Visualizing XML in Manufacturing Systems

Oct. 29, 2003 12:00 AM

The manufacturing industry has been a leader in adopting XML technologies, recognizing the benefits of enterprise-class open standards. Applications in the manufacturing industry often need to live as long as the capital equipment itself - a time frame that can stretch as long as 30 years. The need for an extended life span has driven the adoption of markup languages, guaranteeing the longevity of data and applications.

Manufacturers are turning to Scalable Vector Graphics (SVG) to extend the power of XML open standards even further. Application developers who serve the manufacturing market are mandated to update business processes to improve profitability and achieve a significant return on investment. SVG provides a powerful interface technology that makes this a reality.

This article will explore how SVG is providing significant benefits for manufacturers by Web-enabling the Human- Machine Interface (HMI). Using the same XML framework, we will discuss how these technologies can also support interactive electronic technical documentation in manufacturing. In both of these areas, traditional closed applications and publishing systems are being broken open and distributed using XML and SVG.

What Is SVG?
SVG is the W3C standard for vector graphics presentation over the Web. The standard was created by more than 20 major corporations, including AOL, Adobe, Canon, Corel, Ericsson, Microsoft, and Nokia. The most recent SVG 1.1 recommendation continues to evolve to support small devices and print. It's lightweight and can be read from any browser using a standard-compliant viewer without requiring any specialized applications running on the enterprise desktops.

SVG is XML for graphics. A human-readable markup language, SVG can be developed using specialized tools or edited in a simple word processor. As a vector format, it differs from bitmaps in that SVG is described as points, curves, and fills, and can therefore be "zoomed" into without loss of quality. Most important, because SVG is data, it can be driven by data from any location (i.e., Web services, ODCB, etc.) (see Figure 1). In addition, SVG can be made to support bidirectional interaction with the graphic, allowing the user to interact with the SVG graphic to affect changes on the target server, database, or machine.

One Technology, Many Uses
With any broad technology platform there are obvious questions. What are the best applications of this technology? What is the best way to prove its capabilities?

Some of the benefits of SVG are obvious. Like HTML and GIF, it can be applied to many applications. But SVG gives even more by replacing a baffling array of server-side graphics generation, JavaScript, Java applets, Flash applications, image servers, and Real Players with one development environment. Simply put, SVG gives all the advantages of HTML (ease of use, ubiquity, lightweight), but also enables the creation of applications that are interactive, data-driven, and rich.

As a result of these strengths, a number of opportunities are clear. SVG is an ideal presentation layer for complex information. It is an excellent choice for projects such as HMI, technical documentation, and facilities management. And because SVG is mandated to offer backwards-compatibility, it is an excellent choice for building applications that need to live for more than a few years. When existing applications are being overhauled or displaced, SVG should be a key technology employed for the next generation of systems.

In manufacturing, where complex machinery may need to live for decades, the interface to the equipment must provide the same longevity. Additionally, the solutions being implemented are built to accommodate the increasing demand and capability for customized and distributed access to disparate systems. Customers in manufacturing are relying on XML and SVG by embedding technology (i.e., SVG viewers embedded into applications) or adhering to standards. Ultimately, SVG should be deployed where multichannel communication is needed and where application longevity is key.

Let's focus on HMI as a use-case scenario and then turn our attention to technical documentation. Although they seem different, we will explore how standards in the data and communications layers are enabling XML-based technologies to tackle both challenges in similar ways.

Industrial Automation & Human Machine Interfaces
Industrial automation means different things to different manufacturers, but from an SVG perspective, it generally includes HMI - interfacing with a machine and process monitoring. These functions share defining characteristics such as the collection, storage, and ability to look at data. And unlike some other XML workflows, they also need to access data in real time.

In fact, the report "Scalable Vector Graphics, The Future Look of HMI" by ARC Advisory Group, an industry analyst firm that covers manufacturing, had this to say about SVG and Human-Machine Interfaces:

End users and OEMs should look to SVG as a way to display their production processes and other sources of real-time performance management information.

End users and OEMs should look to SVG as a way to achieve some of their key business drivers, such as a reduction in the total cost of ownership due to easier installation, simpler configuration, third-party interoperability, diverse product compatibility, and scalability.

