Server Side Includes (SSI) is a simple interpreted

server-side scripting Server-side scripting is a technique used in web development which involves employing scripts on a web server which produces a response customized for each user's (client's) request to the website. Scripts can be written in any of a number of s ...

language used almost exclusively for the

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. It is most useful for including the contents of one or more files into a web page on a

web server A web server is computer software and underlying Computer hardware, hardware that accepts requests via Hypertext Transfer Protocol, HTTP (the network protocol created to distribute web content) or its secure variant HTTPS. A user agent, co ...

(see below), using its #include directive. This could commonly be a common piece of code throughout a site, such as a page header, a page footer and a navigation menu. SSI also contains control directives for conditional features and directives for calling external programs. It is supported by

Apache The Apache ( ) are several Southern Athabaskan language-speaking peoples of the Southwestern United States, Southwest, the Southern Plains and Northern Mexico. They are linguistically related to the Navajo. They migrated from the Athabascan ho ...

, LiteSpeed,

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, IIS as well as

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's Jigsaw. It has its roots in

NCSA HTTPd NCSA HTTPd is a discontinued web server originally developed at the NCSA at the University of Illinois at Urbana–Champaign by Robert McCool and others. First released in 1993, it was among the earliest web servers developed, following Tim Bern ...

. In order for a web server to recognize an SSI-enabled

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file and therefore carry out these instructions, either the filename should end with a special extension, by default .shtml, .stm, .shtm, or, if the server is configured to allow this, set the execution bit of the file.

Design

As a simple programming language, SSI supports only one

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: text. Its

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is rather simple, choice is supported, but loops are not natively supported and can only be done by recursion using include or using HTTP redirect. The simple design of the language makes it easier to learn and use than most server-side scripting languages, while complicated server-side processing is often done with one of the more feature-rich programming languages. SSI is

Turing complete Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher and theoretical biologist. He was highly influential in the development of theoretical comput ...

. SSI has a simple syntax: . Directives are placed in HTML comments so that if SSI is not enabled, users will not see the SSI directives on the page, unless they look at its source. Note that the syntax does not allow spaces between the leading "" that closes the element.

Examples

A web page containing a daily quotation could include the quotation by placing the following code into the file of the web page: With one change of the quote.txt file, all pages that include the file will display the latest daily quotation. The inclusion is not limited to files, and may also be the text output from a program, or the value of a system variable such as the current time.

Directives

Common

The following are SSI directives from the times of

(the 1990s). Some implementations do not support all of them.

Control directives

Control directives are later added to SSI. They include the ubiquitous if-elif-else-endif flow control and variable writing as well as more exotic features like loops only found in some implementations.

Notes

References

External links

* Language reference from implementations: ** Apache
Apache mod_include Reference
Calls directives "elements". ** Nginx

Calls directives "commands". **

Original NCSA HTTPd SSI Reference
Calls directives "commands". ** W3C Jigsaw

Calls directives "elements". Highly expanded with

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JDBC Java Database Connectivity (JDBC) is an application programming interface (API) for the Java (programming language), Java programming language which defines how a client may access a database. It is a Java-based data access technology used for Java ...

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, and loops. * Tutorials:
Apache SSI Tutorial
*

*
SSI-Developer, Apache Server Side Includes
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