Become Jythonic when scripting in FDMEE

2. Become Jythonic
Best Practices for FDMEE Scripts
Francisco Amores
Infratects

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only on behalf of Infratects, and may not be
incorporated into any contract. It is not a commitment
to deliver any services or functionality, and should not
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provides no warranties with respect to the offerings
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Safe Harbour

4.  Say hello to Jython
 Coding standards – PEP8
 Best practices when…
 Best practices for FDMEE scripts
 Highlights
 Q&A
Agenda

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7. Goals
What I don’t pretend What I do pretend
● You change all your
scripts after this
session
● You get bored and
leave the room 
● You take best practices
into account
● Loose your fear of
Jython
● You enjoy 

8. JYTHONEER OR JYTHONIST?
Say hello to Jython

9.  Python implementation for JVM
 Functional + object-oriented
 Elegant syntax for clearer scripts
 Key fundamentals
● Code Indentation
● No need to declare types
● Indexes start at 0
● Slicing notation
● Seamless integration with Java
What is Jython?
+
_______

10.  Windows and penguin are both happy
 Easy to learn and code
 Code reusing
 VB Script is obsolete
 JAVA APIs across EPM products
 Jython 2.5.1
Why Jython in FDMEE?

11.  VB syntax = 'Oh God!'
 Jython syntax = 'My Goodness!‘
 Simpler and clearer solutions
 No begin/end tags
 Functions are always defined as def (no Sub)
 More robust and flexible error handling
Key differentiators with VB Script

12.  Idiomatic Jython
● Common scripting idioms
● May not be obvious to newcomers
 How do I get Jythonista?
What is Jythonic?
1. Get it working at all
2. Get it working regularly
3. Reuse code and design for reuse
4. Starting to write idiomatic Jython

13.  Just an example
What is Jythonic?

14. CODING STANDARDS – PEP8
15
“Programs must be written for people to read,
and only incidentally for machines to execute”
—Abelson & Sussman,
Structure and Interpretation of Computer Programs

15.  Scripts easy to read
 Python Enhancement Proposal
 Must-read: coding standards (PEP8)
Coding Style

16. Object Convention
Functions, methods, modules joined_lower, camelCase
Constants joined_lower or ALL_CAPS
Global variable names joined_lower
Variable names camelCase
Naming convention

17.  No hard tabs (never mix)
 Indentation level  4 spaces
 Space after “,” (lists, dicts, args, tuples)
 Space around assignment and comparisons
Indentation and whitespaces
Hanging indent
• No args in 1st line
• Additional indent for args
Implied line
• Vertical Align with opening
delimiter

18.  Line length < 80 chars (73 for
comments)
 Align elements of continuation
lines
● After binary operator
● Vertically below open
delimiter (), [], {}
Long lines and continuations

19.  No need to use break lines
 Log messages SQL queries using the fdmAPI
Triple quotes for long strings

20. Comments and Documentation strings
● # Comment = Why and how the code works
● Block Comments
● Inline Comments
● Doc String = How to use
Please
keep them
up to date

21. Where do you write your scripts?
 Who are you?
● IT  Eclipse (PyDev), Netbean, Emacs, etc.
● Business  Notepad++, others
 Making your way to Jythonista easier
● IDE/Editor integration with PEP8
● Pylint (Python formatting code evaluation utility)
● PEP8 plugin for Notepad++

22.  PEP8 online checker (http://pep8online.com/)
Don’t be scared and try it at home

23. BEST PRACTICES WHEN…
24

24. Using loops and conditional statements
 What are my data structures?
● for iterates thru a collection/iterable/generator
● while loops until a condition is false
 List of triggers better than long conditions
● all and any functions

25.  True and False (type bool)
 Intrinsic truth values
Evaluating conditions
False True
False (== 0) True (==1)
“” (empty string) Any string but “” (“ “, “x”…)
0, 0.0 Any number but 0 (1, 0.2, -2…)
[], (), {}, set () Any non-empty container ([‘Loc’], [‘’]…)
None Almost any object that’s not explicitly False

26. Importing java libraries or modules
 Separate lines unless from same module
 Top of the script/function (after comments)
 Aliases
 Absolute imports preferred (x.y.z)
 from package import func1, func2
 Add path for custom modules to sys.path

27. Handling errors with try-catch
 EAFP Vs. LBYL
 Specify the exceptions to
catch
 Limit code for the try
 Module traceback (stack
traces)
 sys.exc_info (exception +
msg)

28. Working with numbers and dates
 Preferably use java.math.BigDecimal
 Cast int(), long(), float()
 Module datetime or java class
java.text.SimpleDateFormat

