Simplified High-Performance RDS Data Retrieval
SCADA data retrieval in Pegasus is always performed thru 2 Pegasus Public APIs (PDA and PDART).
SCADA data retrieval performance scales linearly as a function of the number of SCADA
Objects, and their Storage Frequency, in the Pegasus RDS™. SCADA data retrieval performance is
constant with respect to the number of years of SCADA data in the RDS (this is very unusual and
virtually impossible to achieve with Relational Databases).
The Server-side of the PDA compresses all data retrieved from the RDS before transmitting it
over the network (10:1 data compression, typical). The Client-side of the PDA expands and
reorients all retrieved data so it appears to the calling application as a well-formed, regular
matrix. The Client-side of the PDA also includes several functions that return not only RDS Data,
but statistics including Data Mins & Maxs, RDS Performance Statistics, Server-side Logs, etc.
Using the PDA-RT is virtually identical to using the PDA (to all calling applications), but PDA-RT
does not compress RDS data before network transmission. PDA-RT also uses much lighterweight
data structures and does not include the extensive logging supported by PDA.
The PDA and PDA-RT support all RDS SCADA data retrieval, including the following
- Interactively using the Smart Client
- Unattended Scripting of the Smart Client (also called The Exporter) to execute large data Exports
- Programmatically, where Custom Applications use the PDA and/or PDA-RT APIs to retrieve near real-time or historical data for any SCADA Objects, for any time period
Both PDA and PDA-RT are 100% “managed code” using .NET Framework 2.0. As such, they
support Custom Applications written in any language that supports .NET Framework 2.0. Both
APIs are very simple to use, typically requiring less than 10 lines of code to retrieve a set of data
for several SCADA Objects, for any time period contained in the Pegasus RDS™.