The Storyboard IO API, formerly known as GREIO, provides a platform independent communication API that allows inter-task and inter-process queued message passing. This is primarily used to allow external communication with a Storyboard application.

The API provides transport delivery guarantees for messages that are placed into the queue regardless of the implementation. The maximum transport size of a message and the total queue capacity varies slightly from implementation to implementation however a 2K message size should be considered a design limit with the practical implementation limit around a 4K message payload size.

Storyboard IO communicates events over a named uni-directional channel. By default, Storyboard applications have a receive channel, named after the deployment bundle file (i.e. [bundlename].gapp). This allows backend applications to send events to the Storyboard Application. A custom receive channel can be specified in the command option for sbengine. The Storyboard application can transmit events on one or more channels. The backend software will need to open the channel and listen for events. See Storyboard IO API for more details.

Storyboard IO integration with the Storyboard Engine is implemented as a plugin. It is possible to create alternate Storyboard IO implementations that take advantage of custom communication facilities available on a platform.

The Storyboard IO plugin provides a single communication channel which clients can used to inject events into the Storyboard application. These events will be queued and dispatched in the same manner as internally generated events.

Client applications can use Storyboard IO to create their own communication channels and then receive events from that channel from the Storyboard application or from any other Storyboard IO client.