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From "Liu, Jervis" <j...@iona.com>
Subject RE: RESTful demo for review
Date Thu, 21 Sep 2006 03:55:26 GMT
Hi Brandon, 

Thanks for the reply. I wont be so sure that HTTP POST should be mapped to an INSERT. As you
mentioned, what spec says about POST is "process this" and GET is "set the state of the resource
to this". My interpretation tends to be same as [1], i.e., POST maps to update and PUT maps
to Creat. But anyway, I guess this again is a controversial topic. The good thing of using
JAX-WS provider as the first step to produce a RESTful demo is that this avoids the debate
and it is up to the user's logic (in Provider.invoke()) to decide how to interpret. 

[1]. http://java.sun.com/developer/technicalArticles/WebServices/restful/

Cheers,
Jervis

> -----Original Message-----
> From: Brandon Smith [mailto:brandon@16cards.com]
> Sent: Wednesday, September 20, 2006 8:24 PM
> To: cxf-dev@incubator.apache.org
> Subject: Re: RESTful demo for review
> 
> 
> There is a lot of debate in various communities on when to use POST
> vs. PUT because the HTTP spec is not as direct with the POST method as
> it is the other methods. The spec basically says POST means "process
> this request."
> 
> It seems the general concensus out there is that a POST on a
> "collection" URI maps to an INSERT operation. The examples provided
> should then be:
> 
> THE GET/RETRIEVE/SELECT OPERATION:
> 
>   The reqeust:
> 
> GET /customerservice/customers?id=1234 HTTP/1.1
> Host: localhost:9000
> 
>   The response:
> 
> HTTP/1.1 200 OK
> ...[other headers]...
> 
> <Customer>
>  <id>1234</id>
>  <name>John</name>
>  <phoneNumber>123456</phoneNumber>
> </Customer>
> 
>   The result:
> 
> Returns an XML document representing the customer entity whose
> identifier is 1234.
> 
> THE POST/CREATE/INSERT OPERATION:
> 
>   The request:
> 
> POST /customerservice/customers HTTP/1.1
> Host: localhost:9000
> Content-Type: application/xml
> Content-Length: [length]
> 
> <Customer>
>   <id>1234</id>
>   <name>John</name>
>   <phoneNumber>234567</phoneNumber>
> </Customer>
> 
>   The response:
> 
> HTTP/1.1 201 CREATED
> ...[other headers]...
> 
>   The result:
> 
> Inserts a customer 1234 with the XML data representation provided into
> the collection.
> 
> 
> THE PUT/UPDATE OPERATION:
> 
>   The request:
> 
> PUT /customerservice/customers?id=1234 HTTP/1.1
> Host: localhost:9000
> Content-Type: application/xml
> Content-Length: [length]
> 
> <Customer>
>   <id>1234</id>
>   <name>John</name>
>   <phoneNumber>234567</phoneNumber>
> </Customer>
> 
>   The response:
> 
> HTTP/1.1 200 OK
> ...[other headers]...
> 
>   The result:
> 
> Updates a customer 1234 with the XML data representation provided.
> 
> 
> THE DELETE OPERATION:
> 
>   The request:
> 
> DELETE /customerservice/customers?id=1234 HTTP/1.1
> Host: localhost:9000
> 
>   The response:
> 
> HTTP/1.1 200 OK
> ...[other headers]...
> 
>   The result:
> 
> Customer entity with identifier 1234 is removed from the collection.
> 
> On 9/20/06, Liu, Jervis <jliu@iona.com> wrote:
> > Hi,
> >
> > Based on the REST discussion we had before in this mailing 
> list, I have created an initial version of RESTful demo ( 
> http://svn.apache.org/viewvc?view=rev 
> <http://svn.apache.org/viewvc?view=rev&rev=448148> 
> &rev=448148).  The intention is to show how to 
> publish/consume RESTful services using the programming models 
> offered by CXF, for the time being, the primary focus is 
> demonstrating the REST based webservices using XML binding 
> and JAX-WS Provider/Dispatch. When CXF grows, we can add more 
> RESTful capabilities into CXF, for example, serving REST 
> service using Spring POJO etc. Please note the current effort 
> is by no means to invent a "real" REST programming model.
> >
> > The RESTful communication scenarios covered by this demo 
> are as below:
> >
> > A RESTful customer service is provided on URL 
> http://localhost:9000/customerservice/customers, users access 
> this URI to query or update customer info.
> >
> > A HTTP GET request to URL  
> <http://localhost:9000/customerservice/customers> 
> http://localhost:9000/customerservice/customers returns a 
> list of customer hyperlinks, this allows client navigates 
> through the application states. The xml document returned:
> >
> > <Customers>
> >   <Customer href="  
> <http://localhost/customerservice/customer?id=1234> 
> http://localhost/customerservice/customer?id=1234">
> >       <id>1234</id>
> >   </Customer>
> >   <Customer href="  
> <http://localhost/customerservice/customer?id=1235> 
> http://localhost/customerservice/customer?id=1235">
> >       <id>1235</id>
> >   </Customer>
> >   <Customer href="  
> <http://localhost/customerservice/customer?id=1236> 
> http://localhost/customerservice/customer?id=1236">
> >       <id>1236</id>
> >   </Customer>
> > </Customers>
> >
> > A HTTP GET request to URL  
> <http://localhost:9000/customerservice/customers?id=1234> 
> http://localhost:9000/customerservice/customers?id=1234 
