What Can Server Side Includes (SSI) Do For You?

You may have noticed as you browse this site, that our pages end with shtml extension instead of the more familiar html or htm. This is because we use Server Side Includes (SSI for short). Used properly, SSI can help make your web site more responsive and can even help make maintaining your site a much easier task.

Simply put, SSI directives in a shtml page will call another file (which can be text file or a program) and merger (include) the result in the finished page sent to browser. In other words, SSI will include or copy files into a web page. Think of it as being sort of like a document merge in word processing.

Take a look at the top menu on this page. In the actual source shtml code, there's no visible text at that place. Instead, I use this line of SSI command:

In the header.txt file, which is a simple unformatted text file created by Notepad, I write these html code just like in any other normal html pages:

<p align="center">
<a href="../index.shtml">Home</a> |
<a href="index.shtml">Web Hosting</a> |
<a href="../webdesign/index.shtml">Web Design</a> |
<a href="../promotion/index.shtml">Web Site Promotion</a> |
<a href="../livehelp/index.shtml">Live Help Service</a> |
<a href="../faq/index.shtml">FAQ</a> |
<a href="../resources/index.shtml">Resources</a></p>

When your browser requested this page, our server first parsed the shtml file, then processed the SSI directive line (called the header.txt file), merged what's in header.txt into the final page, then sent it to your browser. So, instead of seeing the SSI directive, you see a normal top menu retrieved from the header.txt

But if you "view source" of this page, you won't see the SSI directive at all since the server has processed it before sending it to you.

Now look at the menu at left side, at the bottom, even the newsletter subscription form, they're all created by SSI. The reason? It makes web site maintenance much easier.

The ECHO directive allows you to include information from the environment in your pages. For example, date and time.

This offer is going to be expired at midnight of Saturday December 21 2024.
Order It Now!

The following little snippet of source code is all you need to add this feature to your page:

This offer is going to be expired at midnight of <b> </b>.

The ECHO directive DATE_LOCAL displays the local time of where your server is - US for this web site. The CONFIG command adjusts the time format.

Here is a cute server side includes trick, a back button that actually takes you back to where you came from.

How did the page know where you came from. Remember, SSI can bring in server environment information and one tidbit at our disposal is HTTP_REFERER. This is the URL that brought you to this page. Here is the source code for this trick:

If you came to this page directly such as from bookmark, then (none) would be the value for HTTP_REFERER.

CONTENT_LENGTH - size of input posted from client
CONTENT_TYPE - MIME type of content
DOCUMENT_NAME - document name that was requested
DOCUMENT_URI - URL of the document
LAST_MODIFIED - document modified date
PAGE_COUNT - number of accesses to current document since server was brought on line
REMOTE_ADDR - IP address of the client
REQUEST_METHOD - HTTP method: GET OR POST
SERVER_NAME - server hostname
SERVER_SOFTWARE - name of the server software
TOTAL_HITS - total pages served by server since brought on line

Another great thing about server side includes is the ability to either run programs as straight system executions, or as CGI Scripts. For security reasons, only use them if you know what you're doing.

As you can see, SSI is a very useful tools for webmasters. However, sometimes you may need to take another thing into consideration - performance. When a regular HTML page is requested, the server only has to handle sending that page to the browser requesting it. With SSI, the server must first read the SHTML file, process any directives (which can be program output or files to be included in) and then deliver the assembled page to the browser.

If you are expecting thousands of hits per minute, that can be a lot of extra work for the server. On the other hand, keeping your pages trim will more than make up for the SSI performance cost in most cases.

Today, horsepower is cheap and getting cheaper. If your hosting service provider does not allow SSI because it may slowdown their server significantly, you can be sure they're not that trustworthy.

Feel free to use this article in your publication or web site.
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The only requirement is to include this resource box:

Article by Zac Hewlett at 1stSingaporeWebHosting
Visit http://www.1stSingaporeWebHosting.com for more
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Server Side Includes (SSI) Is A Very Useful Tool For Webmasters

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