I am not sure if this is the correct place to ask but since there are a lot of questions of this kind i ll go ahead and ask.
A year ago i developed an iOS application that was connecting to a server with HTTP requests exchanging JSON files etc. I was told at that time that the server was a web (REST) service. I didnt care much since for me was just a black box.
The last months i am developing a hybrid mobile application where i use native code + jquery mobile for the front end part and php + mysql for the back end part. The application is about registering new users to the data base , having users to subscribe in various kinds of events , get notifications on them etc. So for all the communication between the front ent(client) and back end(server) i make http requests(POST) , ajax calls using json files.
Is this a RESTfull Web Service? I am a bit confused on the definition of REST. According to wikipedia REST is :
REST-style architectures conventionally consist of clients and servers. Clients initiate requests to servers; servers process requests and return appropriate responses.
So is what i am building a Restfull Web Service? Also do we call Rest only the server part or in general the client-server architecture?
Is it just a web Service? And if yes what kind of web service?
there is no difference when you invoke a controller (aka web service) from browser through http or from a client code (java, .NET or any language). when you want to invoke a service from outside world from your code.. you have choice of soap or rest .. soap is protocol, where as REST is an architecture style.. so REST is methodology of calling a service (which is simple http POST or GET call) from outside world .. not necessarily from a browser .. it may from client code which acts as browser to get response from outside world service..this is based on my experience..
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Due to the fall of SOAP::WSDL which had generated me real Perl modules I have to look for something other in order to handle a SOAP service. The generated modules won't work starting from Perl v5.18.
I have the following situation with my web application.
I have a PSGI compatible, Dancer2 driven, persistent web application.
The web application handles multiple concurrent customers.
The web application is between the customer and an external SOAP service.
The SOAP service uses customer sessions via cookies which have to be integrated on the web application internally for the customer.
The web application holds an WSDL file copy of the SOAP service.
I'm looking for a module that creates an interface out of the WSDL file and handles parameter/schema validation and communication with the SOAP service. I would like to call a method (SOAP call) with parameters (SOAP call parameters) and receive a cleaned data or object structure of the response.
The problem is that the web application needs to handle multiple concurrent customer cookie sessions. So I need a module which offers the possibility to override the cookie jar for that particular request and extract the cookies after the request without causing interference with other concurrent requests.
I found XML::Compile which I can initialize as a singleton at web application start up. But with this solution I ran into problems with interfering other customer requests. So the requests are not separated. Initializing XML::Compile for every request is not the solution either because it will parse the WSDL and generate handlers over and over again for every request the customer sends to the web application.
Is there any solution/module that fits my needs or do I miss something with XML::Compile and it's possible with it?
Are you using Catalyst?
I've been happy using Catalyst::Controller::SOAP and its companion Catalyst::Model::SOAP to build SOAP/WSDL servers and consumers, being able to integrate Perl Applications even with Microsoft Document Literal-Wrapped thing.
Even if not using Catalyst you may probably learn from its code. It uses XML::Compile::WSDL11.
I am new to RESTful webservice. Whatever I have read over the internet about RESTful webservice, I came to know that REST works similar to servlet + webservice.
Our traditional webservice looks like JSP-> Servlet -> Service -> DAO -> Database.
Will REST replace Servlet in this heirarchy?
My ultimate goal is that my web application should support mobile application and normal browser also. Is it good idea to use REST in that case. If not, in what situation we should use REST?
I hope my question is clear.
Please help me.
Thanks in advance.
There are many ways we can achieve Machine to Machine communication.
Web services also helps communicating between applications made in different platforms.
For example a .net GUI can call a java server side program for data.
REST is one of that kind, based on HTTP protocol.
SOAP web service is heavy weight (using lots of XML) where as REST is simple and you can expose any of your APIS simply using REST.
A services exposed as REST services can be invoked by a client using on of the HTTP verbs GET, POST, PUT, and DELETE with their meaning same as in HTTP.
RESTful Web Services expose the state of its resources.
An 'Employee' data can be queried and represented in any format (Json, XML ...) using REST.
Rest won't replace the Servlet in your hierarchy, actually the HTTP based REST methods are written on this servlets.
Please go through this URL : http://docs.oracle.com/javaee/6/tutorial/doc/gijqy.html
Using REST is not related to browser experience on mobile or other devices. It totally depends on the client side technology used and your browser compatibility with those technologies.
Using REST is a good idea to access data at client side using simple AJAX calls.
REST means Representational State Transfer. It is a way of thinking about architecting network communication between client and server, with the focus being on transferring a resource from server to client and back again.
To understand the significance of this first consider a different architecture, Remote Procedure Call. This is where the client calls a function on the server as if the function existed on the client.
