Advanced Tab (REST)¶
In this dialog you can configure several advanced settings of the Web service.
The Virtual DataPort Web services are deployed to an application server (usually in the Web service container embedded in the Denodo Platform). Each time a Web service operation is invoked, it sends a query to the Virtual DataPort server to obtain the required results. It is possible to configure the parameter of these connections established from the Service to the Server: Chunk Size, Chunk Timeout, Query Timeout, Enable Pool, Initial Size and Max. Active. These parameters are explained in the section Connection from the Web Services to the Server.
By default, the Denodo REST Web services explicitly specify that a value
of a field is
NULL by adding the attribute
xsi:nil="true" to the
element. E.g. if in a row, the value of the field
NULL, the service returns the following:
<field_name xsi:nil=“true” />
If you do not want the Web Service to specify
NULL values with the
xsi:nil="true", select the Represent NULL values as
empty elements check box. In this way,
NULL values will be
represented with an empty element. E.g.
<field_name />. The problem
of enabling this option is that, for
text fields, there is no
difference between a
NULL value and an empty string.
Note that this only applies to the XML representation of the views.
When an application sends a request to a REST web service of Denodo to obtain the data of a view, it can add the parameter “$select” to the URL, to select the fields to project. By default, the value of this parameter can be a comma-separated list of fields and expressions. These are the same expressions you can use in the SELECT clause of a query.
See more about how to use the parameter “$select” in the table Parameters supported by the Denodo RESTful Web service and published REST Web services of the section Parameters of the RESTful Web Service.
If you clear the check box Process functions in $select parameter, the value of $select has to be a comma-separated list of fields of the view, not expressions.