29. Working with strings
 Delimited by “ or ‘
 Use built-in functions when possible

30.  String formatting %s (no casting)
Working with strings

31. Working paths and files IO
 Paths
● Use fdmContext[“OUTBOXDIR”] and similar
● Use os module functions
● os.path.join(path1, path2…)
● Raw strings for hard-coded paths r’E:f1.log’
 Module codecs
 Enumerate if you need line number

32. Working with dictionaries
 Dictionaries are great
 Dictionary[key]  value
 Natural replacement of
select case (VB)

33.  Complex data structures will look simple
 Custom error library (localization)
Working with Dictionaries

34. Working with SQL
 FDMEE DB
● Get API functions when possible
● Commit after DML (fdmAPI.commitTransaction())
● Close result sets (fdmAPI.closeResultSet(rs))
● No need to open/close the SQL connection
 Remote DB
● Use java.sql (or specific DB modules)
● Open SQL connection (or dblinks, synonym, remote
query…)
● Commit, close ResultSet, close connection

35. Working with SQL
 Use parametrized SQL (avoid injection attacks)

36. IT’S NOT ALL BEING
JYTHONIC
Best Practices for FDMEE Scripts
37

37. Migrating old VB Scripts
 Line by Line = FAILURE
 Clean up mess
 Avoid mixing technologies
 JAVA API ≠ FDM VB API
 FDM VB API ≠ FDMEE
VB API
 This is a good start
(raspberry)
Script Language
Import Jython
Event Jython/VB
Custom Jython/VB
Mapping Jython/SQL
Drill-Thru JavaScript
Logic Accounts Jython
Check Rules Jython

38.  Object with context properties
 Not all properties available in all scripts
 Not all documented
Object fdmContext[“<PROPERTY NAME>”]

39. The JAVA API
 Young API
 fdmAPI.function(params)
 fdmContext > fdmAPI > SQL Query
 SQL query better than nothing 
 Write your own API (modules, aif-custom.jar)
Some examples Description
executeDML Insert, Update SQLs
executeQuery Select SQL
showCustomMessage/File Shows messages/files to end users
getCustomScriptParameters Parameters from custom scripts

40. Event scripts
 Actions Bef/Aft workflow steps
 FDM Classic events > FDMEE events
 Different scripts per target app 
 def EventName
 Select the right one
● When do you want to do what?
● TDATASEG or TDATASEG_T?

41. Example: Inserting new records
 No API available
 TDATASEG_T preferred over TDATASEG
 DATAKEY (MSSQL)
● Identity in TDATASEG_T but not in TDATASEG
● Insert into TDATASEG_T (datakey is generated)
 DATAKEY (Oracle)
● Uses a sequence
● TDATASEG_DATAKEY_S.NEXTVAL

42. Mapping scripts
 New API (replacing old varValues)
 Update multiple TDATASEG_T columns at
once
 Multi-dimension better than script
 #SQL preferred  1 update in one shot

43. Writing in the FDMEE process log
 Add debugging code to your scripts
● Disable in Production (log level < 5)
● Use the FDMEE process log to learn 
 Use API functions to log messages
API function Use Log Level
logFatal(msg) Fatal error occurs All
logError(msg) Error occurs >=2
logWarn(msg) Warning condition occurs >=3
logInfo(msg) Informational message >=4
logDebug(msg) Debug message 5

44. Error handling in Import Scripts
 Scripts evaluated before being executed
 Lines skipped if there are evaluation errors
Hard to find the error
Why?
Better capture
the exception

45. Error handling in Event scripts
 Errors shown in aif-WebApp.log
 Use try-except to control errors
● Log the error in the FDMEE process log

46. Working the workflow status - Set
 No published API available to set status
 Update table AIF_PROCESS_DETAILS if needed
● Undocumented API fdmAPI.updateProcessDetails
 Raise exception or sys.exit(“errmsg”)
 Can use a dictionary for error messages

47. Highlights
 Keep your scripts simple
 Make it working before being Jythonic
 Configure your IDE/Editor for PEP8
 Don’t forget adding comments
 Don’t reinvent the wheel… Google is your BF 
 Use the Java API
 Understand the product inside out (log level 5)
 Focus on Jython 2.5.1 (for now)

48. Call for papers is now open. Registration
opens May 2015.
Announcing
Infratects Top Gun US 2015
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Friday, September 18, 2015
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Dallas, Texas

49.  You can always contact me
Email: francisco.amores@infratects.com
Mobile: +34674209000
LinkedIn: http://lnkd.in/dgpfvMW
Twitter: @akafdmee
Blog: http://akafdmee.blogspot.com
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