Thank you Ümit! 
I will follow the second approach. It is also described a bit better.



On Wednesday, December 9, 2015 at 3:37:15 PM UTC+2, Ümit Seren wrote:
>
> Well as for any SPA (Single Page App)  authentication and authorization is 
> a concern of the server and not really the client. 
>
> This is how I usually do it: 
> 1.) Make the index.html page dynamic. The backend adds information whether 
> the user is logged in or not (
> http://www.gwtproject.org/articles/dynamic_host_page.html) when it is 
> rendered.
> 2.) When GWT loads check the host page and retrieve the user information. 
> If the user is not logged in, display Login Button/Menu item or whatever. 
> 3.) When the user clicks on the login menu item/button you can either a.) 
> open a GWT dialog and display a form that creates a post request to the 
> backend server or b.) navigate to a seprate Non-GWT login page with a 
> similar form. (I prefer the Non-GWT login page because it is a bit easier)
> 4.) Once the user submits the form with the credentials, the backend will 
> check if the user credentials are correct and if so will create a session 
> (using a session cookie for example). Usually the backend server/framework 
> will handle this for you.
> 5.) For the Non-GWT login page you just need to redirect to the dynamic 
> index.html (for the GWT dialog option you probably need to refresh the 
> site).
>
> Based on the user information that you retrieve from the dynamic 
> index.html page you can hide and display specific UI elements. 
> Nevertheless there is one important rule: *YOU SHOULD NEVER TRUST THE 
> CLIENT. *
> So you must validate and check every GWT request to the backend. Usually 
> this can be done by a backend framework automcatically. For example with 
> Spring you can annote your service layer with security annotations and the 
> backend will throw an AccessDenied Exception. 
>
> The second example you posted is basically describing this approach and 
> you don't really mix GWT and Spring here because GWT has no idea of the 
> Spring context. 
>
>
>
>
> On Wednesday, December 9, 2015 at 12:12:10 PM UTC+1, [email protected] wrote:
>>
>> Hello all,
>>
>>        I have found GWT project documentation and examples at website 
>> fantastic. All major subjects are described with nice examples. What do I 
>> really miss there is user login and security (sessions, validation, etc.) 
>> Can't really imagine any web-project without user handling. For sure Google 
>> has found many articles in this area and basically there are two options as 
>> I understand:
>>
>>    1. 
>>    
>> https://code.google.com/p/google-web-toolkit-incubator/wiki/LoginSecurityFAQ
>>    2. 
>>    
>> http://examples.javacodegeeks.com/enterprise-java/gwt/gwt-spring-security-example/
>>
>>       The first article seems to be a bit old though it describes basic 
>> principles of custom log-on implementation. Second one seems to be more 
>> solid, but I am a bit scare of the fact that just for single page I need to 
>> add Spring context. Mixing GWT and Spring does not make me confident I am 
>> doing right thing.  Is there other ways to do log-on or these two patterns 
>> are the most common?
>>
>>
>>
>> Thank you.
>>
>

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