computer science

XML appliance

XML appliance is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand XML appliance rather than just read about it. In short: An XML appliance is a special-purpose network device used to secure, manage and mediate XML traffic. They are most popularly implemented in service-oriented architectures (SOA) to control XML-based web services traffic, and increasingly in cloud-oriented computing to help enterprises integrate on premises applications with off-premises cloud-hosted applications.

Key takeaways

XML appliance belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect XML appliance to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of XML appliance from memory before moving on to harder problems.

Reference excerpt

An XML appliance is a special-purpose network device used to secure, manage and mediate XML traffic. They are most popularly implemented in service-oriented architectures (SOA) to control XML-based web services traffic, and increasingly in cloud-oriented computing to help enterprises integrate on premises applications with off-premises cloud-hosted applications. XML appliances are also commonly referred to as SOA appliances, SOA gateways, XML gateways, and cloud brokers. Some have also been deployed for more specific applications like Message-oriented middleware. While the originators of the product category deployed exclusively as hardware, today most XML appliances are also available as software gateways and virtual appliances for environments like VMWare.

History of XML appliances The first XML appliances were created by DataPower and Vordel in 1999, Sarvega in 2000, Forum Systems in 2001, Managed Methods in 2005 and Layer 7 Technologies in 2002. Early vendors like DataPower focused on the XML acceleration problem which they solved through specialized hardware. While several vendors like DataPower (purchased by IBM in 2005) and Layer 7 Technologies continue to offer hardware accelerated options for high performance situations, advances in computing speed has made software or vmware based "appliances" practical in many common customer situations. Early use cases for XML appliances included banking and cross-agency government information sharing. Today XML appliances are widely used across finance, telecommunications, government, energy, logistics commensurate with the growing usage of XML as a cross-division and cross-company data exchange protocol. In 2005, XML appliances (or SOA appliances, as they came to be known) became increasingly associated with service-oriented architectures and more specifically the problem of governing SOA. The governance of SOA comes down to the control of how applications delivered as "services" can be shared with or called by other applications. Appliances became a popular way of controlling or governing SOA because addressed message security, availability and translation of data so that an application can call another application irrespective of the data format and security policies. Governance of SOA became so critical that Gartner published a dedicated Integrated SOA Governance Technology Sets Magic Quadrant on the topic that covered both SOA management and SOA appliances in March 2007 and most recently in March 2009.

Use cases of XML appliances High-speed transformation and processing of XML traffic Security and governance of service-oriented architectures or SOA Control of web application APIs that are commonly today exposed as XML-based REST interfaces Integration of enterprise applications to services hosted in the cloud

Common features of XML appliances They can parse, validate, transform and route XML messages via XPath and XSLT They can control access to applications that expose data and functionality through XML APIs They can control SLAs for how XML-based services get shared with other applications They can track XML traffic and usage of specific application services exposed through XML interfaces

Classification of XML appliances Although the term XML appliance is the most general term to describe these devices, most vendors use alternative terminology that describe more specific functionality of these devices. The following are alternative names used for XML appliances:

XML accelerators — are devices that typically use custom hardware or software built on standards-based hardware to accelerate XPath processing. This hardware typically provides a performance boost between 10 and 100 times in the number of messages per second that can be processed. Integration appliance — (also known as application routers) are devices that are designed to make the integration of computer systems easier. XML firewalls are classes of XML appliances focused on identity and message security. They typically implement WS-Security message standards along with standards like SAML, WS-I BSP, WS-Policy and so forth. Message-oriented middleware appliances - are hardware devices supporting the sending and receiving of messages between distributed systems. SOA Gateways are commonly used to govern SOA traffic. API proxies are commonly used to manage Web APIs. Cloud brokers or gateways are commonly used to integrate enterprise applications with cloud services.

See also SOAP WS-Security Apache Axis Integration appliance Message-oriented middleware

References

Worked examples

Example 1 — a first encounter with XML appliance

Start with the simplest possible case. Write down what XML appliance claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to XML appliance before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about XML appliance ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of XML appliance

In research: XML appliance appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses XML appliance in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: XML appliance is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer-related introductions in 1999, Networking hardware, XML, so understanding it makes those chapters shorter.
In everyday life: Look for XML appliance outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study XML appliance in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what XML appliance means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain XML appliance out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is XML appliance in simple terms?

Why does XML appliance matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study XML appliance?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on XML appliance.