I created a Web Service using JaxWs. I belive that exist two ways to consume a web service in the client.
using wconsume e putting the generated classes as stubs in the client.
using Dynamic Proxy, whitch means, there wil be no files to be send to client as stubs.
I imagine that the only advantage of this approach is that if the wsdl changed, there will be not need to generat stubs files. However it doesn't look too practical, as I will probably need to change something in the client code and recompiled anyway. I didn't use this tecnichy yet. I found this option when I was reaserching the reason why I need to generate proxy file when developping Java client but I didn't when I using .Net.
Then, I have two question:
What's the difference between stubs and Dynamic Proxy tecnich?
Why .Net client doesn't need proxies files? Or is there the files automaticlly generated and I don't know where to find? Am I loosing performance or security when using stubs versus dynamic proxy?
1.What's the difference between stubs and Dynamic Proxy tecnich?
JAX-RPC is deprecated.
The new standard is JAX-WS.
JAX-WS allows programmers to invoke a web service, as if they were making a local method call.
For this to happen a standard mapping from WSDL to Java has been defined.
This mapping correlates a wsdl:port definition with a Java Interface which is called Service Endpoint Interface (SEI).
The SEI is the Java representation of the web service endpoint.
At runtime JAX-WS creates an instance of a SEI that can be used to make web service calls by simply making method calls on the SEI.
Now the way used to create an instance of a SEI is via the dynamic proxy class.
It is called dynamic proxy since it is created dynamically.
No stubs are need to implement a proxy, but the SEI must already have been implemented in order to be used.
The proxy uses/is based on the stub classes to function, which have been generated by the WSDL.
So the stubs are a prerequisite.
So there is no separation of techniques as you say in your post.
You have misunderstood the concept
Related
I am first time working with wsdl. I apologize if its a very novice question.
I have a wsdl file for a webservice. I want to create a java console application to consume the service.
I have generated class files using wsimport tool and wsdl. A good number of class file have generated.
I am confused at this point should I need further documentation from webservice provider to implement the service or there is any conversion regarding using the generated files.
Any suggestion would be very helpful.
WSDL file already have whole definition you need, including data-type, request and response wrappers for every method, etc. That mean, that since you have generated the client implementation via wsimport, the only thing you have to do is to import this files into your current java project and use it to access the web-service.
You can find a wide number of examples, how to use this generated client code. Here is one of them. In short, you have two main generated classes, representing web-service: an Interface annotated with #WebService annotation and some service annotated with #WebServiceClient. You just need to get an instance of the intarface from the service, like:
HelloWorldImplService helloService = new HelloWorldImplService();
HelloWorld hello = helloService.getHelloWorldImplPort();
Here us HelloWorld is an interface, which provides all the methods of the web-service from WSDL. And then you'll get it, you can use it to call the web-service. Just don't forget, that you may have to override the default ip-address of the web-service client, if it's not the one you need.
The only additional documentation you may need, is some documentations providing the information about the web-service business purposes, which may be usefull for the developer, whot interacts with this web-service.
Simply you can create a service client object from the class annotated with #WebServiceClient and call the related method with parameters.
WebServiceClient client = new WebServiceClient();
AnswerType answer = client.GetSoap().theMethodYouWantUse(some_parameters);
I am reading Professional XML
By: Bill Evjen; Kent Sharkey; Thiru Thangarathinam; Michael Kay; Alessandro Vernet; Sam Ferguson
Chapter SOAP & WSDl focusses on,
After you have found the service you want to consume, the act of discovery should bring you to the location of the Web service's WSDL file. The WSDL file is an XML description of the Web service's interface. After you have found the WSDL file of the Web service, you can create a proxy class (or your environment automatically creates one for you) that enables you to send messages back and forth to the Web service.
What is the proxy class in para above means and by whom it gets instantiated?
Is the Web Method which I wish to invoke through the SOAP constructed message format is also a method of the object of the proxy class?
The WSDL file is the technical contract which defines the communication interface with a service.
