Dynamic Flash Charts – FusionCharts style

As web developers, we build applications that feed on data. We parse it, process it and report it. Our reports take the form of tables, grids, and diagrams such as charts, gauges, and maps. Parsing and processing are backend tasks that are unseen by the user. The actual reporting of data, however, is the bulk of the experience a user has with our application.

To make our reports interesting and insightful, it is important to provide a highly engaging and functional face to the data in context. While tables, grids, and basic charting are natively supported by most web scripting languages, creating advanced or interactive charts require the use of third-party components. FusionCharts Suite is one such suite of components that help you deliver a delightful experience by aiding the creation of animated and interactive charts, gauges, and maps.

Before we jump in and look at what FusionCharts can do for you, let us see where charts, gauges, and maps can be helpful. Google Analytics, a tool that most web developers swear by, is a beautiful example of effective data presentation. In case you do not know, it is a tool that records a ton of information such as visitor demographics, referrers, advertising, browser information, and so on. With so much data recorded, it is of utmost importance to present it in a compact, yet insightful way, as shown in the following screenshot:

 

 

Note how the Dashboard has a very clean and non-cluttered look, despite the large data set it represents. Extra information, which is not required in the main layout, is displayed as tool tips and annotations. Interactive features such as a clickable world map lets you explore the data the way you want to. The selection of chart types is also immaculate, with the line chart showing the trend of the most commonly used metric—the number of visitors to the site. Other relevant metrics such as Pageviews and Pages/Visit are communicated in large text along with sparklines providing a historical context. A world map is used to display where the traffic is coming from. FusionCharts Suite helps you build similar dashboards with a lot more chart types and interactivity. Without further ado, let us proceed and set the goals for this article.

What is FusionCharts Suite?

FusionCharts Suite is a collection of four products, each of which help generate different types of charts, gauges, or maps in web applications. These data-visualization components are ideal for use within reports, dashboards, analytics, surveys, and monitors in web and enterprise applications. The visualizations are rendered using both Adobe Flash and JavaScript (HTML5), thereby making the experience seamless across PCs, Macs and a wide spectrum of devices including iPads and iPhones.

The four products in the suite are:

• FusionCharts XT: This helps create the 45 most used chart types such as pie, column, bar, area, line, stacked, combination, and advanced ones such as Pareto and Marimekko.
• FusionWidgets XT: This helps create Key Performance Indicators ( KPI) and make real-time data in dashboards, monitors, and reports more insightful. It includes a wide variety of charts and gauges such as dial charts, linear gauges, Gantt charts, funnel charts, sparklines, data-streaming column, line, and area charts.
• PowerCharts XT : This helps create charts for domain-specific usage such as those in network diagrams, performance analysis, profit-loss analysis, financial planning, stock price plotting, and hierarchical structures.
• FusionMaps XT: This consists of over 550 geographical maps, including all countries, US states, and regions in Europe for plotting business data.

All the products are built on a common framework and offer similar ways to use and configure them. To start with, we will create charts using FusionCharts XT and later explore charts of other products. Without further ado, let us get started and build our first chart. For that, you will first need to download FusionCharts Suite.

Getting FusionCharts

FusionCharts allows you to download the trial version from its website http://www.fusioncharts.com. This trial does not have any feature restriction or an expiry date. The only caveat is that the charts in the evaluation version have FusionCharts printed on the chart, which can be removed by purchasing a license of FusionCharts and later just replacing the Shockwave ( SWF ) and JavaScript( JS ) files, as we shall see later.

Time for action – downloading and extracting FusionCharts

1. Go to http://www.fusioncharts.com/download and fill in your particulars in the download form and click on Download.
2. On the next page, you will find links to either download the entire FusionCharts Suite, or individual products from the suite. In this article, we will work with FusionCharts XT only and hence will explore that.
3. Once the ZIP file has been downloaded, extract it to a folder on your hard drive, which is conveniently located at C:FusionChartsSuiteFusionChartsXT on Windows or Users/{YourName}/FusionChartsSuite/FusionChartsXT on Mac or UNIX based systems. Throughout this book, we will refer to this folder as the FusionCharts Installation Folder.

The steps to install and use FusionCharts remain the same, whether you are using the trial or licensed version.

What just happened?

