Science Service Bus

The Science Service Bus is a Mule application which is targeted towards the scientific/research community but may have uses elsewhere as well. The target use case is a bioinformatics research lab. In labs, there is typically a large variety of data transferred about which is processed by a various analysis tools. New tools are frequently being added and removed, new experimental tools developed, etc., so the environment is very dynamic. The SSB supports this sort of usage of Mule.

The Mule version has several main ideas:

• A service is a function with one input and one output. A service is identified with its signature, which includes the service type and the data types of the inputs and outputs.

• An agent is a map from service signature to Mule URI, along with an agent name and ID. An agent represents several related Mule services. Each agent can be in its own Mule instance or several agents can share the same Mule instance. Agents communicate with the agent registry.

• An agent registry which keeps track of all the existing agents and notifies other agents when a new agent arrives or an existing agent unregisters.

• A translator is a 3-tuple of "from data type ID", "to data type ID", and "transformer ID." The registry keeps a directed graph of translators. When an agent registers with the registry, it arranges for the agent to receive all data for which there is some transformation path from source type to destination type. For messages which require translation, the data actually gets sent to the server, run through one or more transformers, and then delivered to the destination.

• Support for dynamic routing slips. Each message carries a routing slip which determines the sequence of processing steps for that message. After an agent processes a message, the message is routed to any available agent which can perform the next processing step specified in the route. More information is available here: SSB Routing.

The SSB is backwards-compatible with the Gaggle system. More information is available here: Gaggle Compatability.

You can listen to a podcast about this program here: http://blog.mulesource.org/2009/04/mulecast-a-conversation-with-the-creator-of-the-science-service-bus-ssb/.