Compression/Decompression with the HTTP Invoke/Get/Post/Head/Put/Delete Request activity

The compression/decompression runtime behavior of the HTTP Invoke/Get/Post/Head/Put/Delete Request activity is dependant on the following conditions:

• If the endpoint supports compression/decompression
• The values of the Content-Encoding and Accept-Encoding headers at the message level
• The setting of the Use Compression/Decompression check box at the activity level

The affect of these conditions on the compression/decompression runtime behavior of the HTTP Invoke/Get/Post/Head/Put/Delete Request activity are described in the following sections and in the tables provided in the Runtime Compression/Decompression Behavior section.

Endpoint support for compression/decompression

The Integration Appliance determines whether or not the HTTP Endpoint supports compression when the Integration Appliance sends the first HTTP request in the compressed format to the HTTP Endpoint (the HTTP Server), if the HTTP Server returns an error code indicating that HTTP Server does not support compression or does not support the specified Content-Encoding type, the Integration Appliance re-sends the first request in uncompressed format and all subsequent requests to this Endpoint are sent in the uncompressed format. In addition, the HTTP response sent by the HTTP Server is not decompressed when received by Integration Appliance.  

Endpoint support for compression/decompression is represented by the column labeled Endpoint Supports Compression? in the tables provided in the Runtime Compression/Decompression Behavior section.  

Content-Encoding and Accept-Encoding values at the message level

The value of the Content-Encoding header in the HTTP request determines if the body of the request is compressed and the type of encoding that is used. For example, if the Content-Encoding is equal to deflate, the Integration Appliance sends the body of the request compressed in the deflate format as shown in the second row of the first table labeled Compression Behavior When Sending a Request and in the following figure.

The value of the Accept-Encoding header in the request defines the types of encoding that the HTTP client accepts in the response. For example, if the Accept-Encoding is equal to gzip,deflate in the request, the HTTP server can send the body of the response compressed in gzip or deflate formats to the Integration Appliance (acting as a client) as shown in the following figure:

Figure 1.

By default, if nothing is mapped to the optional httpheaders input parameter in the Map Inputs task of the HTTP Invoke/Get/Post/Head/Put/Delete Request activity, a set of default headers are created.  For example, the URL header is automatically set with the value provided in the Configure pane of the HTTP Invoke/Get/Post/Head/Put/Delete Request activity.

The values for the Accept-Encoding and Content-Encoding headers for the request can be explicitly set using name/value pairs in the optional httpheaders input parameter of the Map Inputs task in the HTTP Invoke/Get/Post/Head/Put/Delete Request activity. For example, to set the Content-Encoding to deflate, set the following name/value pair in the optional httpheaders input parameter:

• httpheaders/httpheaders/otherHeaders/headerItem/name is set to the string: Content-Encoding
• httpheaders/httpheaders/otherHeaders/headerItem/value is set to the encoding type, for example the string: deflate.

If unsupported values or no values are set for the Accept-Encoding and Content-Encoding headers of the request, default values are provided as shown in the following tables:

• Compression behavior when sending a request
• Accept-Encoding Header value passed to the request

The values of the Accept-Encoding and Content-Encoding headers in the request are used by the Integration Appliance and the HTTP server to determine the compression/decompression behavior.

Setting compression/decompression at the activity level

By default, compression/decompression is not used for all HTTP activities. You can select compression or decompression at the activity level by using the Use Compression/Decompression check box that is displayed in the Configure task of the activity. The column labeled Use Compression/Decompression Check Box in the table shown in Runtime Compression/Decompression Behavior represents the setting of the Use Compression/Decompression check box.

Runtime compression/decompression behavior

The table provided in the Compression behavior when sending a request section describes the compression runtime behavior when the Integration Appliance sends a HTTP request to the HTTP server.

The table provided in the Accept-Encoding Header value passed to the request section describes the value of the Accept-Encoding header passed in the HTTP request.

The table provided in the Decompression behavior when receiving a response section describes the decompression runtime behavior when the Integration Appliance receives the HTTP response from the HTTP server.

Compression behavior when sending a request

The following table describes the compression runtime behavior when the Integration Appliance sends a HTTP request to the HTTP server.

Accept-Encoding Header value passed to the request

The following table describes the value of the Accept-Encoding header passed in the HTTP request.

Decompression behavior when receiving a response

The following table describes the decompression runtime behavior when the Integration Appliance receives the HTTP response from the HTTP Server.