You have now successfully downloaded FusionCharts XT and extracted it in the FusionCharts Installation Folder. We will soon learn how to use these files to build charts. Before that, let us quickly explore the contents of the FusionCharts package.

Within the FusionCharts Installation Folder, you will find multiple folders. Some of the folders are internal folders used to store documentation and gallery files, for example, Contents, Gallery, and so on. The folders that you will mostly use are Charts, Code, SourceCode, ExportHandlers, and the Tools folder for the following purpose:

Folder Name

What it contains?

Charts

Contains all the SWF and JS files that form the core of FusionCharts – we will refer to it as Core FusionCharts files. The FusionCharts SWF files have been created using Adobe Flash 8 and need Flash Player 8 (or above) to run. The JavaScript is compatible with IE6 (or above), Firefox, Chrome, Opera, and Safari, including that on iPads and iPhones.

Code

Consists of code samples in various programming languages that you can explore, to quickly learn or get started with.

SourceCode

Present only in Enterprise and Enterprise Plus license, this folder contains the source code of FusionCharts in both Flash Source files (.fla) and JavaScript files.

Tools

Consists of utility applications in three subfolders:

FCDataConverter helps you convert the FusionCharts XML data to JSON data and vice versa. We will explore this later in the chapter, after we have created our first chart.

FlashPlayerSecuritySetup contains scripts that help you configure security settings on your local machine only when using FusionCharts with JavaScript. We will explore this later in the book when we build advanced examples of FusionCharts integrated with JavaScript.

XMLGenerator is a visual interface to generate XML data for FusionCharts. This is primarily intended for non-developers and would not be of much help to us.

The FusionCharts Installation Folder also contains three files in the root folder:

Filename

What it contains?

FusionCharts License Agreement.rtf

Contains the license agreement that governs the usage of FusionCharts. You may want to read through it before using FusionCharts.

Version.txt

Contains the detailed version history of FusionCharts XT.

Index.html

The main page that you use to start exploring FusionCharts package.

When you run Index.html, you will see a page similar to the following screenshot:

When you click on the Documentation link, it opens the documentation for FusionCharts XT, as shown in the following screenshot:

This documentation is an exhaustive resource for FusionCharts including sections for beginners, chart parameter lists, API references, and sections on advanced charting.

From Index.html, you can also explore all the chart types present in FusionCharts XT by clicking on Chart Gallery. It presents a list of chart types and multiple examples for each, as shown in the following screenshot. We recommend you spend some time exploring this, as this is a good learning resource to get a real-world feel of the charts and understand what you can create once you are familiar with FusionCharts.

The Live Demos section, accessible from Index.html, lets you explore sample dashboards and examples created using FusionCharts—both offline and online.

Now that you have had a taste of what FusionCharts can do for you, it is time to create your own chart, your first chart using FusionCharts.

Creating your first chart

In our examples, we will create charts for a fictional supermarket, Harry’s SuperMart, so that Harry, the owner of the supermarket, can make more sense out of his data. Harry’s SuperMart, with 11 stores located in four states in the US, offering over 2,000 types of products and a customer base of around 25,000, records an intensive amount of data, which when presented effectively gives a lot of actionable insights. We will learn how to build meaningful charts that can facilitate this. For our first chart, let us build a simple Revenue by Year chart.

Once completed, the chart should look similar to the following screenshot:

Steps to create a chart using FusionCharts

Fundamentally, for each chart you build, you should ask yourself the following questions to ensure that the chart serves a meaningful purpose, as opposed to just being a fancy object on the page:

• Who will view this chart and why will this data interest him? This person is the end user.
• What type of chart is best suited to represent this data? Are there any alternate charts that we can use?
• Is this chart part of a bigger report/dashboard, or standalone? This helps us decide how to split information across multiple charts.

For our first chart that we build, Harry is the end user. This chart lets him compare the revenues of this year against the last two years. We would plot this data on a 3D Column chart, as Harry uses this to compare the revenues instead of seeing the overall trend. Had Harry wanted to see the trend of revenues over multiple years, we would have used an area or line chart. Also, to keep things simple, we will build this as a standalone chart.

Thereafter, technically, there are three steps to build a chart using FusionCharts:

1. Set up FusionCharts for the entire application, typically done only once per application.
2. Encode the data for the chart, either in XML or format.
3. Write the HTML and JavaScript code to include the chart in a web page.

Let us cover them one-by-one.

