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From Vassilis Virvilis <v.virvi...@biovista.com>
Subject Re: registering ParamConverterProviders with cxf
Date Wed, 13 Aug 2014 14:43:33 GMT
Ok

I made some progress and in the mean time I understood some of the 
things you have been saying... I think the following descriptions 
summarizes my status. I have also asked for help from resty-gwt forum. I 
will let you know what comes up...

Thanks for the help so far. Much apprecieated...

https://groups.google.com/forum/#!topic/restygwt/T98XXEHiCl0


Hi everybody,

Here are some must do reading that I found...
http://stackoverflow.com/questions/3182033/pass-list-to-restful-webservice
https://github.com/resty-gwt/resty-gwt/issues/92

So what I am trying to do? Basically this.

     @POST
     @Path("existing-entities")
     @Consumes("application/x-www-form-urlencoded")
     public void getExistingEntities(
             @FormParam("entities") List<Entity> entities,
             MethodCallback<List<Entity>> callback);

This however transmits the entities as one jsonified array with [{x:"a", 
y:"b"}, {x:"c", y:"d"}] if you know what I mean. CXF in the other 
doesn't parse it as per  JAX-RS spec probably but I am not sure. So what 
are the options?

1) Use a list wrapper. Ugly and as I said I am porting existing services 
and I don't feel like filling my sources with useless wrapper classes. 
Never mind the changes to the clients of the services. This is my last 
option. I will do that when all else fail.

2) Don't use @FormParam. This actually works

     @POST
     @Path("existing-entities")
     public void getExistingEntities(
             List<Entity> entities,
             MethodCallback<List<Entity>> callback);

This puts the payload to MessageBody.
The disadvantage is that you can send only one list this way. As I said 
previously I am porting... and there are cases that I need to transmit 2 
or more lists as input parameters.

3) Third option and here I may need some help. If you actually post a 
form with the same option name CXF (and probably Jersey) puts it in a 
list. I have verified with curl

       curl --data 'entities=`urlencode {x:"a", 
y:"b"}`&entities=`urlencode {x:"c", y:"d"}`' 
http://localhost/ws/rest/v1/ported/existing-entities -H 'Accept: 
application/json'

and it works. So what I need is a way to teach Resty-GWT to do that kind 
of form posting and not the entities: [{x:"a", y:"b"}, {x:"c", y:"d"}] 
thingy when encounters

     @POST
     @Path("existing-entities")
     @Consumes("application/x-www-form-urlencoded")
     public void getExistingEntities(
             @FormParam("entities") List<Entity> entities,
             MethodCallback<List<Entity>> callback);

I suppose I have to use a custom MessageBodyWriter in the client side. 
Is this possible in resty-gwt? I don't mind mucking with resty-gwt 
source but I don't know from where to start. Any ideas?

    Thanks in advance.



