Re: [libmicrohttpd] Regarding Flow control

[Santos Das]

Hi Christian,

Thanks a lot. I have few questions in this regard -

a.    When we put the connection in suspend state, can we pass a timeout at the expiry of which the connection will be automatically resumed?

b.    For asynchronous communication , i.e the application received the request but is not able to send the response now (it needs to do some work may be creating another request to another endpoint) , is it mandatory to use suspend-resume only or there is some other mechanism that we can use ?

c.   How does the keep alive works in the HTTP server library ? 

Sorry, lot of questions. But, please see if you could help in this.

On Tue, Sep 18, 2018 at 3:12 PM Christian Grothoff <address@hidden> wrote:

If you suspend a connection, you are responsible to schedule some job to
resume it, after which MHD's timeout counter will start again (and of
course your response logic could then also just force MHD to close the
connection once MHD asks for response data).  MHD timeouts are there to
detect (idle) clients that just keep connections open, not to prevent
the server from suspending a connection.

If the client closes a connection, it'll be detected if/when we try to
send data to the client and handled appropriately.

Happy hacking!

Christian

On 09/17/2018 09:01 PM, Kunal Ekawde wrote:
> If the connection is suspended and cases of:
> a. client closes the connection before response is sent.
> b. server app doesn't respond at all post suspend.
>  
> both cases there is no notification by MHD even if connection timeout is
> specified and notify callback. How can these cases be handled ?
>
> Thanks,
> Kunal
>
> On Mon, Sep 17, 2018 at 9:02 PM Santos Das <address@hidden
> <mailto:address@hidden>> wrote:
>
>     Hi,
>
>     Just to add more, my application is single threaded and I am running
>     MHD inside that. I don't create additional threads. I use suspend
>     and resume as suggested earlier as I do async processing.
>
>     So, I am thinking how can we implement flow control in this scenario..
>
>     Thanks, Santos
>
>
>
>     On Mon, Sep 17, 2018 at 8:22 PM Santos Das <address@hidden
>     <mailto:address@hidden>> wrote:
>
>         Hi,
>
>         Could you kindly let me know how can we implement the flow
>         control ? Protection against the badly behaving clients.
>
>
>         HTTP/1.1 servers SHOULD maintain persistent connections and use TCP's flow control
>
>         mechanisms to resolve temporary overloads, rather than terminating connections with
>
>         the expectation that clients will retry. The latter technique can exacerbate network
>
>         congestion.
>
>          
>
>         https://www.w3.org/Protocols/rfc2616/rfc2616-sec8.html
>
>
>         Thanks, Santos
>
>
>
>
> --
> ~Kunal