Time for action – set up FusionCharts for our first chart

1. Create a folder on your hard-drive to centrally store all the examples that we will build iteratively. If you are working on a web server, you can create this under the root folder of the web application. Let us name it as LearningFusionCharts. You can give it any other name as well.
2. Create a subfolder called FusionCharts within this folder. This folder will contain all the SWF and JavaScript files of FusionCharts, which are the FusionCharts Core files. If you are working on a web server, create this folder under the root of the web application, so that the entire web application can conveniently access this.
3. Copy all the SWF and JS files from the Charts folder under the FusionCharts Installation Folder (where you had earlier downloaded and extracted the FusionCharts ZIP file) to the newly created FusionCharts folder. This step completes the installation of FusionCharts for your application.
4. Create another folder under LearningFusionCharts and name it as FirstChart. This will be used to store the XML data and the HTML file for our first chart.

Upgrading the FusionCharts version, or converting from trial to licensed

If you are upgrading to a newer version of FusionCharts, or converting from evaluation to a licensed version, all you need to do is copy the SWF and JS files from the new or licensed version and overwrite the existing files in the FusionCharts folder.

What just happened?

You just installed FusionCharts. It involved copying of all the SWF and JavaScript files of FusionCharts, which are the FusionCharts Core files. If you intend to plot just a subset of chart types, you can select only those SWF files and paste them here. However, copying all files makes it easier in the future whenever you need to create a new chart type in your application. Each SWF file is used to plot a particular type of chart in Flash and the name of the file represents the chart type. You can find the complete list of charts in FusionCharts Documentation | Introduction | List of Charts. For our first chart, we are going to use Column3D.swf to plot a 3D Column chart.

The FusionCharts folder also contains six JavaScript files that aid in embedding and configuring charts, along with rendering them in JavaScript when viewed on devices that do not support Flash. These files are as follows:

Filename of the JavaScript Class

Purpose

FusionCharts.js

This is the main JavaScript class for FusionCharts, which helps you embed charts in your web pages in a user-friendly way, and offers functionalities such as updating chart data, retrieving chart data, supporting multiple data formats, and event handling.

FusionCharts.HC.js

This framework contains code to render FusionCharts in JavaScript.

FusionCharts.HC.Charts.js

Contains chart specific code to render FusionCharts XT in JavaScript.

jquery.min.js

Minified jQuery framework used by FusionCharts class for internal functions.

FusionCharts.jqueryplugin.js

FusionCharts jQuery class that lets you embed FusionCharts using jQuery syntax.

FusionChartsExportComponent.js

The charts generated by FusionCharts can be exported as images or PDFs in the browser itself, using a module called Client-side Export Component, as we will see later. This JavaScript file provides interfaces to link the Client-side Export Component to the charts.

While creating your chart, as you will soon see, you just need to include FusionCharts.js in your page. The other files such as FusionCharts.HC.js, FusionCharts.HC.Charts.js, and jquery.min.js are dynamically loaded by the code in FusionCharts.js.

With the basic setup in place, let us focus on the data for our chart.

Time for action – creating XML data for our first chart

1. 1. Create an empty XML file within the FirstChart folder named as Data.xml. This can be done using your text editor (Notepad on Windows, or TextEdit on Mac). To do so, while saving an empty text file, rename the extension to .xml.
   2. Write the following XML code in the file and save it:

1. Check whether the XML is valid by opening Data.xml in Internet Explorer or Firefox. If the browser shows the XML properly, you are good to go. Otherwise, review the error message and fix the error in XML accordingly.

What just happened?

Here, we have encoded the data, as shown in the following table, to an XML format supported by FusionCharts:

Year

Revenue

2009

$1,487,500

2010

$2,100,600

2011

$2,445,400

Each chart in FusionCharts is powered by data. This data could be static and hand-coded as we will build in this example, or dynamically generated by live scripts that are connected to databases or web services. FusionCharts can accept this data in two formats—XML and JSON. Both are commonly used formats for data exchange on the Web, with XML being easy on the human eyes.

The XML format that we just created is called single-series XML in FusionCharts parlance, as we are plotting just one series of data. Later in this chapter, we will explore multi-series charts that let you compare more than one series of data, for example, revenue split across Food and Non-Food products for each year across last three years.

