Re: [phpGroupWare-developers] linking items across applications

[Dave Hall]

Hi Sigurd,

On Sat, 2007-10-27 at 10:53 +0200, Sigurd Nes wrote:
> Hi all,
> 
> As Dave already has announced - there is a project hosted in Norway to
> develop phpGroupWare into a Facilities Management System. A lot of work
> has been focused on the application "property".
> At this stage we are looking into possibilities of linking items across
> applications - some sort of "interlink" (there might be a better word
> for it).
> As an example - it would be nice to be able to link in projects from the
> application "projects" as work performed with internal employees - as
> opposed to work order from external vendors (which already is implemented).
> 
> I have used a similar approach within the app "property" - linking items
> from the helpdesk with reports/requirements/orders.
> 
> So - is there a interest in the community to have this as a general
> feature within the API?
> 
> My proposal (as it is used in property) is as follows:
> The idea is to link from a location (the acl-location) within an
> application as origin - to a corresponding destination.
> 
> origin <--> destination
> 
> For this I think we need a table "phpgw_interlink" (see attachment) to
> hold the relations - and a new column in the table "phpgw_acl_location"
> - let's call it "baselink"
> 
> phpgw_acl_location.baselink can hold the information on where to point
> the link.
> 
> example:
> The baselink for tts (the helpdesk) within property would be "uitts.view"
> 
> Any thoughts or better ideas ?

I don't think storing this information in the ACL table is appropriate.
The ACL table should store data for access control, not data links.  

The ACL table proposal doesn't sllow for edit links.  Once data is
linked we need a system to ensure that dangling links aren't left behind
when users delete a record.

I think any linking system must allow for the following functionality:

* get a list of links with summaries
        - summaries should be "[module] summary"
        - ACLs need to be enforced
        - where user doesn't have read rights they should receive a messge like
"[type] summary unavailable (owner: XXX YYY)"

* display edit link if user had the appropriate rights

* display "delete link" link subject to ACLs

* check that there is no linked records before deleting a record
        - if records exist give user a choice of actions - subject to ACLs

* links should be 2 way and displayed to users in both contexts

* allow administrators to manage links

I think the follow schema allows for all of the above

'phpgw_interlink' => array(
        'fd' => array(
                        'interlink_id'  => array('type' => 'int', 'precision' 
=> 4, nullable => False),
                'app1_name' => array('type' => 'varchar','precision' => 
'25','nullable' => False),
                'app1_class' => array('type' => 'varchar','precision' => 
'12','nullable' => False),
                'app1_id' => array('type' => 'int','precision' => 
'4','nullable' => False),
                'app2_app' => array('type' => 'varchar','precision' => 
'25','nullable' => False),
                'app2_class' => array('type' => 'varchar','precision' => 
'12','nullable' => False),
                'app2_id' => array('type' => 'int','precision' => 
'4','nullable' => False),
                'is_private'    => array('type' => 'int', 'precision' => 
'2','nullable' => false),
                'account_id' => array('type' => 'int','precision' => 
'4','nullable' => false),
                'entry_date' => array('type' => 'int','precision' => 
'4','nullable' => false)
        ),
        'pk' => array('interlink_id'),
        'fk' => array(),
        'ix' => array('app1_name', 'app1_class', 'app1_id', 'app2_name', 
'app2_class', 'app2_id', 'is_private', 'account_id'),
        'uc' => array()
),

(I am unsure if we should define another table to locations do joins,
and apps can register in that table)

The app?_class will list a class - it should be a bo class.  The class
would need to implement the following method

        /**
        * Get the summary of a record
        *
        * @param int $id the record id
        * @return array the summary data
        */ 
        public function summary($id);
        {
                return array
                (
                        'text' => 'the text summary',
                        'view' => 'menuaction.used4.viewing_record', //null if 
not permitted by ACLs
                        'edit' => 'menuaction.used4.editing_record' //null if 
not permitted by ACLs
                );
        }
        
I have notes on how the linking class itself should work.  I am happy to
post a stubbed class if people think it is worthwhile :)

Cheers

Dave
-- 
Dave Hall (aka skwashd)
API Coordinator
phpGroupWare
e address@hidden
w phpgroupware.org
j address@hidden
sip address@hidden
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