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Derby Network Server

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Derby Server and Administration Guide

CS (the default isolation level) provides the best balance between concurrency and
consistency in multiple-client environments.

RS provides less consistency than RR but allows more concurrency.

RR provides greatest consistency.

UR provides maximum concurrency, if uncommitted values are allowed in the query.
It is typically used if approximate results are acceptable.

See "Types and Scope of Locks in Derby Systems" in the Derby Developer's Guide for
more information.

Multi-connection and multi-threading:

Derby allows multiple simultaneous connections to a database, even in embedded mode.
Derby is also fully multi-threaded, and you can have multiple threads active at the same
time. However, JDBC semantics impose some limitations on multi-threading. See the
Derby Developer's Guide for more information.

Administrative tools:

Derby provides some tools and features to assist database administrators, including:

· Consistency checker
· Online backup
· Procedures for importing and exporting data
· Database replication
· The ability to put a database's log on a separate device
· Locking information monitoring
· Reclaiming unused space

These tools and features are discussed in Part Two of this guide. See the sections in that
part for more information.

The Derby Network Server

The Derby Network Server provides multi-user connectivity to Derby databases within
a single system or over a network. The Network Server uses the standard Distributed
Relational Database Architecture (DRDA) protocol to receive and reply to queries from
clients. Databases are accessed through the Derby Network Server by using the Derby
Network Client driver.

The Network Server is a solution for multiple JVMs that connect to the database, unlike
the embedded scenario where only one JVM runs as part of the system. When Derby is
embedded in a single-JVM application, the embedded JDBC driver calls the local Derby
database. When Derby is embedded in a server framework, the server framework's
connectivity software provides data to multiple client JDBC applications over a network or
the Internet.

To run the Derby Network Server, you need to install the following files:

· On the server side, install

derby.jar

and

derbynet.jar

· On the client side, install

derbyclient.jar

There are several ways to manage the Derby Network Server, including:

· Through the command line
· By using .bat and .ksh scripts
· Through the servlet interface
· With your own Java program (written using the Network Server API)
· By setting Network Server properties