Workflows in AEM

Workflows enable you to automate Experience Manager activities. Workflows consist of a series of steps that are executed in a specific order. Each step performs a distinct activity such as activating a page or sending an email message. Workflows can interact with assets in the repository, user accounts, and Experience Manager services. Therefore, workflows can coordinate complicated activities that involve any aspect of Experience Manager.

Basics of AEM Workflow Model
Creating a workflow allows the user to define and execute a series of steps. In AEM we call workflow as Workflow models. Below are the basic terms used in the AEM workflow model.
Model: It is made up of WorkflowNodes and WorkflowTransitions. Workflow models are versioned. Running Workflow Instances keep the initial workflow model version that is set when the workflow is started.
Step: There are different types of workflow steps:

• Participant (User/Group): These types of steps generate a work item and assigns it to a user or group. A user must complete the work item to advance the workflow.
• Process (Script, Java method call): This type of step is executed automatically by the system. An ECMA script or Java class implements the step. Container (Sub Workflow): This step starts with another workflow model.
• OR Split/Join: Uses logic to decide which step to execute next in the workflow.
• AND Split/Join Executes multiple steps simultaneously. All the steps share the following common properties: Autoadvance and Timeout alerts (scriptable).

Transition: Defines the link between two consecutive steps.
WorkItem: A workflow instance can have one or many WorkItems at the same time (depending on the workflow model).
Payload: References the resource that has to be advanced through a workflow. The payload implementation references a resource in the repository (by either a path or a UUID) or a resource by a URL or by a serialized java object. Referencing a resource in the repository is very flexible and in conjunction with sling very productive: for example, the referenced node could be rendered as a form.
Lifecycle: It is created when a new workflow is started and ends when the end node is processed. The following actions are possible on a workflow instance:

• Terminate
• Suspend
• Resume
• Restart

Completed and terminated instances are archived.
Inbox: Each logged-in user has its own workflow inbox in which the assigned WorkItems are accessible.
Launcher: Allows you to define a workflow to be launched if a specific node has been updated. When we create a new workflow model it consists of three default steps Flow Start, Flow End, and a dummy participant step named as step 1.

• Flow Start and Flow End represent the start and end of the workflow.
• Step1 Participant Step is assigned to the admin user to configure a work step. We can edit or delete this step and add new steps as required.

Custom WorkFlow
//This is a component so it can provide or consume services
@Component
@Service

@Properties({
@Property(name = Constants.SERVICE_DESCRIPTION, value = "Test Email workflow process implementation."),
@Property(name = Constants.SERVICE_VENDOR, value = "Adobe"),
@Property(name = "process.label", value = "Test Email Workflow Process") })
public class CustomStep implements WorkflowProcess
{

/** Default log. */
protected final Logger log = LoggerFactory.getLogger(this.getClass());

//Inject a MessageGatewayService
@Reference
private MessageGatewayService messageGatewayService;

public void execute(WorkItem item, WorkflowSession wfsession,MetaDataMap args) throws WorkflowException {

try
{
log.info("Here in execute method"); //ensure that the execute method is invoked

//Declare a MessageGateway service
MessageGateway<Email> messageGateway;

//Set up the Email message
Email email = new SimpleEmail();

//Set the mail values
String emailToRecipients = "tblue@nomailserver.com";
String emailCcRecipients = "wblue@nomailserver.com";

email.addTo(emailToRecipients);
email.addCc(emailCcRecipients);
email.setSubject("AEM Custom Step");
email.setFrom("scottm@adobe.com");
email.setMsg("This message is to inform you that the CQ content has been deleted");

//Inject a MessageGateway Service and send the message
messageGateway = messageGatewayService.getGateway(Email.class);

// Check the logs to see that messageGateway is not null
messageGateway.send((Email) email);
}

catch (Exception e)
{
e.printStackTrace() ;
}
}
}