High Quality

High Test Coverage

The JPam team believe that the first and most important quality measure is a well designed and comprehensive test suite.

JPam has a relatively high test coverage of source code. This has edged higher over time.

Automated Load, Limit and Performance System Tests

The JPam JUnit test suite contains some long-running system tests which place high load on different JPam subsystems to the point of failure and then are back off to just below that point. The same is done with limits such as the amount of Elements that can fit in a given heap size. The same is also done with performance testing of each subsystem and the whole together. The same is also done with network tests for cache replication.

The tests serve a number of purposes:

  • establishing well understood metrics and limits
  • preventing regressions
  • reproducing any reported issues in production
  • Allowing the design principle of graceful degradation to be achieved. For example, the asynchronous cache replicator uses SoftReferences for queued messages, so that the messages will be reclaimed before before an OutOfMemoryError occurs, thus favouring stability over replication.

Specific Concurrency Testing

JPam also has concurrency testing, which uses 15 concurrent threads hammering a piece of code. The test suites are also run on multi-core or multi-cpu machines so that concurrency is real rather than simulated. Additionally, every concurrency related issue that has ever been anticipated or resulted in a bug report has a unit test which prevents the condition from recurring. There are no reported issues that have not been reproduced in a unit test.

Concurrency unit tests are somewhat difficult to write, and are often overlooked. The team considers these tests a major factor in JPam's quality.

Production tested

JPam has been in production for 18 months.

Fully documented

A core belief held by the project team is that a project needs good documentation to be useful.

In JPam, this is manifested by:

  • comprehensive written documentation
  • Complete, meaningful JavaDoc for every package, class and public and protected method. Checkstyle rules enforce this level of documentation.
  • an up-to-date FAQ

Conservative Commit policy

Projects like Linux maintain their quality through a restricted change process, whereby changes are submitted as patches, then reviewed by the maintainer and included, or modified. JPam follows the same process.

Full public information on the history of every bug

Through the SourceForge project bug tracker, the full history of all bugs are shown, including current status. We take this for granted in an open source project, as this is typically a feature that all open source projects have, but this transparency makes it possible to gauge the quality and riskiness of a library, something not usually possible in commercial products.

Responsiveness to serious bugs

The JPam team is serious about quality. If one user is having a problem, it probably means others are too, or will have. The JPam team use JPam themselves in production. Every effort will be made to provide fixes for serious production problems as soon as possible. These will be committed to trunk. From there an affected user can apply the fix to their own branch.

Open Source Licensing

Apache 2.0 license

JPam's original Apache1.1 copyright and licensing was reviewed and approved by the Apache Software Foundation, making JPam suitable for use in Apache projects. JPam 1.0 is released under the updated Apache 2.0 license.

The Apache license is also friendly one, making it safe and easy to include JPam in other open source projects or commercial products.