I know that there are two types of web services called asynchronous web services and synchronous web services. What I want to know are
1.
Can I identify whether a web service is asynchronous or synchronous by inspecting the WSDL of the service? Or is there any other way such as inspecting the generated stub etc?
2.
Can I develop an asynchronous client for a synchronous web service? Does it make sense?
Thank you.
I'm not an expert, but I'll give my two cents and hope that you find this useful.
Well I assume that it depends. You can have an asynchronous architecture with no signs of it. Someone could implement the following
The client makes a request to the service.
The service responds with a success or error message just to indicate the status of the request.
The service begins to process the request.
The service makes a request to another endpoint. This request is the actual response for the first request.
The service get a response, that the message was received successfully.
This is an asynchronous architecture. The service (actual service) when finished sends the actual response to an endpoint. This endpoint is actually the client that sent the first request.
This endpoint, the one that the client is listening to, for the actual response can be predefined (hard coded), or can be included as a parameter (callback) in the first response. If the case is the latter, then I guess you could deduce that this is an asynchronous web service.
For the second part of your question. Yes you can. Check this Asynchronous web services calls with JAX-WS: Use wsimport support for asynchrony or roll my own? and this http://cxf.apache.org/docs/asynchronous-client-http-transport.html
Related
Currently I'm doing the integration work of one project. In this project, we need to expose a restful api with java framework Wink. Since we have several other components to integrate, we put a message queue(activemq) between the api layer and other service parts.But this time the api layer will communicate to the lower level in an asynchronous way. In my understanding, the restful api should run in a synchronous way. For example, in the api layer, if one thread received a request, the response will get returned in the same thread. So there is a internal mismatch between these 2 communication styles. My question is how can we integrate these 2 parts to make the api layer work without sacrificing the features in message queue like reliability and performance?
Any suggestions will be apprciated here.
Thanks
Asynchronous callback is possible in REST communication, see this JERSEY framework example:
https://jersey.java.net/documentation/latest/async.html
But yes the latency should be controlled as your client would be waiting for server to respond, and would be good if client calls it in AJAX way.
Simplest way would be to fork a new process through "executor service", which sends a message in a channel to lower level api and listens back for response in another channel(MQ communication). And on process completion return a response, which then the higher API will push back to client.
I have a service layer which is calling a webservice. The number of requests generated by the service layer could potentially be very large and i want to build in some contingency in case the volume of requests becomes to much for the web service to handle. I know i can add some exception handling which can tell if the request failed or not however i don't want to keep hitting the service if its down or struggling to handle the requests.
How can i tell my service layer to stop making calls when the service is unavailable and then resume once its active again? I know this can be done manually using a file containing a flag which the service would check before making a call to the webservice. This flag could then be updated whenever the server goes dowm, however i would prefer something automatic.
Thanks,
I think it is easily could be done with interceptors. Just make your own interceptor and implement the logic in here.
I have created a Rest based web service Using jersey. I want to make it Asynchronous web service using polling mechanism. I want to know the service side implementation.
Requirements on the web service side:
Create request tokens and send it to client
Manage the tokens
Send response when client requests for the response using this token
Run the the service business logic in different thread
I am not finding useful posts and code snippets. Everywhere the mechanism is discussed but how can we implement this?
Does the webservice adaptor's function is let different webservice(eg,http/jms) can call each other?Does it like a proxy such as transform soap/http webservice to soap/jms webservice?
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In the picture there exist three webservice,webservice-1 and webservice-1 are published by third part,adaptor-A and adaptor-B are used to call them,webservice-3 is published by adaptor-c.first,when someone call webservice-3,the adaptor-c intercept the soap request and send it to esb ,the esb have a broadcast router and the router send it to adaptor-A & adaptor-B,adaptor-A & adaptor-B then analyse the message and call webservice-1&webservice-2.after that adaptor-A & adaptor-B send webservice response to esb,esb also have a aggregator in it,then aggregator assemble these two response and send it to adaptor-c,At last,adaptor-c send the final result to webservice-3 user!
I want to if this flow is feasible?if feasible,how to design the adaptor-A and adaptor-B and adaptor-c?
yes, this is well suited scenario for an ESB. When your adapters don't implement a special business logic and are only responsible for "speaking" the protocol expected by the Web service, you can probably connect the services directly to the ESB. This kind of "protocol virtualization" is basically provided by all kinds of ESBs, even plain Web service stacks like Axis2 or CXF can deal with a large set of transport protocols.
Regarding the business logic there are different possibilities. For simple scenarios you can consider using a EIP-aware framework like Apache Camel and chain Enterprise Integration Patters (EIP) [Hohpe et al] to achieve the desired integration. For more complex scenarios you can consider using BPEL (Business Process Execution Language). BPEL is descriptive parallel programming language with focus on orchestrating Web services in a transactional, long-running fashion. BPEL can be executed e.g. by Apache ODE.
I thought there would be lot more info/tutorials on this one, but some how I'm not able to figure out how to call an async SOAP web service using Java. The web service in question may not necessarily be a Java web service. I only have access to web service's run time WSDL.
Any pointers will be greatly helpful.
Also would it be possible to dynamically call such a web service? The Dynamic Invocation Interface method javax.xml.rpc.Call allows that for sync calls, but haven't found anything on async calls.
See the JAX-WS standard for the use of Future objects to communicate, asynchronously, with services. For some examples see CXF documentation on JAX-WS clients.
It is possible to do an asynchronous web service invocation, so that the client is not blocked waiting for the response. Check this link text