Hello group,

I have been coordinating with the platform spec to give CDI interceptors for method validation a late priority. We had to build both the notion of priority and the notion of constructor interceptors.

Quickly read through this email which capture the result of the priority discussions. IMO the agreed proposal is good. 

Emmanuel

Begin forwarded message:

From: Linda DeMichiel <linda.demichiel@oracle.com>
Date: 5 février 2013 03:48:30 UTC+01:00
To: Emmanuel Bernard <emmanuel.bernard@jboss.com>
Cc: Bill Shannon <bill.shannon@oracle.com>, Marina Vatkina <marina.vatkina@oracle.com>
Subject: Fwd: [jsr342-experts] Re: Priority of interceptors

Hi Emmanuel,

Setting the priority for Bean Validation to PLATFORM_AFTER+800 is
fine with me as well.   This belongs in the Bean Validation spec, so
please proceed with that.

thanks,

-Linda


-------- Original Message --------
Subject: [jsr342-experts] Re: Priority of interceptors
Date: Mon, 04 Feb 2013 14:26:15 -0800
From: Bill Shannon <bill.shannon@oracle.com>
Reply-To: jsr342-experts@javaee-spec.java.net
To: jsr342-experts@javaee-spec.java.net
CC: Emmanuel Bernard <ebernard@redhat.com>,        Paul Parkinson <paul.parkinson@oracle.com>,        Marina Vatkina <marina.vatkina@oracle.com>

Linda DeMichiel wrote on 02/04/13 11:53:

Feedback and questions regarding interceptor priority from

the Bean Validation spec lead.  Please weigh in as appropriate

thanks,

-Linda

On 2/4/2013 11:10 AM, Emmanuel Bernard wrote:

(Linda, can you forward to the jsr342 list, I don't think I have write

access).

Thanks for this work.

## Question

The spec claims:

An interceptor bound to a component using interceptor binding, may be enabled

for the entire applica- tion by applying the Priority annotation, along with

a priority value, on the interceptor class.

Does that mean that without @Priority, the interceptor is not enabled

for the entire application?

Unless you enable it in beans.xml.

And to clarify my doubts, you still enforce

that the binding annotation must be present for the interceptor to be

applied on a given method or class, correct?

I believe that's still a requirement.

## Proposal

Have you guys considered adding a END_OF_PLATFORM_AFTER = 5000 so that

if for some reasons, people want to go after Java EE platform elements,

they can do so.

I suppose we could consider it.

BTW, I think the spec should clarify that negative priority are accepted

and that signed number ordering happen.

We already decided to reserve negative numbers for a future use.

## Bean Validation priority

If we go with that route (allocating 1000 to the platform_after

section), I'm tempted to place Bean Validation priority to

PLATFORM_AFTER+800.

Why? Well:

1. it makes for a beautiful symmetry with JTA :)

2. and it reflects our opinion that BV should happen relatively late

just like JTA should happen relatively early, but still offer an open

door to override these propositions.

Seems fine to me.

Emmanuel

On Thu 2013-01-31 11:22, Linda DeMichiel wrote:

The revisions to the Interceptor spec to accommodate the improved

managed bean alignment are nearly complete.  You can download the

current draft of the spec from the interceptor-spec.java.net project

at http://java.net/projects/interceptors-spec/downloads

One of the issues that we still need to resolve, however, is the

assignment of priorities to the new transactional interceptors being

defined by JTA and the Bean Validation interceptors that handle

method validation.

Section 5.5 of the Interceptors spec defines the following Priority

values (see the spec for the details):

Interceptor.Priority.PLATFORM_BEFORE = 0

Interceptor.Priority.LIBRARY_BEFORE = 1000

Interceptor.Priority.APPLICATION = 2000

Interceptor.Priority.LIBRARY_AFTER = 3000

Interceptor.Priority.PLATFORM_AFTER = 4000

In our earlier discussions, we concluded that transactional

interceptors needed to come relatively early in the interceptor chain.

To put a stake in the ground, we propose that we define these to have

a priority of Interceptor.Priority.PLATFORM_BEFORE+200.

Validation interceptors, however, should come relatively late,

since they will ensure that the parameters that reach the method

(which might have been modified by other interceptors) are valid.

Again, to put a stake in the ground, we'll propose a priority of

Interceptor.Priority.PLATFORM_AFTER+1000.

Comments please!

Emmanuel, Paul, could you please consult with your expert groups

for further input as well...

thanks,

-Linda

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