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
62 lines
2.0 KiB
ReStructuredText
62 lines
2.0 KiB
ReStructuredText
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:
|
|
|
|
Polling
|
|
.......
|
|
|
|
By default, a module inheriting from :class:`Readable <frappy.modules.Readable>` is
|
|
polled every :attr:`pollinterval` seconds. More exactly, the :meth:`doPoll`
|
|
method is called, which by default calls :meth:`read_value` and :meth:`read_status`.
|
|
|
|
The programmer might override the behaviour of :meth:`doPoll`, often it is wise
|
|
to super call the inherited method.
|
|
|
|
:Note:
|
|
|
|
Even for modules not inheriting from :class:`Readable <frappy.modules.Readable>`,
|
|
:meth:`doPoll` is called regularly. Its default implementation is doing nothing,
|
|
but may be overridden to do customized polling.
|
|
|
|
In addition, the :meth:`read_<param>` method is called every :attr:`slowinterval`
|
|
seconds for all parameters, in case the value was not updated since :attr:`pollinterval`
|
|
seconds.
|
|
|
|
The decorator :func:`nopoll <frappy.rwhandler.nopoll>` might be used on a :meth:`read_<param>`
|
|
method in order to indicate, that the value is not polled by the slow poll mechanism.
|
|
|
|
|
|
.. _client notification:
|
|
|
|
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:
|
|
|
|
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
|