Don Henderson - SAS Server Pages: Generating Dynamic Content

On the surface, dynamic content generation is a simple concept. Web pages can be dynamically generated at the time of access by a user, and the generated output can be customized. That customization can be defined by a number of criteria, including, for example, the results of interaction with a user, a change in the underlying data sources, and so on.

With the release of SAS/IntrNet software in 1997, the delivery of dynamically generated Web pages became a key feature of SAS software. The initial release of SAS/IntrNet software relied on the infrastructure provided by Base SAS software to generate Web content (for example, HTML pages). The Output Delivery System (ODS) is another popular way to implement dynamic content generation (such as HTML) using SAS software, and it has worked quite well for reporting applications. The DATA step with FILE/PUT statements is also widely used to generate custom HTML. These techniques are very powerful, but also somewhat limiting. ODS is simple to use, but it is limited primarily to tabular and graphical reporting. The FILE/PUT statements in the DATA step can be used to generate virtually any content, but many SAS programmers find it difficult to write, understand, and maintain these programs. This is primarily due to conflicts in how certain special characters (for example, double quotation marks, ampersands, and so on) are interpreted in SAS versus HTML.

The evolution of dynamic content generation using SAS software mirrors the evolution of the Web. It started with the idea of static HTML documents using Base SAS software and quickly evolved to dynamic content generation via SAS/IntrNet and, later, via the SAS BI tools.

SAS Server Pages grew out of a need for more extensive and flexible ways to generate HTML-based dynamic content. They were initially described in the SAS Press book Building Web Applications with SAS/IntrNet: A Guide to the Application Dispatcher . SAS Server Pages have been used by a number of SAS developers as a way of creating custom user interfaces for Web-based applications. The basic idea behind SAS Server Pages is to embed logic into the HTML files themselves. Their use is thus similar to how Active Server Pages (ASP) and Java Server Pages (JSP) are used in the development of Web applications in general.

In earlier releases of SAS, the creation of SAS Server Pages is supported by a SAS macro that leverages the infrastructure provided by the DATA step.

SAS Server Pages can be used with any SAS product but are typically used with the following software:

SAS/IntrNet Application Dispatcher software

SAS Stored Processes, which are part of SAS BI and SAS Enterprise BI software

Base SAS software

The STREAM procedure is an experimental procedure in SAS 9.3. Similar to ODS and the DATA step, PROC STREAM and SAS Server Pages provide a foundation technology that greatly expands the capabilities of SAS for dynamic and rich content generation. Through the use of PROC STREAM and the Macro facility, SAS can now be used to generate any type of markup or text-based content such as HTML, XML, CSV, and so on.

PROC STREAM significantly expands what can be done with SAS Server Pages. It includes, but is not limited to, the following features:

SAS code can be defined and executed in a SAS Server Page.

SAS Server Pages can dynamically include other SAS Server Pages (analogous to what is referred to as Server Side Includes in JSP and ASP applications).

There is no longer a 32K limit on how much text a macro can generate.

The focus of this book is to illustrate how to generate SAS Server Pages using PROC STREAM. For readers who might not yet have access to SAS 9.3 and PROC STREAM, see SAS Server Pages , and specifically Generating SAS Server Pages in Different Releases of SAS , for details about how SAS Server Pages can be generated in previous releases of SAS.