Using wsadmin scripting with Jython

Jython is an alternate implementation of Python, and is written entirely in Java™.

The wsadmin tool uses Jython V2.7. The following information is a basic summary of Jython syntax. In all sample code, the => notation at the beginning of a line represents command or function output.

For additional Jython V2.7 specific information, see Jython V2.7 behavior changes

If Jython V2.1 is required, then you must explicitly configure it using one of the following methods:

  • Specify Jython V2.1 using the wsadmin command:
    wsadmin -conntype soap -usejython21 true -f test.py
  • Specify Jython V2.1 using a custom property in the wsadmin.properties file:
    com.ibm.ws.scripting.usejython21=true

    The default value is false.

Note: The Jython library modules are shipped with the Jython binary in WebSphere Application Server Version 9.0. However, we do not provide any technical support if you encounter problems with any Jython library modules. For any Jython technical issues, post the question to the The Jython Project.

Basic function

The function is either the name of a built-in function or a Jython function. For example, the following functions return "Hello, World!" as the output:

print "Hello, World!"
=>Hello, World!

import sys
sys.stdout.write("Hello World!\n")
=>Hello, World!

In the example, print identifies the standard output stream. You can use the built-in module by running import statements such as the previous example. The statement import runs the code in a module as part of the importing and returns the module object. sys is a built-in module of the Python language. In the Python language, modules are name spaces which are places where names are created. Names that reside in modules are called attributes. Modules correspond to files and the Python language creates a module object to contain all the names defined in the file. In other words, modules are name spaces.

Avoid trouble: When you issue a Jython command in a wsadmin script that invokes a WebSphere Application Server MBean operation, and the MBean method returns a string that includes some NLS translated characters such as the French accent character, Jython automatically converts the string to a python unicode string, and returns the converted string to wsadmin. If you include the Jython print output command in the script that invokes the MBean method, the NLS translated characters are included in the string that the MBean method returns to wsadmin instead of the python unicode values. To avoid the displaying of NLS translated characters, use a variable for the MBean return (for example, output = AdminControl.invoke(mbean)) and then use print output. Use the Jython print command to convert strings that contain NLS translated characters correctly.
Avoid trouble: When you issue a Jython command in a wsadmin script that invokes a WebSphere Application Server MBean operation, and the MBean method returns a string that includes some NLS translated characters such as the French accent character, Jython automatically converts the string to a python unicode string, and returns the converted string to wsadmin. If you include the Jython print output command in the script that invokes the MBean method, the NLS translated characters are included in the string that the MBean method returns to wsadmin instead of the python unicode values. To avoid the displaying of NLS translated characters, use a variable for the MBean return (for example, output = AdminControl.invoke(mbean)) and then use print output. Use the Jython print command to convert strings that contain NLS translated characters correctly.

Variable

To assign objects to names, the target of an assignment goes on the first side of an equal sign (=) and the object that you are assigning on the other side. The target on the first side can be a name or object component, and the object on the other side can be an arbitrary expression that computes an object. The following rules exist for assigning objects to names:

  • Assignments create object references.
  • Names are created when you assign them.
  • You must assign a name prior to referencing it.

Variable name rules are like the rules for the C language; for example, variable names can have an underscore character (_) or a letter plus any number of letters, digits, or underscores.

The following reserved words cannot be used for variable names:
  • and
  • as
  • assert
  • break
  • class
  • continue
  • def
  • del
  • elif
  • else
  • except
  • exec
  • finally
  • for
  • from
  • global
  • if
  • import
  • in
  • is
  • lambda
  • not
  • or
  • pass
  • print
  • raise
  • return
  • try
  • while
  • with
  • yield

For example:

a  = 5
print a
=> 5

b =  a
print b
=> 5

text1, text2, text3, text4  = 'good', 'bad', 'pretty', 'ugly'
print text3
=> pretty

The second example assigns the value of variable a to variable b.

Types and operators

The following list contains examples of the built-in object types:

  • Numbers. For example:
    8, 3.133,  999L,  3+4j
    
    num1 = int(10)
    print num1
    => 10
  • Strings. For example:
    'name',  "name's", ''
    
    print str(12345)
    => '12345'
  • Lists. For example:
    x = [1, [2,  'free'], 5]
    y = [0, 1, 2, 3]
    y.append(5)
    print y
    => [0, 1, 2, 3, 5]
    
    y.reverse()
    print y
    => [5, 3, 2, 1, 0]
    
    y.sort()
    print y
    => [0, 1, 2, 3, 5]
    
    print list("apple")
    => ['a', 'p', 'p', 'l', 'e']
    
    print list((1,2,3,4,5))
    => [1, 2, 3, 4, 5]
    
    test = "This is a test"
    test.index("test")
    => 10
    
    test.index('s')
    => 3

The following list contains examples of the operators:

