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Q&A: What’s the difference between a Windows Service and a Web Service?

Windows Service vs Web Service
I see that your website has a lot of information about Windows Services and you also make AlwaysUp Web Service. How is a Windows Service different than a Web Service? When would I use one over the other? I’m new to programming and a bit confused by the terminologies.

— Justin

Hi Justin.

Yes, the terminology can be confusing! Let’s start with some definitions.

What is a Windows Service?

A Windows Service:

  • Is a Windows application that integrates with the Service Control Manager.
  • Is controlled through the Services Control Panel application.
  • Implements system-level tasks that must operate outside the boundaries of a user’s login session.
  • Is usually long-running, starting when the computer boots and running uninterrupted, 24/7.
  • Works invisibly in the background. A service can’t easily show itself on a user’s desktop.
  • Can do anything that a “regular” application can. Services can read and write files, print documents, check the time, access the network, and much more.
  • Runs on Windows only. Windows Services are not available on Linux, macOS, Andriod, iOS or any other operating system.
  • Is typically written in C++ or C# (to best work with the low-level Windows Services API).
  • May or may not communicate with other programs. Inter-application communication is not a key feature and most services do not expose an interface of any kind.

A modern PC comes with one to two hundred Windows Services pre-installed, each managing an important aspect of your computing experience. For example:

  • Print Spooler: Manages all printing on your computer.

  • Power: Implements your computer’s power schemes, policies and notifications.

  • Task Scheduler: Responsible for automatically launching executables, batch files and scripts at specified times, without human intervention.

What is a Web Service?

A Web Service:

  • Interacts with other applications or services using a well-defined system of data exchange (such as REST or SOAP).
  • Typically communicates over HTTP with an appropriate messaging format on top (such as XML or JSON).
  • Is usually hosted in a web server/container, like Apache Tomcat, Microsoft IIS or Play Framework. A good framework provides easy-to-use messaging “plumbing” and makes it significantly simpler to develop a robust web service.
  • Has a web-based interface (if any at all).
  • Is not restricted to Windows alone. In fact, most web services are deployed on UNIX servers.

Examples of web services include:

Amazon Simple Storage Service (S3): Integrate cloud storage into any application.
Google Maps: Lookup addresses, plot directions, access street views and more.
WorldTimeAPI: Get the current time in any time zone.

The upshot: Windows Services and Web Services are very different!

The only things they have in common are that they are both server technologies and have the word “Service” in their names. 🙂 As a developer, you shouldn’t have much trouble choosing which technology is appropriate for your project.

However, the W* Services are not completely complementary. Though rare, there are a few applications that are both a Windows Service and web service. A good example is our own AlwaysUp Web Service, which must run 24×7 on Windows while providing an XML web service to control the computer remotely.

I hope these similar-sounding technologies make a bit more sense now. Please be sure to get in touch if you have any other questions.

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