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Axion
Axion is a product of Tigris.org. Tigris is the same open source community that brings us the Subversion products discussed in Chapter 4. Axion is a relational database system written in Java and described as being a “lightweight, scalable, modular, and complete relational database.” The following table provides a brief overview of Axion.
At this time, Axion seems to be the least mature of all of the Java database products that we cover in this section. Although it can be a useful product in situations where memory is a concern, the other products have more features. We hope that this situation will change as the Axion project moves forward. The Axion project has submitted a proposal to become part of the newly formed http://db.apache.org. If the proposal is accepted, then it is likely
that Axion will mature quickly as its visibility to the open source community is increased. Axion has a number of dependencies on Apache projects already. In order to install and run Axion, you must also install two .jar files from the Jakarta Commons project. To install Axion, download the current distribution from Tigris.org and decompress the file into a subdirectory. You will also need to download the following files:
· commons-collections.jar
· commons-logging.jar
These files can be downloaded from the Jakarta Commons project at http://jakarta.apache.org/commons. Entering the following command for Windows starts Axion: java -cp axiondb.jar;commons-collections.jar;commons logging.jar \ org.axiondb.Axion dbname [dbpath]
The command is the same for Linux, except for replacing the classpath separator with colons as follows: java –cp axiondb.jar:commons collections.jar:commons-logging.jar \ org.axiondb.Axion dbname [dbpath] The parameter dbname is the name of the database that will be opened or created. This name is used to reference the database using the JDBC driver. The optional parameter dbpath is for persistent or disk-based databases. It providesthe filename and path for the database. Axion provides a simple command-line interface that accepts SQL commands. Axion also supports access by those using products such as Squirrel (discussed later in this chapter). However, Axion currently only works as an embedded database and does not have a server mode. This essentially limits Axion databases to access by a single JVM at a time. This may not be an issue for applications that need to embed a database into a servlet environment or a standalone Java application, but for many purposes this is too restricting.
