Views Service Overview (version 22)
The Canary Views Service is available to both Canary applications and third-party applications to interact with the data stored in a single or multiple Canary Historian archives. The Canary Views service is primarily used to read data from the historian.
The functionality of a single endpoint to service client requests for data stored within the Canary System consolidates all data streams and simplifies system administration.
As you can see from the architecture below, Views connects the Canary Historian to the Calculation Server, Events, remote Mirror services on other Canary Systems, the Axiom Core, Publisher, the ODBC Server, the Excel Add-in, as well as provides a public facing Web API. In fact, the only data service that Views does not interact with is the legacy OPC HDA Server which still reads directly from the historian.
Connectivity to the Views service follows these steps:
- Client data requests are made to the Views Service
- Views leverages WCF authentication for the requesting client based on admin-defined Views authorization permissions
- Canary Historian DataSet HDB (historian database) files are read and requested before data is provided to the Views
- Views performs all necessary aggregation or processing of the data based on the client's request
- WCF services encrypt and transport data packets from Views to client
Beyond serving as gatekeeper for client activity, Views play a significant role in the contextualization of data. This is accomplished by:
- Adding tag metadata not collected during data logging
- Creating multiple virtualized views of the historian archive
- Organizing tags into asset models with defined asset types