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4.3. Overall Sequencing Process
The information in this section is intended to supplement, not replace, the Overall Process Behavior section of IMS SS. Refer to IMS SS for more details.
The Overall Sequencing Process provides the overarching control process for the LMS’s sequencing implementation. It defines how the various sequencing behaviors are applied within the context of a sequencing session. The Overall Sequencing Process encapsulates the following sequencing behaviors:
Navigation Behavior – Describes how a navigation request is validated and translated into termination and sequencing requests.
Termination Behavior – Describes how the current attempt on an activity ends, how the state of the activity tree is updated and if some action should be performed due to the attempt ending.
Rollup Behavior – Describes how tracking information for cluster activities is derived from the tracking information of its child activities.
Selection and Randomization Behavior – Describes how the activities in a cluster should be considered during processing a sequencing request.
Sequencing Behavior – Describes how a sequencing request is processed on an activity tree in attempt to identify the “next” activity to deliver.
Delivery Behavior – Describes how an activity identified for delivery is validated for delivery and how an LMS should handle delivery of a validated activity.
Figure 4.3a: Conceptual Model of the Overall Sequencing Process
IMS SS describes the behaviors listed above as independent, stand-alone processes that all act on the same data model – the tracking model (refer to Section 4.2). The conceptual model of the Overall Sequencing Process (Figure 4.3a) graphically depicts the relation of the various sequencing behaviors to one another, the activity tree and the tracking model. The entry point for the Overall Sequencing Process is a navigation request issued by the LMS. Typically, navigation requests will be generated in relation to some learner-triggered navigation event or a content-triggered navigation request (refer to Section 4.4.3: Navigation Requests). The exit point for the Overall Sequencing Process is either the identification of the “next” activity to deliver, which could be nothing, or an
exception. If an activity is identified for delivery, the LMS will launch the activity’s associated content object. SCORM does not define behavior for the cases where no activity is identified for delivery or some sequencing process produced an exception. It is recommended that the LMS provide some indication to the learner of the Overall Sequencing Process result, and further, that the indication allow for graceful continuation of the sequencing session.
The Overall Sequencing Process exhibits the behavior of the sequencing loop when a sequencing session starts and ends. The steps of the sequencing loop are described in detail below.