Re: [Cppcms-users] Design decision

[Christian G. <chr...@gm...>]

2012/10/4 Artyom Beilis <art...@ya...>:
>>________________________________
>
>> From: Christian Gmeiner <chr...@gm...>
>>To: cpp...@li...
>>Sent: Thursday, October 4, 2012 11:01 AM
>>Subject: [Cppcms-users] Design decision
>>
>>Hi all.
>>
>>My cppcms based web application is in a quite good shape and I got
>>some ideas what
>>new features could be added.
>>
>>+ Detection of networking changes via PF_NETLINK socket
>>
>>At the moment it is possible to configure networking settings via
>>cppcms. For instance,
>>it is possible to use manual mode for an ethernet interface to specify
>>ip. netmask etc. or
>>use DHCP mode. If DHCP gets used the running system starts dhcp client
>>and it could
>>takes some seconds until it got a valid IP address.
>>
>>The basic idea is now to use SSE (server send events) and some
>>detection threads.
>>
>>Create a (cppcms ?) thread per ethernet interface and run something like
>>http://stackoverflow.com/questions/579783/how-to-detect-ip-address-change-programmatically-in-linux
>>
>>Then I would have a singleton class for SSE where I can call e.g.
>>SSE::instance()->ethernet("eth0", ip,...) and my front-end can update
>>the values.
>>
>>Can this work?
>>
>>
>>---
>>Christian Gmeiner, MSc
>>
>
> Why not?
>
> Several points
>
> 1. In there link there is an example to use it without polling, so just use basic_io_device to check
>    for readability and then call recv
>
>    So basically you don't need threads just implement event driven
>    handling in the event loop (see tutorial for examples)
>

This looks like the elegant solution I am looking for :)

But... I don't get it up and running :/

I decided to go this way:

#ifndef NETLINK_H_
#define NETLINK_H_

#include <booster/aio/basic_io_device.h>

class Netlink : public booster::aio::basic_io_device
{
public:
    Netlink();
    ~Netlink();

    void read(booster::system::error_code const &e);

private:
    char _buffer[4096];
};

#endif /* NETLINK_H_ */


And this is my main()

    // start cppcms service
    try
    {
        cppcms::service srv(argc, argv);

        booster::aio::io_service &io_srv = srv.get_io_service();

        Netlink netlink;
        netlink.set_io_service(io_srv);
        netlink.on_readable(std::bind(&Netlink::read));

        srv.applications_pool().mount(cppcms::applications_factory<Tssw>());
        srv.run();
    }
    catch (std::exception const &e)
    {
        std::cerr << e.what() << std::endl;
    }


The big big problem is how should I use on_readable(..) ? The above example does
not compile.

----
Christian Gmeiner, MSc