I recently tried using gzip compression to improve web UI performance. I configured Tomcat Connector as below.

noCompressionUserAgents="gozilla, traviata"

Below is RequestHeader - Accept-Encoding is gzip, deflate.

Key Value
Request GET /app/jquery-ui.min.js HTTP/1.1
Accept  */*
Referer https://cdduat.app.com/Apptech/
Accept-Language en-US
User-Agent  Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; Trident/7.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; InfoPath.3)
Accept-Encoding gzip, deflate
Host    cdduat.app.com
Connection  Keep-Alive
Cache-Control   no-cache
Cookie  JSESSIONID=CB793FFEE9A34B5B8E7DE34A17C90B5D; mbox=session#1436174197635-942865#1436176058|PC#1436174197635-942865.28_07#1437383802; s_fid=498342221B10B4ED-297E46742B9393BE; s_vi=[CS]v1|2ACD23BB851D5DBF-40001903C00C9391[CE]; oo_event_entry=41eebf1007f6e19f5b0ee4b5841be2441e970f9c

For response header - there is no Accept-enconding key value. Moreover I'm not sure if its working or not. Below is Response Header. Web form load time is still the same. Not sure if I am doing anything wrong here.

Server  Apache-Coyote/1.1
Accept-Ranges   bytes
ETag    W/"238326-1435860126000"
Last-Modified   Thu, 02 Jul 2015 18:02:06 GMT
Content-Type    application/javascript
Content-Length  238326
Date    Mon, 13 Jul 2015 22:22:23 GMT

Also I could see Cache-control value as no-cache. Does it mean browser wont cache JS files and request for those resources again on subsequent request?

I noticed Transfer-encoding as chunked. Not sure if it may or may not override gzip encoding. Any help or guidance would be really helpful.

  • I am trying compression only on standalone tomcat. Is it even possible? All js files are minified. Is it a valid scenario for gzip compression? – pratikpawar Jul 16 '15 at 20:27

Shortly: You have to add this attributes for all connectors and their protocols:

compression="on" compressionMinSize="0" useSendFile="false"

See Apache Tomcat HTTP Connectors Attributes

1. http connector

<Connector port="8080" protocol="HTTP/1.1"
           compression="on" compressionMinSize="0" useSendFile="false"
           redirectPort="8443" />

2. https connector (change certificates files names to yours)

<Connector port="8443" protocol="org.apache.coyote.http11.Http11AprProtocol"
           compression="on" compressionMinSize="0" useSendFile="false"
           maxThreads="150" SSLEnabled="true" >

        <Certificate certificateKeyFile="conf/localhost-rsa-key.pem"
                     type="RSA" />

If you use http2 protocol and tomcat9 - add this line there too:

3. http2 connector

<UpgradeProtocol className="org.apache.coyote.http2.Http2Protocol"
                 compression="on" compressionMinSize="0" useSendFile="false" />
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