Suppose that I have Apache/lighttpd or whatever to receive http requests. Now I want the web servers to act as a proxy for my web services running on internal servers written in Java/Clojure/Erlang?
What I want is to separate the layer that handles client connections and the server that handle application logic. These two should be separated and language independent. Is JSON or XML the format for communicating? If so, how do I perform it from the web servers?
Note: May be I missed the point of your question in this response. Pls do let me know if that is the case.
I dont think you should consider this as "forwarding" of the original request.
If your web-tier that receives the original request makes a call to one/more underlying services (thru HTTP or otherwise) it is part of the "processing" of the original request.
So, there is nothing different here than what you are already familiar with.
i.e You make a HTTP request in place where you would make a SOAP/XML request or a DB call or post a message.
When you say or think in terms of "forwarding", it is misleading.
Also, the data exchanged between your controller and services is solely based on your convenience.
It could be XML or JSON or regular POST parameters that gets sent over HTTP transport
I have seen some of the SOAP- Example- Mediators. I have not found a transformation based on the endpoint-WSDL.
I want to send some nested named array in json or POX and that data should go into a complete namespaced headered (username, password) SOAP-Request based on the names.
All the examples I have found had either a very simple wsdl or the namespaces were static in the XSL-Transformation.
It should be possible to do that, as I see in for example php-NuSOAP. You feed it with a wsdl-endpoint, the operation you want to execute and the parameter-array, and it calls the Webservice.
I am looking for a solution which is not too much hardcoded for every single service, so the proxy still works when the wsdl changes and Server Clients get changed.
As far as I understand the payload factory mediator in (https://stackoverflow.com/a/12969814/2277620) you would have to hardcode the soap-format in the mediator.
If WSO2 is the wrong tool for that I'd like to have a hint which tool could help.
Thanks in advance!
Marco.
For my understanding, you want to have a proxy, but it's backend service/wsdl may vary..
What , you can do is, you can save the wsdl (dynamic wsdl)in registry and point that in your proxy. whenever you edit the wsdl, proxy will automatically adopt to that..But the request, which you send to your backend should follow the wsdl definitions..It is totally client side responsibility..
I am new to Spring web services. I am going to create an xml request, and send it as a SOAP request to a web service and receive the response.I read different documents but still confused as I could not find a working sample yet.
I know that I should use WebServiceTemplate and WebServiceMessageSender, SaajSoapmessageFactory (please let me know if I am wrong) but not sure how to use them.
Do I need WSDL? if yes why?
If you have any sample code please send me to get clear on it.
Thanks
If you want to send SOAP requests, you would like to be a SOAP client. Seems like you want to use spring-ws project. Check out their great documentation on the client side. The same documentation will guide you through the process of creating a server. There are plenty of examples and ready-made configuration snippets waiting for you.
Spring-WS is built on top of XML Schema description of your message, so you will need WSDL to generate e.g. JAXB models of your requests and responses.
AFAIK, for "web services" , the WSDL file is the machine blueprint of the "ports" as they are called However! ports in WSDL "means" java language(or any other programming language used with a routine or sub or procedure or function) method and has a specific naming scheme associate the .wsdl xml file(template of the service). Each WSDL port(language method) has specifications of return value and data specifications for how to feed it arguments and their type values.
I am reading so many things to understand various things in WCF.
Very soon, actually, i want to move/convert existing WSE3 web services to WCF. In existing WSE web services, I have some (data) classes that model entities in our environment.
While transforming those classes, should I use Data Contract/Data Member attribute or the MessageContract attribute?
1. How to decide between Message Contract and Data Contract in WCF?
2. Does type of binding (like basicHttpBinding) has any role in this decision?
3. Does proxies created at client side (when we add web reference) change significantly depending on the Data or Message Contract?
(PS: I am trying to find a way so that existing WSE clients should be able to consume the WCF service without much alterations/modifications. Is it possible to use the current proxies generated from ASMX web services, to connect to the new WCF service just by setting URL of the proxy to WCF service?)
Here is a quick go at answering your questions:
1) Unless there is a specific reason like tweaking the structure of the soap XML, use DataContract instead of MessageContract.
2 & PS) Since you are currently using soap over HTTP, you'll most likely need the new services to be configured for basicHttpBinding. This will provide the interoperability that you need for the ASMX clients.
3) It shouldn't if the soap structure created by the WCF service matches your current soap.
I vaguely remember that WSE 3.0 supported some of the WS-* standards. If your current code depends on these then you may be able to also expose a wsHttpBinding for these operations but I don't think a default ASMX client works with a wsHttpBinding configured service.
It depends on control you need over resulting SOAP message. DataContract defines part of message body wrapped by element defined by operation. MessageContract defines a structure of whole message - you can use multiple body members, you don't have to use default wrapper element and you can also place some data into SOAP headers.
In your scenario the most important part is to define WCF to use same SOAP messages as your former WSE3 service. Here the important is how do you currently serialize data? If you use Xml serialization (and attributes) you can use it directly in WCF by switchinig from data contract serialization to xml serialization.
Btw. why did you use WSE3 instead of plain ASMX? Did you use message security? In such case you will need another binding. BasicHttpBinding is not able to do message security.
General answer is yes, you can create service wich your current client proxies will be able to consume. But in reality the effort depends on your current service and current code.
