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After attending a software development conference, you usually return back home with a bunch of new ideas and cool things you want to try out. But most of the time your ideas remain in experimental stage, since it’s often hard to find a problem that’s just right for all newfound solutions…
But returning from GeekOut 2014 was different – Michael Hunger’s talk “Using Ascii Art to Analyze Your Source Code with Neo4j and OSS Tools” had an elegant solution to an actual, unsolved problem of mine that had surfaced just a couple of weeks earlier.
A system I am involved in as a developer relies on custom parsing of the source code to find all concrete subclasses of a particular class, excluding inner classes. These subclasses represent units for which user access can be configured. If this list is incomplete, the configuration will be incomplete, which in turn means missing user access. We had just seen our first case of generics showing up in this class hierarchy, and the parser couldn’t handle that properly.
Mattias is a software developer with project management experience. He is a quick learner with excellent analytical, design and problem solving skills. He has long experience from design and development of technically challenging systems. He has also been involved in team and technical project management as well as architecture work. He is comfortable working independently or as part of a team and always strives to perform his best and deliver on time and in full.
The objective is to extract all concrete subclasses of a particular class into a custom format file, and this should be part of the build. This file serves as a template for access control configuration for the scanned rich client application.
The steps will be described in more detail below, using this sample project. It’s a real-world example, but the actual code scanned and the custom report plugin have been replaced with sample code.
To set up jQAssistant, make sure you have the following:
Add the following to your
settings.xml, located in the
.m2 folder of your home directory:
This makes it easier to run jQAssistant from the command line. Now you’re good to go.
Since jQAssistant scans bytecode, you need to build your Maven project.
Before you can scan your application, you need to add the jQAssistant Maven plugin to your POM:
This also includes configuration of the report writer described later, the file to which the result should be written.
Now you can scan your code using
With your code scanned, it’s time to write your Cypher query. The Neo4j web interface is very useful for experimenting with queries, start it by executing
Now you can browse to https://localhost:7474 and start writing and testing your queries.
Now only we have a query that returns all concrete subclasses of
Animal, inner classes excluded.
To stop the server, return to the console from where it was started and hit Enter.
Now it’s time to create a rule file to integrate the query into the build. Rule files are XML files located in the
Now that we have a query that do the extraction from the compiled code, we just need to put that in a file. In this example, we just want to write the fully qualified name for each class found by the query. To do that, we implement a custom report writer:
When we plug in this report writer, the result from the query will be available in the
Result parameter passed to the
setResult method. The rows can be retrieved and written to a file in the desired format.
To let jQAssistant know about your plugin, create a file called
jqassistant-plugin.xml and place it in the
META-INF folder of your report writer project.
The final step is to let jQAssistant execute your query and generate the report, which is done by executing
As simple as that.
Thanks to Michael Hunger for a great talk on jQAssistant and Neo4j at GeekOut 2014, and many thanks to Dirk Mahler for helping out, sharing knowledge and enhancing jQAssistant to allow plugging in your own custom report writer. Awesome.
For more details check out https://jqassistant.org where you’ll also find reference documentation and examples.