Re: [oslc-core] Discovery scenarios (LDPCs)

[Martin P Pain <martinpain@uk.ibm.com>]

I've added the examples to this page, and
finished the walk-through of how servers think about discovery:
https://wiki.oasis-open.org/oslc-core/Discovery/Scenarios#How_servers_think_about_discovery

Ideally this would also then need to
look at how clients consume those examples, to validate that they are useful,
and what if any value there is in using LDP at each layer.

However, I have just realised that my
examples are not compatible with OSLC v2, as I've made the oslc:Service
resources separate resources with their own URIs, whereas the v2 spec requires
them to be "Local Resources" (for which it says "i.e. blank
nodes", but I think the intention was to allow hash URIs as well -
but I may be wrong). But I don't have time to correct this now.

I any case, it would be good if you
could all have a look at the "How servers think about discovery"
half of that page before the meeting tomorrow (although I admit it's not
easy to scan - sorry). I suggest we walk through this page at that meeting
to bring us to a decision on whether we use LDPCs in discovery or not.

Martin Pain
Software Developer - Green Hat
Rational Test Virtualization Server, Rational Test Control Panel

E-mail: martinpain@uk.ibm.com Find me on:  and within IBM on:

IBM United Kingdom Limited Registered in
England and Wales with number 741598 Registered office: PO Box 41, North
Harbour, Portsmouth, Hants. PO6 3AU 



From:      
 Martin P Pain/UK/IBM@IBMGB
To:      
 OASIS <oslc-core@lists.oasis-open.org>
Date:      
 28/08/2015 17:03
Subject:    
   [oslc-core]
Discovery scenarios (LDPCs)
Sent by:    
   <oslc-core@lists.oasis-open.org>

---

I've added most of the work I've done
so far on thinking through discovery using LDPCs here: https://wiki.oasis-open.org/oslc-core/Discovery/Scenarios

So far there is:

• A walk through of how OSLC Automation discovery works in v2
• The first half of thinking about how a server using LDPCs would want OSLC discovery to work

I'm also intending to fill in the third column of the table with how a
client would take advantage of LDPCs having been used in discovery (although
of course such a client would not be compatible with v2 servers unless
they programmed the v2 approach anyway). 

I've also got some worked examples to go with the "servers" section,
which I haven't worked into the wiki page yet, but I'll copy them here
so you guys have a chance to see them, think about them, comment on them
etc in good time for Thursday. 

Please have a read through all of this (in particular the servers section
on the wiki page an the examples below) and think about whether this is
how you would expect OSLC discover to work with LDPCs, and whether LDPCs
give us (or anyone) any benefits. 

Here are the examples, but you'll have to correlate them to the text
in the wiki page yourself for now. These examples are not complete in that
they don't go as far as Service Providers or SPCs, but as far as creation
factories & services are concerned I don't have any further changes
in mind (although there probably are more scenarios that could be covered).



Scenario: Server contains one LDPC, with one resource type.

LDPC: 

GET /discovery HTTP/1.1 
Host: example.com 

200 OK 
Content-Type: text/turtle 
Link: http://www.w3.org/ns/ldp#BasicContainer;
rel="type", 
      <http://www.w3.org/ns/ldp#Resource>;
rel="type" 

@prefix dcterms: <http://purl.org/dc/terms/>.
@prefix ldp: <http://www.w3.org/ns/ldp#>.

<> 
   a ldp:BasicContainer; 
   dcterms:title "Container of all this server's resources (which
are all of one type)"; 
   ldp:contains </r1>, </r2>, </r3>.


Plus Creation Factory: 

GET /discovery HTTP/1.1 
Host: example.com 

200 OK 
Content-Type: text/turtle 
Link: http://www.w3.org/ns/ldp#BasicContainer;
rel="type", 
      <http://www.w3.org/ns/ldp#Resource>;
rel="type" 

@prefix dcterms: <http://purl.org/dc/terms/>.
@prefix ldp: <http://www.w3.org/ns/ldp#>.
@prefix oslc: <...>. 

<> 
   a ldp:BasicContainer, oslc:CreationFactory;
   dcterms:title "Container of all this server's resources (which
are all of one type)"; 
   ldp:contains </r1>, </r2>, </r3>;
   oslc:creation <>; # Itself 
   oslc:resourceType <http://example.com/resource-type>.
# Optional 


Plus Service: 

GET /discovery HTTP/1.1 
Host: example.com 

200 OK 
Content-Type: text/turtle 
Link: http://www.w3.org/ns/ldp#BasicContainer;
rel="type", 
      <http://www.w3.org/ns/ldp#Resource>;
rel="type" 

@prefix dcterms: <http://purl.org/dc/terms/>.
@prefix ldp: <http://www.w3.org/ns/ldp#>.
@prefix oslc: <...>. 

