[IndexedDB] Explaining Asynchronous event-style interface

[Nikunj Mehta]

(starting a new thread to focus discussion on identifying shortcomings  
of currently specced API)

As specced, it is possible to have multiple concurrent requests at  
various API entry points, except for the IndexedDatabaseRequest  
interface. In this particular case, you can only have one request to  
open a database in a Window object. Given that this is setup kind of  
work, it does not appear that this limitation amounts to much. If  
multiple connections to a single DB are required, or if different DBs  
have to be opened, that would have to be done sequentially, i.e.,  
start a new request only after the previous one completed.

Once you have an IDBDatabaseRequest object, it is possible to make one  
request at a time to open a cursor or create a transaction. It is  
possible to do this concurrently with opening another database. If  
multiple concurrent requests are to be made to create and/or open  
object stores or indexes, different connections in the form of  
IDBDatabaseRequest objects will be needed. Again, this appears largely  
an initial set up kind of thing. Besides, given that it is possible to  
check whether a request is in progress, developers can avoid getting  
into trouble.

One can create as many IDBIndexRequest and IDBObjectStoreRequest  
object as required. Once these objects are created multiple operations  
can be performed in parallel.

Same goes for IDBCursorRequest objects and performing operations on  
several different such objects.

I am trying to explain this to those who haven't had a chance to  
review the spec but might be able to weigh in on our discussion

Nikunj