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Re: [IndexedDB] Explaining Asynchronous event-style interface

From: Shawn Wilsher <sdwilsh@mozilla.com>
Date: Mon, 22 Mar 2010 10:49:44 -0700
Message-ID: <4BA7ADB8.4000501@mozilla.com>
To: Nikunj Mehta <nikunj@o-micron.com>
CC: public-webapps WG <public-webapps@w3.org>
On 3/13/2010 1:43 AM, Nikunj Mehta wrote:
> 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.
This seems like an artificial constraint to me.  Is there any reason why 
we couldn't open up more than one database connection at a time (or at 
least allow the possibility for a UA to do so).

> 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.
Being forced to have more than one database open to do concurrent work 
seems like an artificial constraint too.  It isn't just an initial setup 
task; there is a fair amount of complexity that the consumer would have 
to manage to know which connection to use.  It should be fairly trivial 
for the UA to manage the concurrency (even if the UA just serializes 
requests) and lets the consumer not have to concern itself with this.

> One can create as many IDBIndexRequest and IDBObjectStoreRequest object
> as required. Once these objects are created multiple operations can be
> performed in parallel.
Only by opening more database connections though, right?



Received on Monday, 22 March 2010 17:49:08 UTC

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