So you want to edit a photo that exists on the server. Your client is a photo editing app that uses RPC to achieve this. You want to blur the photo so your client calls the blur() function using RPC, and the server blurs the image and sends back the updated image. Then you want to rotate the image, so your client calls the rotate() function and the server rotates the image and sends the rotated image to your client.
You might have noticed two issues. Firstly, every time you carry out an action on the photo the server needs to do some work and send you back the updated image. This uses a lot of bandwidth.
Secondly what happens if tomorrow the server developers (who might be nothing to do with the client developers) decide that rotate() is the wrong function name, it should really be rotate_image(), and they update the server. Your client continues to call rotate() but this now fails because such a function doesn't exist on the client.
REST is an alternative way of thinking about client/server communication. Instead of telling the server to carry out an action on the resource (eg rotate the photo), why doesn't the client not just get a representation of the resource and carry out all the actions it wants to (blur, rotate etc) and then send the new state of the resource back to the server.
If you did it this way the protocol to communicate between client and server can be kept very simple and will require very few updates. All you need is functions for the client to get the resource and functions to put it back on the server. The client will have to know how to blur the image and rotate the image, but it doesn't need to know how to tell the server to do this, it just needs a way of telling the server to save the updated image.
This means that the developers of the client can work away implementing new features independently to the developers of the server. Very handy if the developers of the client are nothing to do with the server (the developers of Firefox have nothing to do with the New York Times website and vice versa)
HTTP is one such protocol that follows this architecture pattern and it allows the web to grow as it has. There are a small set of verbs (functions) in HTTP and they are concerned only with transferring a representation of the resource back and forth between client and server.
Using HTTP your photo client simply sends a GET message to the server to get the photo. The client can then do everything it wants to to the photo. When it is finished it sends the PUT message with the updated photo to the server.
Because there are not domain specific actions in the protocol (blur, rotate, resize) this protocol can also be used for any number of resources. HTTP doesn't care if the resource is a HTML document, a WAV file, a Javascript script, a PNG image. The client obviously cares because it needs to understand the resource it gets, and the server might care as well. But the protocol between the client and server doesn't need to care. The only thing HTTP knows is that there is a variable Content-Type in the HTTP header where the server can tell the client what type of resource this is.
This is powerful because it means you can update your client independently to updating your server without updating the transfer protocol. HTTP hasn't been updated in years. HTML on the other hand is updated constantly, and web servers and web browser are updated constantly (Chrome is on version 33). These updates can happen independently to each other because HTTP never (rarely) changes.
A web browser from 10 years ago can still communicate with a modern web server over HTTP to get a resource. The browser might not understand the resource, say it gets a WebM video that it can't understand, but it can still get this resource without the network communication failing.
Contrast that with the example of RPC above where the client server communication will break if the server changes rotate() to rotate_image(). Every single client will have to be updated with this new function or they will crash when trying to talk to the server.
So REST is a way of thinking about client server communication, it is an architecture design/pattern. HTTP is a protocol that works under this way of thinking that focuses on simply transferring state of a resource between server and client.
Now it is important to understand that historically a lot of people, including web developers, didn't get this. So you got things like developers putting verbs into resource names to try and simulate Remote Procedure Call over HTTP. Things like
GET http://www.mywebsite.com/image/blur_image
And they would hard code the URI /image/blur_image into their client and then try and make sure the guys developing the server never changed the URI blur_image. You get back to all problems of RPC. As soon as the server guys move the resource blur_image (which is not really a resource to start with) to /image/blur_my_image the client falls over because it has that hard coded as an action to perform, rather than simply getting /image and doing what ever it wants to it.
So there are lot of examples on the web of doing REST wrong. Anything that tightly couples client and server communication is doing REST wrong. Your client should be able to survive URIs changing, or Content-Types being updated, without falling over. It can complain it doesn't understand a resource (eg Netscape Navigator 2.0 complaining it has no idea what a HTML5 document is), but it should complain that a URI has changed. This is the discoverability aspect of REST, which I haven't gone into too much, but basically your client should be able to start at the root of the server http://www.mywebsite.com and if it understand the content types it should be able to continue on to the resource it wants. You should never need to hard code a URI into your client other than the root of the server.
I could write a book about this stuff (and many have), but I hope that serves as a good introduction about what REST actually is.
#javafan I just checked the mykong example you provided. Please note that that is not standard http servlet implementation, it is a Jersy way of implimentinmg rest. So when you map all your URIs goes through this servlet com.sun.jersey.spi.container.servlet.ServletContainer and you write classes with annotation #path etc the Jersy runtime environment will do the necessary processing for you like converting the input and output objects to necessary formats (json, xml etc) depending on your configuration. You can write a simple servlet and add methods in it with #path annotation in it and that will be invoked inturn when you make the corresponding request. but the doGet and doPost methods are standard servlet methods that processes GET and POST method by default. You can ad another methods to the same servlet and add more qualifiers to process your request.
