Hi there
I am using following code to display generated SVG images (charts) to an org.zkoss.zul.Image:
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AImage aImage = new AImage("chart1.svg", data);
chartImage.setContent(aImage);
It works perfectly! The problem is that the generated SVG image may become very large. I could see with Firebug Network Analyzer that the content of the SVG image is NOT zipped while transferring from server to browser.
Is there a way to force zipping the AImage content? SVG images are actually perfect to zip (XML content).
Thank you Best Regards Dieter
I had a second look and found a tomcat configuration that seems to work:
in server.xml add the 3 compressionXXX parameters which will enable compression of svg responses. I didn't enable any other mime types since ZK enabling gzip compression by default for many other resource responses (css/js/zul) - to avoid double gzipping (see configuration reference on ZK AU Engine, ZK Loader and if enabled DSP Loader).
<Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443"
compression="on"
compressableMimeType="image/svg+xml"
compressionMinSize="0"
/>
I tested the following zul file on a tomcat 8 with the configuration above:
<zk>
<image id="chartImage"></image>
<zscript><![CDATA[
import org.zkoss.image.AImage;
import org.zkoss.util.media.AMedia;
AImage aImage = new AImage("chart1.svg", "<svg xmlns=\"http://www.w3.org/2000/svg\" height=\"100\" width=\"100\"><circle cx=\"50\" cy=\"50\" r=\"40\" stroke=\"black\" stroke-width=\"3\" fill=\"red\"/></svg>".getBytes());
desktop.getDynamicMediaURI(chartImage, "chart1.svg");
chartImage.setContent(aImage);
]]></zscript>
</zk>
This url was generated:
Request URL:http://localhost:8080/mytestapp/zkau/view/z_2zl/dMAP0/hhh1/1/c/chart1.svg
As you can see in the headers the compression was enabled:
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Accept-Ranges: bytes
Content-Type: image/svg+xml;charset=UTF-8
Content-Language: en-US
Transfer-Encoding: chunked
Content-Encoding: gzip
Vary: Accept-Encoding
Date: Thu, 23 Feb 2017 01:09:58 GMT
I hope this information (even if only tomcat specific) helps for your application.
Update: another (less global) way is to implement a Servlet Filter with a filter-mapping for only /zkau/view/* and then apply the compression manually only when needed based on your own specific rules.
Robert
topic about gzip filter on stack overflow: http://stackoverflow.com/questions/4755302/which-compression-is-gzip-the-most-popular-servlet-filter-would-you-suggest
cor3000 ( 2017-02-23 01:53:07 +0800 )editHello dis,
I found some interesting articles based on your idea. Basically you enable compression on your application server as shown below:
http://viralpatel.net/blogs/enable-gzip-compression-in-tomcat/
For more info please refer to the following:
https://betterexplained.com/articles/how-to-optimize-your-site-with-gzip-compression/
Best Regards,
Darksu
zk enables compression by default for specific responses since images as gif/png/jpg are already compressed by default: see https://www.zkoss.org/wiki/ZKConfigurationReference/web.xml/ZKAUEngine.
cor3000 ( 2017-02-22 07:19:38 +0800 )editshould be possible by adding the svg mime type (image/svg+xml) to the list of compressible mime types by your application server. Which application server are you using: here the docs for tomcat https://tomcat.apache.org/tomcat-8.0-doc/config/http.html#Standard_Implementation
cor3000 ( 2017-02-22 08:39:59 +0800 )editHello Robert
Thank you for your solution. This works perfectly for our Tomcat installations. We use also an embedded Jetty server in production. It works similar for Jetty: a GzipHandler must be added as an additional handler.
Dieter
Asked: 2017-02-17 10:25:26 +0800
Seen: 41 times
Last updated: Feb 23 '17
