Palm webOS

HTML 5 Storage

Clearly, the Cookie and Depot objects are simplistic, and while attractive for casual data storage and caching, they won’t fulfill the need for formal database support. To address that need, Palm webOS includes support for the HTML 5 Database object to create, update, and query an SQL database. Like the Depot, the HTML 5 database interfaces are asynchronous, requiring you to use callbacks for much of your database handling.

Creating Large Databases

By default, Palm webOS stores databases within a size-constrained local file store, which is the reason that HTML 5 databases are restricted to a 1MB maximum. The bulk of the storage on the Palm Prē is in the mass storage partition or USB accessible storage, reserved for media use.

You can store your HTML 5 database or Depot in the mass storage partition, where it is not subject to a maximum size other than by the amount of available memory. To do that, specify the database name with a prefix, as in:

openDatabase( "ext:mydbname", ... );

The “ext:” will be mapped by the system to the mass media partition on the Palm Prē and an appropriate mapping on future devices.

The HTML 5 specification includes extensions for structured client-side storage, including support for the Storage and Database objects. Palm webOS does not support the Storage object, a list of name/value pairs that grew out of Firefox’s DOM Storage object, but it does support the Database object.

The openDatabase() method will create a new database or open an existing ...