IvyScript Language

The Ivy scripting language IvyScript provides elements to write simple computational expressions but also more complex elements to program conditional-, loop- and exception handling blocks.

The Ivy Script Data Types are defined for easy use. Especially, IvyScript bewares the programmer from null pointer exceptions because ivy data objects are automatically initialized to a default value. Read the section Null handling / Automatic object creation for more details.

IvyScript can also directly manipulate Java objects in an easy way. Thus Java objects can be used without mapping and auto-casting simplifies the usage.

Language Elements

Conditions

Conditional expressions

Java style

cond ? ifExpr : elseExpr

Function style

IF (cond, ifExpr, elseExpr)

Conditional statements

if (cond) { ... } else { ... }

Loops

for

for (init; cond; increment)
{
// do something here
 ...
}

for (element: list)
 // do something here
...
}

while

while (cond)
{
 // do something here
...
}

Exception Handling

IvyScript supports the try/catch/finally construct to handle exceptions that happen while executing external Java code.

try
{
// some code here
...
}
catch (Exception ex)
{
// compensate code
...
}
finally
{
// some code that is executed regardless of whether exceptions occurred
...
}

Null handling / Automatic object creation

IvyScript supports auto-initialization of the ivy basic types, i.e. you don’t have to create/initialize fields or variables explicitly with new after declaration. Strings are initialized to an empty String, Numbers to zero, Lists to an empty List.

Ivy composite types (ivy Data Classes) are automatically created. Due to that automatic object creation, a null check expression like if(in.customer == null) is always false.

You can use the .# operator to suppress the automatic object creation.

if (in.#customer == null)
{
  // object is null
}

if (in.#customer is initialized)
{
  // object is not null or has been set to a non-default value
}

Note

Any fields or variables of Java classes are also created automatically if they’re referenced for the first time and if the type has a default constructor. Interface types and abstract class types are not auto-created because no instances can be created of such types in Java.

Note

Inside IvyScript it is generally recommended to use is initialized rather than comparing against null with the == operator. Because Java types may be null and IvyScript base types never, this operator will always ensure the correct checking depending on the type of the tested object.

Axon.ivy also supports auto-initialization of AXIS types:

org.apache.axis.types.Time to '00:00:00'
org.apache.axis2.databinding.types.Time to '00:00:00'
org.apache.axis.types.Duration to 'PT0S'
org.apache.axis2.databinding.types.Duration to 'PT0S'

A java.util.Date is auto-initialized to a default value of '0001-01-01 00:00:00'.

However, you do not have to compare the values of those types against hard coded default values in your code, simply use is initialized to find out if a value has been changed by the user or still bears the default value.

if (webserviceData.caseDuration is initialized)
{
  // do something
   ...
}