Defining and Implementing Actions

When defining your own server context actions, it's necessary to specify properties of their definitions, i.e. name, description, format, permission level, help text, and group.

Many classes related to actions are part of Iotellect Server rather than open-source Java SDK. Those classes are not available in source code. To get access to those classes you need to add the following JAR files to your classpath: aggregate-commons.jar server-core.jar Those JARs can be found in the /jar subfolder of Iotellect Server installation folder.

To declare new action, create an instance of ServerActionDefinition object and set its properties. Here is an example:

// Creating the definition and providing action implementation class
ServerActionDefinition ad = new ServerActionDefinition("configurationWizard", ActionImplementationClass.class);

// Setting action description
ad.setDescription("Configuration Wizard");

// Setting permission level
ad.setPermissions(ServerPermissionChecker.getManagerPermissions());

Once done, add the action definition to a context by calling Context.addActionDefinition() method. Server plugins and drivers should add actions from inside install() and start() methods.

Action implementation is the class extending ServerAction class. It must override execute() method that performs the actual action, i.e. the combination of server-side operations and interactions with a human operator.

Once an action is launched by an operator (or in headless mode), a new instance of action implementation object is created and its execute() method is called.

Hierarchy of ServerAction has the following methods providing access to action's environment available during execution:

• getDefiningContext() returns a Context the action was called from.
• getActionDefintion() returns the ActionDefinition of the action.
• getActionContext() returns an instance of ServerActionContext that contains advanced information about the execution environment.

Here is an example of simple action implementation:

public class ShowDeviceCountAction extends ServerAction
{
@Override
public ActionResult execute(ServerActionInput parameters) throws ContextException
{
DataTable deviceStatusTable = getDefiningContext().getVariable("status", getCallerController());
String status = deviceStatusTable.rec().getString("statusMessage");
getProcessor().showMessage("Current Device Status", "Device Status: " + status);
}
}

When an action is running, it may, at its discretion, decide to "talk" to a human operator that has launched it. These interactions are called UI procedures.

All UI procedures are initiated by calling diverse methods of ServerActionCommandProcessor object that is accessible from within an action via getProcessor() method.

Here is a non-complete list of available UI procedure calls:

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