Multipart requests or responses

In GWS REST there is support for the standard multiple part message, in which one or more different sets of data are combined in a single body.

You can specify an HTTP multipart request or response for transferring data of several MIME types, such as JSON, XML, simple string, and to upload or download files. An input parameter or return value in your function without a REST parameter attribute, is automatically sent in the message body.

Multipart/form-data support

In the multipart/form-data type, entire files can be included in the data transfer without encoding. This is ideally suited for uploading and downloading image or text files to a Web service.

Separate parts are identified by the GWS REST engine's naming convention sequence for headers and body parts that starts with "rv0" and goes to the "rvn^th" number of parts. You can change default header naming by adding a value in the WSName attribute to your parameter.

The GWS REST engine also creates a "boundary" string in the "Content-Type: " header. This boundary, is placed between the various parts, and at the beginning and end of the body of the message.

Define multipart request body

You automatically define a multipart request body when you have an input parameter without any of the REST parameter attributes (WSHeader, WSQuery, WSCookie).

Important:

A message body is required when you perform an HTTP PUT or POST request to a resource, otherwise the request results in the error-9106.

If you have more than one input parameter without a REST attribute, the GWS treats the request as a multipart of form-data type. The example is of a multipart request function. The input parameter values "a" and "b" are sent in separate parts in the request body:

PUBLIC FUNCTION add2( a INTEGER, b INTEGER )
  ATTRIBUTES (WSPut,
              WSPath="/Add2")
  RETURNS INTEGER
    RETURN a + b
END FUNCTION

Define multipart response body

Similar to the request, there is one response body per return value which does not have a REST attribute. A notable difference is that only the WSHeader attribute is allowed in responses. If there are more than one return values without WSHeader attributes, the multipart is of type form-data.

Important:

A message body is required when you perform an HTTP operation on a resource returning a value, otherwise the response results in the error-9106.

This is a multipart response sample REST function. The string return value is not defined with a WSHeader attribute and its value is therefore sent in the response body:

PUBLIC FUNCTION help()
  ATTRIBUTES (WSGet,
              WSPath="/help")
  RETURNS (INTEGER ATTRIBUTE(WSHeader), STRING)
    RETURN 3, "hello world"
END FUNCTION