Suppliers should evaluate their existing HMI software offerings and determine how they can incorporate SVG technology into their current or future products, delivering the benefits and key business drivers that the end users and OEMs demand. Let's take a further look at these benefits.

To understand how manufacturers can make use of SVG, we must first understand the underlying technologies. There are two standard ways to interact with a machine, through a local Programmable Logic Controller (PLC) or through networked OLE for Process Control (OPC) drivers. Although the PLC is not specifically related to the networked operation of machinery, changes implemented at the client need to be reflected in the data sent over the network so the communication is bidirectional.

Before we discuss the details of how these components fit together into a workflow with XML open standards, let's take a closer look at PLC and OPC, shown in Figure 2, which shows a graphical overview of machinery interacting with other applications in the industry, where an SVG interface is the point of human consumption of underlying corporate data from multiple repositories.

Programmable logic controllers (PLC)
PLC is a local hardware device that contains embedded software for controlling the state of a machine. For example, a PLC can be a gray-scale LCD screen with controls and intelligence that acts as a counter that shuts down a machine after a specific number of cycles. In general, PLCs are not designed to be networked, so, while the reader needs to understand their critical role in controlling machinery, they are not specifically part of the final IT project.

OPC connectivity
OPC stands for OLE for Process Control (OPC) and is used to connect devices. The standard is controlled by a consortium of equipment manufacturers. Because the majority of value is in the hardware, the vendors realized that they could sacrifice custom controls in favor of interoperability without loss of revenue related to proprietary software features. The result is that a number of low-cost and open source alternatives are available to developers looking to build applications connected to machines.

By opening windows into the control of the devices, OPCenabled machines can interact with other machines to enable assembly lines (or shop floors) to be combined and controlled by enterprise dashboards. This is managed via a communications layer (or driver) and represents a middleware tier to the huge variety of equipment (custom and mass market) needed in the broadly classified manufacturing vertical.

OPC servers can feed into, or play the role of, the application server tier. They optimize the communications, allow a tag-based database for multi-channel communication, and also enable the separation of data, machine, and logic layers for more rapid programming and maintenance.

It is important to note that by separating the tiers, the enterprise can integrate non-OPC systems that are critical to their operations into a common SVG interface.

SVG in Industrial Automation
SVG is a visualization layer on top of the OPC Driver layer in the enterprise infrastructure. SVG offers significant advantages in this process - SVG applications are lightweight, highly customizable, low cost, and interoperable with other XML technologies. The manufacturing floor can represent a complex interaction with OPC-enabled equipment, CAD floor plans, HR systems, accounting systems, and inventory management systems. Clearly, enabling the control of machines is not sufficient for realizing the dramatic improvements possible through networked control and monitoring. Combining disparate systems using XML and an SVG interface enables enterprises to integrate truly smart dashboards into their systems.

Complexity, variation, and the diverse needs of companies require the majority of effective control systems to undergo some degree of customization (see Figure 3). Customization of SVG interfaces is easy since the standard supports reuse of components, the streamlining of the design-development workflow, and a diversity of supported devices. Figure 4 shows some benefits of SVG characteristics.

Where Else? SVG and XML in Technical Documentation
If you are talking about SVG within the manufacturing industry, you cannot ignore the benefits provided for technical documentation. The advantages of XML for text are widely documented, but the benefits of XML-based graphics are equally compelling - particularly when you are looking to reduce the overall costs of technical documentation.

Technical documentation for capital equipment is very complex. The process involves multiple authors and technical illustrators consuming, revising, and publishing content. This content is reused in a wide variety of documents including training manuals, parts catalogues, operations manuals, and maintenance manuals. Absolute accuracy is necessary, and if the machinery is a major capital purchase, the end product is very often customized. For example, a particular model of airplane can have over 70,000 pages of documentation with content that must be customized for every airline and every aircraft based on tracking the planes by tail number.

Tech doc workflows supported by SVG
Here is a typical workflow without open standards. Technical illustrators consume CAD files using any number of commercially available vector illustration tools (like CorelDRAW or Adobe Illustrator) and export a 2D representation. The illustrator enhances the graphics, tailoring them for a specific purpose. The graphics are then passed to the technical writers who make multiple requests to the illustrators and engineers for customized versions to support their writing. And finally, if the end result is bound to inventory systems or MRO systems, a developer needs to create the associations between the graphics and the underlying data. This can be a difficult and cumbersome process.

