Data Adaptor - Sample Code (Autosave with Derby)

The sample Autosave scenario in this example does the following:

During the investigation of a goal, as the user answers questions the DataAdaptor 'save' function is called to save after each screen
After completing the investigation of the goal, the DataAdaptor 'save' function is called to save
An ID is automatically created for the user when he/she starts the Web Determinations Interview
The DataAdaptor 'save' function saves all the attributes that has an instance value provided by the user

The sample code demonstrates

How to setup an Event Handler to handle events (for this scenario, to handle Events fired when the user answers a question, and completing a goal)
Calling the DataAdaptor functions from an Event Handler
The Event Handler need to have access to the SessionContext (Platform Events) to provide the necessary input arguments for DataAdaptor save() (case ID and InterviewSession)
Using an Event Handler and Data Adaptor together to implement 'autosaving' functionality during a Web Determinations Interview

The sample code provides functionality for requirements such as the need to be able to autosave based on triggers.

Setup

This sample code needs the following to run:

DerbyAutoSave plugin
ExtFrameworkAutoSave (rulebase)
DERBY SQL database (examples\web-determinations\auto-save\src\create_db.sql

Further information about the DERBY database can be found at http://db.apache.org/derby

About the DERBY SQL database schema

The DERBY SQL database is created by using create_db.sql which is located in examples\web-determinations\auto-save\src.

AUTOSAVE
ID
age
income
old
low_income
old_low_income
eligible

About the Plugins:

The Event Handler that triggers the Data Adaptor to save is the AutosaveTrigger,
- The AutosaverTrigger handles the OnGetScreenEvent and OnInvestigationEndedEvent (both Events are a Platform event and thus has access to SessionContext - see Events and Event Handlers)
- The AutosaverTrigger handles both Events by implementing the EventHandler interface for both events.
- It needs to handle both Events because:
  - The OnGetScreenEvent calls the handler for each event. To prevent the handler from calling the Data Adaptor save() outside of an investigation (for example, Summary screen, Data Review), the handler only calls the Data Adaptor save() for OnGetScreenEvents when a goal is currently being investigated
  - With the restriction of a goal needing to be investigated, the Data Adaptor save() is not called when the investigation ends, thus failing to save the user's answers in the last Question screen
  - The OnInvestigationEndedEvent is useful for this issue - it calls the handler only when an investigation is finished, and thus saving the user's answers in the last question screen
The Data Adaptor that handles the save functionality is the AutosaveSaver, and it saves onto the DERBY datasource
The DataAdaptor and Event Handler plugins are configured to work on a rulebase named 'ExtFrameworkAutoSave'.

To setup this scenario:

Create the SQL Database using create_db.sql which can be found in examples\web-determinations\auto-save\src
Copy the rulebase .zip file (ExtFrameworkAutoSave.zip) from examples\rulebases\compiled to the rulebase folder in Web Determinations (for example, <webroot>\WEB-INF\classes\rulebases)
Copy and install the DerbyAutoSave.jar file (located in examples\web-determinations\auto-save) into Web Determinations; for more information, refer to Create a Plugin
Copy the DERBY libraries to the library folder in Web Determinations (for example, <webroot>\WEB-INF\lib)
Ensure that DERBY is run in network server mode
Run a Web Determinations Interview

Note:

If you need to modify the database connection details or you need class files for your specific database implementation, then you will need to edit the source code, recompile and JAR the DerbyAutoSave.

How the Autosave works

The autosave functionality happens:

After every investigation question screen
After an investigation of a goal is completed

When the above events are met, the AutosaveTrigger Event Handler calls the save() method of the AutosaveSaver Data Adaptor.

The AutosaveSaver simply saves all of the attributes into the Autosave table in the DERBY database.

Table AUTOSAVE

ID	age	income	old	low_income	old_low_income	eligible
VARCHAR(255)	DOUBLE	DOUBLE	INT	INT	INT	INT

Table 'Autosave' view - start of investigation, to completing an investigation

While going through the Interview, when the user starts an investigation of a goal and the current Case ID is empty - a new Case ID will be created. You can see this in the database; for example:

ID	age	income	old	low_income	old_low_income	eligible
8821b2f8-76e3-4762-a4a5-af8c10aac521	NULL	NULL	NULL	NULL	NULL	NULL

After the Case ID is generated, as the user answers the questions in the investigation (for example, age=31 below), answers and inferenced data will be added onto the same row item in the database (for example, old = Yes, eligible = Yes).

ID	age	income	old	low_income	old_low_income	eligible
8821b2f8-76e3-4762-a4a5-af8c10aac521	31	NULL	Yes	NULL	NULL	Yes

Source Code

To view the source code for the DerbyAutoSave sample, refer to examples\web-determinations\auto-save in the Java runtime zip file.