Markus Zolliker
e1d5170a90
add tutorial for Berlin hands-on workshop
+ improve the documentation (hints for structure welcome)
+ remove 'optional' parameter property
(is not yet used - should not appear in doc)
+ added test property in frappy_demo.cryo alters Parameter class
('test' property appears in Parameter doc)
Change-Id: I3ea08f955a92f72451fd23a5ff00d1185c7fb00e
2.0 KiB
Frappy Internals
Frappy is a powerful framework, which does everything behind the scenes you need for getting a SEC node to work. This section describes what the framwork does for you.
Startup
TODO: describe startup: init methods, first polls
Polling
By default, a module inheriting from Readable <frappy.modules.Readable> is polled
every pollinterval
seconds. More exactly, the doPoll method is called, which by default calls read_value and read_status.
The programmer might override the behaviour of doPoll, often it is wise to
super call the inherited method.
- Note
Even for modules not inheriting from
Readable <frappy.modules.Readable>,doPollis called regularly. Its default implementation is doing nothing, but may be overridden to do customized polling.
In addition, the read_<param> method is called every slowinterval seconds for all
parameters, in case the value was not updated since pollinterval seconds.
The decorator nopoll <frappy.rwhandler.nopoll> might be used
on a read_<param> method in order to indicate, that
the value is not polled by the slow poll mechanism.
Client Notification
Whenever a parameter is changed by assigning a value to the attribute
or by means of the access method, an update message is sent
to all activated clients. Frappy implements the extended version of the
activate message, where single modules and parameters might
be activated.
Type check and type conversion
Assigning a parameter to a value by setting the attribute via
self.<param> = <value> or
<module>.<param> = <value> involves a
type check and possible a type conversion, but not a range check for
numeric types. The range check is only done on a change
message.
TODO: error handling, logging