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Subject: Re: [ebsoa] Does SOA Require Registry-Based Dynamic Discovery?


Tim:

This is not the goal.  Architectures can be (and are) based on reference 
models.  Our goal is to create a reference model for those who wish to 
create architectures that embrace service orientation.  The RM may also 
allow others to create reference architectures like the eb SOA work we 
were doing.

Slides 20, 23, 24, 25 elaborate this concept:
http://www.cs.newcastle.edu.au/~hye/Seng442/Lecture/Lect1.pdf

Duane

tmathews@lmi.org wrote:

>Duane - Totally agree, this is my point,
>
>SOA - Service Oriented Architecture
>RM - Reference Model
>
>If you have an SOA RM then you are mixing apples and oranges (eg.
>Architecture with abstract).  Is this the goal?
>
>TM 
>
>-----Original Message-----
>From: Duane Nickull [mailto:dnickull@adobe.com] 
>Sent: Wednesday, December 15, 2004 4:10 PM
>To: MATHEWS, Tim
>Cc: yunker@amazon.com; chiusano_joseph@bah.com; mattm@adobe.com;
>ebsoa@lists.oasis-open.org
>Subject: Re: [ebsoa] Does SOA Require Registry-Based Dynamic Discovery?
>
>Tim:
>
>A Reference Model is not architecture, nor is an architecture a
>reference model (although an architecture may make reference to a RM).  
>The role of the RM is to guide those who develop architectures.  The
>example you show below is an architecture.
>
>I think that what you are discussing is valuable in the context of an
>architecture.  Once we have penned an SOA RM, the development of an
>architecture that uses it should include many of the concepts you have
>noted below.
>
>RM = Abstract
>Architecture = mapping abstract to concrete Implementation = concrete
>
>Duane
>
>tmathews@lmi.org wrote:
>
>  
>
>> 
>>This discussion sounds like its coming from a service/application only
>>    
>>
>
>  
>
>>perspective.  We need to scope the SOA RM very carefully.  If we are 
>>looking for a SOA RM that can be applied in any domain, then I am 
>>still not a proponent of calling it an 'SOA' RM.  If I apply all 
>>components of the SOA reference model, then I have an SOA, right?  The
>>    
>>
>
>  
>
>>more abstract the reference model the more delta you have between 
>>implementations/specializations, so the RM really would be only
>>be valuable with specializations as a deliverable.   Call it a 'web 
>>services' or equivalent RM, but not an SOA RM.  The argument that 
>>almost everything is an SOA does not hold water with me.  SOA in its 
>>final tangible form has a considerable number of requirements that 
>>make it unique.  I see an SOA RM like a 'three-tier' architecture 
>>model that would be more effective, we all know that is www/app/db 
>>right? http://www.sei.cmu.edu/str/descriptions/threetier.html  What is
>>    
>>
>
>  
>
>>it for SOA?  I argue it should at a minimum include a function/process
>>    
>>
>
>  
>
>>for a registry, in addition it should also include at a minimum 
>>'support' for secure communication.
>> 
>>TM
>>
>>----------------------------------------------------------------------
>>--
>>From: Yunker, John [mailto:yunker@amazon.com]
>>Sent: Wednesday, December 15, 2004 12:35 PM
>>To: Chiusano Joseph; Matthew MacKenzie; ebSOA OASIS TC
>>Subject: RE: [ebsoa] Does SOA Require Registry-Based Dynamic
>>    
>>
>Discovery?
>  
>
>>First, let me agree with Matt that "ebXML Registry (big R)" is just 
>>one way of discovery, however any discovery requires that what is 
>>being discovered is registered .  Let me further assert that discovery
>>    
>>
>
>  
>
>>outside of a tightly controlled group requires some sort of registry 
>>(small r) mechanism for discovery to be effective.  These are the 
>>assumptions I started with.
>> 
>>Sorry if your initial question was only directed towards big R 
>>registry!!! :-)
>>
>>    -----Original Message-----
>>    From: Chiusano Joseph [mailto:chiusano_joseph@bah.com]
>>    Sent: Wednesday, December 15, 2004 9:13 AM
>>    To: Yunker, John; Matthew MacKenzie; ebSOA OASIS TC
>>    Subject: RE: [ebsoa] Does SOA Require Registry-Based Dynamic
>>    Discovery?
>>
>>    Thanks John - I'm going to take all 4 parts of your excellent
>>    comments below separately, and comment further. You basically
>>    
>>
>said:
