How do software updates for windows work?

Question

How does a program installation on windows know that an update to that software is available? When I searched for it, most of the links talked about WSUS. Can someone please explain in simple words?

Answer 1

Like Lochemage said, non-Windows Applications (AVG, Adobe Photoshop, etc) have a built-in procedure to "call home." Many applications have this feature auto-enabled, where they, upon starting, query a list of servers and compare their version to that of the current available version on their server. NOTE: This isn't something you can rely on in an enterprise environment where the end-users have no administrative privileges. For managing software updates on many computers on a domain, keep reading.

WSUS is a management tool that is generally installed on Windows Server that manages updates for Microsoft products for all computers in the server's Domain. We have this set up at my work- it allows us to force updates at defined times, omit patches that are known to cause problems in our environment, etc. WSUS is not used to manage non-Microsoft updates.

There are third-party options for managing non-Windows software on Windows machines remotely. Services such as LogMeIn allow you to update software, but are paid-for (https://secure.logmein.com/products/central/).

You can install some software updates remotely by doing some Powershell scripting, but this method isn't user-friendly and requires the software in question to have an Enterprise installer (usually in the form of a pre-configured .msi file).

We are about to start testing a free, open-source (I think) application that will allow us to do non-Windows software updates. The name escapes me, unfortunately, but I'll update this reply when I can find the information.

Edit:

Thought this was mostly about Windows 2008R2 management, due to the tags. Previous answers seem to indicate that you're more concerned about programming your own project.

Edit2:

Here is the service. It's a "Package Manager like apt-get with Windows in Mind":

http://chocolatey.org/

Answer 2

Basically there is a server somewhere on the interwebz that the game knows how to find (via IP address or whatever). When the game loads, it connects to that server and tells it the game's current version information, the server responds with whether or not a new update is available and whatever other info is needed. After that the game display that an update is available and downloads the update from that server.

That is the basic idea anyway, without getting too technical.

EDIT:

To put it in a possibly better perspective, think about how you manually update things. First you open your web browser, then you navigate to a URL that you know. Once the page is open you can see their latest download version and check if your version is up to date, if it isn't then you click the link to download it and then update it.

Now think of yourself as the game and the webpage as the server. The same concept applies.

Answer 3

WSUS running on the windows machine periodically connects to Micosoft's servers to determine if any new updates are available. You can read more info and see see the names of some of these servers at: http://technet.microsoft.com/en-us/library/cc708605(v=ws.10).aspx