Heartbeat Messages for Sustaining Session Connections
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Solution Overview
Problem
Intermediary computing devices in data communications networks often terminate session connections prematurely, leading to network resource inefficiencies and incorrect user status indications, especially when keep-alive mechanisms are recognized as idle connections by proxy servers.
Innovation Solution
Sending heartbeat messages, such as TCP messages containing only a carriage return and line feed (CRLF), which are valid at the transport layer but ignored by higher protocols, to sustain session connections without relying on TCP keep-alives or extensive computational processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TCP keep-alive messages are sent to sustain session connections, then connection timeout is prevented, but proxy servers may recognize these messages as idle connections and terminate the session
Solution Approach 1:
The patent introduces a proxy server as an intermediary component that sits between the TCP stack and the application protocol. This proxy server intercepts and modifies keep-alive messages, transforming them into protocol-compliant messages that maintain the session connection without being recognized as idle connections by upstream proxies. The intermediary layer resolves the contradiction by decoupling the TCP connection maintenance function from the application protocol semantics.
Solution Approach 2:
The patent changes the parameter of the keep-alive message by modifying its content from a raw TCP-level message to a properly formatted application protocol message (e.g., SIP MESSAGE or PUBLISH). This parameter transformation allows the message to be recognized as a valid session-keeping operation rather than an idle connection indicator, thereby preventing premature termination by proxy servers.
2Reliability
If valid application protocol messages are sent to sustain connections, then connection is maintained, but computational processing and network bandwidth are consumed
Solution Approach 1:
The patent employs disposable, lightweight keep-alive messages that are simple in structure and require minimal processing. These messages are sent periodically but are designed to be computationally inexpensive to generate and process. The ephemeral nature of these messages allows them to be discarded after serving their connection-maintenance purpose, minimizing their impact on system resources while effectively preventing connection timeouts.
3Duration of action of stationary object
If keep-alive messages are sent frequently to prevent timeout, then connection remains active, but network resources are consumed and user presence information may become inaccurate
Solution Approach 1:
The patent implements periodic keep-alive message transmission with carefully tuned intervals. Rather than continuous messaging, the system sends messages at regular periods that are sufficient to prevent timeout conditions but sparse enough to minimize network resource consumption. This periodic action balances connection sustainability with resource efficiency, preventing both premature disconnections and excessive resource usage.
Data Source
AI summary
In an embodiment, techniques for sustaining session connections are provided. The techniques send heartbeat messages when not sending a message may cause the session connection to close because of a timeout condition. Heartbeat messages are valid transport layer messages that will be ignored by protocols at higher levels of a data communications stack. As an example, the techniques may send a TCP message containing only a carriage return and line feed (“CRLF”) in its payload. Because the TCP layer considers a message containing only a CRLF to be a valid TCP message, intermediary computing devices such as proxy servers may not interpret heartbeat messages as “keep alive” messages, and may sustain session connections.