On Mon, Dec 27, 2010 at 5:31 PM, Daniel Stenberg <daniel_at_haxx.se> wrote:

> On Mon, 27 Dec 2010, amit paliwal wrote:
>
> PLEASE don't top-post. It makes the thread totally confusing to read and
> follow.
>
>
> Well, teh Client will be blocked and it will not be doing a continuous
>> polling, but the point is not whether it does blocking or polling, the point
>> is to use server-sent events with HTTP1.1
>>
>
> I don't see how the client's behavior has anything to do with the subject.
> libcurl has both a blocking and a non-blocking API so you could pick
> whichever solution works best for you.
>
>
> It is said that HTTP1.1 support server-sent events, which means it should
>> support asynchronous messages that will be received by client.
>>
>
> "It is said" by whom and where? And where are those "server-sent events"
> specified?
>

Reply: please refer to http://dev.w3.org/html5/eventsource/ standard. It
says server-sent events can be passed on top of standard HTTP, server sent
events abbreviated as SSE is a technology to push events to client any time,
so it means any client having persistent HTTP connection should be able to
receive SSE (which is asynchronous data) from server. Now normally HTTP is a
request-response model, where the client send the request and wait for the
response. for SSE we need not to first sent a request, and this is why I
asked whether we can do it by libcurl or not.

If some SSE comes on socket, will libcutl call my callback's for header and
payload? and if yes, then after parsing will i be able to send a GET message
by calling curl_easy_perform()?

>
> libcurl speaks HTTP1.1 pretty well AFAIK, and I'm confident that if your
> server remains speaking HTTP1.1, libcurl will talk fine with it!
>
> As I explained: "server-sent events" are typically made with long-polling
> clients. (Or using AJAX from within a browser environment.) WebSockets are
> in the process of being defined for this purpose...

Reply: but i am not interested in web sockets, my requirement needs
server-sent events only. will the latest code of libcurl be able to do it?
and if not, can you please help me achieving it?

>
>
> Well I am interested in libcurl to receive asynchronous messages at any
>> time as and when server pushes events and also the client should be able to
>> send GET as and when required.
>>
>
> Possibly your imaginary client would use multiple connections. A client
> that receives data from a server can't just reverse and send a GET back,
> unless of course the request ended there after the "event" and the
> connection can be re-used again for the next request. Thinking about it,
> it's probably quite likely that it will work like that as then the client
> can send whatever it needs in the request, and then it'll sit waiting for
> the server again...

Reply: typical scenario is:
1) receive SSE from server
2) send response to server

>
>
> --
>
> / daniel.haxx.se
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Received on 2010-12-27