O'Reilly logo

Architecting the Industrial Internet by Carla Romano, Robert Stackowiak, Shyam Nath

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Query

A query enables the filtering and selection of data. Queries can be executed against a dataset by a user, by an addressable device (through web sockets), by an application, or through analytical, reporting, visualization, and other tools. Query results can be pushed to a gateway to provide a data source for higher level brokers.

Query models are typically one time or continuous. A one-time query involves selection of data in response to a request, while a continuous query produces a stream of data. One-time queries are used to return a single result set and are well suited for the publish-subscribe data pattern. Streaming data returns data in real-time or at prescribed intervals and can be used in tracking and monitoring real-time analytics ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required