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The OData specification requires an EntityType to denote a set of properties forming a unique key. In SAP
HANA, only tables can have a unique key, the primary key. All other (mostly view) objects require you to
specify a key for the entity. The OData service definition language (OSDL) enables you to do this by denoting a
set of existing columns or by generating a local key. Bear in mind that local keys are transient; they exist only
for the duration of the current session and cannot be dereferenced.
Note: OSDL is the language used to define a service definition; the language includes a list of keywords
that you use in the OData service-definition file to enable the required features.
● Parameter Entity Sets
You can use a special parameter entity set to enter input parameters for SAP HANA calculation views and
analytic views. During activation of the entity set, the specified parameters are retrieved from the metadata of
the calculation (or analytical) view and exposed as a new EntitySet with the name suffix "Parameters", for
example "CalcViewParameters".
● Projection
If the object you want to expose with an OData service has more columns than you actually want to expose,
you can use SQL views to restrict the number of selected columns in the SELECT. However, for those cases
where SQL views are not appropriate, you can use the with or without keywords in the OData service
definition to include or exclude a list of columns.
8.1.3 OData URI Parameters, Query Options, and Features
Since OData fully embraces Web technologies, and more specifically URI concepts, all the actions that manage
the interaction with the service at runtime are controlled by HTTP methods, the URI structure, or URI query
parameters.
The examples listed here illustrate how to use the OData service-definition file to specify what data to extract and
what to do with it. You can find examples of the following features:
● HTTP Methods
For example, HTTPGET
● Resource types
For example: Service documents, entity sets, $metadata, and so on
● Query options
For example, $format, $filter, $select, and so on
HTTP Methods
Since the current OData Infrastructure only supports read services (no Create/Update/Delete), the only
supported HTTP Method is GET and POST for $batch (containing only GET requests). The result is that only read
requests are possible.
SAP HANA Developer Guide
Defining Web-based Data Access
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