The Shale Dialog Manager defines a generic API by which an application may utilize a Dialog Manager implementation to manage conversations with the user of that application. A user may have (at most) one active conversation in each window or frame that he or she is using.
This module contains the Basic Implementation of the Shale Dialog Manager facilities. It is designed to be as simple as possible to configure and use, while encapsulating advanced state management capabilities. It is fundamentally similar in in configuration and use with the legacy Dialog Manager support in Shale versions up through 1.0.3, but many bugs and limitations of the original code have been corrected.
Conceptually, a dialog can be thought of as a set of labelled states, connected by labelled transitions between those states. Indeed, a UML State Diagram is a popular way to represent the architecture of such a dialog. Each dialog has a specified starting state (with an automatic transition to this state when the dialog is first started), and one or more ending states.
Shale supports four state types, with specific implementations realized as described below.
ViewControllerbean that you've associated with the current page) is used to drive the transition to the next state, as described below.
It is not required that all JavaServer Faces
interactions be organized into dialogs -- you can have a mix of
dialog and standard navigation processing. Indeed, to enter a
dialog in the first place, simply have one of your standard action
methods return a logical outcome of dialog:xxxxx,
which will cause the dialog named
xxxxx to be entered
at its starting state. Once that dialog completes, standard
JavaServer Faces navigation will resume.
The configuration of a Dialog is represented as a tree of
JavaBeans defined in the
package, rooted at an instance
Dialog. The set of
Dialog instances is stored in a
keyed by dialog identifier, which is stored in an application scope
attribute named by symbolic constant
Dialog instances may be configured by any desired
mechanism; however, the most commonly used will likely be an XML
document that conforms to a DTD provided by Shale.
To use the Dialog Manager facilities in Shale, take the following steps:
ViewControllerbeans, if you are also using the Shale View Controller Support functionality) that comprise your dialog, using standard JavaServer Faces and (optional) Shale
/WEB-INF/dialog-config.xml, that conforms to the required DTD, which defines all the state transitions:
<!DOCTYPE dialogs PUBLIC "-//Apache Software Foundation//DTD Shale Dialog Configuration 1.1//EN" "http://shale.apache.org/dtds/dialog-config_1_1.dtd"> <dialogs> <dialog name="First Dialog Name" start="Start State Id"> ... <action/>, <view/>, <subdialog/>, and <exit/> elements for states ... </dialog> <dialog name="Second Dialog Name" start="Start State Id"> ... <action/>, <view/>, <subdialog/>, and <exit/> elements for states ... </dialog> ... </dialogs>
<context-param> <param-name>org.apache.shale.dialog.basic.CONFIGURATION</param-name> <param-value>/WEB-INF/foo.xml,/WEB-INF/bar.xml</param-value> </context-param>
/WEB-INF/dialog-config.xmlwill be automatically processed, if it exists, and has not already been loaded.
/WEB-INF/libwill be scanned for configuration documents at
META-INF/dialog-config.xml. Such resources will be automatically processed, making it easy to define JAR files with dialog configurations and corresponding Java classes and resources, which are recognized simply by including this JAR file in the application.
<context-param> <param-name>org.apache.shale.dialog.basic.STRATEGY</param-name> <param-value>xxxxx</param-value> </context-param>
The possible strategy values, and the use cases under which they are appropriate, are as follows:
dataobject associated with this dialog instance is not saved and restored. This works best in cases like a multi-page wizard dialog that is collecting data, where resubmitting the same page again only mutates the state within the
dataobject, and does not cause any undesireable changes to the model state of the application (such as submitting a credit card order more than once). This strategy can not effectively deal with cases where the user has navigated across the start or end of a subdialog, so an exception will be thrown in that scenario.
Positioninformation for the current dialog instance, including any changes to the
dataobject. This strategy is best used when you want, when the user presses the back arrow, to "unwind" any changes that the previous form submit did to the
dataobject. This strategy stores the maximum amount of information in the JSF component tree state, so it might have significant memory or network traffic impacts if the size of your
dataobject is large.
immediateattribute set to
true, to allow the user to get out of a dialog where they have mistakenly tried to submit the same form more than once.