Features in Varnish

Poul-Henning Kamp phk at phk.freebsd.dk
Sat Jul 8 18:29:21 CEST 2006

In message <1300C52E-0DC1-47AD-948A-1098DF295559 at vgnett.no>, Anders Berg writes

>- Very fast
>Varnish is buildt for speed, and should out-perform any other HTTP  

I'm never keen on such absolutes, at least not until I've convinced
my self that they are true :-)

>- Modern operatingsystem technology
>To be able to deliver content as efficient as possible Varnish takes  
>in use the latest operatingsystem features like Kqueue/Epoll and  
>Sendfile. Varnish is also IPv6 compatible

The last bit may need a bit of verification.

>- Powerful configuration possibilities
>Varnish has a powerful configurationlanguage (VCL) which gives you  
>endless possibilities and power over your content. You can reference  
>another configurationfile if say your backend is acting slow

I think the second statement rather detracts from the first by
being very specific.

>- Runtime configuration deployment
>Changing of configurationfiles are done in runtime, no need to stop/ 
>restart your service(s)

... for the policy part of the configuration.

>- Instant purging
>No datastructure traversing will accur, Varnish will instantly purge  
>your document(s)
>- Wildcard purging
>Again, no datastructure traversing is done and all documents (even  
>millions) matching your wildcard or regexp will intsantly be rendered  
>obsolete and not delivered

Since these are basically the same feature, I would combine them:

- Instant wildcard purging of documents
A purge command of specifying a regular expression instantly stops
delivery of any cached documents matching the expression without
wasting time traversing all the cached documents.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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