1:56 p.m.
On Sep 6, 2016, at 11:58 AM, Harald Pehl <hpehl(a)redhat.com>
wrote:
Thanks Brian for bringing this up. Everything which makes the metadata more consistent
helps management client such as HAL. And as more and more forms are based on MBUI
(generated based on the r-r-d metadata) this is even more important.
Right now we already have some logic behind the 'nillable' and
'alternatives' attributes to decide whether an attribute is required or not:
boolean required = attributeDescription.hasDefined("nillable") &&
!attributeDescription.get("nillable").asBoolean();
if (attributeDescription.hasDefined("alternatives") &&
!attributeDescription.get("alternatives").asList().isEmpty()) {
required = false;
}
Ah, good. So my proposed change to how nillable is calculated shouldn’t change the final
result you get above for your required variable. :) So once I do what I propose on the
server side you can adapt to it when convenient.
In HAL we use attribute descriptions to add new resources and to
modify existing resources. For the former we rely on the 'request-properties' node
of the add operation description. The latter uses the 'attributes' node of the
r-r-d op. If we want to make changes, it's important to be consistent and apply them
to both nodes. Right now these two nodes already have slightly different attributes: The
'request-properties' already contain a 'required' attribute whereas the
'attributes' don't.
Yes, this inconsistency is part of the overall task of WFCORE-1556. The actual metadata we
generate doesn’t comply with the spec in [a] and [b] and then the spec itself is
inconsistent between those two sections in how it deals with “required” vs “nillable”. And
there’s no reason for that.
[a]
https://docs.jboss.org/author/display/WFLY/Admin+Guide#AdminGuide-Descrip...
[b]
https://docs.jboss.org/author/display/WFLY/Admin+Guide#AdminGuide-Descrip...
The proposal makes sense to me and the impact on HAL should be minimal. Some questions I
have:
1. Will the metadata contain both 'nillable' and 'required'? With
'required' being the leading attribute and 'nillable' being deprecated but
still there for backwards compability?
It will contain both. I wouldn’t characterize either as leading or deprecated. Rather they
have different functions:
required — indicates the attribute/parameter represents something that must be configured
in some way. But configuring one of the ‘alternatives’ suffices.
nillable — indicates that attribute/parameter may have an undefined value for some reason
So nillable is useful to a client simply wanting to know whether it needs to deal with
‘undefined’. A more sophisticated client would use ‘required’ plus ‘alternatives’.
2. Will your proposal also cover the 'request-properties' for
the add operation?
Yes, they will be made consistent, with all attribute and parameter descriptions exposing
the same metadata fields with the same conceptual meaning.
In terms of the server side implementation, for almost all add operations, the same
AttributeDefinition instance is used for generating both the attribute description and the
add parameter description. And for all parameter descriptions we use the same
AttributeDefinition classes that we use for resource attributes, so the behavior we put in
the AD class will apply to both.
On Tue, Sep 6, 2016 at 3:10 PM, Brian Stansberry <brian.stansberry(a)redhat.com>
wrote:
tl;dr;
It’s not an uncommon thing to have a management attribute A that is required; i.e. must
be set, but also has an alternative attribute B, where setting B satisfies the requirement
for A, making an undefined value for A legal. We’re not handling that correctly and I want
to fix it.[1] But fixing it will require some coordination with the HAL console.
Right now the way AttributeDefinition building works it’s not practical to declare that
an attribute is required but only if no alternative is set. So instead attributes are
declared as if they aren’t really required. This leads to less than helpful input
validation, e.g. [2] and [3], since the attribute definition is imprecise.
The change I’d like to make will alter the read-resource-description output for 4
attributes, changing the value of the ‘nillable’ description from ‘false’ to ‘true’ so I
want to coordinate that with the console team.
Long version
Harald and Claudio you guys are the main audience here. :)
For even longer version see description and comments on [1].
In a nutshell, if devs set the ‘allowNull’ property on an AttributeDefinition to ‘true’,
the r-r-d output for the attribute has “nillable” => true. But there is no way to say
“allowNull but only if an alternative is set.” So people are setting “allowNull” to true
even if the attribute should be set in the absence of alternatives. And HAL has no
metadata available to it to tell users they *must* set one of the alternatives. So I want
to:
1) Add a setRequired(boolean) method to the AD builders where the fact that it means
“must be defined if no alternative is defined” is explicitly declared
2) @Deprecate setAllowNull and point to setRequired
3) Clarify the meaning of setAllowNull(true) as being the same as setRequired(false)
4) Change the builder ‘allowNull’ constructor param name to “optional” and document its
meaning as “allowing undefined values even in the absence of defined alternatives”. I
could call the param ‘notRequired’ which is clearer in meaning but odd.
Then I will add a new ‘required’ metadata field to the r-r-d output and change the impl
of the existing ’nillable’ metadata to a logical “!required || (alternatives != null
&& alternatives.length > 0)”
This will result in a change in the ‘nillable’ value for 4 attributes in the WildFly
model from ‘false’ to ’true':
/subsystem=transactions PROCESS_ID_SOCKET_BINDING and PROCESS_ID_UUID
/core-service=management/security-realm=*/authenticaton=ldap USERNAME_FILTER and
ADVANCED_FILTER
The latter two are not exposed in the console so the issue really is the two transaction
attributes.
I haven’t checked other subsystems in things like Teiid or JDG, but if there are only 4
in all of WildFly I doubt there are many.
Also, if people start using the new behavior to correct problems like [2] and [3] people
may expect the console to understand and reflect the concept of “required but only if
there is no alternative’.
[1] https://issues.jboss.org/browse/WFCORE-1556
[2] https://issues.jboss.org/browse/WFLY-6608
[3] https://issues.jboss.org/browse/WFLY-6607
--
Brian Stansberry
Manager, Senior Principal Software Engineer
JBoss by Red Hat
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---
Harald Pehl
JBoss by Red Hat
http://hpehl.info
--
Brian Stansberry
Manager, Senior Principal Software Engineer
JBoss by Red Hat