
Chapter 18
Application Environment
18.1 Introduction
In this chapter we;
• Describe the function and configuration of MemDB the Rhino SLEE volatile memory database.
• Define optimisation hints, configured to manage the state of application components.
• Discuss features which support very durable and long-life applications.
The JAIN SLEE 1.0 specification defines that SBB components execute within a transaction for all event handling work. Such
a transacted programming model enables application components to be reasonably simple, whilst allowing JAIN SLEE servers
to provide features such as high availability, multi-threading, load sharing and so forth. Transactions can be supported by a
JAIN SLEE implementation through the use of a number of techniques.
For more information to the transaction processing concepts relevant in this chapter please refer to Appendix D.
18.2 Main Working Memory
MemDB is the volatile memory database used to hold the Rhino SLEE main working memory which consists of the run-time
state and the working configuration.
MemDB is designed for high performance and low latency, and is integrated with the Rhino SLEE platform carrier grade
architecture. MemDB supports several replication and concurrency control techniques. This section discusses the replication
and concurrency techniques.
MemDB provides an N-way active clustering architecture and is able to survive multiple point failures, including network
segmentation.
For more information on availability clustering please refer to Chapter 17
18.2.1 Replication Models
MemDB supports several replication models. Each model is intended to meet different application requirements. There is
specific terminology used when describing the Rhino SLEE support for replication. These are as follows:
• Synchronous Replication: before a transaction commits the results of the operations of the transaction are saved into a
durable form.
• Asynchronous Replication: some time after a transaction commits the results of the operations of the transaction are
saved into a durable form.
• Re-synchronization: the process of updating a new cluster member with the state of the cluster.
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