All FusionCharts XML files start with the element. The attributes of the element help you configure the functional and cosmetic properties of the chart. In our example, we have defined the chart caption, subcaption, axis titles, and the currency prefix for numbers on the chart, as in the following line of code:

For each chart type, there are hundreds of optional attributes that you can define. If these are not defined, the chart assumes the default values for each of them.

Special characters in XML need to be encoded

XML documents can contain non-ASCII characters or special characters. However, these need to be encoded before they are provided in the XML document. In our example, note how we have encoded the apostrophe in Harry’s to Harry’s. Had we not done that, the XML document would have been an invalid one and raised errors when opened in a browser.

Each row of data to be plotted on the chart is represented by the element. The label attribute defines the text label for each data point, and the value attribute defines its numerical value to be plotted. There are additional attributes that can be defined for the element, for example, user-defined colors, which we will explore in later chapters. An important thing to note is how the $ prefix or comma separators have been stripped off the revenue numbers, before encoding them as a value for the element, that is, $1,487,500 has been converted to 1487500, as shown in the following line of code:

This is necessary as FusionCharts can interpret only standard numeric values.

While the standard attributes for the and elements are common across chart types, many chart types have special features that are controlled by attributes that are specific for the chart. You can explore a list of all such attributes for each chart in the documentation of FusionCharts, under the section Chart XML API.

With both the basic setup and data in place, we are just one step away from seeing our chart live—writing the HTML and JavaScript to embed this chart, which we will do next.

Time for action – writing the HTML and JavaScript code to embed the chart

1. 1. Create an empty HTML file within the FirstChart folder named as FirstChart.html.
   2. Paste the following code in the file and save it:

1. 1. Open it in a web browser. You should see your first chart coming to life, as shown in the following screenshot. Refresh the browser to experience the animation again, or hover over the columns to see tooltips.

1. 1. If you have access to an iPad or iPhone, open this example using the device. To do so, upload the entire LearningFusionCharts to a server that can be accessed over the Internet. Now point the browser in the device to http://Your_Website_URL/FirstChart/FirstChart.html. You will be able to see the same chart, but this time, rendered using JavaScript. The following screenshot shows a rendering of the chart within Safari in an iPhone. Tap on the columns to see the tool-tips.

What just happened?

You just created your first chart, that’s what happened! This chart renders using Adobe Flash on devices that support it, and automatically switches to JavaScript rendering on devices such as iPads and iPhones. The beauty of the solution is that no additional code or configuration is required to do this.

Let us break down our HTML and JavaScript code into digestible chunks. To create charts using FusionCharts in your page, you first need to include the FusionCharts JavaScript library (FusionCharts.js), as in the following lines of code:

Note that you only need to include FusionCharts.js in your code. The other files required for FusionCharts, namely FusionCharts.HC.js, FusionCharts.HC.Charts.js, and jquery.min.js are dynamically loaded by code in FusionCharts.js.

Next, we create a DIV as a placeholder where the chart would be rendered. We give the DIV an ID—chartContainer. This is done using the following code:

The DIV carries a placeholder text FusionCharts will load here! which will be displayed if there is an error in your JavaScript code, or FusionCharts.js or the chart SWF file could not be loaded. If you see this text instead of the chart, you know what to fix.

Following this, we initialize a chart by invoking the FusionCharts JavaScript constructor, using the following code:

var myChart = new FusionCharts(“../FusionCharts/Column3D.swf”, “myChartId”, “400”, “300”, “0”, “1” );

To this constructor, we pass the following parameters in order:

1. Path and filename of the chart SWF: The first parameter contains the path and filename of the chart SWF file. We have used the relative path to the SWF file, which is recommended.
2. ID of the chart: Each chart on the page needs a unique ID. This ID is different from the ID of the container DIV. As we will learn later, this ID is used to get a reference of the chart for manipulation using advanced JavaScript.
3. Width and height in pixels: Each chart needs to be initialized with width and height, specified either in pixels (specified in numeric format, without appending px) or percentage. In this example, we have used pixels. You can also set it to % values as in the following code:

   var myChart = new FusionCharts(“../FusionCharts/Column3D.swf”, “myChartId”, “100%”, “100%”, “0”, “1” );

   The FusionCharts JavaScript class will automatically convert the % dimensions to pixel dimensions, with respect to the parent container element in HTML, DIV in this case, and pass it to the chart.

