Since: API Level 1
package

org.apache.http.io

The transport layer abstraction of the HTTP components. This layer is used to transfer messages over connections. Connections are typically based on sockets: plain or secure, direct or via SOCKS hosts, with bandwidth throttling, or whatever else you might think of. However, opening connections is not within the responsibility of HttpCore.

Interfaces

HttpMessageParser Generic message parser interface. 
HttpMessageWriter Generic message writer interface. 
HttpTransportMetrics  
SessionInputBuffer Session input buffer for blocking connections. 
SessionOutputBuffer Session output buffer for blocking connections.