Contextual Events Hands On

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ADF Hands-On

Contextual Events

Abstract:

Contextual Events is an ADF Framework feature that

allows developer to etsablish communication between two

independent ADF Region. In this hands-on you create a

contextual event between a region displaying a DVT

graph component and a region displaying a table. You will

set up the contextual event manually on the binding layer

and also write some Java code that helps preserving the

default click behavior on the graph.

Duration: 45 minutes

2010 / 2011

ADF Internal Enterprise 2.0 Training

ADF HANDS-ON Contextual Events

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Introduction The contextual events framework in Oracle ADF defines a publish / subscribe mechanism that

leverages the ADF binding layer to notify ADF Regions about user interaction performed in other

regions, the parent page or a ViewPort (page fragment). Oracle JDeveloper provides declarative

help to setup contextual events for input and action components, but not yet for DVT components

like graphs. Setting up a data visualization component (DVT) to publish contextual events is more

challenging than from an input text field or a table, but it is a good use case to understand how

contextual events work.

The image below shows the application you build in this hands-on. The DVT graph component is

selectable and allows users to click on the graph bars. Clicking on a bar does set the current row

on the underlying ADF binding, making sure the read only form displays the detail information for

the selected bar. At the same time, a contextual event is raised and published to the ADF Region

containing the employee table. The contextual event payload allows a managed bean to access

the selected department Id and query the business service for employees working in it.

Note: This hands-on is created to focus on the ADF Contextual Event functionality. The UI is

functional and no time is spend on making it look beautiful.

Prerequisite and Setup

This hands-on requires a database to be available that has the HR schema installed and enabled. The

Oracle XE and Oracle enterprise database both have this schema available and no scripts need to be run.

The Oracle JDeveloper 11g starter workspace is contained in the ContextualEvent.zip file. Open the zip

file and extract its content to a local directory on your computer.


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Open Oracle JDeveloper and choose Application | Open from the file menu. Navigate to the folder you

extracted the zip file to and select ContextualEvent| ContextualEvent.jws

To change the RDBMS connection, select View | Database | Database Navigator from the Oracle

JDeveloper menu. Select the database connection node in the "ContextualEvent" node and use the right

mouse context menu to edit its properties and change the connect information.

Setting up Contextual Events between two Regions

Using ADF, the business service implementation technology is not really important to know about for the

application developer. What's important is the functionality and data exposed by the business service as it

is displayed in the Data Controls panel.

In this hands-on we use ADF Business Components as a business service. The ADF BC model exposes

two collections (View Objects) to query a list of departments and employees. The employee list is filtered

by a View Criteria that reads the department Id from a bind variable.

To shorten the time it takes to build the hands-on sample, the two bounded task flows and managed

beans were pre-created. In addition, a Java class is provided in the adf.sample.view.ctx package that

receives and handles the event broadcasted by the event producer.

In the first section of this hands-on, you set up the contextual event producer, consumer and the event

mapping. In the second part, you go advanced and invoke the contextual event from Java.

1. Expand the adf.sample.view.pageDef package and select the BrowseDepartmentsPagedef.xml file,

which is the ADF binding file of the page fragment containing the DVT graph component. The ADF

binding file will become the event producer


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2. Open the Structure Window (ctrl+shift+S)

3. Select the "bindings" node and choose Insert inside bindings | Generic Bindings | eventBinding to

create a new ADF event entry

4. Select the eventBinding entry you just created and choose Insert inside eventBinding | events from the

context menu. An event binding can contain multiple events that can be mapped to different event

consumers.


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5. Select the "events" node and use the right mouse to open the context menu

6. Choose Insert inside events | event from the menu to create a new event item

7. Type "ChartEvent" as the event name into the opened dialog


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8. Open the Property Inspector with the "ChartEvent" event selected in the Structure Window. The event

properties include "customPayLoad" and "raiseCondition".

The "customPayLoad" property allows developers to pass information other than what is contained in the

event object to the event handler. The custom payload data can be read from the binding layer, a managed

bean or a memory scope using Expression Language.

The "raiseCondition" provides control over when the event should be broadcasted to avoid unnecessary

and unwanted invocations.

9. Select the "eventBinding" node

10. The "id" property is accessible from EL and Java, as we show later. For now, just set it to

"ChartDrillEvent"

11. In the "Listener" property field, type

oracle.adf.view.faces.bi.event.ClickListener

Its the listener class that matches the click event of the DVT component that is used in this hands-on to

invoke the contextual event producer


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12. To configure the contextual event consumer, expand the adf.sample.view.ctx.handler package in the

JDeveloper Application Navigator

13. Select the "ContextualEventHandler.java" file and choose "Create Data Control" from the right

mouse context menu.

Contextual events are ADF binding events, which mean that event producers and event receivers must be

exposed on the ADF binding. To do so for the event handler, it must be exposed by a Data Control, the

JavaBean Data Control in this case

14. After the DataControl configuration is generated by Oracle JDeveloper, double click the

ContextualEventHandler.java file to open it


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15. The handleEvent(Object payload) method received the click event broadcasted by the contextual

events. At runtime, the class is loaded in the context of the employees task flow and therefore has access

to the managed beans defined on this task flow. It uses this reference to invoke a method on the

"employeeBackingBean" to re-query and refresh the employees table.

