Seem like you just need a convention where you put the human 
readable/pretty name in a key of the configuration and then you can find 
it with listConfigurations if you need to. It is also in the configuration 
when MSF is called. The generated pid of the configuration is just the 
primary key. You can also look up the configuration using a secondary key 
(the pretty name) if you need.
-- 

BJ Hargrave
Senior Technical Staff Member, IBM
OSGi Fellow and CTO of the OSGi Alliance
[email protected]

office: +1 386 848 1781
mobile: +1 386 848 3788




From:   Christian Schneider <[email protected]>
To:     Neil Bartlett <[email protected]>, OSGi Developer Mail List 
<[email protected]>
Date:   2015/04/06 05:29
Subject:        Re: [osgi-dev] Proposal named pids for 
ManagedServiceFactory
Sent by:        [email protected]



Hi Neil,

I agree that a create operation does not make sense in this context. 
What about this:

Configuration getFactoryConfiguration(String factoryPid, String pid)
It could also be named createOrGetFactoryConfiguration. Like for regular 
confiurations it would retrieve an existing configuration or create a new 
one if non exists.
The impl could either use the pid directly as the pid of the configuration 
or create a pid by concatenating factoryPid-pid like fileinstall does.

Raymond explained the use case in a little more general way. What I need 
is indeed some kind of foreign key to identify the configuration with a 
human readable identifier that can be related to some other known name. In 
my data source example from pax-jdbc the idea is to reflect the name of 
the DataSource in the identity of the configuration. At the same time 
there should be one service that watches for such named configurations and 
creates a datasource with that name.

So the problem with current config admin is that each ManagedService and 
ManagedServiceFactory solve some part of my problem but not all of it. 
ManagedServiceFactory allows me to watch for a whole set of configurations 
but does not allow me to name each configuration on creation. 
ManagedService on the other hand allows me to use a nice name but does not 
allow to listen to a whole set of configurations.

One concrete technical use case in relation to file install would be that 
we could create a file when the above getFactoryConfiguration(String 
factoryPid, String pid)
is called. Currently we have the problem that the user can not give the 
configuration a good name when he creates it using the spec interface. So 
we do not have a good way to determine a name.

 
Christian


Am 05.04.2015 um 13:31 schrieb Neil Bartlett:
> Hi Christian,
>
> Unfortunately if you do this then you run into the same problem we have 
with non-factory configurations: what if somebody has already created a 
record for the PID you requested? Notice that for non-factory configs 
there is no “createConfiguration” method in ConfigAdmin, only 
“getConfiguration” which actually has the semantics of “create or get 
existing”.
>
> What is the use case for this anyway? Bear in mind that the -name 
suffixes are purely an artifice of FileInstall, because it relies on a 
flat properties format and most (all?) filesystems disallow multiple files 
with the same name. Other management agents use a single non-flat file, 
such as XML or JSON, and so don’t need this trick.
>
> Neil
>
>
>> On 5 Apr 2015, at 09:57, Christian Schneider <[email protected]> 
wrote:
>>
>> There is a quite typical pattern I see in many uses of 
ManagedServiceFactory in karaf.
>> The config is created as a file with a name like 
etc/<factoryPid>-<name>.cfg.
>>
>> I think this is a good thing as for many types of configs the naming 
makes sense. For example in pax jdbc it is used by convention as the name 
of the data source.
>>
>> The problem is that in ConfigurationAdmin there is only one way to 
create a config for a factory:
>> Configuration createFactoryConfiguration(java.lang.String factoryPid)
>>
>> The real id of the config is created as a random string.
>> So it is not possible to know the name given from the spec perspective. 
In pax jdbc and many other cases we worked around this by creating an 
additional property for this name. This is a bit redundant though. Even 
more the file name can differ from this property value and so mislead the 
user.
>>
>> I know that the config admin spec does not look into mapping to files 
but it would make sense to provide all data to make the mapping easy.
>>
>> So my proposal is to allow to add an id in the creation:
>> Configuration createFactoryConfiguration(String factoryPid, String 
name)
>>
>> The full config pid could then match the file name we use above.
>>
>> This change would make it much easier t map between the files and the 
configs. Config admin could the also add the name/id as a property to the 
config.
>>
>> What do you think?
>>
>> Christian
>> _______________________________________________
>> OSGi Developer Mail List
>> [email protected]
>> https://mail.osgi.org/mailman/listinfo/osgi-dev

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