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From Daniel Koller <dakol...@googlemail.com>
Subject Re: Streaming design for the api2 endpoint - request for comment
Date Tue, 15 Dec 2009 13:38:44 GMT
just a comment on the side:...is it an option to provide a powerful and
scalable  - but generic getMessages()-function with a bunch of parameters
(tags/text/author...date...) and to let the collection e.g. by tags be gone
by the requestor?

On Tue, Dec 15, 2009 at 2:34 PM, Ethan Jewett <esjewett@gmail.com> wrote:

> Actually, having separate streams for each tag is what I'm suggesting,
> I'm just trying to determine when best to create them. If a client
> requests all the streams, they will all be created. Should we talk
> about not streaming individual tags at all? Maybe put a limit on the
> number of streams a client can have open? I'm not sure what the
> performance impact will look like.
>
> Also, I need to amend the original email. I think that because we are
> using Lift Sessions, we will be killing off the session and the
> streams attached to it after a period of time. So I think option 2 and
> option 4 are the same or very similar.
>
> Ethan
>
> On Mon, Dec 14, 2009 at 11:39 PM, Richard Hirsch <hirsch.dick@gmail.com>
> wrote:
> > Yes it sounds reasonable. I don't think it makes much sense to have
> > separate streams for each tag, etc...
> >
> > I agree option 2 is the best choice.
> >
> > D.
> >
> > On Mon, Dec 14, 2009 at 12:29 AM, Ethan Jewett <esjewett@gmail.com>
> wrote:
> >> All,
> >>
> >> In the cwiki, we've documented 5 parts of the API we would like to
> >> stream. They are briefly: user timeline, tags, tracks, conversations,
> >> and pools (and possibly the public timeline)
> >>
> >> Of these, one has been implemented: user timeline
> >>
> >> Today I've been able to take some time to start digging into what
> >> needs to be done to implement the rest of the streaming interfaces.
> >> The way the user timeline streaming interface is implemented in the
> >> old and new APIs is the same (because I just copied and slightly
> >> modified the code). The basic idea is that when a session is created,
> >> the streaming API starts "listening" for new messages. When the user
> >> makes a request to the streaming interface for new messages, all the
> >> messages that have built up are delivered.
> >>
> >> This approach poses some significant problems for other types of
> >> streams. For example, if we were going to stream tags in this manner,
> >> we would end up creating a listener for every single active tag in the
> >> system at the time the user initiates a session. We would also have
> >> the dilemma of creating listeners for new tags as the tags are created
> >> in the middle of a session.
> >>
> >> As such, I'm thinking of implementing the other streaming interfaces
> >> differently. Instead of creating listeners when the session is
> >> initiated, I'll create them when the first streaming request for a
> >> tag, pool, track, or conversation comes in. These listeners would then
> >> live on for the rest of the session. This is, I think the best of
> >> several options.
> >>
> >> To summarize the options available:
> >>
> >> 1. Create listeners for everything at the beginning of the session -
> >> not efficient, suffers from difficulties with new tags, pools, etc.
> >> created during the session
> >>
> >> 2. Create listeners for streams as the user requests them and have
> >> these listeners live on for the rest of the session
> >>
> >> 3. Create disposable listeners for each streaming/long-polling request
> >> that are destroyed once the request is answered - this is problematic
> >> because messages that occur between requests will be missed
> >>
> >> 4. Variation of option 2 and 3: Create listeners for streams as the
> >> user requests them and have these listeners life on for the rest of
> >> the session or a specific period of time, whichever comes first (so
> >> the user would have to make occasional requests to ensure the
> >> continuity of the message stream) - I think this is over-complicated
> >> and potentially confusing to developers, but could be a good option if
> >> we run into performance problems with option 2
> >>
> >>
> >> What we'll be left with is that the user timeline will use option 1
> >> and the other streams will use option 2. The user timeline might
> >> switch to option 2 at some point in the future.
> >>
> >> And that was all a very long way of saying, does that sound reasonable
> >> to everyone?
> >>
> >> Ethan
> >>
> >
>



-- 
---
Daniel Koller
Jahnstrasse 20
80469 M√ľnchen * dakoller@googlemail.com

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