16. Select the "BrowseEmployeesPageDef.xml" file in the adf.sample.view.pageDef package.

17. Open the Structure Window (ctrl+shift+S)

18. Select the "bindings" node and choose Insert inside bindings | Generic Bindings | method Action

from the right mouse context menu

19. Select the "ContextualEventHandler" Data Control.

20. Ensure the "handleEvent(Object)" method is selected

21. Press "Ok"


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22. Double click onto the "ParentContainer.jspx"

23. Drag the "dvt-task-flow-definition.xml" task flow from the Application Navigator and drop it into the

first facet of the Panel Splitter component in the ParentContainer.jspx file


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24. In the opened menu, select "Region" to create a static ADF Region

25. Drag the "employees-task-flow-definition.xml" task flow from the Application Navigator and drop it

into the second facet of the Panel Collection in the PanelContainer.jspx file

26. Select "Region" in the opened context menu to create a static ADF Region

27. The employees task flow requires an input parameter for the initial query of the employees. Click into

the parameter field


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28. and type 10

29. Press OK. When the task flow loads the first time, its page fragment shows a list of employees

working in department 10

30. Select the ParentContainerPageDef.xml file in the adf.sample.view.pageDefs package

31. Open the Structure Window


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32. Select the top node entry and choose Insert inside ParentContainerDef | eventMap from the right

mouse context menu. This creates the ADF binding entry to map the event produces with the event

receiver

33. Select the ParentContainerDef root entry again and choose "Edit Event Map" from the right mouse

context menu

33. In the opened Event Map Editor, press the green plus icon to create a new event mapping


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34. Expand the producer list box

35. Select the BrowseDepartmentsPageDef.ChartDrillEvent entry and double click on it to close the list


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36. The Event Name is automatically added as there is only a single event defined in this binding

37. Expand the Consumer list and select the "BrowseEmployeesPagedef.handleEvent" entry

38. Press the green plus icon to create a new entry in the Consumer Params

39. Define a new parameter with the Param Name payload and the Param Value ${payLoad}. Note that

the parameter name "payload" matches the name of the argument in the event handler method. The

${payload} EL access the event message, which is the event object if no custom payload was defined.


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40. Press Ok to close the dialog

41. Press OK to finish the event mapping configuration


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42. Select the DVT graph component in the BrowseDepartments.jsff page fragment. You can do this in

the visual page editor as shown below, or in the Structure Window after selecting the page fragment

43. Open the Property Inspector (ctrl+shift+I)

44. In the Property Inspector, note the current Expression Language string added to the "ClickListener".

When creating a DVT component graph, you can check a checkbox to make a click on a bar in the graph

to mark the underlying row as selected in the ADF binding. In response to checking the check box, the

EL string is added to the Click Listener property.

45. Select the Expression Language string as shown in the image below and copy it into the clipboard for

later use. To invoke a contextual event in response to a user clicking onto a bar in the graph, while

preserving the configured behavior to mark the underlying row as current in the binding, you will replace

the EL string with a managed bean method reference.


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46. Click the arrow icon next to the "ClickListener" property field and choose "Edit" from the context

menu.

47. Select the departmentBackingBean entry


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48. Press the "New" button to create a new managed bean method to handle the DVT click event

49. Name the method as "onGraphClick"

50. Press OK twice

51. Double click onto the DepartmentBackingBean.java file to open it in the code editor.


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52. To preserve the default behavior, use the EL you saved to the clipboard and invoke it from Java. For

this type the following code into the "onGraphClick" method body

invokeDefaultClickEvent(

"#{bindings.allDepartmentsWithEmployees.graphModel.processClick}",

clickEvent);

53. Next, add code to invoke the contextual event

54. Type or copy the following code lines into the method


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BindingContext bctx = BindingContext.getCurrent();

BindingContainer bindings = bctx.getCurrentBindingsEntry();

JUEventBinding eventBinding = null;

//get a handle to the eventBinding

eventBinding = (JUEventBinding) bindings.get("ChartDrillEvent");

ClickListener cl = (ClickListener)eventBinding.getListener();

cl.processClick(clickEvent);

Note: Oracle JDeveloper needs to import classes for the code to work. Either manually import the

classes, or copy and paste the following lines to the top of the Java file (but still below the package name)

import oracle.adf.model.BindingContext;

import oracle.adf.view.faces.bi.event.ClickListener;

import oracle.binding.BindingContainer;

import oracle.jbo.uicli.binding.JUEventBinding;

The code lines above access the ADF Binding Context to access the Binding Container at runtime. It then

looks up the "ChartDrillEvent" binding to access and invoke the ClickListener

55. Select the PageContainer.jspx file and choose "Run" from the right mouse context menu


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56. In the opened page, click onto a graph bar and watch the read only form and the table refreshing.

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