Add GUI to WAS Python Scripts

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WebSphere® Support Technical Exchange

Adding a Graphical User Interface to your WebSphere Application Server Jython Scripts with SwingBob Gibson <[email protected]>Advisory Software Engineer8 November 2011

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WebSphere® Support Technical Exchange 2 of 43

Agenda

Intentions Starting simple Challenges and opportunities Jython advantages Using rapid prototyping Putting things together

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Background / impetus: ugly is easy

With little effort, we can show what ports are in use: print AdminTask.listServerPorts( 'nodeagent' )

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A simple script to show port numbers

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Simple text input / output: … a little harder

Text output is relatively easy, but user hostile

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Swing is all about Input & Output

High level presentation object include:Trees, Tables, and Lists

Low level presentation objects includeLabels, fields, text areasradio buttons, check boxes, sliderstrees, tables, buttons, images

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Components and containers

Most swing objects are components Some components are also containers Component class names start with J

Note: In order to be seen, a component must be within a container

Top level containers: heavyweightJFrame, JApplet, JWindow, JDialogCan’t be put into other containers

Lightweight containers: used to group components

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Good news / bad news

Good news:There are lots of swing books, articles,

tutorials, demonstration applications, web sites, and documentation

Bad news:Not all of the examples you see are good“Best practices” have changed (somewhat)

over time

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Learning to use swing

Look for swing examples, demos, tutorials Practice converting Java™ swing apps to Jython

Read, study, experiment (play), repeat Things to consider:

Some examples derive from ActionListenerJython doesn’t have anonymous inner classesSome examples don’t use dispatch thread

Note: Be prepared for bad examples

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A trivial Jython swing application

import the required Java & Swing classes Define our application class Define a Runnable class Use SwingUtilities.invokeLater() for thread safety

(to use dispatch thread cycle)Notes:

Application class is derived from JFrame Our class is instantiated by a Runnable class We need to keep script running (raw_input())

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Trivial Jython swing application (cont)

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Trivial application – what it can do

This application can already be:MovedResizedMaximizedMinimizeRestored, andClosed (terminated)

All of this with no additional code!

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Do we really need to invokeLater?

Swing applications are event drivene.g., keystrokes & mouse clicks

Events are generated and passed to the application

Events are received and processed by event handlers

Event handlers are executed on the event-dispatch thread, not your application thread

So, our applications should be implemented accordingly

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Challenges (part 1)

Fight the temptation to throw things together

Try to avoid the urge to keep everything in 1 class

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Opportunities

Jython scripts have complete access to all of the Java Swing object / classes / components

Converting Java Swing examples to Jython can be quite simple (as long as you can read & understand Java)

Remember:Jython isn’t strongly typed like JavaUnlike Java, Jython object attributes aren’t

fixed; we can add to, and remove from them

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Simple Button Example

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More challenges and opportunities Often, there are many ways to do something

e.g., Positioning application window using AWT

vs. using a possibly obscure method

There are many, many more examples

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Some Jython advantages

Java frequently requires many statements:

Jython lets us do more things at once:

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Positioning components

Given a container (e.g., JFrame), and some number of components, how do we position them?

By selecting a Layout Manager for the container

LayoutManager DescriptionFlowLayout Positions components left-to-right, top-to-bottomBorderLayout Positions components within the center or the borders of the

container (default)

GridLayout Lays out components within a gridBoxLayout Lays out components vertically or horizontally within a boxSpringLayout Lays out components subject to a set of constraints

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Layout can be somewhat …challenging

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Where were we?

Initial ideaDisplay AppServer port numbers using a GUI

Where should we start?How can we show the server in our cell?One way is to use a tabbed paneWhat would that look like?

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Using JTabbedPane

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What have we learned?

Advantages:Simple to implementJTabbedPane allows easy traversal using keys

DisadvantagesFor anything other than a simple (small) cell,

it’s easy to get lots (too many) tabsThe relationship between servers isn’t obvious

Can we display the cell hierarchy in a tree form?

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Using JTree to show the cell hierarchy

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JTree: Pro & Con

AdvantagesSimple to implementCell hierarchy maps well to this formatBuilt in keystroke traversalWrapping the JTree in a Scrolled Pane allows

for large cells to be displayed easily Disadvantages

You may not like the default JTree attributes

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Where do we show Server port info?

We can have the JTree shown on a split pane In the other side, we can decide what to display

For branch nodes (i.e., “cell” and “node”), we have to decide what we want to display

For servers, we can show a table containing the port details

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Adding a SplitPane

Start by showing the tree in the left pane:

Note: We don’t want multiple entries selectable

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How do we display port number info?

JTable is very function rich Swing component What do we need to do?

Instantiate it using two arraysData: 2 dimensional array of valuesColumn Headings: An array of strings

table = JTable( data, headings )

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Simple JTable to display port info

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JTable: Built in features / attributes

Editable cells Resizable:

Columns (width)Frame (width / height)

Draggable:Columns (position)

Cell selectable using keystrokes or mouse clicks Note: Use of DefaultTableModel

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With great power …

You can control things (e.g., size & resizing),col.setMinWidth( width )

col.setMaxWidth( width )

col.setPreferredWidth( width )

table.setAutoResizeMode( JTable.AUTO_RESIZE_OFF )

The number of selectable rows, table.setSelectionMode( ListSelectionModel.SINGLE_SELECTION )

Or columns, or just cells…table.setRowSelectionAllowed( BOOLEAN )

table.setColumnSelectionAllowed( BOOLEAN )

table.setCellSelectionEnabled( BOOLEAN )

And lots, lots more…

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comes great responsibility …

We have the ability to:Make only certain cells editable (e.g., port #)Fix column width, and positionMaybe even allow columns to be sortedDo we want to provide ways to filter the data

differently?

• Perhaps, but we don’t have time here

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For example

JTables have many properties… AutoResizeMode can be set to one of:

AUTO_RESIZE_OFFAUTO_RESIZE_NEXT_COLUMNAUTO_RESIZE_SUBSEQUENT_COLUMNSAUTO_RESIZE_LAST_COLUMNAUTO_RESIZE_ALL_COLUMNS

What does this really mean? Let’s find out

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JTable AutoResize example

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Table models

The table model used to create a JTable defines how the table may be used

You may want to define one for your application For example, to:

Define column widths,Prohibit column movement,Restrict cell editing,Define how cells should be displayed

(rendered)

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Table models (cont)

For an application with many similar tables, models can make life easy

Creating a class descending from TableModel lets us:Have all tables look and act the sameLocalize all of the table settingsExperiment with our settings easily

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An application (prototype)

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Are we done yet?

No! There is lots of room for improvement

Event Handler does too much & is too slowShouldn’t be able to select a server until the

port information is already availableWidths (e.g., column, table) are hard codedCurrently: no config changes are made

Are we ever done? … it depends ;-)

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Is it worth the time and effort?

Yes! Rapid prototyping can be quick and easy

Jython + swing lets us test to learn as we goWe can see the implications of our choices

Interaction with WebSphere configuration and environment is easy

Jython is easy to read and understand Iterative improvement is easy

Build the application & testing it as we go

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Summary

Graphical, event driven, applications are possible with Jython

Jython applications can access and use WebSphere administrative objects easily

Jython applications can access and use Java objects easily

Rapid prototyping allows us to determine where to spend our design, development, and testing time

wsadmin + Jython + Swing is a big win!

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Add GUI to WAS Python Scripts