About XBap, XAML, Browser Applications

[dgk]

From what I've been reading, an XBap application could be really good
for a place like mine where everyone will have a PC that has framework
3 loaded and runs IE. The app is downloaded from a server but runs in
the browser, hosted by PresentationHost.exe.

So, since it gets the app from the server each time that it runs
(yes?) it makes maintenance easy. But because it isn't a bunch of html
and javascript but can access almost the full framework, I can program
stuff that is a pain otherwise. There are sandbox considerations.

Is this a reasonable distillation of XBap?

 

[bruce barker]

currently xbap should be used where you'd use flash as it has simular
restrictions. you can code a whole application in it (domloading .net
assemblies), but load time is slower than using wpf/e & javascript.

its sandbox only allows access back to the same server, so be sure to
setup webservices for it to call. it will have no access to the local
box unless your users change their security settings.

-- bruce (sqlwork.com)

 

[Laurent Bugnion [MVP]]

Hi,

From what I've been reading, an XBap application could be really good
for a place like mine where everyone will have a PC that has framework
3 loaded and runs IE. The app is downloaded from a server but runs in
the browser, hosted by PresentationHost.exe.

So, since it gets the app from the server each time that it runs
(yes?) it makes maintenance easy. But because it isn't a bunch of html
and javascript but can access almost the full framework, I can program
stuff that is a pain otherwise. There are sandbox considerations.

Is this a reasonable distillation of XBap?

Actually, the app is cached, so the client doesn't fetch it every time
from the server, unless there is a new version available, or unless the
cache has been cleaned up.

Additionally, in your scenario (Intranet), you could run you XBAP in
full trust, which means that you must install the certificate on every
PC (can be automated). This way, the XBA has the exact same rights as a
ClickOnce installed application (including interop, starting new
processes, file system access, etc...).

Laurent

 

[Laurent Bugnion [MVP]]

Hi,

currently xbap should be used where you'd use flash as it has simular
restrictions. you can code a whole application in it (domloading .net
assemblies), but load time is slower than using wpf/e & javascript.

I disagree that you'd use XBAP where you'd use Flash. XBAPs are another
type of animal. I think that WPF/E can be compared to Flash, but XBAPs
not really. XBAPs are quite a lot more powerful than Flash, if only
because you're having access to the whole .NET framework, while Flash's
code behind is really JavaScript (well, ActionScript).

its sandbox only allows access back to the same server, so be sure to
setup webservices for it to call. it will have no access to the local
box unless your users change their security settings.

-- bruce (sqlwork.com)

I think it would be fair to mention that XBAPs can also be deployed with
full trust, for example in an Intranet scenario. Full trust means that a
certificate must be installed, so it's a limitation.

Also, in .NET 3.5 coming this year (normally), you'll have basic WCF
services in partial trust too.

HTH,
Laurent

 

[dgk]

Hi,


Actually, the app is cached, so the client doesn't fetch it every time
from the server, unless there is a new version available, or unless the
cache has been cleaned up.

Additionally, in your scenario (Intranet), you could run you XBAP in
full trust, which means that you must install the certificate on every
PC (can be automated). This way, the XBA has the exact same rights as a
ClickOnce installed application (including interop, starting new
processes, file system access, etc...).

Laurent

Thanks. I'm not even sure that I need full trust though it's nice to
have the option. I think I'll play around some more.

 

[Alvin Bruney [MVP]]

FYI: You get those exact benefits with managed usercontrols in 2.0.

--
Regards,
Alvin Bruney
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