Point caching allows an application to retrieve point information from a local cache file with or without a valid connection to the host PI Server.
Using the point caching feature when a PI Server connection is available bypasses potentially long delays caused by the latency in network calls required to gather point information from the PI Server, which in turn delays the ability of the application to begin data collection from the Data Source. As an example, an application with 50,000 associated PI points may take several minutes to retrieve all the PI points from the PI Server. Using the point caching feature can reduce the application time to load the same 50,000 PI points from the cache file to approximately 10 seconds. Results will vary depending on the system architecture and network latency. However, using point caching will improve application startup time, especially when large point counts are being used.
The first time the application is started and the point cache file opened, a connection to the PI Server will be required to populate the cache files with the necessary data to support the point caching feature on subsequent application restarts. Two local cache files will be created on the application node. The startup time may be slightly delayed while these files are being created. The cache files contain the required PI Server version, PI point configuration, and DigitalState information to start the application.