MySQL’s Connector/MXJ is a tool that exposes the ability to start and stop an embedded MySQL server through a Java API. You can have the MySQL JDBC driver start up a server just by appropriately configuring your JDBC url or you can programmatically control the server through the MysqldResource class. It does this by bundling precompiled versions of the mysql (client) and mysqld (server) binaries and invoking the correct ones based on the os.name and os.arch system properties. This sounds great for spinning up an instance of mysqld for testing, but there are a few issues to be solved. MySQL hasn’t published any recent versions of MXJ to the central Maven repository, so you’ll have to install the files by hand into your local ~/.m2 (or repo server, if you have one set up). Also, they don’t include 64-bit Linux binaries. Update: I have submitted artifacts for Connector/MXJ 5.0.12 to Maven Central and they have been approved, so you need only add the following dependency to your code and you’re good to go.

<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-mxj</artifactId>
  <version>5.0.12</version>
  <scope>test</scope>
</dependency>

If you’d like to build the artifacts yourself, carry on with the instructions… Download the zip distribution yourself from MySQL’s download page (5.0.12 is current as of this article). When unzipped, you’ll find two jars: mysql-connector-mxj-gpl-5-0-12-db-files.jar (the ‘db-files’ jar) and mysql-connector-mxj-gpl-5-0-12.jar (the ‘mxj’ jar). The mxj jar is quite small and just contains some Java classes. The db-files jar is pretty hefty because it contains the actual binaries for x86 32-bit FreeBSD, Linux, Mac OS X, Windows and Solaris (as well as Solaris on SPARC in case anyone still uses that…). Alas, no 64-bit Linux… If this doesn’t affect you, skip to the end of the article to see how to install the jars correctly into your local ~/.m2 repo. You’ll know that you’re hitting this problem if you get output like this:

[MysqldResource] launching mysqld (driver_launched_mysqld_1)
/tmp/test-mxj/bin/mysqld: error while loading shared libraries: libaio.so.1: cannot open shared object file: No such file or directory

This is (correctly) saying is that the 32-bit mysqld binary cannot find libaio. You should have libaio installed since the 64-bit version we’ll be building will need it, though!

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Another Java web framework? Not really…

There are dozens of web technologies for Java (Struts, Stripes, Tapestry, Wicket, GWT, Spring MVC, Vaadin, Play, plain old servlets and JSP, Dropwizard, etc.) and they all have their advantages and disadvantages.

This article isn’t about comparing frameworks. Instead, I’ll describe how to serve HTTP requests from Java without using a monolithic framework in a way that’s a lot more pleasant than using just HttpServletRequests: Jetty for handling low-level HTTP things, Jersey for request routing, Jackson for serialization and Guice to tie it all together.

Update: If you actually want to write something quickly using stuff shown in this article, Dropwizard has since come out, and looks like a solid choice. If you want to learn more about how to build such a stack, check out the second article in this series.

If you want to write your web UI on the server side (whether it’s translated to JavaScript ala GWT or simply HTML markup like you might put in a JSP), this probably isn’t an approach that will be very attractive. You won’t have a web framework already there to provide pre-canned view helpers or login forms or “is this a phone number” validation or any of that. If you are transitioning towards making the server be more of a data store and putting display logic entirely in the client (regardless of whether the client is a browser or a native mobile app), the no-big-framework approach can make a lot of sense. You don’t need portlets or JavaScript components when you’re simply shoving JSON or XML or what-have-you over HTTP. I’ll be including code samples as new concepts are introduced, but if you want to browse the finished example project, it’s on the Team Lazer Beez GitHub site.

Jetty

Jetty is a HTTP server and servlet container that’s been designed expressly for easy embedding. I think it’s easier to do the edit-restart-test cycle with a simple main method that starts a Jetty server (no IDE I’ve used has ever had integration with a servlet container that works as fast or as reliably as running a main method). If you prefer to run and debug inside a separate container, or if you need container-managed security or JTA or XA or any of that stuff, feel free bundle your code as a war instead of using Jetty. Here’s how you start a Jetty server listening on localhost:8080.

Server server = new Server(8080);
// handlers go here
server.start();

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