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Does caching boost performance for infraEnterprise? (1023407)
infraEnterprise makes extensive use of caching, both in terms of caching data used by the controls and in terms of caching HTML content (JS, GIF, HTML, etc.) on the client.
The infraEnterprise virtual directory is created by our admin console with a content expiry of 24 hours by default. This means that when a user first logs on in the morning (or first accesses a page in the application after a 24 hour period), there is an exchange with the server to either retrieve the content (first time accessed) or check for a newer version. When the content is confirmed as up-to-date then the client does not check for a newer version until either 24 hours has passed or the wrapper is restarted (which flags all client infraEnterprise content as needing a check).
What this means is that the first time you do a New Call after logging in, a round trip to the server checks the version (or retrieve) each item in the call page. This means a considerable number of round trips. If the network transit delay is significant, this can cause the initial new call opening to take quite a few seconds.
Subsequent New Call openings use the client cached versions of each item. This reduces the number of round trips to the server to just two, one to retrieve the dynamic page content for the call details page and one to populate the history control. The problem types control re-use the record set retrieved during the initial new call after logon. Typically the total data volume for this second (and all subsequent) new call pages should be less than 10 Kbytes.
All the controls that can cache data do so, for example, officer groups on forwarding calls and problem types. In addition, all data content sent to the controls is compressed to reduce bandwidth.
On each request, the wrapper modifies the value of:
HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\SyncMode5 = 0x0
... and sets it back to its original value. However, depending on group policy or security settings this may not happen - under these circumstances the browser may cache based on normal network settings. A regmon trace picks this up.
When troubleshooting performance issues, check that IIS has Content Expiration enabled. In IIS 6.0 this setting can be found under Virtual Directory > Properties > HTTP Headers > Enable content Expiration and should be set to Expire After 1 day.
VMware currently knows of two proxies, the open source SQUID proxy and the Webmarshall proxy, that do not handle HTTP 1.1 headers. These proxies effectively disable all caching as well as compression of data. If the client is using a squid proxy, you see excessive round trips and traffic volumes between client and server resulting in decreased performance.
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