WINFO Architecture for SIP Event Subscription Failover

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Solution Overview

Problem

In SIP event notification systems, multiple SIP event servers handle subscription requests for a single watched subscriber entity, making it difficult to provide complete watcher information and leading to undetected failures of notifier servers, which can result in missed updates and unnecessary re-subscription attempts due to the soft state model.

Innovation Solution

A watcher information (WINFO) architecture that receives subscription requests, detects unavailability of notifier servers, and directs watcher entities to generate new subscription requests to failover servers, using a WINFO server to manage and distribute SIP event subscription information and facilitate failover.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple SIP event servers are deployed to handle subscription requests, then the system's capacity and distribution are improved, but the ability to provide complete watcher information and detect server failures deteriorates

Engineering Contradiction:

Improvesubscription request handling capacityVSAvoidwatcher information completeness

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The patent merges the watcher information from multiple SIP event servers into a unified view by having each server publish its watcher subscriptions to a central WINFO entity. This allows any server to retrieve complete watcher information for any watched entity, resolving the information fragmentation problem while maintaining the distributed architecture's capacity benefits.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The WINFO entity acts as an intermediary that collects, stores, and provides watcher subscription information from multiple SIP event servers. This intermediary layer enables any server to access complete watcher information without directly querying other servers, thus maintaining system scalability while ensuring information completeness.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the soft state model is used for SIP subscriptions, then subscription expiration and renewal are simplified, but the detection of notifier server failures deteriorates

Engineering Contradiction:

Improvesubscription management simplicityVSAvoidnotifier server failure detection

Core Design Contradiction:

Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The system implements feedback mechanisms where the WINFO entity continuously monitors subscription states and notifies watchers when their designated notifier server becomes unavailable. This feedback loop enables automatic failure detection while maintaining the soft state model's simplicity, as watchers receive proactive notifications rather than passively waiting for subscription expiration.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The WINFO entity performs preliminary actions by detecting notifier server failures before they impact subscription deliveries. When a failure is detected, the system proactively notifies watchers and facilitates re-subscription to available servers, preventing missed updates rather than reacting after failures occur.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If watcher subscriptions are renewed upon detecting failures, then service continuity is improved, but unnecessary re-subscription attempts to failed servers increase

Engineering Contradiction:

Improveservice continuityVSAvoidre-subscription attempt efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The WINFO entity provides feedback to watchers about the availability of their designated notifier server. This feedback mechanism enables watchers to make informed re-subscription decisions, renewing subscriptions only with available servers and avoiding wasted attempts on failed servers, thus improving both service continuity and energy efficiency.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Watchers autonomously manage their subscription renewals by receiving availability information from WINFO and independently deciding whether to re-subscribe. This self-service approach eliminates unnecessary re-subscription attempts to failed servers while ensuring continuous service through intelligent, availability-based renewal decisions.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS8661077B2Methods, systems and computer readable media for providing a failover measure using watcher information (WINFO) architecture

Publication Date: 2014.02.25 TEKELEC INC

AI summary

Methods, systems, and computer readable media system for collecting and distributing session initiation protocol (SIP) event watcher entity subscription information in a communications network are disclosed. According to one aspect, the method includes receiving, at a first notifier server from a watcher entity client, a first subscription request for SIP event information associated with one or more watched entity clients. The method also includes receiving, at a watcher information (WINFO) entity, SIP event subscription information that includes an identifier indicating that the first notifier server serves the watcher entity client, storing the SIP event subscription information in the WINFO entity, detecting the unavailability of the first notifier server. The method further includes sending an instruction message, based on the identifier in the stored SIP event subscription information, to direct the watcher entity to generate a second subscription request associated for the SIP event information.