unable to set content-encoding to gzip

I'm having issue with response header in webpage...My server.xml is having below details,but not getting "content-encoding" in "Response-header"

<Connector compressableMimeType="text/html,text/xml,text/css,text/javascript, application/x-javascript,application/javascript"
compression="on"
compressionMinSize="128"
connectionTimeout="20000"
noCompressionUserAgents="gozilla, traviata"
port="8080"
redirectPort="8443" protocol="HTTP/1.1" />

I just wanna make sure that,

1].only changing in server.xml is enough?

2].do i have to do any changes in web.xml also?