On 08/12/2014 10:23 PM, Sergey Beryozkin wrote:
> Hi,
> On 12/08/14 19:44, v.virvilis@biovista.com wrote:
>> Hi Sergey,
>>
>> First of all thanks for your prompt reply as always. Your help is
>> appreciated.
>>
>> Secondly, I am sorry I didn't explain the situation more clearly. I am a
>> bit frustrated with this... as always when things don't work as we
>> expect them too. It is quite probable that I lack the necessary
>> understanding to make things work.
>>
>> Now to the problem.
>>
>> I have GWT and Resty-GWT into the client. RestyGWT requires jackson and
>> so I have to use jackson and not jettinson in the server part where I
>> have CXF.
>>
>> In the client I jave something like this
>>
>>      @POST
>>      @Path("existing-entities")
>>      @Consumes("application/x-www-form-urlencoded")
>>      public void getExistingEntities(
>>              @FormParam("entities") List<Entity> entities,
>>              MethodCallback<List<Entity>> callback);
>>
>> In the server I have
>>
>>      @POST
>>      @Path("existing-entities")
>>      @Consumes("application/x-www-form-urlencoded")
>>      public List<Entity> getExistingEntities(
>>              @FormParam("entities") List<Entity> entities) throws
>> SQLException;
>>
>>
>> When I issue the call from the client with two entities: I get in the
>> form contents. This is done by resty-gwt:
>> entities: [{"name":"cca1", "type":"GENE"},{"name":"cca2", "type":"GENE"}]
>>
>> which is a JSONArray payload.
>>
>> What cxf does is to take the full json string and trying to shovel it
>> down the throat of my poor ParamConverter as entity and not as
>> List<Entity>.
>>
> as I explained earlier with the example of a query containing multipal
> parameters of the same name, ParamConverterProvider deals with the
> individual parameters such as Entity in your case
>
>> I am not getting it. I think CXF either should break the array and call
>> the converter for each object or it should leave the converter to
>> convert the array. Now it is not breaking it but it doesn't give me the
>> option to handle the array,
>
> How exactly would CXF or indeed any other generic framework break this
> JSON Array ? It won't. It has no idea about the semantics associated
> with a given parameter.
>
> You were right earlier on, just introduce a wrapper and forget about
> mapping it to the explicit collection :-). Explicit collections just
> make things more complicated unless there's an obvious/straightforward
> mapping as in the example I provided earlier on.
>
> Thanks, Sergey
>
>>
>> INFO
>> com.biovista.ws.impl.jaxrs.JacksonJsonParamConverterProvider.getConverter(JacksonJsonParamConverterProvider.java:41):
>>
>> **** called: arg0: class com.biovista.lib.datatype.Entity arg1: class
>> com.biovista.lib.datatype.Entity arg2:
>> [Ljava.lang.annotation.Annotation;@7f65ae66 providers:
>> org.apache.cxf.jaxrs.impl.tl.ThreadLocalProviders@63aea6a8
>> INFO
>> com.biovista.ws.impl.jaxrs.JacksonJsonParamConverterProvider.getConverter(JacksonJsonParamConverterProvider.java:44):
>>
>> Annotation: @javax.ws.rs.FormParam(value=entities)
>> INFO
>> com.biovista.ws.impl.jaxrs.JacksonJsonParamConverterProvider$1.fromString(JacksonJsonParamConverterProvider.java:71):
>>
>> Called for [{"name":"cca1", "type":"
>> GENE"},{"name":"cca2", "type":"GENE"}]
>> WARN 2014-08-12 17:47:46,722 http-bio-8081-exec-197:
>> org.apache.cxf.common.logging.LogUtils.doLog(LogUtils.java:452):
>> Interceptor for {http://impl.ws.biovista.com/}VizitService has thrown
>> exception, unwinding now javax.ws.rs.ProcessingException:
>> org.codehaus.jackson.map.JsonMappingException: Can not deserialize
>> instance of com.biovista.lib.datatype.Entity out of START_ARRAY token
>>
>> Now what do you think I should do in order to send complex types and
>> collections to the server from the client?
>>
>> About Jersey - I don't know I have never used it. I am not sure how I
>> should research it. In theory everything works. In practice you get to
>> see the weird corner cases.
>>
>> I am not 100% sure but I believe the opposite way (cxf to send
