New page: {{ScoutPage|cat=Tutorial 3.9}} == Introduction == With Release 3.8 the Scout SDK offers support to integrate external JAR files into a Scout application with a few clicks. In this tutori...
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{{ScoutPage|cat=Tutorial 3.9}}
== Introduction ==
With Release 3.8 the Scout SDK offers support to integrate external JAR files into a Scout application with a few clicks. In this tutorial we use this capability to demonstrate how [http://jython.org/ Jython] may be integrated in your Scout application.
According to the [http://wiki.python.org/jython/ Wiki] ''"Jython is a Java implementation of [http://python.org/ Python]"'' and Python itself claims ''"You can learn to use Python and see almost immediate gains in productivity and lower maintenance costs."'' In any case, we need an example library here and combining Java with a powerful scripting language can help to solve a significant variety of problems.
The result at the end of this tutorial will look similar to the screenshot below:
[[Image:Jython_integration.png]]
== Building the Jythonlib.jar ==
For this example we need the jython.jar library extended with the set of the Python standard modules typically provided in the ''Lib'' folder. After downloading jython from the [http://www.jython.org/downloads.html official download page] and installing it to some arbitrary directory you should find the following two items:
* jython.jar
* Lib
Now we are ready to build our '''jythonlib.jar''' according to the [http://wiki.python.org/jython/LearningJython#add-jython-install-stuff-to-our-jar description provided] in the jython Wiki (in case the description moves to some other location it is repeated below):
To build our jar, we first make a copy of jython.jar, then add the
contents of the ''Lib/'' directory (eg Lib/re.py) to it:
$ cd $JYTHON_HOME
$ cp jython.jar jythonlib.jar
$ zip -r jythonlib.jar Lib
== Create New Scout Project and add the Library bundle ==
Create a new Scout project as described in the [[{{BASEPAGENAME}}/HelloWorld|Hello World tutorial]] with the following differences:
* Use ''org.eclipse.scout.jythontest'' as the project name.
* Don't (yet) add any form fields
Once the application model is shown in the Scout Explorer we can add the library bundle. To keep things as simple as possible in this example, we directly use the jython library in the client application. For this, select folder ''libraries'' below the orange client node in the Scout explorer. Then right-click on context menu ''New Library Bundle ...''
[[Image:Sdk_new_library_1.png ]]
In the first dialog of the ''New Library Bundle'' wizard click on the ''Add'' button to select the jythonlib.jar file that we created above (in this step, one or several libraries may be assinged to a new bundle). That's it, we can now click on ''Finish''. The curious reader can click on ''Next'' to see the second dialog of the wizard. For this tutorial all the filled-in default values make sense and don't need to be changed, so please click ''Finish'' now.
[[Image:Sdk_new_library_2.png ]] [[Image:Sdk_new_library_3.png ]]
Behind the scenes the Scout SDK wizard has created the plugin ''org.eclipse.scout.jython.jythonlib'' and added it as a required dependency to the client plugin ''org.eclipse.scout.jython.client'' with the result that we can now access all elements in our jythonlib.jar as if it were part of the client bundle.
== Add and Configure the Form Fields on the Desktop Form ==
In the Scout Explorer expand the ''DesktopForm'' in the folder ''Forms'' below the orange client node and select the ''MainBox'' element.
* In the Scout Object Properties of the ''MainBox'' Set the ''Grid Column Count'' attribute to 1.
* On the ''MainBox'' in the Scout Explorer use context menu ''New Form Field ...''
* Type ''Group box'' in the dialog's seach field and click ''Next''
* In the field ''Class name'' enter '''DesktopBox''' and click on ''Finish''
Inside the ''DesktopBox''
* Add a String field "Line" (double click on ''New Translated Text ...'' in dropdown field to add the proper text translations)
* Add a String field "Python"
* Add a Sequence Box with ''Class name'' "VariableBox"
* Add a String field "Result"
Inside the ''VariableBox'' add the following UI components
* Add a String field "Input"
* Add a String field "Output"
* Add a Button "Run"
Now configure the "Python" field
* In the Scout Object Properties set ''Grid H'' to 5
* Select attribute ''Multiline Text''
* Open section ''Advanced Properties''
* For the ''Tooltip Text'' insert the following text (using PythonExample as key)
* Set the attribute ''Background Color'' to E1EAFF (or use the color picker)
* For attribute ''Font'' select Courier New
Finally, for the "Result" field
* Set the "Grid H" property to 3
* Select attribute ''Multiline Text''
== Add Logic for Jython Interpreter and Interaction with Scout Form ==
# In the Scout Explorer select the ''RunButton'' element of the ''DesktopForm''
# In the Scout Object Properties click on the green plus-icon next to the link ''Exec Click Action'' to add the corresponding method
# Replace the proposed implementation with the code provided below
Remarks:
* Updating the ''sys.path'' should conceptually go to a place such that it is called once per client startup.
* There might be more elegant ways to ensure Jython is able to access the Python modules provided in the ''Lib'' subfolder of the ''jythonlib.jar''.
== Play around ==
In the Scout SDK do the following
# Select top level element ''org.eclipse.scout.jythontest'' in the Scout Explorer
# Start the server by clicking on the corresponding icon in the server box of the section ''Product Launchers''
# Start a client by clicking on corresponding icon in a client box (Swing, SWT, or RAP)
# The client starts and the desktop form is shown
In the Application do the following
# Enter some text into the ''Line'' field. For example '''hello world'''
# Enter a python script into the ''Python'' field. Example script:
Add the Binding Names for Input and Output
# In field ''Input'' specify the Python variable representing the text in the ''Line'' field. For the example above, use '''input_line'''
# In field ''Output'' specify the Python variable holding the output of the Python script. For the example above, use '''output_text'''
# Click on ''Run''. The content of the output variable defined above is transferred to the form field ''Result''