Functional Principles of Registry-based Service Discovery

Abstract

As Service Discovery Protocols (SDP)

On consistency maintenance in service discovery

“…For discovered services to be useful, it is important that the consistency guarantees are specified clearly. We specify the requirements for consistency maintenance in service discovery protocols in the Service Discovery Principles [9], where the Configuration Update Principles require the User and/or Registry to always eventually regain consistency with the Manager after the service changes. The User detects the change in the Manager, and regains consistency by obtaining the correct view of the service, either from the Manager directly (2-party Configuration Update Principle), or via the Registry (3-party Configuration Update Principle).…”

“…The User rediscovers the Manager through (a) broadcast/multicast query with its requirements, where the matching Manager replies with the updated service description, or (b) broadcast/multicast periodic announcement of the Manager, where the User then queries the Manager for the service description, or (c) unicast query to the Registry for the service During communication failure through message loss [10], retransmissions and acknowledgements through SRC1 and SRN1 are useful, as long as subscription remains valid. SRC2 and SRN2 are necessary for satisfying the eventual consistency guarantee in the Configuration Update Principles [9]. In Section 5, we show that during short-term interface and node failures (where nodes recover from failures before the subscription expires), SRN2 is the most effective technique.…”

A model-based analysis of first-generation service discovery systems

“…Further, we have used our consistency conditions to distinguish between latency associated with failure detection and latency due to failure restoration. Other researchers [34] have used our consistency conditions together with a model-checking program to verify a system design. These results indicate the value of formalizing service guarantees.…”