Using SVG, the designer can use a standard, familiar tool (CorelDRAW or Adobe Illustrator) to create the graphic. The writer can use simple tools within an XML authoring platform to highlight or hotspot the portion of the graphic being described. The developer can then code the SVG to an inventory management or parts catalogue system, enabling the end users to access and update it from their PC or mobile device.

From XSLT to SVG - Tools to Get the Job Done
Previous XML-Journal articles have outlined how to use XSLT to generate SVG from XML (see "Database-Driven Charting Using XSLT and SVG" by Avinash Moharil & Rajesh Zade, Vol. 4, issue 5); however, this process typically applies to simple applications. When developers need to connect multiple data types from multiple sources to deliver complicated applications, they are often required to either hand code and debug a significant amount of complicated and lengthy XML language or use an IDE that can do a lot of the work for them (see Figure 5).

XSLT is an XML method to get one form of XML data into another. By leveraging Web services, XSLT, and SVG for application development, enterprises maintain a separation of the data layer, the logic layer, and the presentation layer all in XML standards.

This separation of data, logic, and presentation significantly reduces the cost of maintaining an enterprise application over its lifetime. Now, if the database administrator changes the structure of the data, the application designers and developers simply point the interface at the new data, without being required to make an overhaul to the application.

A number of products are emerging to enable the rapid creation of data-aware SVG applications. Some are closed systems, while others support easy customization. Corel Smart Graphics Studio, for example, is an attributes-based development environment that generates XSLT code in the same manner that other code generation tools (i.e., HTML editors) simplify their respective languages. Corel Smart Graphics Studio builds graphical applications that are XML from end to end. Although there are alternatives based on binary-compiled code, these technologies do not allow enterprises to leverage XML outside of the data layer and fail to take full advantage of this powerful open standard.

Interoperability Without Untenable Planning
HMI and documentation systems use almost the exact same underlying technologies to display live, interactive interfaces that combine text and graphics. They both rely on graphics file conversion XML authoring, and exchanging and interacting with data. The input models are different (OPC versus designer-generated content), but the exchange and presentation technologies are highly similar. Moreover, they also share the requirement to connect with other enterprise systems that are XML capable.

By making the investment in XML and XML-transformation technologies and adhering to open standards, enterprises can implement very large projects in a phased approach and expect interoperability. Through focusing on one system at a time, real enterprise value can be created.

The result? Unlike other IT projects that are typically plagued with a high failure rate, SVG-based projects are more successful because poor technology interoperability is no longer an issue.

Multiple Platforms, Multiple Vendors, Multiple Enterprises
SVG is becoming a widely accepted and supported standard. SVG was ratified by the 3GPPP for inclusion into wireless devices. In addition, several vendors (including Adobe and Corel) and open source communities have produced SVG viewers for PCs. Mozilla has implemented portions of the specification for the open source community and SVG has a profile available for handheld devices.

While native implementations of SVG in Web browsers are not yet available, a leading vendor recently stated that its viewer is deployed on over 70 percent of desktops. However, for the vast majority of manufacturing needs, the applications are deployed on an intranet where desktops can be easily managed by the resident IT department.

All this support means that IT projects can finally come in on time and under budget - giving CIOs a significant opportunity to show value at a limited cost. Because XML streamlines workflows, management decisions mid-stream can be easily reflected in the final application. This is in contrast to binarycompiled applications that are inflexible and cannot be easily modified after components have been implemented.

Ultimately, it is important to note that open standards are often implemented by the open source community. This puts pressure on vendors to maintain interoperability, keep pricing in line, and provide critically needed support for the SVG tools and technology that enterprises are deploying.

SVG, XSLT, XML, and the various vertical-specific standards combine nicely into powerful enterprise solutions for the manufacturing industry. With growing vendor support and powerful tools, enterprises can begin to make investments in the next generation of customizable digital dashboards to support the broad needs of their multiple stakeholders.

About Rob Williamson
Rob Williamson, product manager, Corel Smart Graphics Studio, defines the strategic direction of Corel Smart Graphics Studio. In this role, he encourages the adoption of SVG (Scalable Vector Graphics) and works with enterprise customers to design open-standards implementations.