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  2. Resolving the multiple controller code bases issue

Re: Resolving the multiple controller code bases issue

Rob Sherwood
 

Hi Dave,

I definitely recognize that there is a lot of pressure (from press, developers, even from ourselves) to show that the daylight community can make progress and produce useful code, but I'm not sure that artificially pushing for a final decision on the controllers (one way or another)---especially in this two weeks time frame---is the right way to do it.  

It's my read that the vast majority of people (users, developers, even a number of TSC members) are trying to come up to speed with _what a controller is_ and what is it supposed to do, before even starting on the harder question of "which code base is a better controller".  More so, while I agree with the rough characterization of your three options ( (i) let two controllers exist indefinitely, (ii) merge the controllers, (iii) vote to pick one), we don't yet even know enough to answer the technical feasibility of these options or which one will net result in the best code.

For example, Colin Dixon and I have been talking about potentially merging controllers at the SAL level.  This would mean in net-virt's perspective that the SAL would look like an application, and from the 'controller' project prospective the net-virt controller would look like a SAL plugin.  I think this approach potentially has legs and would solve a lot of problems (and potentially not even be that much work) but we're going to need some time to investigate it.

Last, if we're concerned about being to produce useful code, I would like to submit that working towards some specific user-facing use-case for Q3 (e.g., a full quantum stack with network virtualization support) is a better goal, both from an impact perspective but also because it's less divisive.

What do other people think about this approach to focus on an user-facing deliverable and run the "which controller" question in parallel?

- Rob
.




On Mon, Apr 29, 2013 at 11:57 AM, David Meyer <dmm@...> wrote:
 
[04/29/2013] 
 
As you may know, there have been several proposals floated to 
deal with the problems created by the fact that we have two 
controller code bases. These include but not limited to:  
 
(i).    Work on portability between code bases and maintain two 
        controllers going forward. This would obviously create 
        enormous challenges and inefficiencies over time. In 
        addition, it will continue the lack of clarity over 
        the ODP controller code base. 
 
(ii).   Create a new controller project that would incorporate 
        the desirable components of both controllers (the 
        so-called "merged controller"). Note that the creation of 
        such a third controller project would require extensive 
        resources for design and integration, versus expanding on 
        what we already have. Again, such an approach will also 
        continue the lack of clarity over the ODP controller code 
        base and push our deliverables out an for an undefined 
        period of time.  
 
(iii).  Have the TSC vote for either the Cisco or BSN code base 
        as the ODP controller code base. The TSC could also vote 
        to keep the other code base available in case it ever 
        wanted to pull parts of the other code base in.   
 
(iv).   Others that I might have missed? 
 
Clearly neither option (i). nor option (ii). reach the objective 
of providing a clear understanding for the community of which 
code base ODP is building on (nor would they do so in a timely  
fashion). On the other hand, jumping directly to option (iii). is 
not optimal as we might miss out on compromises that could be 
beneficial to our community (as well as being more "top-down" 
than we would like). 
 
Since our clear goal (and responsibility) is to make ODP into the 
standard open source infrastructure for SDN, it is incumbent upon 
us as the ODP TSC to take affirmative action to clear this 
problem and get ODP moving. To that end and in consultation with 
the Linux Foundation and others, I am formally putting the 
following resolution process in place:  
 
(a).    I will ask Cisco and BSN to create a proposal for one 
        controller code base that comprise the ODP controller 
        code base. This "one code base" could be either code 
        bases or a mashup of the two that Cisco and BSN feel, 
        from a technical point of view, will best serve the ODP 
        community. In addition, the proposal may include 
        proposals to start other ODP projects or sub-projects to 
        address any gaps or future work.  And of course,
        community members are encouraged to participate in 
        this process.
 
(b).   The proposal should be available for TSC review no later 
        than Monday, 13 May 2013. Of course, we should provide 
        for flexibility in the event substantive progress is 
        being made. That said, 13 May 2013 should be our target 
        date.  
 
(c).    If no proposal can be created by Cisco and BSN (possibly 
        working with other community members), the TSC will take 
        an up or down vote on which controller code base ODP will 
        be using going forward. The vote should be taken on 
        Tuesday, 14 May 2013 by email in a private ballot to 
        preclude the appearance of a "deciding vote" being cast 
        by any TSC member. I propose that the Linux Foundation 
        receive, tally, and make public all the votes and the 
        result at the same time.    
 
 
Note that it is not uncommon for an open source project such as 
ODP to have competing code bases, nor is it uncommon for a 
resolution such as described above to be used in these cases. In 
particular, this process is designed to both be as true as 
possible to the open source community and its governance model 
while at the same time providing a forcing function to drive 
resolution of our controller code base problem. 
 
Finally, I have asked Collin Dixon and David Erickson to start a 
discussion of architectural and technical aspects of the two code 
bases on discuss@.... Thanks Colin and David!  
Please join in on that discussion to the extent you have 
time/inclination. This discussion is a crucial part of building 
our community, and we will need such an analysis in the event 
that vote. In particular, this work will give us a technical 
basis on which to base our votes. 
 
Thnx, 
 
--dmm 
 

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