven't looked into XML support for this yet. These arguments
get passed through to the plugin as kwargs. Their names should use the
extension's namespace prefix, but otherwise I don't think any explicit
support in the extension framework is involved.

-Bob

>
> Thanks,
> Irena
>
> -----Original Message-----
> From: netstack-bounces+irenab=mellanox.com [at] lists [mailto:netstack-bounces+irenab=mellanox.com [at] lists] On Behalf Of Robert Kukura
> Sent: Friday, June 08, 2012 6:21 PM
> To: Dan Wendlandt; netstack [at] lists
> Subject: [Netstack] Provider Networks extension advice (was Re: [Openstack] question on get_network_details api call)
>
> Dan, Netstackers,
>
> I need some advice ASAP so I can proceed with the provider-networks BP
> (https://blueprints.launchpad.net/quantum/+spec/provider-networks)
> implementation. This BP will be implemented using a "provider" extension that adds a number of optional attributes (eg. vlan tags) to the core network resource. These attributes will be settable by and visible to those with admin rights.
>
> The main decision I'm looking for advice on is whether to implement this extension as a RequestExtension or as a ResourceExtension. See the email quoted below for details.
>
> If implemented as a RequestExtension, these provider attributes would be returned along with the core attributes from "GET /tenants/{tenant_id}/networks/{network_id}.json", and potentially from all API actions that return the core attributes.
>
> If implemented as a ResourceExtension, the provider attributes would be accessed from a separate sub-resource, such as "GET /tenants/{tenant_id}/networks/{network_id}/provider.json".
>
> As Dan suggested below, I think it would be preferable to extend the core resource itself rather than define a new sub-resource. This would mean using the RequestExtension approach. The issue with this is that I see no way to support XML with this approach, but the ResourceExtension approach can support both JSON and XML.
>
> Is the RequestExtension approach preferable? Is it acceptable even if it cannot (currently) support XML? Or is there a way to extend the XML using a RequestExtension that I'm missing?
>
> Thanks,
>
> -Bob
>
>
> On 06/07/2012 05:19 PM, Robert Kukura wrote:
>> On 06/02/2012 01:56 PM, Dan Wendlandt wrote:
>>> Hi Irena, Bob, Salvatore,
>>>
>>> Just catching up the thread, and looping the netstack and openstack
>>> lists in as well, as this info is general useful in my opinion.
>>>
>>> Our model with Quantum, like Nova, is that it is definitely ok to
>>> extend the content of a core object with additional attributes.
>>> These attributes should be formatted properly as extended attribute,
>>> so that the "key" of the attribute is
>>> <extension-alias>:<attribute-name>
>>>
>>> This is done pretty commonly within Nova. Two simple examples are:
>>> - nova/api/openstack/compute/contrib/scheduler_hints.py
>>> - nova/api/openstack/compute/contrib/extended_status.py
>>>
>>> I do not believe you need to (or should) modify the view-builder code
>>> for the core object when you want to add an extended attribute to it.
>>
>> Thanks Dan! I've now had some success implementing an extension that
>> creates a RequestExtension that adds extended attributes to the
>> response for a core resource. At least with JSON - I have not been
>> able to figure out how to do this for XML, if that is even possible in quantum.
>>
>>> Instead, the extension framework has you write a wsgi controller
>>> specific to the extension that is inserted as its own stage into the
>>> wsgi request and response processing pipeline. Thus, when the
>>> request is passed in, your code gets a chance to parse the data, and
>>> the the response is passed back, your code gets a chance to add data to it.
>>
>> The above description sounds more like a ResourceExtension than a
>> RequestExtension. A ResourceExtension introduces a new Controller,
>> whereas a RequestExtension just adds a handler function called by the
>> core's RequestExtensionController. All examples and descriptions I've
>> seen use ResourceExtension to introduce a new type of resource. Are
>> you suggesting this mechanism can also be used to extend an existing
>> core resource? Would this have any advantage over using a
>> RequestExtension? I still don't see any way a ResourceExtension could
>> add extended attributes into an XML response.
>>
>>>
>>> Using the Nova code as example is probably the best bet if you can
>>> find a good example within quantum. Quantum's extension framework
>>> (and several other openstack projects) all use essentially the same model.
>>
>> The nova and quantum code seem to have diverged significantly. The
>> nova examples use a nova.api.openstack.wsgi.extends decorator on
>> methods of an extension-implemented Controller to do "request
>> extensions", but quantum doesn't have this decorator. Also, nova uses
>> XML templates that are extensible, whereas the _serialization_metadata
>> in quantum core resources does not seem to be extensible.
>>
>> At this point, quantum's RequestExtension mechanism seems able to do
>> the job for the provider-networks BP, assuming that a JSON-only
>> solution is acceptable. If both JSON and XML support are needed, then,
>> unless I am missing something, creating a new (sub-)resource using a
>> ResourceExtension (similar to the portstats extension) seems like the
>> only straightforward option.
>>
>> -Bob
>>
>>>
>>> Dan
>>>
>>>
>>> On Sat, Jun 2, 2012 at 8:43 AM, Robert Kukura <rkukura [at] redhat
>>> <mailto:rkukura [at] redhat>> wrote:
>>>
>>> On 06/02/2012 05:02 AM, Irena Berezovsky wrote:
>>> > Hi,
>>> > Bob, Dan,
>>> > I ran into following wiki page:
>>> >
>>> http://wiki.openstack.org/QuantumAPIExtensionsaction=AttachFile&do=view&target=quantum_api_extension.pdf
>>> <http://wiki.openstack.org/QuantumAPIExtensionsaction=AttachFile&do=view&target=quantum_api_extension.pdf>
>>> > 'port profile' is exactly what I was looking for to expose in the
>>> plugin.
>>> > I would like to add the port profile retrieval capability and
>>> contribute the implementation.
>>> >
>>> > Can you please advise if there is any disagreement on getting it
>>> into core API? Shall I do it via extension?
>>> > Bob, seems that you are dealing with similar issues.
>>> > What do you suggest?
>>> >
>>> > Thanks a lot,
>>> > Irena
>>>
>>> Irena,
>>>
>>> I'm not sure there is any consensus around using a "network profile" for
>>> this. I did see that document as well as archived discussion about
>>> defining "port profile" and "network profile" as extensible collections
>>> of attributes. But the existing "port profile" extension looks to be
>>> Cisco-specific, and seems to serve a somewhat different purpose.
>>>
>>> My current thinking is that we'd be better off long term following the
>>> lead of Nova and other projects in supporting "extension data" within
>>> the existing resources instead of requiring introduction of a new
>>> resource just to hold plugin-specific attributes.
>>>
>>> But, in the short term, it might make the most sense for each extension
>>> just to provide its own resource extension with its attributes. That's
>>> what I'm tentatively planning to do for the provider-network blueprint,
>>> but would reconsider if there was consensus that either the "extension
>>> data" support or a more general "network profile" should be added now.
>>>
>>> -Bob
>>>
>>>
>>>
>>>
>>> --
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> Dan Wendlandt
>>> Nicira, Inc: www.nicira.com <http://www.nicira.com>
>>> twitter: danwendlandt
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>
>>
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