#The Persistent List Manager Module The persisent list manager (plm) is an OpenMRS module that allows other modules to store and retrive items that are stored persistently. If persistent storage is not required, this module should not be used. The intent for this module is to provide a very basic workflow-like process so that other modules can put patients or other entities into persistent lists as needed. These lists can be implemented as any data structure so that retrieval can be automatic; for example, a waiting room may need to have a persistent list that is implemented as a queue (first in, first out).

##Example Usage The general usage is as follows:

####From module 1 //Get the module service from the OpenMRS service context PersistentListService service = Context.getService(PersistentListService.class);

// Ensure the list exists (creating it if it does not)
PersistentList list = service.ensureList(PersistentQueue.class, "waitingRoom");

// OR Get and Create the list
PersistentList list = service.getList("waitingRoom");
if (list == null) {
	list = service.createList(PersistentQueue.class, "waitingRoom");
}

// Create some new items for the list
PersistentListItem item1 = new PersistentListItem("person1_id")
PersistentListItem item2 = new PersistentListItem("person2_id")
PersistentListItem item3 = new PersistentListItem("person3_id")

//Add the items to the list
list.add(item1, item2, item3);

###From module 2 // Get the service and list as above PersistentList list = ...

// Get the list items (in the order defined by the list type)
PersistentListItem[] items = list.getItems();

// You can also just get the next item
PersistentListItem item1 = list.getNext();

// Or get the next item and remove it
PersistentListItem item1Again = list.getNextAndRemove();

##Events Service events yet implemeneted

PersistentListService service = ...
service.onListAdded(...);
service.onListRemoved(...);

PersistentList list = ...
list.addListEventListener(...);

public class ListEvent {
	public Object getSource () { ... }
	public ListOperation getListOperation() { ... }
	public PersistentListItem getItem() { ... }
}
	
public interface ListEventListener {
	void itemAdded(ListEvent event);
	void itemRemoved(ListEvent event);
	void listCleared(ListEvent event);
}