Relay Host Heartbeat for Proactive Firewall Messaging
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Solution Overview
Problem
Existing communication protocols between client and server computers behind a firewall do not effectively allow proactive delivery of urgent messages without compromising security or scalability, as current methods like polling are resource-intensive and vulnerable to exploitation.
Innovation Solution
Designating a relay host computer behind the firewall to maintain a continuous connection with the server through heartbeat messages, enabling the server to proactively send urgent messages to multiple clients without requiring all clients to be continuously connected, thus minimizing security risks and achieving scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polling is used to deliver urgent messages to client computers behind firewall, then message delivery is possible, but resource consumption is very high and scalability is poor
Solution Approach 1:
A relay host computer is introduced as an intermediary between the server and client computers. The relay host maintains a persistent connection with the server and forwards urgent messages to clients when needed, eliminating the need for continuous polling by all clients while maintaining efficient message delivery capability.
2Loss of time
If polling interval is reduced to improve message delivery speed, then message delivery time decreases, but resource consumption increases significantly
Solution Approach 1:
The relay host acts as a mediator that maintains a persistent connection with the server, allowing urgent messages to be pushed immediately to clients without waiting for polling intervals. This achieves fast message delivery (reducing time loss) while consuming minimal resources since only the relay host maintains the connection, not all clients.
3Productivity
If firewall ports are opened to allow server-initiated connections to clients, then proactive message delivery is enabled, but security vulnerability increases
Solution Approach 1:
The relay host serves as a security intermediary positioned behind the firewall. The server connects only to the relay host through a single open port, not directly to individual clients. This enables proactive message delivery while maintaining firewall security, as the relay host acts as a controlled gateway that limits exposure to the internal network.
Solution Approach 2:
The system segments the connection architecture into three distinct components: the server outside the firewall, the relay host as an intermediary layer, and the client computers behind the firewall. This segmentation allows the server to initiate connections proactively through the relay host without creating direct security vulnerabilities to individual client systems.
4Speed
If each client maintains active connection to server for immediate message delivery, then message delivery speed is maximized, but device complexity and resource usage increase
Solution Approach 1:
Multiple client connections to the server are merged into a single connection through the relay host. The relay host consolidates the communication channel, allowing the server to send urgent messages to one endpoint (the relay host) which then distributes them to all clients. This maintains fast delivery speed while dramatically reducing connection management complexity.
Data Source
AI summary
A subnetwork of client computers includes a designated relay host computer that communicates through a firewall with an outside server computer located within the same computing environment or over an Internet connection. A specially-designated URL on the server is used when the relay host requests that a downlink connection be kept alive indefinitely with the server computer. The server receives the HTTP request and activates a continuous heartbeat program. Heartbeat messages are sent continuously from the server computer to the relay host to keep the downlink connection open indefinitely. When the server needs to send an urgent message to the client computers it can do so immediately by using the already open downlink connection. The relay host forwards messages to the other component client computers in the subnetwork. The relay host may also use a proxy server. The downlink connection uses a standard request-reply protocol.