Consistent and Scalable Cache Replication for Multi-tier J2EE Applications

Abstract

Abstract. Data centers are the most critical infrastructure of companies demanding higher and higher levels of quality of service (QoS) in terms of availability and scalability. At the core of data centers are multi-tier architectures providing service to applications. Replication is heavily used in this infrastructure for either availability or scalability but typically not for both combined. Additionally, most approaches replicate a single tier, making the non-replicated tiers potential bottlenecks and single points of failure. In this paper, we present a novel approach that provides both availability and scalability for multi-tier applications. The approach uses a replicated cache that takes into account both the application server tier (middle-tier) and the database (back-end). The underlying replicated cache protocol fully embeds the replication logic in the application server. The protocol exhibits good scalability as shown by our evaluation based on the new industrial benchmark for J2EE multi-tier systems, SPECjAppServer.

D2STM: Dependable Distributed Software Transactional Memory

“…To avoid an unbounded growth of this data structure, we rely on a distributed garbage collection scheme (analogous to the one employed in [36]), in which each replica exchange (as a piggyback to the AB-casted transaction validation message) the minimum snapshotID of all the locally active update transactions. This allows each replica to gather global knowledge on the oldest timestamp among those of all the update transactions currently active on any replica.…”

Versioned transactional shared memory for the FénixEDU web application

“…In most systems, the current approach to implement it is to use a multi-tier J2EE architecture where the business logic and data are modeled using Enterprise Java Beans, being the data stored in databases by means of an Object/Relational mapping tool. The solution proposed in [13] presents a way to replicate such systems by adding fault tolerance mechanisms on both the application server and the database. The authors rely on a locking based approach and propose a replication protocol based on Snapshot Isolation.…”

Evaluating database-oriented replication schemes in Software Transactional Memory systems

“…As for this aspect, the difficulty to exactly identify the data items to be accessed by transactions before these are actually executed, may lead to the adoption of conservative conflict assumptions based on coarse data granularity, e.g. whole, or large slices of, database tables [13]. However, unlike relational database systems, STM-based applications are characterized by arbitrary memory layouts and access patterns, which make harder, or even impossible, to a-priori identify, with a reasonable accuracy (or even a reasonable overestimation), the boundaries of the memory regions that will be accessed by transactions prior to their execution.…”