RPE & Google Charts Tools to generate charts

In some cases numeric data is much easier to understand when presented as a chart. Rational Publishing Engine does not have a special module for chart generation like BIRT or other specialized reporting tools, but leave open the possibility to generate charts using javascript language and some charting engines.

Such an engine is Google Charts Tools

What are Google Chart Tools?

The Google Chart Tools enable adding live charts into your document.

The advantages of the Google Chart Tools are:

• A rich gallery of visualizations provided as:
  • Image charts – using a simple URL request to a Google chart server
  • Interactive charts – using a Google developed JavaScript library
• Simple to use and free

Figure 1: Static Charts

The Google Chart API returns a PNG image of a chart in response to a URL GET or POST request. The API can generate many kinds of charts, from pie or line charts to QR codes and formulas. All the information about the chart that you want, such as chart data, size, colors, and labels, are part of the URL.

To make the simplest chart with the Chart API, you just need a URL that specifies the chart type, the chart data, and the chart size.

Take a look at this simple example:

http://chart.apis.google.com/chart?chs=250×100&chd=t:60,40&cht=p3&chl=Hello|World

Use Case Scenario

To demonstrate you how RPE deals with chart generating, I’ll consider a simple use case:

Let’s say that we have a list of requirements in DOORS, each requirement having assigned a “Priority” attribute. We want to generate a report with all the requirements and at the end of the document to create a chart that will expose the information about the priority attribute.

The possible values of the “Priority” attribute are: Luxury, Mandatory, Important and Minor importance

Figure 2: DOORS Edit Attribute Dialog

How to customize RPE template in order to generate charts?

In order to extract all the requirements from a DOORS module, we have to create a RPE template, to add a DOORS data source, and then to use a container to iterate through all objects. For each object we need to display Object Heading/ Object Text attribute. To generate the final chart we have to number all the requirements accordingly to each priority. Then insert an image element in the template, and configure the image URL with the customized Google Chart URL.

Step 1: Create RPE template, add DOORS data source

• open RPE Document Studio
• create a new template
• select Data-> Add new Data Source Schema from the main menu. Select DOORS schema to be added.
• customize DOORS schema if necessary, using DOORS Data Source Discovery wizard

Step 2: Add a container element, and iterate through all the objects

• drag and drop a container element into the template
• drag the Module/Object query on that container

Step 3: Add paragraphs elements to display Object Heading and Object Text attributes

• drag 2 paragraphs into container
• drag the Object Heading attribute in the first one
• drag the Object Text attribute in the second one

Step 4: Insert a container to do all the count variables assignments

Figure 3: Set Assignments Editor

Figure 4: Variable Assignments Editor

Figure 5: RPE Template

Step 5: Add an image to the template and create the image URL, using the internal variables values
In our example I will create a simple “pie chart” showing proportional between luxury, mandatory, important and minor attributes.

Image URL:

“http://chart.apis.google.com/chart?chs=400×150&chd=t:” + luxuryCount + “,” + mandatoryCount + “,” + importantCount + “,” + minorCount + “&cht=p3&chl=luxury|mandatory|important|minor&chdl=”+luxuryCount+”|”+mandatoryCount+”|”+importantCount+”|”+minorCount

The generated chart will look like this:

Figure 5: Final chart

To add more fancy charts into your document please read more about:

• How to create advanced “Pie charts”
• How to create advanced “Bar charts”