Handling streaming services

[ridoo]

Consuming remote service via Qt is normally being done by async requests. To be capable of fitting in asyncronous handling pattern the system must be adapted in order to allow feature/raster-iterators accessing data lazily.

[MartinSchouwenburg]

all dataaccess to the coverage is handled by iterators. Iterators are well suited for streaming access. As the actual organization of the data is in all cases hidden from the clients of the interfaces it is realtively easy to change between async and sync access. This will be further developed when a first implementation of WFS (features) is available.