T.A. McGlynn, K.A. Scollick, N.E. White
NASA/GSFC
We have built a Java interface to the SkyView Virtual Observatory. This interface portably replaces our X-windows based Interactive Interface while maintaining and in some cases enhancing functionality. Providing support for many capabilities was surprisingly easy, e.g., zoom, interrogating pixels, and handling multiple images. However, a lack of Java FITS classes, the inflexibility of the Java layout managers, and poor Java support for mathematical operations, array manipulation, and formatted input/output all hampered our efforts. Most of these problems are likely to be addressed as the Java environment matures. Performance was adequate on workstation class machines, with the overheads caused by Java only slightly increasing the total retrieval times for an image. However, for less powerful machines, the interface could be painfully slow. The security restrictions on applets doubled the network overhead since any users who wished to retrieve their data needed to copy the FITS files twice, once to read into the applet, and a second time to save the image on their local disk area. Overall, given Java's novelty, our experience was positive. The new interface has substantially greater capability than the X-windows interface, and is usable from Windows and MacIntosh native environments. Since most of our users now come from these environments this is an critical issue.