Procedure invokeHttp(action in STRING, request in OBJECT, endpoint in STRING, stream in BOOLEAN, contentType out STRING, headers in CLOB) returns BLOBRest translator
The Rest translator, known by the type name rest, exposes stored procedures for calling REST services. Results from this translator will commonly be used with the TEXTTABLE, JSONTABLE, or XMLTABLE table functions to use CSV, JSON, or XML formated data.
Execution properties
There are no rest importer settings, but it can provide metadata for VDBs.
Usage
The rest translator exposes low level procedures for accessing web services.
InvokeHTTP procedure
invokeHttp can return the byte contents of an HTTP(S) call.
Action indicates the HTTP method (GET, POST, etc.), which defaults to POST.
A null value for endpoint will use the default value. The default endpoint is specified in the rest source configuration. The endpoint URL may be absolute or relative. If it’s relative then it will be combined with the default endpoint.
Since multiple parameters are not required to have values, it is often more clear to call the invokeHttp procedure with named parameter syntax.
call invokeHttp(action=>'GET')The request can be one of SQLXML, STRING, BLOB, or CLOB. The request will be sent as the POST payload in byte form. For STRING/CLOB values this will default to the UTF-8 encoding. To control the byte encoding, see the to_bytes function.
The optional headers parameter can be used to specify the request header values as a JSON value. The JSON value should be a JSON object with primitive or list of primitive values.
call invokeHttp(... headers=>jsonObject('application/json' as "Content-Type", jsonArray('gzip', 'deflate') as "Accept-Encoding"))Recommendations for setting headers parameter:
-
Content-Typemight be necessary if the HTTP POST/PUT method is invoked. -
Accept is necessary if you want to control return Media Type.
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Note
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Native queries
You cannot use native queries or direct query execution procedures with the web services translator.
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Streaming considerations
If the stream parameter is set to true, then the resulting LOB value may only be used a single time.
If stream is null or false, then the engine may need to save a copy of the result for repeated use.
Care must be used as some operations, such as casting or XMLPARSE might perform validation which results in the stream being consumed.