The "proxy class" in your citation, is just the logical representation of the service in your program. You can do this class by yourself, or have it made automatically. Most IDEs out there allow you to import a WSDL and they will generate most of the code needed to communicate with the service. The import tool will most likely create classes with methods and variables that correspond directly to operations and types in the WSDL file.
Your application instantiates the class and you call the methods you need to call by just filling the data as parameters and receiving the response in return. The class handles Object to SOAP message conversion for you. Keep in mind that even though it looks very similar to local function call, it is not - it is not nearly as fast and it involves network communication risks. It is quite possible to have communication errors that you need to handle.
Previously, I've written SOAP clients in Python and used the SUDS library. Without getting into the details, the "stub" generation is really quite dynamic as it's done at runtime and, with Python being so typeless, I'm able to reference the expected methods generated by the WSDL without a pre-compiled stub. I'm fine with generating a stub with something like wsimport, because it's great to have the composition of SOAP messages being handled via a nice Java object structure. So, I'm not looking for a dynamic generation mechanism akin to SUDS in python.
My problem is that all the simple JAX-WS examples I see are for what I'll call a "statically located web service". What I'm trying to do is connect to a web service with a known WSDL from which I could generate stubs at compile time but whose location is only known at runtime. For example, say I want to access Microsoft SharePoint Web Services. Wherever my application is deployed, there will a different SharePoint server (or servers) running which will need to be specified at runtime. All the simple examples I've seen have the service location URL hard-coded into the stubs through wsimport. Is there a way to generate stubs but supply the service location at runtime?
I'm really surprised not to find any examples of this because I figure what I'm trying to do should be very common as Web Services go. Perhaps the answer is that I can't be lazy and get a nice objectified version of the WSDL methods if the server location is only known at runtime. I've seen SAAJ examples but there, of course, I have to generate the SOAP messages by hand myself. That would be such a shame when the WSDL is known at compile time. Can't I have my cake and eat it too?
If I understand your question right, you want to connect to multiple web services that expose the same WSDL but are located at different addresses and your client contains only the address of the service used to generate it?
In that case have a look at this post: Changing WSDL url (endpoint) in JAX-WS client.
We have an application server that exposes a host of webservices. We are running a tomcat on the side that uses those webservices in JSF applications to provide a user interface. Suppose we have a bean that has a method "getWebservice()" that returns the proxy class used by jaxws to communicate with the webservice. This allows us to interact with the webservice with minimal effort: generate using wsimport, then use #{myBean.webservice.myProperty} etc
However as you can see this would require a lot of webservice interaction when reusing exposed methods. In our usecase most methods are rather static, at least for the duration of a #RequestScoped bean so the interaction of most methods should be cached once it is called (at least for one request).
Currently our setup is to create wrapper services in the bean and each wrapper does exactly the same thing:
if (methodResponse == null)
methodResponse = getWebservice().getMethod();
return methodResponse;
You can see that this gets very tiresome very quickly. Is there a way to annotate a jaxws method for caching? Or can I generate my own proxy class based on the interface and somehow "chain" it to the proxy used by jaxws (and perform generic caching) or can I create my own annotation that performs the caching?
You can create another caching Proxy around your web service client proxy object, and provide it with an InvocationHandler, that caches the result of method invocations.
Check out this blog post to see the complete step-by-step instruction and download sample code.
I want to build a web services client that takes wsdl link as the input and generates java classes. I know we can do this directly using Netbeans IDE where we provide the wsdl location during project setup. But I want the wsdl location to be provided when the client starts running. How do I do this?
Is the location that will be provided just used to specify the SOAP endpoint (for a web service whose WSDL was known at development time), or will it be a completely arbitrary WSDL?
In the first case, the web service client that was created by Netbeans has methods that accept an alternate SOAP endpoint URL. You can call those to use the client with a server whose location is not hard-coded in the client.
If however, the WSDL describes a completely unrelated service, how are you going to write Java code against it? You cannot use any interfaces derived from the WSDL (because they are not known at development time). You could only have a very generic SOAP client, where the user almost directly types in the XML that will be sent.