To try out streaming in Visual Studio 2005, follow these steps. This assumes the ArcIMS Web ADF is installed on the computer.

1. Create a new streamed map service in ArcIMS. If you installed the Tutorial Data (in <ArcIMS install>\Samples\), use the SantaClaraStream.axl to create the map service. Otherwise, create an AXL file and add the OUTPUT tag described above under Remarks.
2. If necessary, create a new Web Site in Visual Studio 2005, and add a new web form (.aspx page). An existing page can also be used.
3. Use the Toolbox to add to the page: a Map control (ESRI.ArcGIS.ADF.Web.UI.WebControls.Map) and a MapResourceManager control(ESRI.ArcGIS.ADF.Web.UI.WebControls.MapResourceManager).
4. In the MapResourceManager, use the ResourceItems property to open the MapResrouceItem Collection Editor. Add a new resource item, and use the Definition property to connect to your ArcIMS server and point to the streamed map service.
5. For the Map control, set the MapResourceManager to the control you added above. Also make sure the UseMimeData property is true.
6. View the page in a browser. You should see the map drawn on startup, and you should be able to zoom with a mouse wheel and pan the map by clicking and dragging. You can verify that no images are being produced by examining the ArcIMS output directory (usually C:\ArcIMS\Output on the server).

If true, the map image in a draw operation is streamed as a Base64 encoded byte string in the response, and no image is written to disk. These image data are read into the MimeData property of the CartoImage returned in the draw operation. If false, the map is written out to disk as an image file, and the URL of the image is set in the Url property of the CartoImage returned from the draw.

This property will only be true for standard image services. Does not apply to ArcMap Server image services.

This property is read only. Streaming is defined in the ArcXML configuration file for the service. This is done by adding the following tag to the <PROPERTIES> section of the configuration file:

<OUTPUT method="stream" />

For more information on setting up streaming in a map service, see the ArcIMS Help, in the ArcXML Guide section, under OUTPUT.

Using streaming with the Map control

Streaming can be used with the Map control to send data to the browser without writing temporary images on the server's disk. This is enabled by setting up streaming in the map service (see above), and by setting the UseMimeData property on the Map control to true.

This approach is useful in a system where a firewall is placed between the ArcIMS Spatial Server and the Web server. Without streaming, the map image must be passed through the firewall with some scheme such as a reverse proxy server or having the servlet engine inside the firewall. By using streaming, the image is passed through the firewall along with other AXL requests and responses via the ArcIMS Connector Port (default is TCP 5300).

Be aware that streaming images places a greater burden on the Web server. The Web server must store the images temporarily in memory and send them to the client. If the server has many clients requesting images, this could consume considerable memory and resources on the server. Load testing is recommended to determine if this approach is satisfactory for your application.

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