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How to make WebKit or IE call your application (.NET) from HTML page opened in browser?

Answer 1

A:

This is not possible. A browser does not have arbitrary access to resources on the machine it's running on. In particular, it does not have access to the file system, and cannot launch applications.

The best you could do is to have your application mapped as the application that runs when some particular file type is opened. You could register it for .myfiletype, for instance, and then have your button click attempt to download http://server/somefilename.myfiletype. This would (eventually) launch your application to open the file. Your application could then take its parameters from the content of the file.

When I wrote this answer, I misread the question. Given that the application to be run, and the browser, are both running on Windows, a registered protocol handler is the best way to go, assuming all interesting browsers support it. Considering that the link above is from the MSDN documentation on Internet Explorer Development, I can imagine that some browsers might not want to support this mechanism.

John Saunders 2010-03-12 00:53:42

so how does Steam or iTunes load from URL's?

Alastair Pitts 2010-03-12 01:00:26

@Alastair: according to http://stackoverflow.com/questions/2429770/how-to-make-webkit-or-ie-call-your-application-net-from-html-page-opened-in-br/2429792#2429792, they register a protocol handler. I'm only suggesting registering as the launch application for a file extension, which I believe would be lighter-weight.

John Saunders 2010-03-12 01:04:22

But less intuitive. The user still has to run the file to launch your program.

Alastair Pitts 2010-03-12 01:44:17

@Alastair: I agree. If all interesting browsers support protocol handlers defined in this manner, and if non-Windows browsers are not a consideration, then the protocol handler technique is the best, by far.

John Saunders 2010-03-12 01:49:31

@John: The lack solid of cross-platform support for it is a real downer.

Alastair Pitts 2010-03-12 02:14:29

@Alastair: I've done a lot of cross-platform work in my career, and I can't imagine how this could be implemented in a cross-platform manner. You'd have to implement it in stdlib or something.

John Saunders 2010-03-12 02:22:55

@Downvoter: care to say why?

John Saunders 2010-03-13 01:10:53

Answer 2

A:

I'd suggest that the only way to do this is by roundtripping to the server. The webpage triggers something on the server. The app is also connected to the server. I think it's probably unreasonable to do it any other way. If you want to get really dirty, it's possible to use Flash's LocalConnection (which uses a memory mapped file for communication) to chat to a .net app. Darron Schall has managed it (but is not sharing).

If it requires an app, why bother with a web page?

spender 2010-03-12 00:54:25

Answer 3

+3 A:

You can't have a Webkit-based browser to open an application directly. Your best hope (and what Apple does to open the iTunes Store) would be to have your .NET application register for opening certain types of URLs, use a link that points to an URL of this type.

For instance, if your application can open myapp:// URLs, you could use the following HTTP header:

Location: myapp://mysettings

or a more conventional link:

<a href="myapp://mysettings">Foo</a>

And then the browser will take care to open an application that can handle the myapp:// URL scheme (in this case, your application).

zneak 2010-03-12 00:56:00

Answer 4

A:

You can register a protocol handler that points to your application, then have a link pointing to a URL with that protocol and whatever parameters you need.

Max Shawabkeh 2010-03-12 00:56:58

Does this work for both IE and WebKit?

John Saunders 2010-03-12 01:03:27

It should work on any conforming web browser. I know it works at least in IE, Firefox and Chrome.

Max Shawabkeh 2010-03-12 01:06:21

@Max: but that would only work on Windows, right? And, "conforming" to what? The ability to register a protocol handler is Windows-specific, isn't it? Do all browsers support arbitrary URL schemes through registered protocol handlers?

John Saunders 2010-03-12 01:08:48

@John Saunders: Just as much as `mailto:` links open your email client, any other protocol should open the corresponding program under any browser. Registering protocols to certain apps requires platform-specific code, but that possibility exists on every decent OS.

zneak 2010-03-12 01:11:05

@zneak: but "mailto" is a well-defined protocol scheme and has been around for a long time. That would naturally work for any browser. In particular, it would work for a browser that contained a hardcoded list of protocol schemes it handles. Such a browser would not handle a newly-registered scheme.

John Saunders 2010-03-12 01:14:31

@John Saunders: To be fair, the question explicitly talks about Windows, and all popular Windows browsers follow the standard protocol-handling methods that the Windows API defines. However, a quick Google search seems to indicate that UNIX also provides some mechanism for this.