> returns a customer instance whose id is 1234. The xml 
> document returned:
> >
> > <Customer>
> >   <id>1234</id>
> >   <name>John</name>
> >   <phoneNumber>123456</phoneNumber>
> > </Customer>
> >
> > A HTTP POST request to URL  
> <http://localhost:9000/customerservice/customers> 
> http://localhost:9000/customerservice/customers with data:
> >
> > <Customer>
> >   <id>1234</id>
> >   <name>John</name>
> >   <phoneNumber>234567</phoneNumber>
> > </Customer>
> >
> > updates customer 1234 with the data provided.
> >
> > The demo client side codes demonstrate how to sent HTTP 
> POST with XML data using JAX-WS dispatch and how to sent HTTP 
> GET using URL.openStream().
> >
> > There are some immediate improvements we can make to this demo:
> >
> > 1. Remove the presence of WSDL files from both server and 
> client side: REST does not need WSDL file. JAX-WS 
> provider/dispatch does not need WSDL too. However our current 
> implementation of provider/dispatch can not work without 
> wsdl, that's why you can see wsdl files in this RESTful demo. 
> This needs to be fixed
> >
> > 2. Support sending HTTP GET using JAX-WS dispatch: A HTTP 
> GET request can be sent by using URL.openStream or by using 
> JAX-WS dispatch. Though I do not see much benefit of using 
> the latter, we do need to support it. According to JAX-WS 
> spec, this can be done by adding extra non-standard 
> properties into request context. A code snippet may look like below:
> >
> >         Service service = Service.createService();
> >         service.addPort(portQName, "  
> <http://cxf.apache.org/bindings/xformat> 
> http://cxf.apache.org/bindings/xformat", endpointAddress);
> >         Dispatch<Source> d = 
> service.createDispatch(portQName, Source.class, Service.Mode.PAYLOAD);
> >
> >         Map<String, Object> requestContext = d.getRequestContext();
> >         requestContext.put(Message.HTTP_REQUEST_METHOD, new 
> String("GET"));
> >         requestContext.put(Message.QUERY_STRING, queryString);
> >         requestContext.put(Message.PATH_INFO, path);
> >
> >         Source result = d.invoke(null);
> >
> > Does this look alright to everybody?
> >
> > Moving forward, I also want to see following things being discussed:
> >
> > 1. How to expose an existing Web Service as a RESTful 
> service. Say, I have an existing Web Service written in 
> JAX-WS, it would be really great if CXF can help me to 
> publish it as a RESTful service with minimal changes. In this 
> case, I see the need to support SEI on both server and client 
> side. Several issues involved:
> >
> > c. We will need a REST binding. This REST binding does have 
> WSDL file. We can have a wsdltorest tool to help generating 
> the WSDL binding part for REST binding. Probably this is the 
> only thing users need to do to port an existing web service to REST.
> >
> > a. How to map between REST resources and service 
> operations. The easiest approach is using fixed method names 
> for the REST operations. I.e., given a base URI context like  
> <http://localhost/foo> http://localhost/foo (this is the 
> http:address in the wsdl file), a SEI method sayHi is mapped 
> to URL  <http://localhost/foo/sayHi> 
> http://localhost/foo/sayHi. Based on our previous discussion, 
> this does not conform to REST semantics very well. But one 
> could argue that the traditional applications are not REST 
> anyway, we just make it serving services with more REST flavors.
> >
> > b. We need a method dispatch and parameter 
> marshal/unmarshall mechanism different from JAX-WS. For HTTP 
> POST, the data sent on the wire should be a raw xml , it is 
> the URL who indicates the method being requested. The xml 
> data itself still needs to conform to xml schema in WSDL. For 
> HTTP GET, we need encode/decode method name and parameters into URL.
> >
> > Anyway, this story seems need a bit work to do. I see this 
> as a valid requirement but I am not very sure the above is 
> the right way to approach. FYI, Axis2 does support publishing 
> existing SOAP service as REST service, but it is a pure hack 
> to me.   
> <http://people.apache.org/%7Esamisa/ApacheCon_EU_2006_REST.ppt
> > http://people.apache.org/%7Esamisa/ApacheCon_EU_2006_REST.ppt
> >
> > 2. As Steve pointed out before, how to better support 
> navigation of application state via hyperlinks. "CXF has to 
> enable and perhaps help the server-side application to 
> generate the URLs required to identify new resources that it 
> creates and tie servants/ implementations to them. 
> Applications have to play their part, too,  by following the 
> semantics of HTTP, such as ensuring that GETs are idempotent, 
> and ensuring that the URLs it produces for its resources  and 
> state aren't just always temporary or transient."
> >
> > 3. Look into WSDL2's HTTP support to see what we can 
> leverage from there.
> >
> >
> >
> > Thoughts and comments?
> >
> > Thanks,
> > Jervis
> >
> >
> >
> >
> >
> >
> >
> >
> 

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