SAD and Python with EPICS

at IHEP,Beijing, 2002.8.21Noboru Yamamoto

KEK, JAPAN

Simple, well understood behavior

High Level Applications in KEKB

● Applications and Operator displays in KEKB Application Launcher

SAD medm Python misc Total

268 19 31 5 292Top Level Applications

●SAD is widely used for high level applications.●medm/dm2k is used for simple displays.●Python is also used for application development.

SAD applications● Operator Interface

– Optics measurement– Optics calculation and Optics – Collision Monitors ...

● Slow Feedback (with OPI)*– iBump:a system keeps beams in collision– Closed orbit correction

*)It is preferable to separate FB loop and its user interface into different processes.

KEKB Launcher

● Program written in SAD/KEKB Frame● Starting point of KEKB operation● User can register a new command on the

fly*.● simple load balancing between servers.● User can select a host to execute a

command.

*) Application reads a configuration file , kbl.conf, at start up and on request by operator.

Applications in KBL

A sample SAD/KBFrame application

Applications using Python and Pmw

SAD and Python compared

● SAD– Accelerator modeling– Developed at KEK– Mathematica like

scripting– support CA and Tk

widget – Modules for KEKB

operation

● Python– General Purpose Object

Oriented dynamic language– Developed by Open source

project– Simple and Clean syntax– Support CA and Tk widget– RDBMS interface– Variety of extension

modules

SAD installation

● SAD Source Download Page– http://acc-physics.kek.jp/SAD/SADDownloadPage.html– You need ID and password to download the source code.

Contact susumu.kamada@kek.jp for your ID and password.

– You also need Tcl/Tk source code and a patch specific to SAD/Tkinter.

– Electric conference room for SAD (in Japanese).

SAD script● SAD Scripts follows Mathematica(R) syntax.No

statements, just functions. ● Every Elements has a form:

– Head[arg1, arg2,...]– eg. If[cond, st1, st2 ]

● Some Element has a special notation– Plus[ 1, 2] <-> 1+2– List[a,b,c] <-> {a, b, c}

● Name of element/function is same as that of Mathematica.

KEKB Frame

● Framework, i.e. a collection of programs/scripts, to support development of GUI Application– Standard Menu– Help menu including “Process

Info”– status bar including print button

● Build upon Tkinter Widget Set

Extending SAD

● SAD modules can be used to extend SAD script functionality, i.e. add a new function to SAD script.

● SAD modules is a library written in SAD script.● Fortran and C is used to develop SAD program

itself.● Fortran or C can be used add a new functionality

to SAD script.

Python installation

● Python Web site: http://www.python.org/– Source code and binary(Windows, Mac, rpm)– gnuzip;tar; configure; make from tar.gz file.– Use of Pmw(Python mega widget) together with

Tkinter is recommended– Use of Gtk+(PyGtk) is another possibility.– Get CA interface from ANL EPICS web site or

KEKB web site (or Both)

Python syntax

● Python uses indentation to specify a block structure of a program e.g.:

if cond :statements_1

else:statements_2

other_statements● Usage of special characters are common to most

of programing language.

Extending Python

● Python modules add new functions and/or classes to Python language.

● There already exists a rich set of Python modules.● C or C++ can be also used to develop new

modules ( C-modules).● Tools such as SWIG can be used to develop a C-

module.

Embedding Python

● Python can be used as an extension language of the existing program.

● It adds flexibility and extendability to the program.

● For example, PostgreSQL, a free RDBMS, can use Python to define a stored procedure or define a new object.