Home ›

Creating Web Plots on Demand

Issue 52

From Issue #52
August 1998

Aug 01, 1998  By Mark Pruett
 in
Mr. Pruett tells us how his company creates on-the-fly plots of database information for web display.
Cleaning Up the GIF Files

One minor issue remains. We create a new GIF file each time our Perl program is run, so we must get rid of them when they're no longer needed.

In my case, each night I simply run a script under crontab that deletes any GIF files created during the day. Since most of our applications are run during the daytime hours, the chances of deleting a GIF file I still need are very small.

This scheme might not be acceptable in every situation, so you may need to devise a different way to clean up the GIF files that collect on your web server. [The find command will fit this purpose admirably—Ed]

Reviewing the Steps

While I've provided a specific example of on-demand plotting, the techniques used can be applied to any type of data you might want to plot. If you can extract the data to a simple text file, and if the data lends itself to two- or three-dimensional plotting, you can deliver it to the Web. The basic steps are always the same:

  • Build a text file with the data to plot.

  • Build a gnuplot command file.

  • Run gnuplot to build the plot in PPM format.

  • Convert the plot to GIF format using ppmtogif.

  • Build an HTML page with the image tag and send it to the browser.

Tying together tools like gnuplot and NetPBM to quickly build a useful program shows that software doesn't necessarily have to come packaged in the latest object-oriented component, tied together with ActiveX or CORBA. Often, good solid tools, text files and a touch of Perl will more than suffice to do the job.

Resources

Mark Pruett received his M.S. in computer science from Virginia Commonwealth University. Mark is a programmer who writes about programming. He hopes some day to be a writer who writes about how to write program documentation. He can be reached at pruettm@vancpower.com.

______________________

White Paper
More Resources
Fabric-Based Computing Enables Optimized Hyperscale Data Centers

Today’s modular x86 servers are compute-centric, designed as a least common denominator to support a wide range of IT workloads. Those generic, virtualized IT workloads have much different resource optimization requirements than hyperscale and cloud applications. They have resulted in a “one size fits all” enterprise IT architecture that is not optimized for a specific set of IT workloads, and especially not emerging hyperscale workloads, such as web applications, big data, and object storage. In this report, you will learn how shifting the focus from traditional compute-centric IT architectures to an innovative disaggregated fabric-based architecture can optimize and scale your data center.

Learn More

Sponsored by AMD

White Paper
More Resources
Red Hat White Paper: Using an Open Source Framework to Catch the Bad Guy

Built-in forensics, incident response, and security with Red Hat Enterprise Linux 6

Every security policy provides guidance and requirements for ensuring adequate protection of information and data, as well as high-level technical and administrative security requirements for a system in a given environment. Traditionally, providing security for a system focuses on the confidentiality of the information on it. However, protecting the data integrity and system and data availability is just as important. For example, when processing United States intelligence information, there are three attributes that require protection: confidentiality, integrity, and availability.

Learn more about catching the bad guy in this free white paper.

Learn More

Sponsored by DLT Solutions