Overview
The Open Data Protocol (OData) is a web protocol for querying and updating data that builds upon web technologies such as HTTP, Atom Publishing Protocol (AtomPub) and JSON to provide access to remote information.
The OData specification defines the request and response rules for the retrieval of both spatial and non-spatial geographic information using either ATOM or JSON, however the reader currently only uses and understands ATOM format.
This chapter assumes familiarity with the OData, ATOM, HTTP, XML, feeds, entries, properties, URIs and cloud computing in general.
The OData reader currently supports version 2.0 through 4.0 of the protocol specification which can be found at the OData website www.odata.org. Notably, the OData reader now has support for spatial data, including geometry and geography types. The difference between these two types will be explained in this document.
OData is released under the Open Specification Promise to allow anyone to freely interoperate with OData implementations.
Reader Overview
OData services are composed of feeds (also referred to as entity sets), which are collections of typed entries. Each entry represents a structured record with a key that has a list of properties of primitive or complex types.
The OData Reader produces an FME feature for each entry in a feed for the provided service. Each property on an entry becomes an attribute on the FME Feature.
Reader Terminology
The following table maps each OData term to its FME counterpart.
| OData | FME |
|---|---|
| Service | Dataset |
| Entity Set (Feed) | Feature Type |
| Entry | Feature |
| Property | Attribute name |
| Complex Type | Attribute containing sub-attributes |