This change adds limited support for using Asio with the Windows
Runtime. It requires that the language extensions be enabled. Due to the
restricted facilities exposed by the Windows Runtime API, the port comes
with the following caveats:
* The core facilities such as the io_service, strand, buffers, composed
operations, timers, etc., should all work as normal.
* For sockets, only client-side TCP is supported.
* Explicit binding of a client-side TCP socket is not supported.
* The cancel() function is not supported for sockets. Asynchronous
operations may only be cancelled by closing the socket.
* Operations that use null_buffers are not supported.
* Only tcp::no_delay and socket_base::keep_alive options are supported.
* Resolvers do not support service names, only numbers. I.e. you must
use 80 rather than http.
* Most resolver query flags have no effect.
[SVN r85764]
Four new protocol classes have been added:
- asio::generic::datagram_protocol
- asio::generic::raw_protocol
- asio::generic::seq_packet_protocol
- asio::generic::stream_protocol
These classes implement the Protocol type requirements, but allow the
user to specify the address family (e.g. AF_INET) and protocol type
(e.g. IPPROTO_TCP) at runtime.
A new endpoint class template, asio::generic::basic_endpoint, has been
added to support these new protocol classes. This endpoint can hold any
other endpoint type, provided its native representation fits into a
sockaddr_storage object.
When using C++11, it is now possible to perform move construction from a
socket (or acceptor) object to convert to the more generic protocol's
socket (or acceptor) type. If the protocol conversion is valid:
Protocol1 p1 = ...;
Protocol2 p2(p1);
then the corresponding socket conversion is allowed:
Protocol1::socket socket1(io_service);
...
Protocol2::socket socket2(std::move(socket1));
For example, one possible conversion is from a TCP socket to a generic
stream-oriented socket:
asio::ip::tcp::socket socket1(io_service);
...
asio::generic::stream_protocol::socket socket2(std::move(socket1));
The conversion is also available for move-assignment. Note that these
conversions are not limited to the newly added generic protocol classes.
User-defined protocols may take advantage of this feature by similarly
ensuring the conversion from Protocol1 to Protocol2 is valid, as above.
As a convenience, the socket acceptor's accept() and async_accept()
functions have been changed so that they can directly accept into a
different protocol's socket type, provided the protocol conversion is
valid. For example, the following is now possible:
asio::ip::tcp::acceptor acceptor(io_service);
...
asio::generic::stream_protocol::socket socket1(io_service);
acceptor.accept(socket1);
[SVN r84363]