  • x or y

    y is evaluated only if x is false. For example:

    print 0 or 1
    => 1
  • x and y

    y is evaluated only if x is true. For example:

    print 0 and 1
    =>  0
  • x + y , x - y

    Addition and concatenation, subtraction. For example:

    print  6 + 7
    => 13
    
    text1 = 'Something'
    text2 = ' else'
    print text1 + text2
    => Something else
    
    list1 = [0, 1, 2, 3]
    list2 = [4, 5, 6, 7]
    print list1 + list2
    => [0, 1, 2, 3, 4, 5, 6, 7]
    
    print  10 - 5
    => 5
  • x * y, x / y, x % y

    Multiplication and repetition, division, remainder and format. For example:

    print 5 * 6
    => 30
    
    print 'test' * 3
    => test test test
    
    print 30 / 6
    => 5
    
    print 32 % 6
    => 2
  • x[i], x[i:j], x(...)

    Indexing, slicing, function calls. For example:

    test = "This is a test"
    print  test[3]
    => s 
    
    print test[3:10]
    => s is a
    
    print test[5:]
    => is a test
    
    print test[:-4]
    => This is a 
    
    print len(test)
    => 14
    
  • <, <=, >, >=, ==, <>, !=, is is not

    Comparison operators, identity tests. For example:

    L1 = [1, ('a', 3)]
    L2 = [1, ('a', 2)]
    L1 < L2, L1 == L2, L1 > L2, L1 <> L2, L1 != L2, L1 is L2, L1 is not L2
    => (0, 0, 1, 1, 1, 0, 1)

Backslash substitution

If a statement must span multiple lines, you can also add a back slash (\) at the end of the previous line to indicate you are continuing on the next line. Do not use blank space characters, specifically tabs or spaces, following the back slash character. For example:

text =  "This is a test of a long lines" \
" continuing lines here."
print text
=> This is a test of a long lines continuing lines here.

Functions and scope

Jython uses the def statement to define functions. Functions related statements include:
  • def, return

    The def statement creates a function object and assigns it to a name. The return statement sends a result object back to the caller. This is optional, and if it is not present, a function exits so that control flow falls off the function body.

  • global

    The global statement declares module-level variables that are to be assigned. By default, all names assigned in a function are local to that function and exist only while the function runs. To assign a name in the enclosing module, list functions in a global statement.

The basic syntax to define a function is the following:

def name (arg1, arg2, ... ArgN)
   statements
   return value

where name is the name of the function being defined. It is followed by an open parenthesis, a close parenthesis, and a colon. The arguments inside parenthesis include a list of parameters to the procedures. The next line following the colon is the body of the function. A group of commands that form the body of the function. Once you define a Jython function, it is used just like any of the built-in functions. For example:

def intersect(seq1, seq2):
   res = []
   try:
      for x in seq1:
         if x in seq2:
            res.append(x)
   except:
      pass
   return res

To call this function, use the following command:

s1 = "SPAM"
s2 = "SCAM"
intersect(s1, s2)
=> [S, A, M]

intersect([1,2,3], (1.4)) 
=> [1]

Comments

Make comments in the Jython language with the pound character (#).

Command-line arguments

The Jython shells pass the command-line arguments to the script as the value of the sys.argv. In wsadmin Jython, the name of the program, or script, is not part of sys.argv. Unlike wsadmin Jython, Jython stand-alone takes the script file as the initial argument to the script. Since sys.argv is an array, use the index command to extract items from the argument list. For example, test.py takes three arguments a, b, and c.

wsadmin -f test.py  a  b  c

test.py content:

import sys
first  =  sys.argv[0]
second = sys.argv[1]
third = sys.argv[2]
arglen = len(sys.argv)

Basic statements

There are two looping statements: while and for. The conditional statement is if. The error handling statement is try. Finally, there are some statements to fine-tune control flow: break, continue, and pass.

if

The if statement selects actions to perform. The if statement might contain other statements, including other if statements. The if statement can be followed by one or more optional elif statements and ends with an optional else block.

The general format of an if looks like the following:

if test1
   statements1
elif test2
   statements2
else
   statements3

For example:

weather = 'sunny'
if weather == 'sunny':
   print "Nice weather"
elif weather == 'raining':
   print "Bad weather"
else:
   print "Uncertain, don't plan anything"
while

The while statement consists of a header line with a test expression, a body of one or more indented statements, and an optional else statement that runs if control exits the loop without running into a break statement. The while statement repeatedly runs a block of indented statements as long as a test in the header line keeps evaluating a true value. An example of while follows:

while test1
   statements1
else
   statements2

For example:

a = 0; b = 10
while a < b:
   print a
   a = a + 1
for

The for statement begins with a header line that specifies an assignment target or targets, along with an object you want to step through. The header is followed by a block of indented statements which you want to repeat.

