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.