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From Marcel Offermans <>
Subject Re: Client REST API
Date Tue, 06 Aug 2013 12:37:10 GMT
Hello Elmar,

On Aug 6, 2013, at 13:19 , Elmar Zeeb <> wrote:

> i'm looking into apache ace to check if i can use it as backend for a web based market
to install software extensions on an osgi based application. In this use case i can't use
the vaadin based ui but started to implement a java based client for the client REST API.

Underneath the Vaadin, REST and (very recently) GoGo client API's lies the same Java Client
API. In other words, that's a good place to start with your own client. In this case, the
"Workspace" class that is an abstraction on top of that (part of the REST client) can be used
to start.

> I'm aware of the amdatu ace client, but i wanted to implement a client on my own to understand
the api and apache ace. Currently i'm able to create, modify and delete different client resources
(artifact, feature, distribution and target) but have problems with associations. I have looked
at the client rest api docu on and at
to get a better understanding of associations filters and queries.


> I don't understand how to set the leftEndpoint and rightEndpoint attributes of associations.
As written on the web site these attributes are LDAP filters. Does this mean that i have to
parse the LDAP filter on the client side to check which resources are associated?

Yes, they are LDAP filters.
No you don't need to parse them yourself, that is something the associations will do for you.
Just provide the filter condition and it will be evaluated against objects on the left or
right hand side of the association.

> Is there a way to let ace do the filtering and return resource ids? I'm aware of the
ace/clients/tmp/9876/artifact2feature?left=&right=query. Is there something like ace/clients/tmp/9876/artifact2feature/12345/leftResourceIdsto
query all left resource ids of an association?

If you create an association, you can set the left and right hand filters yourself.

> The vaadin UI uses attribute based LDAP filters to create associations. I would like
to have static associations based on resource ids - so i use LDAP filters like "(id=[resource
id])" to specify endpoints.

Take a look at the Workspace.cas() method (a generic way to create an association) where you
can do something like:

 ws.cas("distribution2target", "(name=foo)", "(id=bar)");

Optional arguments to specify the cardinality can be used to force ACE to use a 1:1 (or 1:N,
N:1 or N:N) cardinality.

> The vaadin ui can't display these associations.

Actually, if you click on some object, it will always highlight everything that is associated,
even if you do it via these programmatically created associations.

> ACE-151 mentions that there are no checks for LDAP filters so the filter may not work.
> So my question is how to specify association endpoints and how to query resource ids
of associates resources with the client REST API?

My advice is to use the Java API. If you have an Assocation object, you can simply ask it
to getLeft() or getRight() and you will get a list of all associated objects on either side.

Greetings, Marcel

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