>> List<Entity>) works as expected. I will test and report tomorrow.
>>
>> Again thanks for the patience.
>>
>>
>> On 2014-08-12 12:17, Sergey Beryozkin wrote:
>>> On 12/08/14 17:13, Sergey Beryozkin wrote:
>>>> Sorry, do not understand what you are trying to do.
>>>>
>>>> Why do you use a single parameter (query, header, or may be form) to
>>>> send a JSON array ? This is typically sent as a message body, in which
>>>> case JAX-RS MessageBodyReader takes care of it.
>>>>
>>>> Imagine this case:
>>>>
>>>> ?a=1-2-3&a=4-5-6
>>>>
>>>> here we have 2 'a' query parameters, one with value "1-2-3" and another
>>>> - with "4-5-6"
>>>>
>>>> and we have this signature:
>>>>
>>>> Response get(@QueryParam("a") List<Integer> list);
>>>>
>>>> In this case we convert each parameter to Integer (the converter would
>>>> remove '-'), the runtime takes case of creating a List.
>>>> If we expected the converter to convert a String to List<Integer> then
>>>> what would the runtime pass to the converter, "a=1-2-3&a=4-5-6" and
>>>> expect it to parse it manually ? Not sure it makes sense.
>>>
>>> And given that ParamConverterProvider is expected to be reusable, what
>>> would we do with
>>>
>>> and a sequence like
>>>
>>> /path;a=1-2-3;a=4-5-6
>>> Response get(@MatrixParam("a") List<Integer> list);
>>>
>>> the converter would have to parse both
>>> "a=1-2-3&a=4-5-6" and "a=1-2-3;a=4-5-6"
>>>
>>> IMHO it is not how it should work, but please do not hesitate to
>>> investigate it further with Jersey
>>>
>>> Cheers, Sergey
>>>
>>>>
>>>> Can you investigate what Jersey does ? I'm pretty sure it was
>>>> discussed,
>>>> specifically that the runtime should take care of dealing with the list
>>>> itself, but they might deal with it differently
>>>>
>>>> Cheers, Sergey
>>>>
>>>>
>>>>
>>>> On 12/08/14 16:45, Vassilis Virvilis wrote:
>>>>> Aah,
>>>>>
>>>>> So in order to make this work through CXF is to define an
>>>>> EntitiesListWrapper class. Right? Then the ParamConverter will be
>>>>> called
>>>>> with EntitiesListWrapper as argument and jackson will deserialize.
>>>>> Right?
>>>>>
>>>>> Is there any other way to break the input of
>>>>>              final String entities_json = "[{\"name\":\"cca1\",
>>>>> \"type\":\"GENE\"},{\"name\":\"cca2\", \"type\":\"GENE\"}]";
>>>>> so the paramconverter will be called with the correct substring each
>>>>> time?
>>>>>
>>>>> This looks weird.
>>>>>
>>>>>      Vassilis
>>>>>
>>>>>
>>>>> On 08/12/2014 06:22 PM, Sergey Beryozkin wrote:
>>>>>> Hi
>>>>>>
>>>>>> AFAIK ParamConverterProvider is expected to be called once per every
>>>>>> entity in the list.
>>>>>>
>>>>>> Thanks, Sergey
>>>>>>
>>>>>> On 12/08/14 16:12, Vassilis Virvilis wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> Some time before I have started a thread with jackson and form
>>>>>>> parameters in cxf
>>>>>>> http://mail-archives.apache.org/mod_mbox/cxf-users/201406.mbox/%3C53AAC4CC.8010206@biovista.com%3E
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Sergey suggested that I should use ParamConverterProvider.
>>>>>>>
>>>>>>> I tried it today and it worked. Great.
>>>>>>>
>>>>>>> Now I am trying the next step which is to pass List<Entity>
>>>>>>> instead of
>>>>>>> Entity in the input. The problem is that my
>>>>>>> ParamConverterProvider is
>>>>>>> not called with the actual input class as specified in the interface
>>>>>>> (List<Entity>) but with plain Entity as you can see from
the
>>>>>>> logs. It
>>>>>>> then fails because due to
>>>>>>>          *** Can not deserialize instance of
>>>>>>> com.biovista.lib.datatype.Entity out of START_ARRAY token ****
>>>>>>>
>>>>>>> INFO
>>>>>>> com.biovista.ws.impl.jaxrs.JacksonJsonParamConverterProvider.getConverter(JacksonJsonParamConverterProvider.java:41):
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> **** called: arg0: class com.biovista.lib.datatype.Entity arg1:
>>>>>>> class
>>>>>>> com.biovista.lib.datatype.Entity arg2:
>>>>>>> [Ljava.lang.annotation.Annotation;@7f65ae66 providers:
>>>>>>> org.apache.cxf.jaxrs.impl.tl.ThreadLocalProviders@63aea6a8
>>>>>>> INFO
