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.