## Object Names and IdHandler Service Contract

### Object Names

When presenting a list of objects in a package not native to the objects (i.e. permissioning, community-member, category-usage) there has to be a fast and easy way to figure out the name of objects. Until now, this has been done by using something like

    acs_objects.name(object_id)

which essential means that for every object to be displayed (and since the mentioned pages are in no means scalable and therefore are likely to display a huge amount of objects) this pl/sql proc will have to figure out which package-specific pl/sql proc to call which itself will do at least one query to get the object-name.

Obviously, this is highly undesirable since it is not scalable at all. Therefore, a new way had to be found to get the name of an object:

    -------------------
    -- NAMED OBJECTS --
    -------------------

    create table acs_named_objects (
    	object_id	integer not null
    			constraint acs_named_objs_pk primary key
    			constraint acs_named_objs_object_id_fk
    			references acs_objects(object_id) on delete cascade,
    	object_name	varchar2(200),
    	package_id	integer
    			constraint acs_named_objs_package_id_fk
    			references apm_packages(package_id) on delete cascade
    );

    create index acs_named_objs_name_ix on acs_named_objects (substr(upper(object_name),1,1));
    create index acs_named_objs_package_ix on acs_named_objects(package_id);

    begin
            acs_object_type.create_type (
                    supertype       =>      'acs_object',
                    object_type     =>      'acs_named_object',
                    pretty_name     =>      'Named Object',
                    pretty_plural   =>      'Named Objects',
                    table_name      =>      'acs_named_objects',
                    id_column       =>      'object_id'
            );
    end;
    /
    show errors

This means that every displayable object-type should no longer be derived from acs_objects, but from acs_named_objects and that by using triggers or extending the appropriate pl/sql procs, every displayable object (certainly not acs_rels or something the like) should have an evtry in that extension of the acs_objects table.

In that way, when having to display a list of objects, one can simply join the acs_named_objects table to get the names and package_ids in an easy and - more importantly - fast and scalable way.

The only shortcomming of this solution is the disregard of internationalization, but in cases where there objects in more than one language, it should be the triggers / pl/sql procs task to make sure that acs_named_objects contains names in the default language if possible.

### IdHandler Service Contract

Besides displaying the names of objects, some pages also want to provide links to the objects. Unfortunately, there currently is no way to do so.

First, we need to know that package_id of the package responsible for the object. This information is currently impossible to get since we would need to go up the context hierarchy until we finally get hold of an apm_package object. But lets assume we get this information by using the new acs_named_objects table, then we would need to figure out the url to that package instance. This can be done, but again by calling a highly unefficient pl/sql proc. But even then we would need the local url to the page being able to display a certain object. Since a package may have more than one type of objects (i.e. file folders, files, file versions), we can not simply store additional package information about which page to call to display an object.

The solution to this kind of problem is by not resolving the url at all during display-time, but doing so at the time the user actually wants to see an object. The links would simply direct to /o/$object_id, which is a global virtual-url-handling page that will figure out the package instance url (by using acs_named_objects and the pl/sql proc) and then relying upon a Service Contract to get the local url - that means every package holding displayable objects should implement this interface for its objects:

    declare
        v_id	integer;
    begin
        v_id :=  acs_sc_contract.new(
    	    contract_name => 'AcsObject',
    	    contract_desc => 'Acs Object Id Handler'
        );
        v_id := acs_sc_msg_type.new(
    	    msg_type_name => 'AcsObject.PageUrl.InputType',
    	    msg_type_spec => 'object_id:integer'
        );
        v_id := acs_sc_msg_type.new(
    	    msg_type_name => 'AcsObject.PageUrl.OutputType',
    	    msg_type_spec => 'page_url:string'
        );
        v_id := acs_sc_operation.new(
    	    contract_name => 'AcsObject',
    	    operation_name => 'PageUrl',
    	    operation_desc => 'Returns the package specific url to a page
    that displays an object',
    	    operation_iscachable_p => 'f',
    	    operation_nargs => 1,
    	    operation_inputtype => 'AcsObject.PageUrl.InputType',
    	    operation_outputtype => 'AcsObject.PageUrl.OutputType'
        );

        v_id := acs_sc_impl.new (
                  'AcsObject',
                  'apm_package_idhandler',
                  'acs-kernel'
        );
        v_id := acs_sc_impl.new_alias (
                  'AcsObject',
                  'apm_package_idhandler',
                  'PageUrl',
                  'apm_pageurl',
                  'TCL'
        );
        acs_sc_binding.new (
                  contract_name => 'AcsObject',
                  impl_name => 'apm_package_idhandler'
        );

        v_id := acs_sc_impl.new (
                  'AcsObject',
                  'user_idhandler',
                  'acs-kernel'
        );
        v_id := acs_sc_impl.new_alias (
                  'AcsObject',
                  'user_idhandler',
                  'PageUrl',
                  'acs_user::pageurl',
                  'TCL'
        );
        acs_sc_binding.new (
                  contract_name => 'AcsObject',
                  impl_name => 'user_idhandler'
        );
    end;

The appropriate tcl-procs look like the following:

    ad_proc -public apm_pageurl { object_id } {
        Service Contract Proc to resolve a url for a package_id
    } {
        return
    }

    namespace eval acs_user {
        ad_proc -public pageurl { object_id } {
    	Service Contract Proc to resolve a url for a user_id
        } {
    	return "shared/community-member?user_id=$object_id"
        }
    }

Note that the name of the implementation has to be the object-type followed by _idhandler.