Thanks Alex for your kind suggestion, I will surely plan for WAS 8. Also, for internal reasons, I would like to prepare for WAS 7 000-377 certification.
Could you please let me know how to approach for this exam. I have downloaded the PDF for WAS 7:
http://www.redbooks.ibm.com/redbooks/pdfs/sg247615.pdf, which is administration and configuration guide. Is this enough or have you referred to any other material/textbooks. Please share online link if any. Thanks in advance..and Merry Christmas...

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Note: Do you have a document for WAS 7 for concepts and design similar to the one shared for WAS 8.