4. Whether to start the chart in Debug mode: While developing your charts, if you face any issues, you can initialize them in debug mode by setting this parameter to 1. The Debug mode gives you behind-the-scenes information on where the data is loaded from, errors, and so on. In our example, we are rendering the chart in normal mode, by setting this parameter to 0.
5. In previous versions of FusionCharts, you had to manually set the last parameter to 1, if you wanted FusionCharts to communicate with JavaScript. Now that FusionCharts is very well integrated with JavaScript, this parameter is a mandatory 1.

Alternate compact constructor method

A chart can also be initialized using the static render() method of the FusionCharts class, as shown below.

There are additional possible syntaxes of this constructor and are detailed in FusionCharts Documentation | FusionCharts and JavaScript | Constructor methods.

Once the chart is constructed, we tell the chart where to source data from. We use a relative path to Data.xml , as it is stored in the same folder.

myChart.setXMLUrl(“Data.xml”);

If you recall, FusionCharts accepts data in two formats – XML and JSON – either provided as a string or a URL that points to the data file. In our example, we have used XML as the data format, which is stored in Data.xml. So, we use the setXMLURL() function to pass the URL of the XML data file to the chart.

What if the XML data file was stored in another location or subdomain?

If your data file was stored in a different folder, you would have to specify the relative path to the folder and then the filename, for example, ../ Source/Data/MyData.xml. We do not recommend specifying absolute URLs, because, if you move your web page or data file to another domain, cross-domain security issues would crop up and the chart would stop working.

Flash Player’s sandbox security model blocks loading of files across different sub-domains. If you need to load your XML data from another subdomain, you will have to create a Cross domain policy XML file, as explained at http://www.adobe.com/devnet/articles/crossdomain_ policy_file_spec.html.

Finally, to render the chart in the DIV that you had earlier created, you invoke the render() function and pass to it the ID of the DIV.

myChart.render(“chartContainer”);

Do remember that each chart and DIV needs to have its own unique ID.

What to look for if your chart is not rendered?

If you do not see any chart, there could be multiple reasons behind it. You should check for the following, based on what you see in your browser:

What do you currently see instead of the chart?

Corrective measures you should take

”FusionCharts will load here!” text that you had placed in the container DIV

Check whether FusionCharts folder is present in LearningFusionCharts folder and contains all JavaScript files required for FusionCharts.

Check whether you have provided the correct relative path to FusionCharts.js in the page FirstChart.html

Check for errors in your JavaScript code that you have written to embed the chart. Use the browser’s developer tools to check this.

Ensure that you have given different IDs for container DIV, chart JavaScript variable and the chart object in the constructor.

Empty white area instead of the chart

Check whether you have copied Column3D.swf to FusionCharts folder.

Check whether the relative path provided to Column3D.swf in FusionCharts constructor is correct.

“Error in loading data”

Check whether Data.xml is present within FirstChart folder

Check whether the path specified to Data.xml is correct in setXMLUrl() method

“Invalid data”

Check for the validity of XML data in Data.xml by opening it in a browser or an XML editor. Or, you can also switch the debug mode of chart to ON by changing the last but one parameter in constructor to 1. That will highlight the error in XML, as shown in the following screenshot:

With these measures, you should be able to locate the error and get your chart working. Before we move ahead to explore the other aspects of FusionCharts, let us understand how FusionCharts automatically switches between Flash and JavaScript mode.

Converting the chart to a pure JavaScript chart

By default, FusionCharts renders its charts using Adobe Flash. However, as you have seen earlier, when you view the chart on iPads or iPhones, FusionCharts automatically switches to JavaScript rendering, as Flash is not supported on those devices. This is internally checked by FusionCharts.js, and the auto-loaded files FusionCharts.HC.js, FusionCharts.HC.Charts.js, and jquery.min.js then aid in rendering the chart using JavaScript, using the same datasource and configuration.

FusionCharts also provides an option to entirely skip Flash rendering and use JavaScript as the default rendering, irrespective of the device. This feature can be very nifty for developers who want to develop JavaScript-only applications or even frameworks. Let us quickly see how to attain that.

