ARRIS Enterprises, Inc. Confidential Information

Storage Structure

All information objects handled by the Information Service are arranged in a common storage structure. This structure defines how information objects get their initial values and how various parts of the system are allowed to manipulate these values.

Information Sources

The basis for the storage structure is the hierarchy of information sources. The source defines how an object gets its initial value, and also regulates how the value may be changed in various ways.

Information sources in priority order
Source	Description	Initial value determined at	Allows changes	Allows removes
Recovery	The recovery source provide recovery values for some information objects. Since this source has the highest priority it can rescue a persistent object with an incorrect value. Recovery values are provided at boot image build time by using the kreatv-option-is-recovery IIP.	Build	No	No
Volatile	Information objects may be introduced, changed, and removed in run-time. The volatile objects survive stand-by.	Run-time	Run-time	Run-time
Flash User Configuration	The value is stored in flash and may by changed during the boot process.	Production	Boot	No
Flash Production Data	The value is defined in production and used during the boot process.	Production	No	No
Flash File System	Information objects may be introduced, changed, and removed in run-time. The objects are stored permanently and survive stand-by and system reboot.	Run-time	Run-time	Run-time
Infocast	Information objects and their values are controlled from the IP-STB Server.	Server controlled	Server controlled	Server controlled
OS	The value is based on information from the operating system.	Boot	No	No
Derived	Information objects have values that are derived from other information objects.	Boot	No	No
Build	Information objects about the build.	Build	No	No
Default	The default source provide default values for some information objects. Since this source has the lowest priority it is truly default. Default values can be provided at boot image build time by using the kreatv-option-is-default IIP.	Build	No	No

Search Algorithm

The same information object may in general be stored in more than one place (i.e., have multiple sources) at the same time. When the value of an information object is requested, the sources are searched in priority order, i.e., it starts looking in the volatile source and continues searching down the hierarchy. When a source is found which defines the object, the search ends and the object gets the value as defined by that source. In effect objects defined by one source hides any definition of the same object in lower priority sources. If no valid source is found this is indicated with an error. When a new information object is introduced, changed, or removed, all subscribers to that particular information object are notified, given that there is no value for the object in a higher priority source.

A general observation can be made by applying this search algorithm on the storage structure. New information objects are allowed to be introduced in run-time only for the flash file system, infocast, and volatile sources, but depending on the source used, objects will express different time to live properties.