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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 > > > > --------------------------------------------------------------------- > To unsubscribe from this mail list, you must leave the OASIS TC that > generates this mail. You may a link to this group and all your > TCs in OASIS > at: > https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php > > -- Regards, Farrukh Najmi Web: http://www.wellfleetsoftware.com
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