I'm a bit confused about the difference between a facebook canvas application and a facebook mobile web application. Here is the context of my confusion..
I have a canvas application, let us call its namespace as myfbapp, and I basically can access it from https://apps.facebook.com/myfbapp and after I login to FB it opens up with in Facebook. I'm using java (apache / tomcat) for my server side implementation and for simplicity sake let us say I just have an index.html and a authenticationfilter.java (which implements Filter) in my web application. I don't have any Facebook specific Javascript API (no FB.init() javascript or anything like that ) or code in my index.html. Whenever user accesses my canvas application I first get a request to my web application where I get the signed_request , oauth_token , FB user ID etc which I can use for my internal authentication, session creation etc. I have absolutely no issues with this canvas application and every thing works fine. Please note that when user accesses this app the request I get from the browser to my app server has the signed_request , user_id etc.
Now I wanted to make this app available on mobile devices as well and I thought, oh well all I need to do is add the mobile URL for this app in the mobile web app section in Facebook for the same myfbapp. I did that and as expected when I login to facebook from my android phone myfbapp is listed under the apps section, so far so good. The problem starts when I click on the app. I get the request on my app server but it doesn't contain the signed_request , user_id etc.. ????? I was expecting the mobile app to work the same way as the canvas app but apparently it doesn't or I'm doing some thing wrong.
Then I started reading more about facebook mobile app at http://developers.facebook.com/docs/guides/mobile/web/#register where it talks about adding various Facebook Javascript API's in the index.html (I never did anything like that in my canvas app) and then I started thinking , may be then mobile web app is more (or exactly) like a regular web app with FB connect and not like canvas application (meaning it doesn't really load with in Facebook) , is this true?
On mobile facebook you can not see any custom pages/tabs. They are apparently wokring on that at the moment.
So it will be different to a canvas app. Your mobile app will be a completely seperate site and page not in an iFrame on Facebook.
Some behaviour i discovered recently with Facebook Canvas / Page Tabs on mobile devices. Maybe this helps to understand a little bit better how facebook behaves in mobile context.
Mobile Browser
Access App URL
Example URL http://apps.facebook.com/myapp/
Redirects to the configured mobile website under Settings > Website > Mobile Site URL and adds additional params /?ref=web_canvas&code=<signed_request_code_field>
About the signed_request code field
An OAuth Code which can be exchanged for a valid user access token via a subsequent server-side request
Access App Center
There is no way to access the Facebook App Center via the mobile browser.
Access Page Tab
Example URL http://facebook.com/a_facebook_page/custom_page_tab_url
Custom Page Tabs are not visible via the mobile browser.
Facebook Open Graph Search
Searching for myapp returns the link to the Facebook Canvas.
Same behaviour like Access App URL via Mobile Browser
Mobile Facebook Client
Access App URL
There is no way to access this url directly.
Access App Center
There is no way to access the Facebook App Center.
Access Page Tab
Example URL http://facebook.com/a_facebook_page/custom_page_tab_url
Custom Page Tabs are not visible via the mobile facebook client.
Facebook Open Graph Search
It says that this app is not compatible with this devices.
You need to register an iOS / Android App and send the user to this app to get rid of this error. Probably it helps the user if you add the link to the standalone application to the Facebook description of the app. Which should then be visible there.
来源：https://stackoverflow.com/questions/8753179/facebook-canvas-app-vs-facebook-mobile-web-app