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Responses from origin web servers include entity tags (ETags), which are arbitrary strings attached to a document that specify some characteristic of the document, such as a version, serial number, or checksum of content. A changed document includes a different ETag, enabling a client's GET request to use an If-None-Match conditional header to acquire a new copy of the document. Because not all web applications generate ETags consistently, the WebAccelerator™ system creates its own ETag for each cached document that is based on a signature, or checksum, of the document's content. The WebAccelerator system stores content signatures in the Metadata cache for other optimizations, including Intelligent Browser Referencing.
WebAccelerator system applications provide options to always or never send metadata. Additionally, you can specify a maximum size for the Metadata cache, in megabytes. All WebAccelerator applications share the same Metadata cache.
WebAccelerator system policies cache ETag headers, which include the following:
For the General Options list, this table describes the Advanced settings and strings for Metadata Cache Options.
|Send Metadata||Always||This setting determines whether and how the WebAccelerator™ system performs Metadata caching for responses.
|Metadata Cache Max Size||25||Specifies the size in megabytes (MB) for the maximum Metadata cache size.|