Basset

Basset is a framework for antispam modules.

It consists of two components: a frontend that runs as a mod_wsgi script within httpd, and a worker that runs as a separate service. They communicate with eachother using an AMQP broker (tested with RabbitMQ).

Frontend

The frontend is a very small, single script whose only job is to get "messages" from external systems and put these messages into the broker.

Each message is a notification that a user has done something that could possibly be spam, and asks Basset to decide whether or not this is (likely) spam.

Its output is a JSON dictionary, where the key "result" has one of the following values: - "accepted": the checks resulted in acceptance of the submitted query. - "denied": the checks determined that this request should be denied. - "manual": the checks could not come to a conclusion, and a human should look at the request and make a decision. This most likely means that some parameters in the Basset configuration needs to be tweaked more specific to the setup. - "checking": the checks are taking a bit longer, which means that the worker will later on connect to the service via an application-specific API to enact its decisions

In the current version, it will always return "checking", but applications should support the "accepted", "denied" and "manual" results as well, and act accordingly. If a result is provided as part of this API, the worker will NOT also enact the decision itself.

Worker

The worker is the part of Basset that does the real work of checking for spam. It retrieves messages from the message broker, and for each message determines a spam probability score, based on the enabled Score plugins.

If the spam probability score exceeds the configured threshold for denial, it will decide to deny the request and enact its decision. If the spam probability score does not exceed the threshold for denial, but it does exceed the threshold for manual checks, it will tell the application that it should ask for an administrator to check the request. If neither of these thresholds are exceeded, it will decide to accept the request.

Each message may result in 0 or more decisions: a decision is an action that Basset will take as a direct consequence of the message it just processed.

The processing of decisions is done by Decision Plugins, and only after every decision has been processed correctly will the original message be acknowledged to the message broker, which means that the worker becomes available for the next message.