code review 10704046: net/rpc/jsonrpc: Add HTTP support

net/rpc/jsonrpc: Add HTTP support

Because http server/client create ServerCodec/ClientCodec in net/rpc package,
so we need pass ServerCodec/ClientCodec factory to rpc.Server/rpc.Client.

New type/func for net/rpc package:

        type ClientCodecFactory interface {
                NewClientCodec(conn io.ReadWriteCloser) ClientCodec
        }
        type ServerCodecFactory interface {
                NewServerCodec(conn io.ReadWriteCloser) ServerCodec
        }

        func DialWithCodecFactory(network, address string, factory ClientCodecFactory) (*Client, error)
        func DialHTTPWithCodecFactory(network, address string, factory ClientCodecFactory) (*Client, error)
        func DialHTTPPathWithCodecFactory(network, address, path string, factory ClientCodecFactory) (*Client, error)
        func NewServerWithCodecFactory(factory ServerCodecFactory) *Server

New type/func for net/rpc/jsonrpc package:

        func NewClientCodecFactory(conn io.ReadWriteCloser) rpc.ClientCodec
        func NewServerCodecFactory() rpc.ServerCodecFactory

Fixes issue 2738.

[chai2010, 2013-06-28 09:40:35]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
http://code.google.com/p/go

[rsc, 2013-07-01 22:54:50]

Thanks for looking into this, but I think this is probably best left out of the
standard library. It is still possible to write a wrapper that invokes rpc for
an existing connection by creating a codec, and there is no agreed-upon meaning
for "jsonrpc over http". Instead everyone seems to define their own slightly
different one. It's best to leave to third-party libraries.

Russ