Store Streams Overview

Purpose

Provides stream types suitable for use in stores (structured data storage).

Architectural relationships

The Store Streams API is based on the abstract stream types defined by the Streaming API. They are designed to be used in conjunction with the structured data storage defined by the Stores API.

Description

The API has threee key concepts: store streams, stream dictionary, and swizzle.

Store streams

The store streams extends the base stream types defined in the Streaming API, to allow streams to be used in stores.

The store streams classes are RStoreReadStream and RStoreWriteStream .

Stream dictionary

A stream dictionary maintains a list of two-way associations between UIDs and stream IDs ( TStreamId ). They are used in the root streams of some stores: from them other streams in the store can be found.

The stream dictionary class is CStreamDictionary .

Swizzle

For large stores, it can be desirable to defer reading some objects from streams into memory. A swizzle is a device for handling a dual representation of an object:

if it is not in memory, by the relevant stream ID

if in memory, by a pointer

Full access is available to the object through the swizzle.

Swizzles for non-const objects are provided by the template class TSwizzle . Swizzles for const objects are provided by the template class TSwizzleC .

Store map

A store map is a table of entries where each entry consists of a swizzle and a stream ID. It is provided by CStoreMap .

See also

Store Streams Overview

Streaming Overview