>  
>
>>     
>>    An SOA without registry by definition is limited
>>     
>>    [JMC] Limited in what way? I assume because there is no dynamic
>>    discovery, and if the interface requirements and/or service
>>    location changed, it would require an out-of-band mechanism. I
>>    would assert that it is limited if the technical and business
>>    requirements led to an anticipation of updates to the interface
>>    requirements and/or service location on a regular basis -
>>    otherwise, is it *really* limited? 
>>     
>>    [yunker] Limited in the ability of the SOA to support broad groups
>>    or communities.
>>     
>>    An SOA without registry by definition is private
>>     
>>    [JMC] So if a SOA-based system is being used among 2 or more
>>    organizations, and the technical and business requirements *do not
>>    lead* to an anticipation of updates to the interface requirements
>>    and/or service location on a regular basis, then the SOA is
>>    "private"? Seems orthogonal to me...
>>     
>>    [yunker] Private in that some out-of-band communication must be
>>    supported.
>>     
>>    An SOA with a registry is open
>>     
>>    [JMC] Open to who? If it does not have a registry, it is not open?
>>     
>>    [yunker] Open, in that you don't need to be on the mailing list of
>>    the service provider to know that a service is available.
>>     
>>    An SOA with a registry is dynamic
>>     
>>    [JMC] Agree! (one out of 4 ain't bad ;)
>>     
>>    Thanks again!
>>     
>>    Kind Regards,
>>    Joseph Chiusano
>>    Booz Allen Hamilton
>>    Strategy and Technology Consultants to the World
>>     
>>
>>
>>    
>>
>------------------------------------------------------------------------
>  
>
>>        From: Yunker, John [mailto:yunker@amazon.com]
>>        Sent: Wednesday, December 15, 2004 12:06 PM
>>        To: Chiusano Joseph; Matthew MacKenzie; ebSOA OASIS TC
>>        Subject: RE: [ebsoa] Does SOA Require Registry-Based Dynamic
>>        Discovery?
>>
>>        From my view the "registry requirement" is more a function of
>>        the distributed nature of the participants, the number and
>>        type of services, and the amount of change.  A registry
>>        provides a method for decoupling "the use of an SOA" from
>>        "direct communication of the participants about HOW to use the
>>        SOA".
>>         
>>        An SOA without registry by definition is limited and private
>>         
>>        An SOA with a registry is open and dynamic
>>         
>>        John
>>
>>            -----Original Message-----
>>            From: Chiusano Joseph [mailto:chiusano_joseph@bah.com]
>>            Sent: Wednesday, December 15, 2004 9:01 AM
>>            To: Matthew MacKenzie; ebSOA OASIS TC
>>            Subject: RE: [ebsoa] Does SOA Require Registry-Based
>>            Dynamic Discovery?
>>
>>            Thanks Matt. From that I take:
>>             
>>            - Discovery in general is required for SOA (cannot
>>            function without it)
>>            - Whether it is (what I will call) "fundamental" discovery
>>            - meaning your first example below - or "registry-based"
>>            discovery depends on technical and business requirements.
>>             
>>            I just cannot foresee trying to convince a current or
>>            potential customer that they have to put up $XX,XXX for a
>>            registry product if the technical and business
>>            requirements do not call for it, just to comply with
>>            someone's definition of the term "SOA".
>>             
>>            Kind Regards,
>>            Joseph Chiusano
>>            Booz Allen Hamilton
>>            Strategy and Technology Consultants to the World
>>             
>>
>>
>>    
>>
>------------------------------------------------------------------------
>  
>
>>                From: Matthew MacKenzie [mailto:mattm@adobe.com]
>>                Sent: Wednesday, December 15, 2004 11:57 AM
>>                To: Chiusano Joseph; 'ebSOA OASIS TC'
>>                Subject: RE: [ebsoa] Does SOA Require Registry-Based
>>                Dynamic Discovery?
>>
>>                My opinion is that a registry is nothing more than a