What is WSDL? How is it related to SOAP? Where does REST fit in all of that?
A WSDL is an XML document that describes a web service. It actually stands for Web Services Description Language.
SOAP is an XML-based protocol that lets you exchange info over a particular protocol (can be HTTP or SMTP, for example) between applications. It stands for Simple Object Access Protocol and uses XML for its messaging format to relay the information.
REST is an architectural style of networked systems and stands for Representational State Transfer. It's not a standard itself, but does use standards such as HTTP, URL, XML, etc.
Example: In a simple terms if you have a web service of calculator.
WSDL: WSDL tells about the functions that you can implement or exposed to the client. For example: add, delete, subtract and so on.
SOAP: Where as using SOAP you actually perform actions like doDelete(), doSubtract(), doAdd(). So SOAP and WSDL are apples and oranges. We should not compare them. They both have their own different functionality.
Why we use SOAP and WSDL: For platform independent data exchange.
EDIT: In a normal day to day life example:
WSDL: When we go to a restaurant we see the Menu Items, those are the WSDL's.
Proxy Classes: Now after seeing the Menu Items we make up our Mind (Process our mind on what to order): So, basically we make Proxy classes based on WSDL Document.
SOAP: Then when we actually order the food based on the Menu's: Meaning we use proxy classes to call upon the service methods which is done using SOAP. :)
Every time someone mentions SOAP/WSDL, I think of objects and classes defined in xml...
"You use SOAP just the same way that you would any PHP class. However, in this case the class does not exist in the local applications file system, but at a remote site accessed over http."
...
"If we think of using a SOAP service as just another PHP class then the WSDL document is a list of all the available class methods and properties. "
http://www.doublehops.com/2009/07/07/quick-tutorial-on-getting-started-with-soap-in-php/comment-page-1/
..and whenever someone talks about REST I think of HTTP's commands (request methods) like POST, GET and DELETE
SOAP -> SOAP(Simple object access protocal) is the application level protocal created for machine to machine interaction. Protocol defines standard rules. All the parties who are using the particular protocol should adhere to the protocol rules. Like TCP, It unwinds at transport layer, The SOAP protocol will be understood by Application layer( any application which supports SOAP - Axis2, .Net).
WSDL -> SOAP message consist of SoapEnevelope->SoapHeader and SoapBody. It doesn't define what would be message format? what are all the transports(HTTP,JMS) it supports? without this info, It is hard for any client who wants to consume the particular web service to construct the SOAP message. Even if they do, they won't be sure, it'll work all the time. WSDL is the rescue. WSDL (Web Service description Language) defines the operations, message formats and transport details for the SOAP message.
REST -> REST(Representational state transfer) is based on the Transport. Unlike SOAP which targets the actions, REST concerns more on the resources. REST locates the resources by using URL (example -http://{serverAddress}/employees/employeeNumber/12345) and it depends on the transport protocol( with HTTP - GET,POST, PUT, DELETE,...) for the actions to be performed on the resources. The REST service locates the resource based on the URL and perform the action based on the transport action verb. It is more of architectural style and conventions based.
You're not going to "simply" understand something complex.
WSDL is an XML-based language for describing a web service. It describes the messages, operations, and network transport information used by the service. These web services usually use SOAP, but may use other protocols.
A WSDL is readable by a program, and so may be used to generate all, or part of the client code necessary to call the web service. This is what it means to call SOAP-based web services "self-describing".
REST is not related to WSDL at all.
SOAP stands for Simple (sic) Object Access Protocol. It was intended to be a way to do Remote Procedure Calls to remote objects by sending XML over HTTP.
WSDL is Web Service Description Language. A request ending in '.wsdl' to an endpoint will result in an XML message describing request and response that a use can expect. It descibes the contract between service & client.
REST uses HTTP to send messages to services.
SOAP is a spec, REST is a style.
Wikipedia says "The Web Services Description Language is an XML-based language that provides a model for describing Web services". Put another way, WSDL is to a web service, as javadoc is to a java library.
The really sweet thing about WSDL, though, is that software can generate a client and server using WSDL.
Some clear explanations (for SOAP and WSDL) can be found here as well.
Difference between a SOAP message and a WSDL?
REST is light-weight in terms of encoding, much more useful for light weight devices i.e. non strict APIs.
REST is format independent. XML, HTML, JSON all options are available.
REST provides abilities for on 2 point message transfer (not surprising since REST stands for REpresentational State Transfer) where WSDL/SOAP interaction is multiple point message interaction.
REST does not require a new extension for XML messages, where in WSDL/SOAP this is the case.
WSDL/SOAP uses multiple transport protocols, REST relies on only HTTP. Therefore WSDL/SOAP can be used like a RESTful way, however simple requests can be overly complicated/heavy weighted.
A simple analogy: REST is like a motoboy delivers your food easy and quick. XML extended WSDL/SOAP more like UPS delivery, more structured and serious stuff but comes with a cost.
A WSDL document describes a webservice. It specifies the location of the service and the methods of the service using these major elements:
data types using in webservice
data elements for each operation
describe the operations that can be performed and the messages envolved
SOAP (Simple Object Access Protocol) is a messaging protocol that allows programs that run on disparate operating systems to communicate using http and xml.