Unified Data Sources

Unified Data Sources define the semantics for data retrieval from any source be it on the local or a remote computer, be it inside an ARX archive or outside. ARX supports the notion that an item's data may come from various sources. This creates a very high degree of flexibility as this notion isn't destroyed or even touched when Merging takes place.

In libarxx a data source is accessed by means of a data channel. A data channel is an object that is a descendant from Arxx::DataChannel and implements its abstract interface including a function Arxx::DataChannel::vFetchData(Arxx::Item &) which is responsible for retrieving the data from the data source. The retrival logic is completely implemented in a Arxx::DataChannel descendant. This way it is possible to have many various data sources referenced in an ARX archive.

When you set an item's data source, you specify compression type, compressed and decompressed data size and the a URI that locates the data source. This URI is translated to a specific data channel by the Arxx::DataRepository, an object that employs URI matching algorithms to identify the most appropriate Arxx::DataChannel that it has registered.

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