<> 
   a ldp:BasicContainer, oslc:CreationFactory, oslc:Service;
   dcterms:title "Container of all this server's resources (which
are all of one type)"; 
   ldp:contains </r1>, </r2>, </r3>;
   oslc:domain <http://example.com/custom-oslc-domain>;
   oslc:creationFactory <>; 
   oslc:creation <>.



Scenario: Automation - with separate LDPCs for AutoPlans, AutoRequests
& AutoResults (another option would be to have one LDPC for all 3 types):

LDPC: 

GET /autoPlans/ HTTP/1.1 
Host: example.com 

200 OK 
Content-Type: text/turtle 
Link: http://www.w3.org/ns/ldp#BasicContainer;
rel="type", 
      <http://www.w3.org/ns/ldp#Resource>;
rel="type" 

@prefix dcterms: <http://purl.org/dc/terms/>.
@prefix ldp: <http://www.w3.org/ns/ldp#>.

<> 
   a ldp:BasicContainer; 
   dcterms:title "Tasks available for execution";
   ldp:contains </autoPlans/1>, </autoPlans/2>, </autoPlans/3>.


Very similar for /autoRequests/ and /autoResults/.


Plus Creation Factory: 

GET /autoPlans/ HTTP/1.1 
Host: example.com 

200 OK 
Content-Type: text/turtle 
Link: http://www.w3.org/ns/ldp#BasicContainer;
rel="type", 
      <http://www.w3.org/ns/ldp#Resource>;
rel="type" 

@prefix dcterms: <http://purl.org/dc/terms/>.
@prefix ldp: <http://www.w3.org/ns/ldp#>.
@prefix oslc: <...>. 
@prefix oslc_auto: <...>. 

<> 
   a ldp:BasicContainer; 
   dcterms:title "Tasks available for execution";
   ldp:contains </autoPlans/1>, </autoPlans/2>, </autoPlans/3>.
    
_:factory 
   a oslc:CreationFactory; 
   oslc:creation <>; # The request URI 
   oslc:resourceType oslc_auto:AutomationPlan.


Service: 

GET /automation/ HTTP/1.1 
Host: example.com 

200 OK 
Content-Type: text/turtle 

@prefix dcterms: <http://purl.org/dc/terms/>.
@prefix oslc: <...>. 

<> 
   a oslc:Service; 
   oslc:domain <http://open-services.net/ns/auto#>;
   dcterms:title "Task automation";
   oslc:creationFactory [ 
      oslc:creation </autoPlans/>;
      oslc:resourceType oslc:AutomationPlan.
   ]; # Note: OSLC Automation doesn't require creation of plans
   oslc:creationFactory [ 
      oslc:creation </autoRequests/>;
      oslc:resourceType oslc:AutomationRequest.
   ]; 
   oslc:creationFactory [ 
      oslc:creation </autoResults/>;
      oslc:resourceType oslc:AutomationResult.
   ]. # Note: OSLC Automation doesn't require creation of results


GET /autoPlans/ HTTP/1.1 
Host: example.com 

200 OK 
Content-Type: text/turtle 
Link: http://www.w3.org/ns/ldp#BasicContainer;
rel="type", 
      <http://www.w3.org/ns/ldp#Resource>;
rel="type" 

@prefix dcterms: <http://purl.org/dc/terms/>.
@prefix ldp: <http://www.w3.org/ns/ldp#>.

<> 
   a ldp:BasicContainer; 
   dcterms:title "Tasks available for execution";
   ldp:contains </autoPlans/1>, </autoPlans/2>, </autoPlans/3>.
    
    
    
If we wanted to make the Service an LDPC itself (this time considering
the case where the server doesn't support creation of Plans or Results):

GET /automation/ HTTP/1.1 
Host: example.com 

200 OK 
Content-Type: text/turtle 

@prefix dcterms: <http://purl.org/dc/terms/>.
@prefix oslc: <...>. 
Link: http://www.w3.org/ns/ldp#BasicContainer;
rel="type", 
      <http://www.w3.org/ns/ldp#Resource>;
rel="type" 

<> 
   a oslc:Service, ldp:BasicContainer; 
   oslc:domain <http://open-services.net/ns/auto#>;
   dcterms:title "Task automation";
   oslc:creationFactory [ 
      oslc:creation ; 
      oslc:resourceType oslc:AutomationPlan.
   ]; # Note: OSLC Automation doesn't require creation of plans
   oslc:creationFactory [ 
      oslc:creation </autoRequests/>;
      oslc:resourceType oslc:AutomationRequest.
   ]; 
   ldp:contains </autoPlans/>, </autoRequests/>, </autoResults/>.
# Useful for querying, discovering dialogs, etc, etc.

Martin Pain
Software Developer - Green Hat
Rational Test Virtualization Server, Rational Test Control Panel

E-mail: martinpain@uk.ibm.com Find me on:  and within IBM on:

IBM United Kingdom Limited Registered in England and Wales with number
741598 Registered office: PO Box 41, North Harbour, Portsmouth, Hants.
PO6 3AU 
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
3AU

Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
3AU