>>>>>>> com.biovista.ws.impl.jaxrs.JacksonJsonParamConverterProvider.getConverter(JacksonJsonParamConverterProvider.java:44):
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Annotation: @javax.ws.rs.FormParam(value=entities)
>>>>>>>
>>>>>>> Here is my ParamConverterProvider
>>>>>>>
>>>>>>>
>>>>>>> package com.biovista.ws.impl.jaxrs;
>>>>>>>
>>>>>>> import java.io.IOException;
>>>>>>> import java.lang.annotation.Annotation;
>>>>>>> import java.lang.reflect.Type;
>>>>>>>
>>>>>>> import javax.ws.rs.ProcessingException;
>>>>>>> import javax.ws.rs.core.Context;
>>>>>>> import javax.ws.rs.core.MediaType;
>>>>>>> import javax.ws.rs.ext.ContextResolver;
>>>>>>> import javax.ws.rs.ext.MessageBodyReader;
>>>>>>> import javax.ws.rs.ext.ParamConverter;
>>>>>>> import javax.ws.rs.ext.ParamConverterProvider;
>>>>>>> import javax.ws.rs.ext.Provider;
>>>>>>> import javax.ws.rs.ext.Providers;
>>>>>>>
>>>>>>> import org.apache.commons.logging.Log;
>>>>>>> import org.apache.commons.logging.LogFactory;
>>>>>>> import org.apache.cxf.jaxrs.ext.MessageContext;
>>>>>>> import org.codehaus.jackson.map.ObjectMapper;
>>>>>>>
>>>>>>> @Provider
>>>>>>> public class JacksonJsonParamConverterProvider implements
>>>>>>> ParamConverterProvider {
>>>>>>>      private final Log log = LogFactory.getLog(getClass());
>>>>>>>
>>>>>>>      @Override
>>>>>>>      public <T> ParamConverter<T> getConverter(final
Class<T>
>>>>>>> rawType,
>>>>>>>              final Type genericType, final Annotation[]
>>>>>>> annotations) {
>>>>>>>
>>>>>>>          log.info("**** called: arg0: " + rawType + " arg1: "
+
>>>>>>> genericType
>>>>>>>                  + " arg2: " + annotations + " providers: " +
>>>>>>> providers);
>>>>>>>          for (final Annotation annotation : annotations) {
>>>>>>>              log.info("Annotation: " + annotation);
>>>>>>>          }
>>>>>>>
>>>>>>>          return new ParamConverter<T>() {
>>>>>>>              @Override
>>>>>>>              public T fromString(final String value) {
>>>>>>>                  try {
>>>>>>>                      log.info("Called for " + value);
>>>>>>>                      return mapper.reader(rawType).readValue(value);
>>>>>>>                  } catch(IOException e) {
>>>>>>>                      throw new ProcessingException(e);
>>>>>>>                  }
>>>>>>>              }
>>>>>>>
>>>>>>>              @Override
>>>>>>>              public String toString(final T value) {
>>>>>>>                  try {
>>>>>>>                      return
>>>>>>> mapper.writer().writeValueAsString(value);
>>>>>>>                  } catch(Exception e) {
>>>>>>>                      throw new ProcessingException(e);
>>>>>>>                  }
>>>>>>>              }
>>>>>>>          };
>>>>>>>      }
>>>>>>> }
>>>>>>>
>>>>>>>
>>>>>>> How can I register different ParamConverterProvider for different
>>>>>>> input
>>>>>>> types? Or is that List is handled specially? By jackson or CXF?
In
>>>>>>> jackson I just need to do
>>>>>>>          final List<Entity> entities =
>>>>>>> mapper.readValue(entities_json,
>>>>>>>              new TypeReference<List<Entity>>() {
>>>>>>>              });
>>>>>>>
>>>>>>> but I don't know how to do this from inside CXF. I am using CXF
3.0
>>>>>>>
>>>>>>>      Thanks
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>
>

-- 

__________________________________

Vassilis Virvilis Ph.D.
Head of IT
Biovista Inc.

US Offices
2421 Ivy Road
Charlottesville, VA 22903
USA
T: +1.434.971.1141
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T: +30.210.9629848
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www.biovista.com

Biovista is a privately held biotechnology company that finds novel uses 
for existing drugs, and profiles their side effects using their 
mechanism of action. Biovista develops its own pipeline of drugs in CNS, 
oncology, auto-immune and rare diseases. Biovista is collaborating with 
biopharmaceutical companies on indication expansion and de-risking of 
their portfolios and with the FDA on adverse event prediction.



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