[wildfly-dev] Proposing capabiities at completion time

Thu Sep 15 08:21:08 EDT 2016

I’m adding wildfly-dev in cc.

Yes, the names of the parameters are ambiguous. And it’s not necessary for them to be ambiguous, as the “alternatives”, “required” and “requires" stuff lets us use clearly named params for different cases:

“attribute” — required=true, alternatives=[parameter]
“parameter - required=true, alternatives=[attribute], requires=[operation]
“operation” - required=false

An alternative is we could just drop all of those. The operation and attribute params are not necessary if the client has already done a read-resource-description or read-operation-description and already knows the value of the “capability-reference” descriptor. Then it could simply be

/core-service=capability-registry:suggest-capabilities(address=[(subsystem=foo),(child=bar)],static-name=org.wildfly.network.socket-binding)
{
    “outcome” => “success”,
    “result” => [
        “http”,
        “https”
     ]
}

When thinking about this we should remember the dot/bracket syntax we allow for updating details of complex attributes via write-attribute:

:write-attribute(name=complex.nested[2].field,value=http)

For the CLI, just passing through “attribute”=>"complex.nested[2].field” is easier as there is no need for it to unpack the ‘.’ and ‘[]' syntax and find the description of ‘field’ and get the capabiity-reference.

For the console, it may be easier to get the capability-reference and pass it instead. Easier than going from some code backing a gui widget and synthesizing "complex.nested[2].field” to pass to the server.  

> On Sep 15, 2016, at 6:40 AM, Jean-Francois Denise <jdenise at redhat.com> wrote:
> 
> The operation argument is an optional argument that contains the resource operation name. In case the operation is present, the attribute argument means operation argument. Otherwise the attribute contains the name of an attribute. This is a draft of operation, the operation naming could be reviewed.
> I don't think that this operation updates the capabilities registry, this is a readonly operation to retrieve capabilities.
> JF
> 
> On 15/09/16 12:41, Harald Pehl wrote:
>> That looks very promising. Having such an operation would also cover the requirements of HAL. What's behind the "operation" parameter? Does it allow add / modify?
>> 
>> On Thu, Sep 15, 2016 at 12:04 PM, Jean-Francois Denise <jdenise at redhat.com> wrote:
>> Hi,
>> 
>> I have spent some time looking at the semantic of the capability scopes (thanks to Brian help). 
>> A client "could" try to base its capability resolution by looking at capabilities present in the capabilities registry. Scope can be very complex, are possibly not fully modeled yet, and semantic could evolve in the future. So difficult for a client to rely on scopes to                  resolve the accessible capabilities.
>> 
>> The server side has the logic to check the capabilities and could expose part of its engine logic to clients for capabilities resolution. Brian is proposing that the capabilities registry would expose a new operation:
>> /core-service=capability-registry:suggest-capabilities(address=[(subsystem=foo),(child=bar)],operation=add,
>> attribute=socket-binding)
>> {
>>     “outcome” => “success”,
>>     “result” => [
>>         “http”,
>>         “https”
>>      ]
>> }
>> 
>> It seems that the CLI "completion requirements" would be covered by this addition. I am wandering if it would also cover the HAL ones?
>> 
>> Thanks.
>> 
>> JF
>> 
>> 
>> On 13/09/16 21:50, Harald Pehl wrote:
>>> See my answers inline. 
>>> On Tue, Sep 13, 2016 at 12:04 PM, Jean-Francois Denise <jdenise at redhat.com> wrote:
>>> Hi Claudio and Harald, thank you for your reply. Some questions in-lined. I am just discovering the capabilities topic ;-) On 12/09/16 19:47, Claudio Miranda wrote:
>>> Your suggested approach looks similar to the way HAL does, however there are some differences. 1) There are many attributes that doesn't declare the capability-reference, (example: subsystem=transactions, attribute jdbc-store-datasource), then we emulate it.
>>> How do you emulate this? You are hard coding the list of attributes that are reference to capabilities? You can point me to some code? Harald, what is the technical difficulty there? Are they real capabilities? If the referenced resource can't register capabilities, are they actual capabilities?
>>> We have an internal registry [1] which is basically a map with the capability name as key and a class holding information about the capability as value [2]. Most entries in our registry are taken from /core-service=capability-registry, but to provide the capabilities also for WildFly < 11, we need to manually add entries to our registry during startup [3]. 
>>>  
>>> 2) The capabilities and addresses are associated at bootstrap, this way HAL associates all capability-reference names to the target address it should lookup on at runtime. https://github.com/hal/core/blob/26bb90653f60cfad2f3c3aac5964c4f125e18777/gui/src/main/java/org/jboss/as/console/client/meta/CoreCapabilitiesRegister.java
>>> This is the information that the capabilities registry contains? Right? I should be able to retrieve all that from the registry?
>>> Yes we read everything from /core-service=capability-registry 
>>> 3) For domain mode, the attributes that declares capabilities resources out of profile, as socket-bindings, there is a small inconvenient, we need to display the full resource address, as there is no way to associate the profile to the socket-binding, we need to show all socket-binding of all socket-binding-groups, see http://i.imgur.com/86VP1F9.png
>>> The /<profile>/subsystem=transactions/process-id-socket-binding should be tagged with "capability-reference". Right? And it doesn't seem to be. Do you now the rational?
>>> Right, the r-r-d result for  /<profile>/subsystem=transactions does not contain a "capabilities-reference" for the attribute "process-id-socket-binding". This seems to be a bug in the transactions subsystem. But actually it's a good example how we can still provide typeahead support for attributes which do not have a "capability-reference" info [4]. This does not involve the capabilities registry. It's just about adding typeahead support for attributes which reference some other resources, but do not yet have a "capabilities-reference"
>>> Once the user has chosen a value, what are you setting as the value for the process-id-socket-binding attribute? Harald, you are saying that the resource name is taken as form input. So it means that only the last part of the resource address is stored? For example only "ajp"? Is it enough to fully identify the actual resource? Don't you need (full capabilities name + scope)?
>>> Yes that's right, only the resource name is stored. Let's take the server-group resource as an example. It has the attribute "profile" which declares the "capability-reference" "org.wildfly.domain.profile". When adding the resource, only the profile name is stored. AIUI to identify / verify the profile the attribute value and the information from the capabilities-regisrty are used. 
>>>  
>>> Thank-you.
>>> [1] https://github.com/hal/hal.next/blob/develop/meta/src/main/java/org/jboss/hal/meta/capabilitiy/Capabilities.java
>>> [2] https://github.com/hal/hal.next/blob/develop/meta/src/main/java/org/jboss/hal/meta/capabilitiy/Capability.java
>>> [3] https://github.com/hal/hal.next/blob/develop/app/src/main/java/org/jboss/hal/client/bootstrap/functions/ReadCapabilities.java#L65
>>> [4] https://github.com/hal/hal.next/blob/develop/app/src/main/resources/org/jboss/hal/client/configuration/subsystem/transactions/TransactionView.mbui.xml#L47
>>> --- Harald Pehl JBoss by Red Hat http://hpehl.info
>> --
>> --- Harald Pehl JBoss by Red Hat http://hpehl.info

-- 
Brian Stansberry
Manager, Senior Principal Software Engineer
JBoss by Red Hat