I will be happy to get advice from more experienced developers about adding Web Sockets into my HTTP-based project.
That’s the thing. I have developed the REST API based service. Everything works well enough, but… In some special cases my server needs a long time to serve client requests. It may be from 1 minute to several hours (and even days)! I implement some not-so-good algorithm to address this issue:
Client sends HTTP request
Server replies about registering request
Client starts sending HTTP requests to get necessary data (if response does not have needed information the client sends another request and so on)
That is all in a nutshell.
And it seems to be a bad scenario and I am trying to integrate web sockets for adding duplex-channels in this architecture. I hope that my API will be able to send info about updated data as soon as possible without the necessity of many requests from the client.
But I am a bit confused in choosing one of two ways to use web socket (WS).
Variant A.
The server only tells the client via WS that data is ready. And the client gets data by standard request-response HTTP method from REST API.
Variant B.
The server sends all data to the client via WS without HTTP at all.
What variant is more suitable? Or maybe some other variants?
I do not want to remove HTTP at all. I just try to implement WS for a particular kind of end-points.
Variant A would be more suitable and easy to implement. You can send message to the client after the data is ready, and he can then send request for the data. It will be like a simple chat websocket, and will serve your purpose.
I don't have any reference to give here to show my research (because none of the links are to the point) and even Google doesn't have an exact answer. Everyone says web service is stateful but that's confusing. By principle, I believe, SOAP is stateful and REST is stateless. So, Why/How SOAP is stateful ?
Basically Stateful means that server stores information about the client and uses that information over a series of requests. So performing one request is dependant upon the state of some other request (e.g. previous). Implementing this is possible with http protocols.
So you can have stateful or stateless SOAP - it's only a matter of how you design it.
Also please note that comparing SOAP and REST is not really correct.
The first one is basically Protocol (or at least it's trying to be) and REST is just a architecture pattern/style.
I know this is not exactly answering your question but please take a look at this link: SOAP vs REST (differences)
It's extremely well written and can help you understand those technologies a bit better.
First off, SOAP is protocol. In other way we have services like REST, WSDL, WCF and many more. SOAP can be used as protocol in all kind of services. This mean, soap provide mechanism to pass data between client and server.
By design and main purpose SOAP is data protocl to be use between server and clients. Server(service) save, preserve and response data.
Soap as data can be used in both variants in service - stateful or stateless.
By default soap service is stateless. For example WSDL soap service is stateless. Simple WebAPI, REST. They are all stateless.
WCF - Single Instance is stateful.
WCF - Per call is stateless.
Being stateful is not one of SOAP protocol principles or ideas behind it. Service can be stateful or stateless.
Is there a way to find out if a webpage uses REST or SOAP web services in it's back-end? If there is a way then what is it?
Thank you
You can check the network requests using a browsers developer tools.
Checking the headers for text/xmland a SOAP envelope might indicate SOAP
If its using REST you can check to see the header method is using GET, PUT, POST, DELETE with application/json which might indicate REST
SEE:
How can I debug a HTTP POST in Chrome?
And an in depth explanation of what I mean by "might be":
Representational state transfer (REST) and Simple Object Access Protocol (SOAP)
We have a bunch of services that support Post over HTTP similar to normal web app processing where in a form is sent via post and also SOAP over HTTP via the IBM soap gateway, our design is slightly messy today as we had combined a lot of processing logic tied to the transport protocol where we parse the XML contents via DOM parser and have seperate classes for Post and SOAP over HTTP, etc. We want to streamline this such that we have a common service class independent of transport that serves for both SOAP and POST over HTTP. I did find that Apache CXF supports both JAX-RS and JAX-WS via single service class. Does this mean I can use the JAX-RS similar to Form posting over HTTP and JAX-WS for the SOAP. The idea is we don't want to change any of the existing consumers client code and just stream line at the provider end. Any suggestion to this regard is welcome. Thanks.
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.