Server Handoff via Namespace Replication in Content Delivery Networks
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Solution Overview
Problem
Existing systems face challenges in performing load balancing across edge servers in a content delivery network (CDN) without disrupting service to clients, as they often require clients to continue communicating with overloaded servers until new servers are fully utilized, leading to prolonged performance issues.
Innovation Solution
A server-handoff system utilizing a content-centric network (CCN) architecture that detects data-handoff conditions, replicates namespaces to alternative content producers, synchronizes namespace configurations, and updates routing information to seamlessly redirect client requests, allowing for fine-grained load balancing without reconfiguring client devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the CDN system configures client devices to direct new download requests to a new server, then the new server can handle incoming requests, but ongoing requests continue to download from the previous server causing it to remain overloaded
Solution Approach 1:
The system performs preliminary actions by replicating the entire namespace (including ongoing session data) to the new server before the handoff is triggered. This ensures the new server is fully prepared and can immediately take over ongoing sessions without interruption, while the old server can stop accepting new requests without remaining overloaded.
2Ease of operation
If the system performs load balancing by assigning new client requests to particular servers, then server utilization can be managed, but client devices must be reconfigured which interrupts active sessions
Solution Approach 1:
The system creates a complete copy (replica) of the namespace including all data and session state on the new server. This copying approach allows the new server to become a full substitute for the old server, enabling seamless client redirection without session interruption, as clients can continue their sessions on the new server with identical data and state.
3Reliability
If the previous server continues to serve ongoing requests after a new server is brought online, then service continuity is maintained, but the previous server remains overloaded for an extended time period
Solution Approach 1:
The system performs preliminary replication of the namespace to the new server before the handoff condition is triggered. This advance preparation ensures that when the handoff occurs, the new server is already fully equipped to handle ongoing sessions, allowing the old server to immediately stop its workload and recover performance without extended overload period.
Data Source
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AI summary
A server-handoff system facilitates replicating or migrating a data collection or service to one or more alternative servers of a distributed service. During operation, the system can detect a data-handoff condition for migrating or replicating data to an alternative or newly started server, and determines a namespace that is to be migrated or replicated. The namespace includes a data collection or an application publication space associated with one or more structured name prefixes. The system then identifies the alternative servers to which the namespace is to be replicated, and synchronizes a namespace configuration with the alternative content producer. The namespace configuration identifies a set of data items from the namespace which facilitates the alternative content producer to host the data or service. The alternative content producer can use the namespace configuration to obtain the data items associated with the namespace before hosting the data or service.