NCI Flicker Proxy Web Server

Loading gel images from anywhere on the Internet into Flicker - using the proxy server

Because of security considerations with JAVA, the current versions of Netscape (3.x) and Microsoft Internet Explorer (3.x) enforce a highly restrictive security. Java applets running on these web browsers can not read or write local files nor download data from web location URLs other than the web server from which the applet came.

We have developed an interim solution to allow access to images on any computer on the internet without violating the browser security. When new versions of web browsers are released which allow direct access, we will shut down this service. The solution uses the NCI Flicker Server to provide a URL proxy service integrated with Flicker. When a URL is requested for a host other than the NCI Flicker server, Flicker passes this request the NCI Flicker server. It in turn acts as a proxy and gets the image data for the URL. Furthermore, it converts the image to GIF format - increasing the variety of image formats which Flicker can handle. The proxy service can handle images up to 1.5 Mbytes in size and with http:// and ftp:// protocols. It may have problems with cgi-bin image access methods.

Because this uses Flicker Server computer resources, we request that its use be restricted to biomedical images. The following figure illustrates this process.

                                   Internet
 User's Web browser  <----  Flicker Proxy Server ----> Web server URL
 running Flicker

  Steps:  
  1. Request for Web server URL            ===> Flicker Proxy Server
  2. Flicker Proxy Server requests URL     ===> Web server URL
  3. Proxy Server receives image           <=== (download image from URL)
  4. Image converted to GIF on Proxy Server
  5. User's Web browser receives image     <=== (download GIF image
                                                 from Proxy Server)


Last revised $Date: 1997/05/07 13:49:54 $ by P. Lemkin.
Send comments on this server to lemkin@ncifcrf.gov
Return to the LECB home page