>>                very explicit service discovery device.
>>
>>                 
>>
>>                An SOA does need a method of discovering services, and
>>                consuming them, but this method may in some cases be
>>                subtle.  For example, my SOA may operate on the
>>                premise that consumers all are aware of an enumeration
>>                of service types, and their port numbers (think
>>                /etc/services in the unix world), and allowable IP
>>                ranges for finding services.  Clients may be
>>                configured something like:
>>
>>                 
>>
>>                {
>>
>>                            Services imap, http, ssh, daytime, pop3,
>>                portmap
>>
>>                            IPRange 192.168.0.0/24
>>
>>                }
>>
>>                 
>>
>>                A client with such a configuration does have a way of
>>                discovering services that are available to it, and of
>>                course, a way of binding to them.
>>
>>                 
>>
>>                Contrast this with a registry driven SOA:
>>
>>                 
>>
>>                {
>>
>>                            ServiceRegistry http://foo/registry
>>
>>                }
>>
>>                 
>>
>>                The only difference is in the implementation detail
>>                and verbosity of information available.  Conceptually,
>>                they are the same.
>>
>>                 
>>
>>                 
>>
>>                --Matt MacKenzie
>>
>>                
>>----------------------------------------------------------------------
>>--
>>
>>                From: Chiusano Joseph [mailto:chiusano_joseph@bah.com]
>>                Sent: Wednesday, December 15, 2004 11:38 AM
>>                To: ebSOA OASIS TC
>>                Subject: [ebsoa] Does SOA Require Registry-Based
>>                Dynamic Discovery?
>>
>>                 
>>
>>                What is the TC's opinion on the answer to the question
>>                of "does SOA require registry-based dynamic
>>                discovery"? I know that Discovery is a pattern in the
>>                .047 spec, which leads me to believe that the position
>>                is that SOA does not *require* registry-based
>>    
>>
>discovery.
>  
>
>>                 
>>
>>                For example, suppose that:
>>
>>                 
>>
>>                - 2 organizations are using Web Services in a
>>                "SOA-like" manner (meaning shared services represented
>>                as Web Services, that are invoked by other Web
>>    
>>
>Services).
>  
>
>>                 
>>
>>                - There is no registry-based dynamic discovery,
>>                perhaps because the organizations agree that these
>>                service locations are completely (or relatively)
>>                stable, and that if the locations change, there will
>>                be some out-of-band mechanism for propagating updated
>>                WSDL documents
>>
>>                 
>>
>>                Are these 2 organizations therefore *not* using a
>>                service-oriented architecture? That is, does the
>>                second point completely negate the first? Or, is it
>>                all really a matter of business and technical
>>                requirements?
>>
>>                 
>>
>>                Kind Regards,
>>
>>                Joseph Chiusano
>>
>>                Booz Allen Hamilton
>>
>>                Strategy and Technology Consultants to the World
>>
>>                 
>>
>>    
>>
>
>--
>***********
>Senior Standards Strategist - Adobe Systems, Inc. - http://www.adobe.com
>Vice Chair - UN/CEFACT Bureau Plenary - http://www.unece.org/cefact/
>Chair - OASIS eb SOA TC -
>http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=ebsoa
>***********
>
>  
>

-- 
***********
Senior Standards Strategist - Adobe Systems, Inc. - http://www.adobe.com
Vice Chair - UN/CEFACT Bureau Plenary - http://www.unece.org/cefact/
Chair - OASIS eb SOA TC - http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=ebsoa
***********



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