Welcome to Orion Context Broker.
Orion is a C++ implementation of the NGSI9/10 REST API binding developed as a part of the FIWARE platform.
Orion Context Broker allows you to manage all the whole lifecycle of context information including updates, queries, registrations and subscriptions. Using the Orion Context Broker, you are able to register context elements and manage them through updates and queries. In addition, you can subscribe to context information so when some condition occurs (e.g. a context element has changed) you receive a notification. These usage scenarios and the Orion Context Broker features are described in this document.
Github's README.md provides a good documentation summary. The User Manual and the Admin Guide cover more advanced topics.