Chapter 7. Putting events in context
The skill of writing is to create a context in which other people can think.
Edwin Schlossberg
The way we view things in our daily life is affected by their context. This context can relate to the time of day; for example, at night you can open your car with the remote control from quite a long distance, but you may have to come quite close on a sunny day. Context can also relate to location: you might feel safe enough to carry money in your wallet in your own city, whereas in countries which have a reputation for muggings, you hide your money. Context may relate to other external conditions such as the state of the traffic. The route you choose to drive to the airport might depend on your knowledge of likely traffic conditions, or on congestion reports that you have picked up from the radio. In this chapter we introduce context as an explicit building block in our event processing model and dive deeply into the idea of context applied to event processing by covering the following topics:
- Discussion of the notion of context and its role in event processing
- Detailed discussion of the various context dimensions: temporal, spatial, state-oriented, and segmentation-oriented
- Context composition
- Context in the Fast Flower Delivery application
- Context definitions in practice