Name for HTTP Request+Response

The spec calls them "exchanges" (or "request/response exchanges"),

In HTTP/1.0, most implementations used a new connection for each
request/response exchange. In HTTP/1.1, a connection may be used for one or more request/response exchanges.

_{(answer originally taken from a duplicate question)}

• RFC2616 calls it an Exchange.
• Wireshark and HTTPNetworkSniffer call it a Request/Response.
• Fiddler calls it a Session.
• Charles calls it a Sequence.
• HTTP Scoop calls it a Conversation.
• Other vocabulary includes: Message, Transaction, Communication.

I would go for Exchange or RequestResponse.

I also went to name it Operation in my code as I would queue Operations, flush Operations, pause or resume Operations.