Currently there are two main ways a ColdFusion developer can prevent whitespace; via the ColdFusion Administrator and by including certain tags in their code:

1. ColdFusion Administrator

Under the Server Settings > Settings menu item there is a checkbox called ‘Enable Whitespace Management’. This checkbox should always be checked. According to the description, checking this checkbox “reduces the file size of the pages that ColdFusion returns to the browser by removing many of the extra spaces, tabs, and carriage returns that ColdFusion might otherwise persist from the CFML source file.” I am yet to be convinced, but it is worthwhile enabling it.

2. ColdFusion Tags

<cfsetting enablecfoutputonly="true"></cfsetting>

The cfsetting tag controls aspects of page processing, such as the output of HTML code in pages (inside and outside the cfsetting tag body). If enablecfoutputonly is set to true, HTML output is blocked if it is not wrapped in a cfoutput tag. Therefore, this tag ‘can’ be used to minimise the amount of generated whitespace.

<cfsilent></cfsilent>

The cfsilent tag supresses output produced by CFML within a tag’s scope. Therefore, you simply need to wrap the tag around anything you don’t want to output to the browser. As it does not return anything from with in it, so you have to be a little be careful when debugging.

<cfprocessingdirective supresswhitespace="true"></cfprocessingdirective>

One of the cfprocessingdirective‘s purposes is to remove excess whitespace from ColdFusion generated content in the tag body. However, it does not affect any whitespace in HTML code. You can nest the tags and toggle supresswhitespace on and off, not that I ever identify a good reason to do so.

But there is a little known third way, using a servlet filter called Trim Filter.

Servlet filters are tools available to web application developers. They are designed to be able to manipulate a request and response (or both) that is sent to a web application.

Trim Filter lets you decrease the size of file your server will send to all clients. The filter removes extra spaces and line breaks from outputted documents. This can be especially useful for WAP/WML developers working with mobile devices, where the size for transferred documents is limited.

Setting up the servlet filter in ColdFusion

Using the Trim Filter servlet filter found at the following URL:

http://www.servletsuite.com/servlets/trimflt.htm

• Download the trimflt.jar
• Save trimflt.jar in the WEB-INF/lib folder in the ColdFusion Server wwwroot.
• Edit the web.xml file in the WEB-INF folder in the ColdFusion Server wwwroot with the following code:

<filter-mapping>
	<filter-name>trimFilter</filter-name>
	<url-pattern>*.cfm</url-pattern>
</filter-mapping>
 
<filter>
	<filter-name>trimFilter</filter-name>
	<filter-class>com.cj.trim.trimFilter</filter-class>
</filter>

• Restart the ColdFusion Service

And now, when a ColdFusion page is invoked, the whitespace is suppressed and wow does it do a good job.

Servlet filters are tools available to web application developers. They are designed to be able to manipulate the request and responses that are sent to a web application, without manipulating the servlets, static pages like HTML and, in this case, CFM pages that are being used by the web application (unless of course that is the desired response). Servlet filters act like a chain of steps that a request and response must go through before reaching the page in the application.

Compressing Content Using a Servlet Filter

Compression is a process that reduces the number of bytes required to define a document in order to save disk space or transmission time. It is extremely useful for sending information across the web, because the speed at which people receive information from a web application is dependent upon how much data you are trying to send. The smaller the amount of information that is to be sent, the faster it can be sent. Therefore, compression and the associated responsiveness is a key component to retaining users and generating revenue from those retained users.

Compression can be effectively achieved by having a servlet filter conditionally pipe the produced content to a GZip-compressed file. GZip is supported by the HTTP protocol and almost all modern browsers (hence the servlet filter conditionally compresses the content).

GZip compression usually results in a 6:1 compression ratio, although this depends on how much content is being sent and what the content is.

Setting up the Servlet Filter in ColdFusion

Using the ColdBeans servlet filter found at the following URL:

http://www.servletsuite.com/servlets/gzipflt.htm

• Download the GZipFilter.jar
• Save GZipFilter.jar in the WEB-INF/lib folder in the ColdFusion Server wwwroot.
• Edit the web.xml file in the WEB-INF folder in the ColdFusion Server wwwroot with the following code:

  <filter>
  <filter-name>GzipFilter</filter-name>
  <filter-class>com.cj.gzipflt.GzipFilter</filter-class>
  </filter>
  <filter-mapping>
  <filter-name>GzipFilter</filter-name>
  <url-pattern>*.cfm</url-pattern>
  </filter-mapping>

• Restart the ColdFusion Service

Now, when you invoke any .cfm page the GzipFilter will check out client’s browser settings. If the browser does not support gzip, the filter invokes resource normally. If the browser does support gzip, output will be compressed.