Yes!!! Another achievement, I just googled my requirement to add description into exif information of image and got plenty of open source which can do the job.
After carefully investigating various open-sources, selected one which is "PHP JPEG Metadata Toolkit Version 1.11". This one is best and after very little modification now I can write "Description", "Copyright" and other important details directly to the EXIF. Means I can maintain my photographic portfolio without any database behind and pull information directly from Image for Simpleviewer.
Also while exploring metadata I found that there is thumbnail image already embedded into the image itself, this was a new thing to me. Now my Simpleviewer is showing images from real thumbnails generated from EXIF of images.
I need to create another script which can populate thumbnail and provide an interface to write description… I donâ€™t need any help this time… 😛