The ViewX cache is an area of disk space on a client PC. It is used to store local versions of ViewX documents such as Mimics, Trends and X-Y Plots. It is also used to store scripts on the client.
By storing documents locally, the system is able to minimize the amount of unnecessary traffic on the client - system connection. When a user logs on to the client and attempts to display a Mimic, Trend, X-Y Plot, and so on, ViewX compares the version of the display that is stored in the ViewX cache to the actual display that is stored on the server. If the display stored in the ViewX cache is identical to the original display on the server, ViewX uses the display in the cache. This means that the requested display does not have to be sent from the server to the client. However, if the display in the ViewX cache is different to the corresponding display on the server, ViewX will use the version that is on the server as this is the latest up-to-date version. The display will be sent from the server to the client and will be stored in the ViewX cache (it will replace the out of date version of the display that is already in the ViewX cache).
Example:
A user logs on to a client and attempts to display a Mimic named ‘Main Pipeline’. ViewX immediately compares the version of the ‘Main Pipeline’ Mimic in the ViewX cache to the actual ‘Main Pipeline’ Mimic that is stored on the server.
ViewX determines that the ‘Main Pipeline’ Mimic on the server has been updated more recently than the version that is stored in the ViewX cache on the client. As a result, the ‘Main Pipeline’ Mimic data from the server is sent to the client PC.
The client PC receives the updated ‘Main Pipeline’ Mimic and stores it in its ViewX Cache. It replaces the previous version of the ‘Main Pipeline’ Mimic automatically. ViewX then displays the new ‘Main Pipeline’ Mimic that is stored in the ViewX cache.
The user logs off and another user logs on via the same client an hour later. The new user attempts to display the ‘Main Pipeline’ Mimic. ViewX compares the version of the Mimic in the ViewX cache to the version that is stored on the server. There have been no changes to the server’s version of the Mimic during the last hour, the ‘Main Pipeline’ Mimic in the ViewX cache is identical to the ‘Main Pipeline’ Mimic on the server. As the local version of the Mimic is up to date, ViewX does not have to request an update from the server—the ‘Main Pipeline’ Mimic in the ViewX cache is up to date and is displayed on the client.
ViewX also has an alarm sound cache that is used to store the .wav files that provide the sounds on audible alarms. The sound cache works in the same way as the ViewX cache, except that it only contains sound files and has its own directory.
The location of the ViewX cache and the ViewX Alarm Sound cache varies according to the operating system that is installed on the client (see File Locations (Default) in the ClearSCADA Installation Guide).
Further Information
ViewX Alarm Sounds: see Associate a WAV Sound File with a Severity Range in the ClearSCADA Guide to Server Administration.