Monday, May 16, 2011

PUT Statements in a Workspace Server to generate HTML? Yes you can!

Well, for years I've operated under the assumption that because a SAS Workspace Server (WS) does not support streaming HTML, that a stored process run by a WS could not use DATA steps to write HTML to the user's browser. Because the _webout fileref is not defined, you have to use packages.

Why does this matter? Why not just use a SAS Stored Process Server? Well, there are a multitude of reasons for this, but here are a few use cases that in prior projects have led me to want to use a WS:
  • A WS is started for each client request and thus it is running using the user's credentials. That can be important if you want to control file system access.
  • If a stored process needs to run for a long time (and that is a relative term in the Web world), using a WS does not cause the up and running Stored Process Servers to be tied up with such requests. Using a Stored Process Server for such requests limits access to them for all other user requests (this, of course, also depends on how your pool is set up).
You can read more about the differences at

Because WS use packages, the question then becomes how do you set up the environment so that you have a fileref to write your HTML (as well as other content types) to so that it will be directly displayed by the browser. With some help from Vince @ SAS, it turns out that with a few tweaks in how you call the stpBegin and stpEnd macros, you can do that. The trick is to set things up so that stpBegin and stpEnd create a package, but do not issue an ODS statement.

Here are a few simple (in hindsight) things you need to do:
  • Before calling the stpBegin macro, make sure it does not create any ODS statements by setting the value of the _odsDest macro variable to NONE. You can do this by making it a parameter to the stored process, or by using a %let statement.
  • Then after the stpBegin macro call, simply set the magic macro variable _NAMEVALUE to set the _DEFAULT_ENTRY attribute which specifies the name of the entry in the package that will be displayed to the user. For example:
      %let outfile=streaming.html;
      %let _NAMEVALUE=_DEFAULT_ENTRY=&outfile;

    Note that the macro variable outfile is used because this value will be used in multiple locations in your stored process.
  • Then issue a filename statement to create a fileref that you can use in your DATA Step code:
      filename _webout "&_stpwork&outfile";
That's all there is to it. Your package can contain any number of files, but the _DEFAULT_ENTRY attribute specifies which one will be displayed by the package viewer.

Here is a complete example that is a simplified version of SAS Server Pages that you can try out for yourself. Note that because the name/location of the output file had to be referenced in two places, the code uses a macro variable to ensure the values are consistent.


%let outfile=streaming.html;
%let _odsDest=NONE;

%let _namevalue=_DEFAULT_ENTRY=&outfile;
filename _webout "&_stpwork&outfile";

data _null_;
infile datalines;
file _webout;
_infile_ = resolve(_infile_);
put _infile_;
<h1>Testing a WS running as Process ID &sysjobid
for User &sysuserid</h1>
This test was run at