GZipCompression Filter & a4j

[ckadam]

Hi All,

I have added GZip Compression filter to my web.xml. But after adding that, I have started to notice substantial delay when downloading prototype.js file from the server. (http://hostname/a4j.res/prototype.js.jsf). It takes almost 20 seconds to finish the request.

When inspected the response using FireBug, I found that compressed file was 14kb, but content-length header was set to 54 KB. This mismatch was causing the request to be open for longer time.

Response Headers
Server Apache-Coyote/1.1
X-Powered-By Servlet 2.4; JBoss-4.0.3 (build: CVSTag=JBoss_4_0_3 date=200510042324)/Tomcat-5.5
Last-Modified Wed, 29 Aug 2007 05:18:24 GMT
Cache-Control max-age=86400
Expires Thu, 30 Aug 2007 17:29:25 GMT
Content-Encoding gzip
Content-Type text/javascript
Content-Length 54326
Date Wed, 29 Aug 2007 17:32:02 GMT


Request Headers
Host smdevdk12:8080
User-Agent Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.6) Gecko/20070725 Firefox/2.0.0.6
Accept text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
Accept-Language en-us,en;q=0.5
Accept-Encoding gzip,deflate
Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive 300
Connection keep-alive
Cookie JSESSIONID=8D2F7C25B04C3CEEEE97E53F8AC04C67.localhost

[ckadam]

Has anyone come across this problem ? Thanks.

[sergeysmirnov]

This is a problem of filter, not ours. Default deflate compressor in Tomcat set the length right.

[ckadam]

Sergey, Thanks for quick response.

Once I get rid of GZipFilter from web.xml, then I do not see this problem. But this may not be acceptable solution for us.

So I did debug the GZipCompression filter code, and found that GZipFilter is not changing the content-length header at all. So i am not really sure, who is setting the header value.

Is A4J, serving any of the resources in compressed format ?

Is there any recommended way for applying GZipCompression on JSF pages served using Jboss ?

[alexsmirnov]

Jboss AS bundled with a Apache Tomcat, where is compression built-in at the Connector level. See http://tomcat.apache.org/tomcat-6.0-doc/config/http.html , compression attribute description.
For a Jboss 4.2.1, edit $JBOSS_HOME/server/default/deploy/jboss-web.deployer/server.xml

[alexsmirnov]

Content-Length response header is setted by RichFaces resource framework. It value is important for a properly resource caching ( most browsers don't cache objects for unknown length ).

[ckadam]

Alex,

Thanks for response. I will look into those resources.

But I just wanted to bring up one more thing. On my page, I have modalPanel. So resources related to that are downloaded from these server as well. But I their case, content-length header is set correctly. So I am confused about, what so special about prototype.js resource.

e.g.

http://smdevdk12:8080/a4j.res/org.ajax4jsf.framework.ajax.AjaxScript.jsf

Response Headers
Server Apache-Coyote/1.1
X-Powered-By Servlet 2.4; JBoss-4.0.3 (build: CVSTag=JBoss_4_0_3 date=200510042324)/Tomcat-5.5
Last-Modified Wed, 29 Aug 2007 18:23:42 GMT
Cache-Control max-age=86400
Expires Thu, 30 Aug 2007 19:18:29 GMT
Content-Encoding gzip
Content-Type text/javascript
Content-Length 10268
Date Wed, 29 Aug 2007 19:18:29 GMT


Request Headers
Host smdevdk12:8080
User-Agent Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.6) Gecko/20070725 Firefox/2.0.0.6
Accept */*
Accept-Language en-us,en;q=0.5
Accept-Encoding gzip,deflate
Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive 300
Connection keep-alive
Referer http://smdevdk12:8080/config/showConfigurations.jsf
Cookie JSESSIONID=B260D08B0315E0E534125702FBA3B539.localhost

[alexsmirnov]

Different values for a content length provided by filter, framework itself set real value for a resources with known size.
Wich implementation of a GZipFilter is used ?

[ckadam]

Here is the reference : http://www.onjava.com/pub/a/onjava/2003/11/19/filters.html