XML

Introduction

Davisor Chart makes extensive use of the Extensible Markup Language (XML). XML is an industry standard text format to represent information in a clear, structural way. Davisor utilizes this framework to define a Davisor Chart XML format that serves the following purposes:

All these aspects can be defined and invoked through corresponding Java API methods, too, but in typical use cases, Davisor Chart XML is the most convenient and preferable method to feed data and attributes to Davisor Chart.

Chart Attributes

The first major Davisor Chart XML format function is to declare what kind of graph Davisor Chart should generate from given input data, what would the visual details of that graph be, and into what kind of format the resulting graph should be packed in. These definitions are Davisor Chart Attributes, and in the Davisor Chart XML format, they all are collected under the <attributes/> XML tag.

The most important Davisor Chart attribute is chartType that controls what kind of visualization Davisor Chart should generate. For information and examples of what kind of chart types Davisor Chart supports, please see the separate Chart Types chapter in this guide.

The chartType attribute is one of the few top-level <attributes/> tag attributes. The rest of the Chart Attributes are grouped by their principal function into a number of other XML tags:

Chart Data

The second major Davisor Chart XML format function is to declare what kind of data the graphs should visualize, and from where this data can be acquired from. These declarations define Davisor Chart Data, and in the Davisor Chart XML format, they all are collected under the <data/> XML tag.

The top-level <data/> tag may then contain any number of data sources, each of which defines one or more data series. The set of data series defined collectively by all the data sources forms the input data a Davisor Chart then visualizes.

The principal XML data sources are listed below. For more information about Davisor Chart data sources, please see the separate Data Sources chapter in this guide.

Examples

The following example shows the entire content of a typical Davisor Chart XML file.

<chart>
  <data>
    <column dataType="TEXT" id="month_column" type="label">
      <e>March</e>
      <e>April</e>
      <e>May</e>
      <e>June</e>
    </column>
    <column dataType="INT" id="sales_data" type="value">
      <e>12000</e>
      <e>19000</e>
      <e>15000</e>
      <e>30000</e>
    </column>
  </data>
  <attributes chartType="column">
    <image height="200" width="300"/>
    <axes font="Arial-14-plain"/>
  </attributes>
</chart>

The first thing to note is that the whole thing is wrapped inside a <chart/> tag that is the root tag for all Davisor Chart XML files. Inside the <chart/> tag, the <data/> tag defines then chart input data, and the <attributes/> tag defines chart visual attributes.

Chart Data

Inside the <data/> tag, the two <column/> tags define two inline XML data sources, each defining one data series. Inside these <column/> tags, the data values forming these series are then defined one by one with <e/> tags (as an element), in the order the <e/> elements appear in XML.

The attributes of the <column/> tags define important facts about the data series. The meaning of the attributes of the first <column/> tag are:

dataType="TEXT"
The values of this data channel are plain text. TEXT is one of the specific data value type Davisor Chart recognizes and can act upon.
id="month_column"
The identification of this data channel is month_column. This value has no specific fixed meaning, and any other string value unique within this set of data series would also do.
type="label"
The values of this data channel should be used as data labels. label is one of the reserved series type keywords that has special meaning for all Davisor Chart chart types.

The meaning of the attributes of the second <column/> tag are:

dataType="INT"
The values of this data channel are integers. INT is another specific data value types Davisor Chart recognizes and can act upon.
id="sales_data"
The identification of this data channel is sales_data. Again, any other string value unique within this set of data series would also do.
type="value"
The elements of this data channel should be used as values. value is perhaps the most common series type, and it is always recognized by all Davisor Chart charts.

Chart Attributes

The content of <attributes/> tag determines the visual appearance and style of the image. In particular, the chartType="column" attribute declares that the data should be visualized as a column chart.

The attributes width and height in the <image/> tag determine the resulting image width and height in pixels, respectively. Furthermore, since no image contentType is explicitly set, the resulting image will be of the default Portable Network Graphics (PNG) format.

Finally, the font attribute in the <axes/> tag defines that all texts laid along chart axes should be drawn with 14 pixel high Arial font.

Since no explicit fill paint information was given, Davisor Chart will use colors from the default color palette to fill in the columns of this column chart. Furthermore, since there was just one data series, each column (data point) will be assigned a different color. Should there have been two or more series, each series would have been filled with different color, with all the columns belonging to the same series sharing the same series color.

Result

The image below shows the final result of the definitions given by the example XML file. By pressing the buttons below, you may now re-examine the example XML in more detail, or load the example case into Davisor Designer for further inspection.

Chart created from example XML.