Web enabling applications has been a tremendous success for today's enterprises, offering enhanced user productivity, lower costs, and greater overall efficiencies. But the rush to the web has brought to light all new performance issues. At first, fixing these problems was a relatively simple affair -- tune the application, add hardware, or purchase additional bandwidth for the corporate backbone network. But as user populations grew, especially via new remote users outside of the corporate LAN, additional problems emerged that could not be solved by the old methods.

Traditionally, project collaboration within the enterprise was a simple affair. Documents were shared over a LAN locally, with remote partners included via e-mail and/or fax. During the past decade however, the adoption of more sophisticated document versioning, change control, and workflow systems radically changed how project collaboration was accomplished. Although these advancements improved overall enterprise productivity, they created an insatiable need for global access from both web and client/server environments.

Many different solutions from a variety of vendors soon emerged to meet the demand, and the "best" solution really depended on the specific needs of the enterprise itself. For enterprises with large collaboration projects involving remote participants, suppliers and customers, web-enabled applications were the answer. All members of a given project could access documents in real time and collaborate as if they were in the same location. The trouble is, this put huge demands on the enterprise infrastructure, and many users (especially those on a WAN) found the promise of the Internet to be unfulfilled--both application and network performance were unacceptably slow due to a variety of bottlenecks within the system.

These bottlenecks are associated with the volume of document delivery on the network, and are exacerbated in collaborative environments where fast response time is a requirement. Documents take considerable time to deliver because applications either do not, or cannot, deliver documents to browsers optimally. Even though browsers can accept compressed documents in zip form, web based applications typically do not compress documents before delivery due to unpredictable incompatibilities on the user's client machine. Furthermore, even if a client application will accept a compressed document, the standard compression accepted by browsers is not effective on documents with significant embedded image content, as images are already compressed.

In addition, network resources are wasted on documents that are repeatedly accessed. Organizations routinely solved the "repeat access" problem by deploying simple edge caches in remote offices that, in turn, delivered documents directly from the cache in the remote office and eliminated retransmission over the WAN. However, in collaborative environments, edge caches don't offer significant benefits for variety of reasons:

• Many documents require authentication before delivery, so they can't be served directly by the edge cache.
• Edge caches lack knowledge of when documents in the cache are out of date, and could potentially deliver stale content to users.
• In many web applications that serve documents, URLs for document access are not consistent--many applications generate unique URLs for the same document and the same user--so traditional caching by a document URL gives no benefit.
• Support for document compression in the edge cache is limited--edge caches lack the ability to compress or decompress documents depending on browser and document type -- therefore requiring more time to deliver the documents to the user the first time they are pulled into the cache.

As a result of these limitations, enterprises are discovering that edge caching "solutions" are ineffective for collaborative environments.