Event-Based Subscription Activation in Publish-Subscribe Brokers
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Solution Overview
Problem
In publish/subscribe communications networks, frequent subscribe and unsubscribe operations lead to network communication overhead and latency, especially in low-bandwidth or unreliable connections, causing subscribers to miss messages and resulting in unwanted traffic and storage issues due to durable subscriptions.
Innovation Solution
Implementing a method and apparatus that uses temporally unpredictable events to control subscription matching, allowing the publish/subscribe broker to automatically switch subscription states without requiring frequent subscriber requests, by specifying activation and deactivation events within subscription definitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If subscribers manually initiate subscribe and unsubscribe operations to control message reception, then subscribers can receive desired messages, but network communication overhead increases and latency occurs causing missed messages
Solution Approach 1:
The subscription automatically manages its own activation and deactivation by monitoring events defined by the subscriber. When the specified event occurs, the subscription self-activates to receive messages, and when the event stops occurring, it self-deactivates. This eliminates the need for manual subscribe/unsubscribe operations and their associated latency.
Solution Approach 2:
The subscriber pre-configures the subscription with event criteria and activation conditions before the event occurs. The system prepares the subscription in advance with all necessary parameters, so when the event occurs, the subscription can immediately activate without delay for configuration or manual initiation.
2Adaptability or versatility
If durable subscriptions remain active until explicit unsubscription, then subscribers can resume receiving messages after reconnection, but unwanted messages accumulate in broker storage and create network traffic overhead
Solution Approach 1:
The subscription dynamically changes its active state based on the occurrence and cessation of defined events. Rather than remaining permanently active like traditional durable subscriptions, the subscription automatically transitions between active and inactive states, allowing the broker to clear stored messages when the subscription is inactive, thus managing storage space efficiently.
3Adaptability or versatility
If frequent subscribe and unsubscribe operations are performed, then subscribers can adapt to changing message interests, but network bandwidth is consumed and connection reliability issues arise especially in mobile environments
Solution Approach 1:
The subscription maintains continuous monitoring of the defined event without requiring repeated connect-disconnect cycles. The subscription remains in a suspended state, continuously watching for the event condition, and activates automatically when the event occurs. This eliminates the need for frequent reconnections and maintains adaptability while conserving network bandwidth.
Data Source
AI summary
The present invention provides methods, apparatus and computer programs for event-based control of subscription matching in a publish/subscribe communications environment. Activation and/or deactivation events are associated with subscriptions at a publish/subscribe broker and are used to control when a subscription is active. The broker is responsive to temporally-unpredictable events, such as receipt of a published message on a predefined activation topic, to activate subscription matching for messages that are subsequently received or which have been received earlier and retained at the broker. Conventional subscription matching can be avoided for a registered subscription while that subscription is inactive, and subscribers are not required to explicitly and repeatedly subscribe and unsubscribe.