If this property is true, map images may be streamed to the browser as byte data, if certain conditions apply, rather than as an image file that the browser retrieves via a URL. If Web ADF control settings are left at the defaults and ArcGIS Server services are used, then streaming will generally be used. If UseMimeData is false, the Web application will only return URLs of map images to the browser, and the browser will retrieve the images via the image URL. The default for UseMimeData is true.

Streaming may occur in one or both of two stages in the Web ADF: map service and Web ADF application. The map services used in a Web ADF application may stream image data to the client or Web application. The Web ADF application may also stream image data to the client browser. Service and application streaming are set independently, but may interact within the Web ADF application.

The image handling approach depends on several settings and map service characteristics:

• If Map.ImageBlendingMode is set to Browser (the default):
  • If the Map service serves images as streamed data only, or the RequestMimeData option is set to true in the DisplaySettings for the resource in MapResourceManager (and the resource supports MIME data streaming): images are streamed to the browser if UseMimeData is true. Otherwise, images are written to the VirtualDirectory and a URL for the image is sent to the browser; the browser retrieves the image file from the Web ADF server via the URL.
  • If the Map service only serves images as URL-retrieved files, or RequestMimeData option is set to false in the DisplaySettings for the resource in MapResourceManager: the Web application retrieves the URL of the image from the map server, and returns the URL of the image to the browser. The browser requests the image file directly from the map server.
• If Map.ImageBlendingMode is set to WebTier:
  • If a single map resource is used in the associated MapResourceManager, then image handling is the same as with Browser blending as described above.
  • If multiple map resources are defined in the MapResourceManager, then the Web ADF application retrieves all map images from the map servers, whether those images are streamed or image files. The images are combined into a single image on the Web ADF server. If UseMimeData is set to true, then the Web ADF server streams the merged image to the browser. If UseMimeData is false, then the Web ADF server writes the merged image to the VirtualDirectory on the Web ADF machine, and returns the URL of the image to the browser; the browser retrieves the image file via the URL.

See the VirtualDirectory property of Map or PageLayout for a discussion of how images are output to the Web ADF server, if that location is used.

Support for MIME image streaming

• ArcGIS Server (Local and Internet): service may be set to MIME only or MIME plus image file creation. For MIME+file, the client specifies the output method in its request. For the Web ADF, you specify the choice in the RequestMimeData option in the DisplaySettings for the resource in MapResourceManager.
• ArcIMS (image services): services create image files by default. For AXL-based services, if <OUTPUT method="stream" /> is added to the AXL configuration file, the service will stream byte data instead of creating image files. This is not the same as a Feature service in ArcIMS.
• ArcWeb Services: only supports image file output accessed by URL.
• OGC WMS services: only supports image file output accessed by URL.

Reference