Max Shawabkeh 2010-03-12 01:20:55

@John Saunders: but yet, these browsers magically know which application is the default for the `mailto:` protocol. Isn't that a proof that they're looking at system defaults? That being said, a quick Google search shows that Internet Explorer will launch the registered application for any protocol: http://msdn.microsoft.com/en-us/library/aa767914(VS.85).aspx . Webkit-based browsers will do the same. That's meeting OP's requirements.

zneak 2010-03-12 01:26:45

@zneak: you're not distinguishing between recognizing the protocol and knowing the default application for the protocol, and using registered protocol handlers to handle the default application. One could have a hard-coded list of protocol schemes and still call the default emailer. The question is which Windows-specific techniques the browsers have decided to leverage. I recall a court case some time ago around the time that Netscape decided against using certain published interfaces.

John Saunders 2010-03-12 01:42:30

@zneak: file associations are Win32. Protocol handler registration is more likely WinInet. That may be different - a competing browser might not want to use what is essentially part of IE. That's why it requires verification and not assumption.

John Saunders 2010-03-12 01:43:42

@John Saunders: and yet, IE and Webkit-based browsers are still guaranteed to work with this, which is OP's problem.

zneak 2010-03-12 01:44:19

@Max: I'm just looking for confirmation that "all modern browsers" use this standard Windows mechanism. I can imagine they might think it's "too much like IE". In particular is it so well-ingrained that all new browsers will immediately support it?

John Saunders 2010-03-12 01:47:34

@zneak: If someone would post a link saying that webkit, or "all modern browsers" support this, then I'd be glad to stop asking for such a link to be posted.

John Saunders 2010-03-12 01:48:26

@John Saunders: "Protocol handler registration is more likely WinInet." Sorry, but protocol registration is also Win32. It's exactly at the same place in the registry file associations are. This is explained in the link I've posted.

zneak 2010-03-12 01:50:43

@zneak: first of all, which link did you post? I saw Andy E's link. It showed that you are correct about where in the registry the information is kept. It did not show which API, if any, was provided for creating those registry entries. I'd be interested to know if it's a WinInet API that does so.

John Saunders 2010-03-12 02:13:00

@John Saunders: I posted it in a comment on this answer. It's the seventh from the top. I think it's the same Andy posted; I actually just googled "custom protocol link internet explorer" and it came up first.

zneak 2010-03-12 02:30:36

@zneak: I see it now. I found the same link. Note that Andy posted a link to a blog post, not to the MSDN documentation. Note also that this is documentation from the "Internet Explorer Development" part of MSDN, so you can see why other browsers might decide not to implement this!

John Saunders 2010-03-12 02:37:09

Answer 5

+5 A:

Register a custom URL Protocol Handler. Then you can specify the url using links, etc:

<a href="myapp://doSomething/>Click to run my app!</a>

I can confirm that this works in all versions of Internet Explorer. I've also tested it in the latest versions of Firefox (3.6) and Chrome (whose version escapes me). Chrome will not allow you to enter a custom protocol into the address bar, but it will launch applications from links using custom protocols.

If you have Adobe Reader installed, the acrobat:// protocol is registered. Unfortunately, SO doesn't allow links using custom protocols, so I can't add an example here I'm afraid.

Andy E 2010-03-12 00:58:32

Does your link work for both IE and WebKit?

John Saunders 2010-03-12 01:03:11

@AndyE: BTW, ironically, the link above doesn't display in FF 3.5! It works in IE 8.

John Saunders 2010-03-12 01:13:00

@John Saunders: that is weird. I remember an article detailing a (now fixed) security exploit based on how Safari (WebKit) handles custom url protocols but I can't seem to find it now.

Andy E 2010-03-12 01:18:04

@John Saunders: another point to note is the `itunes://` protocol created by apple, the `irc://` protocol used by mIRC and other applications. Custom protocols have been around for years, it makes sense that browsers would support them.

Andy E 2010-03-12 01:19:50

@AndyE: "support them", yes. "Support them using registered protocol handlers" may be a different thing. You may recall some major controversy about Netscape using Microsoft's dialer interface 'way back. They also weren't too keen on reusing MSHTML. This led to a few court cases...

John Saunders 2010-03-12 01:45:22

Andy E 2010-03-12 09:25:10

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How to make WebKit or IE call your application (.NET) from HTML page opened in browser?

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