Abstract: A reliable messaging channel is created using multiple independent HTTP requests. In one embodiment, a method (a) establishes a session identifier by exchanging messages with a recipient using an application layer communication protocol (e.g., HTTP); and (b) uses the application layer communication protocol to send ordered data to the recipient by assigning one or more sequence numbers according to the predetermined order in the data. The session identifier may be generated, for example, using a random number of generator. In one implementation, the session identifier is not less than 96 bits long. The sender may receive from the recipient acknowledgements each acknowledging receipt of the data bearing a corresponding sequence number. Data to be sent in the opposite direction may piggy-back on an acknowledgement by including the data in a non-zero length payload. Data received out of order are queued. The sender may limit the rate at which data is transmitted to a “window size” (i.e.