Time for action – creating JavaScript only charts

1. 1. Create a copy of our FirstChart.html in the same location and name it as JavaScriptChart.html.
   2. Add the following lines of code before the constructor:

1. 1. Open the page in a browser. You should see the same chart as earlier, but this time rendered using JavaScript. It has animations and interactivity similar to the Flash version as shown in the following screenshot:

How different is the Flash rendering from JavaScript rendering?

The JavaScript version of FusionCharts behaves similar to the Flash version, offering most of the functional and cosmetic configuration. With the exception of a true 3D chart, all charts look and behave almost the same as their Flash counterpart. There are minor visual differences in the JavaScript version such as the width of columns, effect of shadows, handling of long x-axis labels, appearance of scroll bars, and so on. A detailed list of such differences are present in FusionCharts Documentation | Introduction | JavaScript Charting Capabilities | How different is JavaScript charts from Flash charts?

What just happened?

You just converted the previous chart to a pure JavaScript chart, irrespective of the device it is now viewed on. The following snippet of code instructs FusionCharts to switch the rendering mode to JavaScript:

FusionCharts.setCurrentRenderer(‘javascript’);

If your page contains multiple charts, this setting applies to all such charts that are defined after this line of code. Hence, if you declare this at the beginning, all the charts in the page will render using JavaScript. You would not need to declare the same for each chart in the page.

JavaScript cannot access data stored on your hard drive in some browsers

Some browsers restrict JavaScript from accessing the local filesystem due to security reasons. Hence, the JavaScript charts, when running from your local hard drive, would not be able to access XML or JSON data provided as a URL. However, when run from a server, including localhost, they will run fine. An alternate method to get JavaScript charts working locally is to use the Data String method, which we will explore in the next section.

Have a go hero – build a dashboard for Harry

In this example, you created a standalone Column 3D chart. How about inching towards building a complete dashboard? To do so, convert the existing chart to a Column 2D chart and add the following three charts to this page. In addition, specify different width and height for each chart to accommodate the amount of data it presents, and also place them in order of importance of the chart to Harry.

• A Line 2D chart, using Line.swf, comparing monthly revenues for this year. For this, you need to create an XML data with the element for each month of the year.
• A Pie 2D chart , using Pie2D.swf, showing the composition of expenses of this year split under these categories: Salary, Cost of Goods, Marketing Costs, Overheads, and Administration.
• A Column 2D chart , using Column2D.swf, showing the top five salespersons for the year.

All these charts use the same single-series XML format that you had earlier created. Remember to provide a different ID for each chart and its container DIV . Also, do not forget to encode special characters such as & (ampersand) or ‘ (apostrophe) in XML.

Once you are done, let us explore the other way to provide XML data to FusionCharts—as a string, instead of providing a URL, for example, Data.xml.

Using the Data String method to provide data

As we had mentioned earlier, there are two ways to provide data to FusionCharts – either as a URL to the datasource (Data URL method), or as a string (Data String method). Till now, we have used the former method by invoking the setXMLUrl() method on the chart instance and providing Data.xml as the URL. In order to pass the XML as a string to the chart, we can use the setXMLData() method, as explained next.

Time for action – embedding XML in the web page and using the Data String method

1. 1. Create a copy of our FirstChart.htmlDataStringMethod.html.
   2. Change the following lines in code:

1. Open the page in a browser. You should see the same chart as earlier, but this time using data embedded in the page, and not Data.xml.

What just happened?

You just used the Data String method of FusionCharts to power up your chart using XML data embedded in the page, instead of reading it from Data.xml. This was done by invoking the setXMLData() method on the chart instance.

myChart.setXMLData(“”);

The entire XML string is passed to this method. Note how we are using the characters in JavaScript to split the XML data string into multiple lines for enhanced readability. Make sure there are no trailing spaces, when using this approach.

You can also define a JavaScript string variable, store XML data in it, and then assign the variable reference to the chart instance, as shown in the following code snippet:

In the previous example, we had stored the entire XML string in the variable strData, and then passed its reference to the setXMLData() method, instead of the XML string directly.

When using this method to provide data, if your chart is not working or reporting Invalid data, check for the following:

• Make sure that the quotation marks specified in JavaScript to provide parameters and in XML to provide attributes are different. Otherwise, it will result in a JavaScript syntax error. To keep things easy to remember, use double quotation marks for JavaScript, and single quotation marks for XML attributes.
• Ensure that special characters such as ‘, “, &, present as XML attribute values are encoded to ‘, “, &, respectively.