Wince Object Store)

Wince object store by Drizzle QQ: 253786989
2011-10-16

The understanding of Object Store has always been vague. After reading Microsoft's documents, I don't know whether my understanding is appropriate.

When building the wince operating System, you can select RAM and ROM File System as the internal File System. In this way, the root directory (\) after the system is started is mounted as a RAM-based file system, so the files and data stored in the \ directory will be lost after the system is cold started.

What does Object Store contain? The above mentioned RAM file system, database, and RAM-based registry are combined to form an Object Store. You can think of Object Store as a ramdisk, which can be used to save and read and write files.

Physically, the Object Store is stored in a non-volatile RAM chip and has a backup battery, which can be powered when the main power supply powers down, therefore, the content stored in the Object Store can still be saved after the system Code Restart. This is Microsoft's meaning, but we usually do not have the RAM backup power on the hardware board, so after the system is cold started, the content stored in the system root directory will be lost. Currently, many wince systems choose ROM-only File System + Hive registry to persistently store the content stored in the root directory, the biggest advantage of this is that the software installed through the cab package will not be lost after the system is cold-started and can still be used.

For the operating system, it uses Object Store to complete the following tasks:

1. Manage stack and memory heap.

2. compress or expand files as needed.

3. Seamlessly integrate ROM-based applications and RAM-based data.

The data storage mechanism in object store is based on the transaction-based mechanism, which is borrowed from the concept of a database. Transactions have four attributes: atomicity, consistency, isolation, and continuity. These four attributes are generally called ACID properties. That is to say, if the system suddenly loses power, the write operation being performed to the object store either writes all the data or restores it to the status before writing, to ensure that the content stored in the object store is not damaged.