The reporting package generates visual reports of eucalyptus usage statistics. For example, it generates reports of instance usage, S3 usage, and EBS usage.

The reporting package is also responsible for tracking usage statistics and recording them in a database. Some usage statistics (like instance usage) are statistically sampled every interval, whereas others (like S3 usage) are recorded every time some event occurs, like resource allocation.

The reporting system has a single entry point: the generateReport method in the ReportGenerator class. All reports are generated by calling that single method.

Implementation

The reporting system is broken down into several Reporting Modules. Each module tracks its own usage statistics, has its own event listener, and has its own database tables. All reporting modules implement the ReportingModule interface, and are organized as sub-packages under the "com.eucalyptus.reporting.modules" package. When a report is generated, the reporting system calls a specific module to gather aggregate historical statistics, then feeds this information to Jasper to generate a report.

At present, three reporting modules are implemented: Instance, EBS, and S3. Additional reporting modules could be added, by adding additional sub-packages and implementing the ReportingModule interface; this would allow the reporting system to track additional kinds of usage statistics.

All reporting modules gather usage data by means of events. Events are sent from various components of Eucalyptus (like the CLC and Walrus) to the reporting modules, either periodically or whenever some usage occurs. The events are aggregated into reporting statistics which are stored in the various module database tables.

Usage statistics are aggregated and stored in the database as a series of snapshots. Each snapshot contains the total usage for a given (user,account,cluster,avail_zone) tuple at a given moment in time.

The current reporting modules all share a common structure and a similar way of storing statistics as snapshots. However, this is only a convention which has been followed for the existing reporting modules. Any future reporting module need not have similar classes or a similar organiztion; it needs only to have its own module sub-package, and to implement ReportingModule and ReportLine interfaces. It can store, aggregate, and retrieve its statistics in any manner chosen by the developer. It need not necessarily store its statistics as a series of snapshots either.

In addition to the reporting modules, the reporting system also has a super-structure, which loads the modules, queries the modules for data, listens for (and parses) web requests, maintains a queue of events, generates visual reports using Jasper, caches frequently used reports, and so on.

The super-structure has a queue package for transmitting events over the network if necessary, and a units package for unit conversions.