An example of a for statement follows:

for target in object:
   statements
else:
   statements

It assigns items in the sequence object to the target, one by one, and runs the loop body for each. The loop body typically uses the assignment target to refer to the current item in the sequence as if it were a cursor stepping through the sequence. For example:

sum = 0
for x in [1, 2, 3, 4]:
   sum = sum + x
break, continue, and pass

You can control loops with the break, continue and pass statements. The break statement jumps out of the closest enclosing loop (past the entire loop statement). The continue statements jumps to the beginning of the closest enclosing loop (to the header line of the loop), and the pass statement is an empty statement placeholder.

try

A statement will raise an error if it is called with the wrong number of arguments, or if it detects some error condition particular to its implementation. An uncaught error stops the running of a script. The try statement is used to trap such errors. Python try statements come in two flavors, one that handles exceptions and one that runs finalization code whether exceptions occur or not. The try, except, else statement starts with a try header line followed by a block of indented statements, then one or more optional except clauses that name exceptions to be caught, and an optional else clause at the end. The try, finally statements starts with a try header line followed by a block of indented statements, then the finally clause that always runs on the way out whether an exception occurred while the try block was running or not.

An example of try, except, else functions follows:

try:
   statements
except name:
   statements
except name, data:
   statements
else
   statements

For example:

try: myfunction() except: import sys print 'uncaught exception', sys.exc_info() try: myfilereader() except EOFError: break else: process next line here

The general format of a try and finally looks like the following:

try
   statements
finally
   statements

For example:

def divide(x, y):
   return x / y

def tester(y):
   try:
      print divide(8, y)
   finally:
      print 'on the way out...'
The following is a list of syntax rules in Python:
  • Statements run sequentially by default. Statements normally end at the end of the line on which they appear. When statements are too long to fit on a single line you can also add a backslash (\) at the end of the prior line to indicate you are continuing on the next line.
  • Block and statement boundaries are detected automatically. There are no braces, or begin or end delimiter, around blocks of code. Instead, the Python language uses the indentation of statements under a header in order to group the statements in a nested block. Block boundaries are detected by line indentation. All statements indented the same distance belong to the same block of code until that block is ended by a line less indented.
  • Compound statements = header; ':', indented statements. All compound statements in the Python language follow the same pattern: a header line terminated with a colon, followed by one or more nested statements indented under the header. The indented statements are called a block.
  • Spaces and comments are usually ignored. Spaces inside statements and expressions are almost always ignored (except in string constants and indentation), so are comments.

Calling scripts using another script

Use the execfile command to call a Jython script from another Jython script. For example:

Create a script called test1.py that contains the following:

[AIX Solaris HP-UX Linux Windows]
execfile('c:/temp/script/testFunctions.py')
print printName('Cathy', 'Smith')

Create a script called testFunctions.py that contains the following:

def printName(first, last):
   name = first + ' ' + last
   return name

Then pass the following path as a script argument:

[AIX Solaris HP-UX Linux Windows]
wsadmin -lang jython -f 'c:/temp/script/test1.py'

You must use forward slashes (/) as your path separator. Backward slashes (\) do not work.

Running Jython scripts that use packages

If you run scripts that use packages, you must provide the wsadmin tool with the search path for the Jython scripts that use packages.

To provide this information to the wsadmin tool, include the following option when you start the tool:

-Dwsadmin.script.libraries.packages=path1;path2;...

where dir1 and dir2 represent the directory search paths for libraries containing the Jython packages.

[Windows]

Jython usage with Microsoft Windows directories

Jython treats the following list of characters or conditions as special. Do not use the characters, if possible, when using Jython.

  • \a
  • \b
  • \f
  • \n
  • \N
  • \r
  • \t
  • \u
  • \U
  • \v
  • \x
  • a backslash followed by a sequence of numbers between 0 and 7

When specifying Microsoft Windows file paths in Jython you must be aware of these special conditions. When you must use any of these character strings, you can counteract the Jython interpretation of these special character strings by using either "two backslashes" instead of one backslash or by substituting a forward slash for the single backslash. The following examples illustrate how to make these adjustments.

Table 1. Jython file path specifications. Use \\ or / for directory separators in Windows file paths.
Erroneous Path Corrected Double Backslash Path Corrected Forward Slash Path
c:\aadirectory\myfile.txt c:\\aadirectory\\myfile.txt c:/aadirectory/myfile.txt
c:\myfiles\number1.txt c:\\myfiles\\number1.txt c:/myfiles/number1.txt
c:\zebra7\stripe.txt c:\zebra7\\stripe.txt c:/zebra7/stripe.txt
c:\5mod\Net33\residue.log c:\\fivemod\\Net33\\residue.log c:/fivemod/Net33/residue.log
Avoid trouble: In general, try to use the forward slash where possible in specifying directory paths in Jython. The forward slash avoids many of the problems associated with using the backslash.