#GET, #Produces("xml") etc.
I hope this helps.
I have created an android application that calls (using kSOAP library) a SOAP based web service (developed in java, netbeans) over the intranet.
Now i want to make the application live, so this will require my web service to be exposed on the internet.
I have following questions...
How do i make sure that no one knows about the web service link except my android application
No one is able to call the web service except my android application
The data transferred between android application and web service is secure and encrypted
What kind of authentication mechanism should be used
I'm new to web services security so forgive me if my questions are dumb :)
This is impossible. Anyone having your app might use a traffic analyzer like wireshark and see all the requests it makes.
Sign each request you app makes(add some soap header) and check the signature on the server side
Use HTTPS
How to do authentication using SOAP?
I've started learning about webservices recently. Have few question about that:
For webservice, is it always necessary that source should provide wsdl or any other way possible to consume it without needing wsdl?
Till a while ago, I was doing server side XMLhttp post in classic ASP to do modifications in external application & to push data in my application from external application. I'm confused - is that very different from webservice or can be called a sort of webservice(ofcourse without based on SOAP). Any major difference or it is just protocol difference bw webservice and server side XMLhttp post?
Web services can be made asynchronous?(Something like AJAX call through javascript)
Are there any different types of webservices ? (for e.g is there difference bw, webservice providing stock quotes and webservice provided by google)
1.For webservice, is it always necessary that source should provide wsdl or any other way possible to consume it without needing wsdl?
WSDL is a document that publishes an interface. As long as a client complies to the inteface, it is guaranteed to be able to "talk" to the web service. Having said that WSDL is a formal way for a specification when there are many stakeholders. You can proceed without one, as long as you somehow know what the web service expects. Just wrap the application data in a SOAP envelope and send it to the web service. As long as you send what the web service expects (in the SOAP envelope or the application data) and in the way they are expected e.g. transport HTTP etc. it does not matter for the WS if you have used a WSDL or not.
2.Till a while ago, I was doing server side XMLhttp post in classic ASP to do modifications in external application & to push data in my
application from external application. I'm confused - is that very
different from webservice or can be called a sort of
webservice(ofcourse without based on SOAP). Any major difference or it
is just protocol difference bw webservice and server side XMLhttp
post?
In very simple terms web service is XML over some application protocol (usually HTTP). Could be SOAP based or REST. To understand more on this you should read about Service Oriented Applications
3.Web services can be made asynchronous?(Something like AJAX call through javascript)
They could but it is more complicated than that.
4.Are there any different types of webservices ? (for e.g is there difference bw, webservice providing stock quotes and webservice
provided by google)
Not sure what you ask here. Each web service offers something.
I will try to be very simple here:
The W3C defines a "Web service" as "a software system designed to
support interoperable machine-to-machine interaction over a network".
That means first requisite for any software to be web-service is that it should not depend upon platform or software i.e a web service made on java stack can be consumed by client in .net stack on windows or java stack on android.
If your server side implementation XMLhttp post suffice this ,its a
web service.
Types of Web services
Actually, there is no overall and clear categorization on types of web services. But two most popular are :
SOAP based web services. :It use XML messages that follow the Simple Object Access Protocol (SOAP) standard, an XML language defining a message architecture and message formats(WSDL).
REST based web services. With evolution of WEb 2.0 emphasis has been moving away from SOAP based services towards representational state transfer (REST) based communications.[3] REST services do not require XML, SOAP, or WSDL service-API definitions.Read here to get a easy explanation of REST
Need of WSDL to consume SOAP web services?
To consume a SOAP service we only require SOAP endpoint and XML message format. WSDL is a pre-requisite for automatic client side code generation through Java and .NET SOAP frameworks.
Asynchronous web services
Making web services asynchronous is possible.But complexity depends upon frameworks used, for example AXIS2 in JAVA has easy implementation of this.
I want to send an XML file to a Web Service.
The Web Service is a java application.
I know the endpoint of the Web Service.
Typically I know I have to create the request and send it as an http/https request.
What I want to know is what would I have to make to send the request - as in what development tool could I use e.g. Visual Web Developer (preffered as I am familiar with this) or Visual Studio? And what sends the request - e.g. another Web Service, a Website etc?
Where do I even begin with this?
Any comments are much appreciated.
Where do I even begin with this?
One purpose of a Webservice is loose coupling. So it depends on what you want to do. You can write a simple program in what ever language which constructs a request and sends it. You can write a Webservice on its own which uses the other Webservice to handle it's own requests.
You can handle this in a very simple or complex way. You only need to be able to generate a request (per xml) and send it.