Package org.oddjob.state

Class IfJob

java.lang.Object
org.oddjob.framework.extend.BaseComponent
org.oddjob.framework.extend.BasePrimary
org.oddjob.framework.extend.StructuralJob<Object>
org.oddjob.state.IfJob
All Implemented Interfaces:
Serializable, Runnable, ArooaContextAware, ArooaSessionAware, Forceable, PropertyChangeNotifier, Iconic, LogEnabled, Resettable, Stateful, Stoppable, Structural
public class IfJob extends StructuralJob<Object> implements Runnable, Stateful, Resettable, Structural, Stoppable
Author:
Rob Gordon
See Also:

Description

This job implements an if/then/else logic based on job state. This job can contain any number of child jobs. The first provides the state for the condition. If this state matches the given state, the second job is executed. If it doesn't, then the third job is executed, (if it exists).

The completion state is that of the then or else job. If either don't exist then the Job is flagged as complete.

If any more than three jobs are provided the extra jobs are ignored.

If the first job enters an ACTIVE state then condition will not be evaluated until the first job leaves the ACTIVE state. This job will not block while this is happening. The thread of execution will pass to its next sibling and this job will also enter the ACTIVE state.

Example

If a file exists. 

<oddjob id="this" xmlns:state="http://rgordon.co.uk/oddjob/state">

    <job>

        <state:if>

            <jobs>

                <exists name="Check File Exists" file="${this.dir}/data/some.txt"/>

                <echo id="then" name="Echo to Console">File Exists</echo>

                <echo id="else" name="Echo to Console">File Doesn't Exist</echo>

            </jobs>

        </state:if>

    </job>

</oddjob>
An example showing lots of if's. All these if's go to COMPLETE state when run. 

<oddjob>

    <job>

        <sequential xmlns:state="http://rgordon.co.uk/oddjob/state">

            <jobs>

                <state:if>

                    <jobs>

                        <echo>Hello</echo>

                        <echo>Good Bye</echo>

                    </jobs>

                </state:if>

                <state:if>

                    <jobs>

                        <state:flag name="Exception" state="EXCEPTION"/>

                        <state:flag name="Unexpected 1" state="EXCEPTION"/>

                        <echo>No Hello</echo>

                    </jobs>

                </state:if>

                <state:if>

                    <jobs>

                        <echo>Only Hello</echo>

                    </jobs>

                </state:if>

                <state:if state="!COMPLETE">

                    <jobs>

                        <state:flag name="Exception" state="EXCEPTION"/>

                        <echo>No Hello</echo>

                    </jobs>

                </state:if>

                <state:if state="!COMPLETE">

                    <jobs>

                        <echo>Hello</echo>

                        <state:flag name="Unexpected 2" state="EXCEPTION"/>

                    </jobs>

                </state:if>

                <state:if state="!EXCEPTION">

                    <jobs>

                        <echo>Hello</echo>

                        <echo>Good Bye</echo>

                        <state:flag name="Unexpected 3" state="EXCEPTION"/>

                    </jobs>

                </state:if>

            </jobs>

        </sequential>

    </job>

</oddjob>
Asynchronous evaluation. Only when the first job moves beyond it's ACTIVE state will the condition be evaluated and the then job (second job) be executed. The execution of the second job is also asynchronous. 

<oddjob>

    <job>

        <state:if id="if-job" xmlns:state="http://rgordon.co.uk/oddjob/state">

            <jobs>

                <parallel>

                    <jobs>

                        <state:flag/>

                    </jobs>

                </parallel>

                <echo id="then-job">That Worked!</echo>

                <echo id="else-job">This should never be shown.</echo>

            </jobs>

        </state:if>

    </job>

</oddjob>