Introduction | Index | pdr Invocation

## Working principles

pdr and pdr collaborate according to the following schema (the arrow symbolizes the direction of the data):
----------------------------------------->
Twitter feed
\
e-mail-mailbox \ reports (HTML, XML, TXT, ...)
\ \ /
measuring device-+-+- pdr pdx -+
/ / \ / | \
files / Database | diagramms (SVG, PNG)
/ |
... report templates
diagram definitions
On the left side are so called data sources. pdr supports several possible data sources (see reference). These data sources and their specific parameters must be configured in the configuration file .pdrxrc (see configuration). While pdr runs they will be requested in the predefiniened order, one after the other, and the found data will be inserted into the database. The database serves as link between pdr and pdx. Based on the data in the database pdx will now create reports and diagrams also configured in .pdrxrc (see configuration). Therefore pdx uses report templates in the dedicated output format, in example HTML, and diagram definitions, files defining how to create diagrams.
pdr uses transactions to guarantee the integrity of the data. These transactions reach from program invocation (this means the acceptence of the parameters) till inserting the data into the database. It should be made impossible that data from a data source get only partially into the database. If an arror occurs during data processing the processing will be stopped at all. The data source can then be corrected and the processing can be started again. Configured data sources willbe processed each in an own transaction. Data sources specified on the command line (see invocation) will be processed in own transactions if they are files. Expressions specified on the command line will be pooled and processed all in one transaction.
Both programs have a so called interactive mode, pdr (see here) for data correction and manipulation, pdx (see here) for executing queries and especially to test functions needed for reports or diagrams.

Introduction | Index | pdr Invocation