[cdi-dev] New Servlet related scope - @UpgradeScoped (?)

Pavel Bucek pavel.bucek at oracle.com
Thu Dec 4 04:39:46 EST 2014


Hi Antonio,

I saw one thread about moving Servlet related scopes to servlet spec (I 
agree with that step!), but there was no clear conclusion stating that 
it will actually happen.

Just one correction - @UpgradeScoped belongs to Servlet spec; If you 
would want to introduce something into WebSocket spec, it would need to 
be something like @WebSocketSessionScoped; upgrade is defined in Servlet 
and if there is any scope derived from it, it should be there.

@ViewScoped/@FlowScoped are different - there are specific to JSF. 
@UpgradeScoped is specific to Servlet and WebSocket spec just depends on 
that.

Regards,
Pavel

On 04/12/14 10:17, Antonio Goncalves wrote:
> Hi
>
> FYI we are hoping to have no Servlet related topics in the CDI 2.0 
> specification. The idea is for other specifications to use CDI to 
> create their own scope (@ViewScoped/@FlowScoped in JSF, but also 
> @TransactionScoped in JTA). Following this logic, the @UpgradeScoped 
> would make sense in the WebSocket spec.
>
> Antonio
>
> On Thu, Dec 4, 2014 at 9:28 AM, Pavel Bucek <pavel.bucek at oracle.com 
> <mailto:pavel.bucek at oracle.com>> wrote:
>
>     Hello Arjan,
>
>     On 03/12/14 19:44, arjan tijms wrote:
>>     Hi,
>>
>>     On Wednesday, December 3, 2014, Pavel Bucek
>>     <pavel.bucek at oracle.com <mailto:pavel.bucek at oracle.com>> wrote:
>>
>>         Hi all,
>>
>>         I'm trying to figure out how to solve issue in JSR 356 - Java
>>         API for
>>         WebSocket, related to CDI scope usable from WebSocket
>>         endpoints. Problem
>>         is, that "standard" scopes do not apply, because there is no
>>         @RequestScoped (http response is already sent), HttpSession
>>         does not
>>         need to be created and the rest does not seem to be
>>         applicable, ...
>>
>>         I believe that CDI specification should define
>>         @UpgradeScoped, which
>>         would cover usages of HttpUpgradeHandler from Servlet API.
>>         (Similarly as
>>         it does for @RequestScoped, @SessionScoped, ... )
>>
>>
>>     Wouldn't it be a better option to have WebSocket define that
>>     scope, using CDI to implement it?
>
>     That is one possibility, but @UpgradeScoped would be more general
>     than just for WebSocket - it would apply for all HTTP/1.1+ Upgrade
>     applications. In my eyes, it is something which was forgotten to
>     do in Java EE 7 release, since HttpUpgradeHandler was introduced
>     in it.
>
>     Also please note, that other Servlet related scopes are already in
>     CDI spec, so it seems like it belongs there more than anywhere
>     else. This might have multiple reasons - for example, you can
>     easily define relationship between @UpgradeScoped and others,
>     already existing ones. In this sense, CDI specification now
>     depends on Servlet API (it references some of the classes defined
>     in it), but Servlet does not do that for CDI. I don't think that
>     Servlet spec should introduce similar dependency just because of
>     new scope.
>
>     Thanks,
>     Pavel
>
>
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>
>
> -- 
> Antonio Goncalves
> Software architect, Java Champion and Pluralsight author
>
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