Re: [boost] [asio] new version, prototype iostreams support

From: Christopher Kohlhoff (chris_at_[hidden])
Date: 2006-06-25 23:23:56

Hi Peter,

Peter Petrov <ppetrov_at_[hidden]> wrote:
> There is one thing that caught my eye. In the changelog you
> have the following comment:
>
>> * Resolver replaces ipv4::host_resolver.
>>
>> ...
>>
>>     ip::tcp::resolver resolver(io_service);
>
> Why is "resolver" in the "ip::tcp" namespace? A DNS resolver
> certainly has nothing to do with the TCP protocol. It should
> be in the "ip" namespace instead.

Unlike the old host_resolver class, which would resolve a host
name into an address, the new resolvers turn host name and
service name into a list of endpoints. This interface is based
on getaddrinfo() function.

We now have:

- ip::tcp::resolver, which returns a list of ip::tcp::endpoint
  objects

- ip::udp::resolver, which returns a list of ip::udp::endpoint
  objects

Resolvers for other protocols, can (if supported by getaddrinfo
on the target platform) be created by instantiating the
asio::basic_resolver<> template on an appropriately defined
protocol class.

So, ip::tcp::resolver is very much specific to TCP, but
basic_resolver<> isn't - it's not even specific to IP (in
theory, anyway).

Cheers,
Chris