The importance of guaranteed end-to-end QoS increases as business-to-business (B2B) interactions become increasingly sophisticated, lengthy, and involve more sites.
ITRA (Inter-Tier Relationship Architecture) allows collaboration between tiers to provide end-to-end QoS. For example, say you order a book from amazon.com. Amazon checks the inventory to see if the book is in stock, and if not, Amazon contacts the publisher and places an order for the book. When you checkout and are ready to pay for the book, Amazon transfers your credit card information to a credit card bureau to validate your information and verify that you have enough available credit. The transfer of information and collaboration between sites is what occurs during multi-tier computation and is completely transparent to you, the end user.
ITRA extends this multi-tier collaboration to also achieve QoS, such as high availability. The problem is that with the increasing number of processors needed to support high availability, there is more chance of failure. Using the ITRA architecture, web applications can collaborate to transparently recover from failures in multiple tiers, as well as better exploit mutual resources to provide the required availability and failover transparency aspects of end-to-end QoS. Therefore, if the amazon.com site crashes just as you are ready to checkout, the books you selected are saved. When the connection is restoredwhich is also transparent to you, the end useryour books are still in your shopping basket and you can proceed to checkout.
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