Data Store and Registry
The object store provides persistent storage for applications and their related data even when the main power supply is lost, provided there is a backup power supply. One or more memory storage chips, which typically are nonvolatile RAM chips, compose the physical object store.
The following table shows the services available in the object store.
| Service | Description |
|---|---|
| Database Reference | Databases store, access, and sort property-set records. The Windows CE database model is a small, flat structure, optimized for small, efficient storage. As such, the database APIs do not correspond to the Win32 database APIs. Data operations are transactioned, which protects against data loss. If a Windows CE–based device loses power, for example, during a reset, suspend or resume where the RAM is refreshed, during a data transaction, the operating system (OS) reverts all partial database operations to the last known good state. |
| File I/O Reference | Files are stored on storage media and can be organized into groups called directories. The file I/O functions enable applications to create, open, modify, and delete files. They also enable applications to obtain system information, such as what media is present. |
| File Mapping Reference | File mapping is the association of a file's contents with a portion of the virtual address space of a process. The system creates a file-mapping object to maintain this association. A file view is the portion of virtual address space that the process uses to access the file's contents. Processes read from and write to the file view using pointers, just as they would with dynamically allocated memory.
The file-mapping functions allow a process to create file-mapping objects and file views to easily access and share data. |
| FSD Reference | A file system driver (FSD) is a dynamic-link library (DLL) that exports file system entry points that map to standard OS file system functions. When an application calls a file system function, and the function references a file on a volume registered by the FSD, FSD Manager maps the call to the FSD. |
| Registry Reference | The Windows CE registry stores data about applications, drivers, user preferences, and other configuration settings. For example, the default preferences of a user for Pocket Word are stored in the registry. |
| User Profile | Each time a new user logs on, a new hive is created for that user with a separate file for the user profile. This is called the user profile hive. A user's hive contains specific registry information pertaining to that user's application, desktop, environment, network connections, and printer settings. The user profile hive contains all data under the HKEY_CURRENT_USER registry key. When the current user is logged off and another user is logged on, the new user's hive is mounted and the data changes under HKEY_CURRENT_USER. |
See Also
Database Reference | File I/O Reference | File Mapping Reference | FSD Reference | Registry Reference
Last updated on Friday, April 09, 2004
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