The player is the part of the IMS-LD package that present to all the roles of the unit of learning the different activities in a sequence ordered way based on the properties and conditions.
When deciding how the player should interact with the user, we thought two different implementations:
Show a little portlet to the user that indicates the next activity to complete, showing the corresponding link to the appropriate .LRN package.
Render all the information in a single window, in a centralized way. Something that the LORS package currently do when playing an SCORM document.
After analyzing each one of these approaches, we concluded that rendering all the information in a single window was the better option, because we think is more simple for the users (teachers and students) to centralize the visualization instead of following different links, and also it can give us some kind of control of what the user is doing, and we can be sure of what the user is actually seeing on his/her screen.
Also, for example if the activity is a forum and we redirect the user to this forum, the user can easily get distracted and end up reading a forum that does not form part of the activity. In the other hand, if we render the forum inside a centralized window, we have the control on the user's window, and by using some kind of frame, we can easily show any important message to the user and be sure (well, not entirely), that he/she read it. Besides, in this centralized window we can show in the bottom the activities that are completed and, when possible, the ones that are yet to complete.
Therefore the selected option is the single window. The users (students, professors, etc.) will see in the single window in a concrete moment of time, some resource associated with an activity. The user will have at the left hand a list of the possible activities that he/she can see in a concrete moment (this depends on the design of the course). The student can select between the activities presented. Also for each activity it will be a description that will be shown always if the current activity is selected by the user (this description will appear in a little space), and also the user will be able to choice between the different resources of the associated environment of the activity. Therefore the student will select between the given resources for the activity. These resources can be any of the .LRN services or learning objects as files that comes for example in the IMS CP.
The activities presented to the different roles will change in the time depending on the different properties and conditions. For example, it can change depending on the evaluations of the professors, on the results of the assessments, on the user models, etc. Therefore not all the users will see the same information because it is personalized depending on conditions. Also different paths in the workflow can be defined based on roles.