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Subject: Re: [search-ws] FW: OASIS/SRU: Operation Parameter



Again my apologies but I am not familiar with these 2 terms and their 
distinction. I am guessing that SRW is a SOAP based search service while 
SRU is a HTTP GET based Search service. If that is correct then IMHO 
Search-WS should define its core interface with an HTTP GET (RESTful) 
binding and then map the same binding to SOAP where a set of WSDL files 
describe a uniform interface as defined by a small number of resource 
independent operations (e.g. create, read, update, delete - actual names 
may vary but you get the spirit of the idea). This is relatively 
straight-forward and simple a spec task.

IOW, expressing a ROA based service in SOAP is just a stylized use of 
SOAP that restricts the operations to a minimal resource independent 
uniform interface.

BTW, going the other direction and expressing an AOA based service in a 
REST interface is much messier as all operations will need to be modeled 
as resources / algorithms.

Ray Denenberg, Library of Congress wrote:
> Ok, to ask the question more directly:  The philosophy you expressed 
> would argue for including the operation parameter in SRW but not SRU. 
> How do we reconcile this?
>  
> --Ray
>  
>  
>
>     ----- Original Message -----
>     *From:* Farrukh Najmi <mailto:farrukh@wellfleetsoftware.com>
>     *To:* Ray Denenberg <mailto:raydenenberg@starpower.net>
>     *Cc:* search-ws@lists.oasis-open.org
>     <mailto:search-ws@lists.oasis-open.org>
>     *Sent:* Sunday, November 25, 2007 5:44 PM
>     *Subject:* Re: [search-ws] FW: OASIS/SRU: Operation Parameter
>
>
>     I am not sure I understand the distinction between SRW and SRU. To me
>     they are just SOAP and REST bindings to the same abstract interface.
>     IMHO, We can build Search-WS with an ROA based abstract interface and
>     map it to  a REST interface and a SOAP interface.
>
>     BTW it is much easier to map a ROA service to REST *and* SOAP than to
>     map a AOA service to REST.
>
>     Fortunately, I think Search-WS fits ROA better than AOA so we can
>     have
>     both a REST and SOAP interface. It would have been messier if AOA
>     was a
>     better fit for Search-WS.
>
>     Ray Denenberg wrote:
>     > 
>     > Farrukh -- thanks for posting this.  But the question it raises
>     for me is
>     > how do we reconcile SRW with SRU, if SRU is best modeled as ROA
>     and SRW
>     > (based on SOAP) is best modelled as AOA?
>     >
>     > --Ray
>     >
>     > -----Original Message-----
>     > From: SRU (Search and Retrieve Via URL) Implementors
>     [mailto:ZNG@loc.gov] On
>     > Behalf Of Farrukh Najmi
>     > Sent: Sunday, November 25, 2007 3:05 PM
>     > To: ZNG@sun8.LOC.GOV <mailto:ZNG@sun8.LOC.GOV>
>     > Subject: Re: OASIS/SRU: Operation Parameter
>     >
>     > (
>     > Resending after fixing an important typo between ROA and AOA
>     below Please
>     > ignore previous version.
>     > )
>     >
>     > Rob Sanderson wrote:
>     >  
>     >> On Wed, 2007-11-14 at 10:06 -0500, Ray Denenberg, Library of
>     Congress
>     >> wrote:
>     >>  
>     >>    
>     >>> There is a proposal to eliminate the operation parameter,
>     >>> incorporating it instead in the base url, in some fashion. The
>     reason
>     >>> for the proposal is that this parameter is not consistent with
>     REST
>     >>>      
>     > principles.
>     >  
>     >>>    
>     >>>      
>     >> 
>     >>
>     >> REST is not the be all and end all of web services.
>     >>
>     >> Practically speaking it makes it slightly harder to implement as a
>     >> single cgi script becomes out of the question.  I don't see any
>     >> practical advantage.
>     >>
>     >> So, unless someone can explain why this is a good idea without
>     saying
>     >> "because REST says so"...
>     >>
>     >> -1
>     >>  
>     >>    
>     >
>     > Like most things this is not a black and white issue and there are
>     > trade-offs that need to be considered. Let me try and summarize
>     briefly...
>     >
>     > Broadly speaking, there are two architectural approaches to
>     design services:
>     >
>     > 1. Resource-Oriented services
>     > 2. Activity-Oriented services
>     >
>     > In a Resource-oriented architecture (ROA) the resources or data
>     objects
>     > are the focus while the operations or activities you perform on the
>     > resources remain fixed no matter what type of resource one is
>     dealing
>     > with. SQL is an example of a ROA where the fixed interface is
>     define by
>     > SELECT, INSERT, DELETE, UPDATE operations. Another example is
>     REST where
>     > the fixed operations are defined by the GET, POST, PUT, DELETE
>     > operations of the HTTP protocol.
>     >
>     > In an Activity-oriented architectures (AOA), the focus is on the
>     > operations or activities you perform rather than the resources
>     that are
>     > the target of the operations or activities. SOAP is an example
>     of a AOA
>     > (sometimes referred to as Service Oriented Architecture or SOA).
>     >
>     > The benefit of ROA is that the architecture is completely
>     unaffected as
>     > the information model / resources are expanded to meet new
>     requirements.
>     > No new operations are required when new resource types are added. No
>     > interface changes are needed. No protocol extensions are needed.
>     >
>     > The benefit of a AOA is that it is better suited to modeling an
>     activity
>     > such as a banking transaction or medical activity such as a
>     prescription
>     > order.
>     >
>     > So which is better? It depends upon the requirements of the
>     application.
>     >
>     > If the application is focused more on resources, resources are
>     what keep
>     > growing unbounded and resources are more relevant to clients,
>     then ROA
>     > is a better fit. Examples of ROA in practice are Amazon,
>     del.icio.us,
>     > Flickr, Safari etc.
>     >
>     > However, if the application is focused primarily on activities or
>     > operations, activities grow more than resources and activities
>     are more
>     > significant than resources to the client, then AOA is a better fit.
>     >
>     > IMHO, Search-WS fits in the first category where the number of
>     > operations are fairly fixed, number of resources are unbounded
>     and it is
>     > resources and not operations that are more significant to
>     clients. Thus
>     > an ROA is a better fit for Search-WS.
>     >
>     > In an ROA the center of the universe is the resource and not the
>     > activity or operation. The basic tenet is that operations are
>     fixes and
>     > resources are unbounded. Modeling operations in such an
>     architecture is
>     > counter to ROA.
>     >
>     > This is the basic argument why modeling *any* operation in *any*
>     form
>     > (including but not limited to operation parameter) in search-ws
>     protocol
>     > is not desirable, and that whenever possible, we should model
>     resources
>     > or algorithms and not operations within the search-ws protocol.
>     >
>     > Of course, if one can make a convincing argument that Search-WS
>     is an
>     > activity-oriented service then the argument would be to model
>     operations
>     > in the protocol and not resources. Does anyone believe that
>     Search-WS is
>     > an is an activity-oriented service rather than a
>     resource-oriented service?
>     >
>     >  
>
>
>     -- 
>     Regards,
>     Farrukh Najmi
>
>     Web: http://www.wellfleetsoftware.com
>
>
>
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>


-- 
Regards,
Farrukh Najmi

Web: http://www.wellfleetsoftware.com




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