Developers, and users, generally agree that the easiest medium through which to digest data is a graphical one. This rule is particularly true now, considering the volume of data that can be more easily obtained from various distributed data sources using either SQL or XML as a conduit.

Requesting and presenting data in a graphical format, however, has traditionally come at the expense of performance and complexity. Besides the cost of marshaling the data from the disparate sources in order to convert it into a graphical format, image files take a great deal of time to transport over the network and display in client browsers. The number of data points to be represented in a graphical format would normally be directly proportional to the number of performance bottlenecks the system will experience. Introduce the availability of the data to be represented in real time, and that is interactive as well, and most developers would assume that the gains provided by the accessibility of the data in a graphical format would be lost ultimately to the poor application throughput.

Corda Technologies provides both the tools to reduce the complexity when constructing graphical charts and the server to deliver them without hindering performance. Corda's PopChart Server 4.0 delivers a variety of interactive charts representing real-time dynamic data using the latest best-of-breed graphical formats. These formats include Flash, SVG, PNG, GIF, PDF, EPS, WBMP, and descriptive text that is compliant with Section 508 of the Federal Acquisition Regulation for visually impaired users.

Written entirely in Java, PopChart Server 4.0 is a completely portable architecture that can interact with data from a variety of environments. Data can be accessed from XML, flat files, or HTML, directly from a relational database or indirectly from an application server. The PopChart Builder application provides for the quick and easy construction of the appearance files that describe how the data is to be formatted. Furthermore, using the PopChart Builder, developers can describe and implement the dynamic dimensions the charts will represent. For example, if a pie chart represents the employees of a company by country, it would make sense to know how the regions in that country represent those employees. Taking it a step further, a manager using such a chart might desire to drill down even more to see how employees are paid by region. All of this functionality, and more, can be easily facilitated with Corda's products.

Installing / Configuring PopChart Builder and Server
Both PopChart Server and Builder installed easily on the Windows 2000 machine used for this review. No special configuration was necessary other than following the installation screen and providing the software keys for both products. Afterwards it was simply a matter of launching them from the start menu. It's important to mention that Corda recommends that up to 40MB of hard drive space be available for the installation of the Enterprise edition of PopChart Server. It's also suggested that an additional 15MB be available for the PopChart Builder installation.

Another precondition for the installation is the availability of a Java VM compatible with JRE 1.3 or higher. Specifically, Builder needs a 1.3.1 VM while the server needs a 1.2.2 or 1.3.1 VM installed. The installation set makes these VMs available if the current environment doesn't support them. The server runs on Windows 98/NT4.0 or higher, Mac OS X, Solaris 8.0 or higher, and most Unix- or Linux-compatible systems using the equivalent of a Pentium II 233 or higher with 64MB RAM dedicated to your VM. Ideally, 128MB of RAM is desired.

A good variety of sample code is provided for implementing charts in JSP, HTML, JavaScript, Java servlets, ASP, and in the latest version, PHP and ColdFusion. You can plug sample data and appearance files into any of these supporting technologies to get a good feel of how the product is to use and how it functions. I also recommend a visit to www.corda.com to access the variety of powerful real-world examples the company provides to showcase the power of their product.

Working with PopChart Server 4.0
For the purpose of this article, my goal was to create a chart - in this case a pie chart - that organized the employees for a particular company by the country their office was located in. I thought it would also be helpful to see how many employees were associated with a particular region within that country. Finally, the chart had to provide the total payroll for a region and the average employee salary.

In spite of these requirements and an impending deadline, it was very easy to create the format for this chart in the form of an appearance file in Builder. No significant problems were encountered when the file was used within a Java servlet and accessed the data from a relational database. For this example an Oracle9iAS application server was used against an Oracle8i database.

The first step in creating the chart pictured in Figure 1 was starting the Builder and creating a new project from a template. This option provided me with the PopChart Wizard, which I used to create an appearance file from the robust catalog of templates that come with the product. Builder provides four template families, each containing 12 chart types that can be customized by choosing different color themes and by incorporating dynamic functionality. The chart types include area, bar, line, pie, time line, candlestick stock, and bubble graphs, to name a few.

For best image quality, Corda recommends the use of the Macromedia Flash or SVG (Scalable Vector Graphics) formats. These images combine the highest quality resolution with the best performance. They also allow for the interactive capabilities of rollover and popup text, and the ability of the user to drill down on a graph segment to reveal another graph containing more detailed information. Flash and SVG are the only formats that allow for this functionality. However, it's estimated that 96% of Internet users already have the appropriate Flash viewer installed in their browsers for use with PopChart Server. Therefore it's safe to assume that the dynamic functionality will indeed be put to use by your users.

However, if the browser to which the image is being delivered doesn't support either Flash or SVG, then PopChart employs its Best Image Fallback Facility. This feature allows the server to discern what the best format to provide should be, based on the capabilities of the client that is being served. This might mean that instead of seeing the image deployed as a Flash or SVG, a GIF or PNG format might be used. A nice feature of the Builder is that it allows the developer to see how the chart will be displayed in any of these formats. The template can be previewed in the browser so the developer can see simultaneously all of the formats that the appearance file can be displayed in for comparison purposes. Sample data is easily configured for this purpose (see Listing 1).

As a final step, I incorporated the appearance file into a Java servlet for use against live data. A wizard interface is provided to create client code for use against static data in JavaScript, Java servlets, JSPs, ASP, and in the latest version, PHP and ColdFusion. This wizard is an excellent tool for getting the feel of how an appearance file can be incorporated into these technologies. It's not too far from the work necessary to incorporate the same appearance file against dynamic data. The PopChart libraries supply a PopChartEmbedder object that contains the method setDBQuery, which marshals all the necessary data from the relational data source to be incorporated into the graph. After that the developer need only provide the address of the PopChart Server, the path to the appearance file to be used, the name of the data source, and the database driver to be used. A call to the getEmbeddingHTML() method renders the HTML document, along with its supporting JavaScript, which can then be written back to the client.

PopChartEmbedder also has methods for annotating the chart, the desired image format, and whether a link to a Section 508-compliant document should be provided. Section 508 of the Rehabilitation Act of 1973 mandates that federal agencies' electronic and information technology is accessible to people with disabilities. This link appears in the form of a capital "D" in the lower right-hand portion of the screen. When the link is clicked, a document is served describing all of the data in text that, for example, could be served by means of a voice synthesizer to users who are visually impaired.

Product Snapshot
Level Beginner to advanced programmers
Pros

• Multiple image format support
• Easy to use Builder tool for creating appearance files
• Powerful API for use with servlets, JSPs, EJBs
• Fast performance

Cons

• Nothing significant

Corda Technologies, Inc.
350 South 400 West, Suite 100
Lindon, UT 84042
Phone: 801 805-9500
E-Mail: sales@corda.com
Web: www.corda.com

Test Environment
OS: Dell Precision 340 Workstation running
Windows 2000 w/ Service Pack 2
Processor: 1.8 GHz, Intel Pentium IV, 40GB disk
Memory: 512MB

Specifications
Platforms: JRE 1.2 or higher
Pricing: PopChart Server Enterprise Edition, $6,990 including 1 year maintenance; PopChart Builder, $495 including 1 year maintenance