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What exactly is RESTful programming?
What are RESTful web services? What would be an example of it?
What is the difference between the asmx web services and the WCF RESTful service?
REST is a client-server architecture which (among other things) leverages the full capacity of the HTTP protocol.
Some relevant points in REST:
Each URL on the server represents a resource; either a collection resource or an element resource.
A collection resource would be available at a URL like http://restful.ex/items/ which would be a representation of a list of items.
A element resource would be available at a URL like http://restful.ex/items/2 which would be a representation of a single item, identified by 2.
Different HTTP methods are used for different CRUD operations:
a GET is a read operation
a PUT is a write/modify operation
a POST is a create/new operation
a DELETE is a... ok, that one is kind of self-explanatory.
State (or rather, client context) is not stored on the server-side; all state is in the representations passed back and forth by the client's requests and the server's responses.
You can check out Roy Fielding's (the creator of the REST architectural style) wiki page here and then move on to his PhD dissertation here and finally for a quick example just take a look at the Twitter API.
It's basically web services that implement CRUD using the HTTP methods(GET, POST, PUT, DELETE)
RESTful webservices use HTTP methods explicitly by mapping the REST operations to HTTP methods:
Create - POST
Retrieve - GET
Update - PUT
Delete - DELETE
Here is a link to a good summary.
Check description of REST. Web services conforming to this principle are called RESTful.
Related
I was asked "how do you call restful api in angular2 server" in a front end interview before. I said using the http. But interviewer didn't seem satisfied with this answer. What is the correct answer? Thank you!!
I was asked the same question in almost every interview I had, such as
How do you consume Restful web services in Angular 2/4
How do you create RESTful Webservice? and couple other such as
REST vs SOAP, etc.
Since I worked on Angular 2/4 and RESTful web services, I know the story about how they work. So rather than just answering "using Http protocol" I would elaborate on the answer by mentioning
The HttpClient in #angular/common/http offers a simplified client HTTP API for Angular applications
How you call the CRUD operations from service.ts file, use of observables and subscribe() method in component.ts file. (the component subscribes to the method's return value)
https://angular.io/guide/http . - more info
The 5 types of Http methods or for CRUD operations we use like
HTTP GET, POST, PUT, DELETE, PATCH and their functionality,
https://restfulapi.net/http-methods/
The way we use Postman collections (in my case) to test REST API calls or Swagger, etc. The format the data gets processed ( in this case of REST its JSON ). (JSON importance if necessary)
Please comment if you find any other reference or better points to answer coz I am learning too.
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I am new to web application design. It seems contemporary web applications usually take this form:
Front-end leverage various JS frameworks to built the UI.
Then front-end invoke back-end web services with JS to exchange XML or JSON data and update the UI accordingly.
Back-end is separated into tiers and expose Web service APIs to whatever external.
Web service APIs also exist for the communication among the back-end tiers.
So the web service APIs should be the critical part to design.
How do we design it? To be specific:
What data/materials are needed to start the design with?
What tools can we use? (I heard about some tools to convert XML into classes.)
And what does the final output of the design look like?
ADD 1
To be specific, suppose there's requirements like this:
Customer should be able to upload and delete certain files from the
file repository.
Customer must be authenticated before modifying the files on file repository.
How can I convert it into detailed API spec, and then concrete class definition?
A related link: http://piwik.org/blog/2008/01/how-to-design-an-api-best-practises-concepts-technical-aspects/
ADD 2 - Regarding RESTful
After reading some books, I came to this:
RESTful architecture is just one of the many ways to integrate
applications. It leverages Web standards in the hope of making the
integration simple and natural. Resources are identified by URLs,
manipulated with HTTP methods, and transferred in certain serialization
form at the convenience of the integrated parties.
To create a Web API (i.e. RESTful service), you need to follow REST principles. I think that this link could give you some hints about the design of RESTful services / Web API: http://restlet.com/blog/2015/03/16/designing-a-web-api/.
To be short, RESTful services should leverage HTTP methods they are designed for:
method GET: return the state of a resource
method POST: perform an action on the resource (creation of an element in a resource list, ...). Be careful not to use an action name within URLs (something like /elements/some-action-name) because it's not RESTful.
method PUT: update the complete state of a resource
method PATCH: update partially the state of a resource
method DELETE: delete a resource
You need also to be aware that they can apply at different levels, so methods won't do the same things:
a list resource (for example, path /elements)
an element resource (for example, path /elements/{elementid})
Other important things you must consider are:
To use status codes to tell the client if the request is sucessful (2xx family), fails because of the client (4xx family) or of the server (5xx family)
To leverage HTTP headers. For example, the header Content-Type for the type of content used (application/json for JSON for example) and Accept for content negotiation if needed...
Otherwise there are some formats like Swagger and RAML you can leverage to craft your Web API. A tool like Restlet Studio could a good help to create the structure of your REST service online, get the corresponding Swagger and RAML contents, and even generate server skeletons or client SDKs. You can notice that this tool only follows REST principles...
Regarding security, you need to leverage the Authorization header. There are several strategies:
Basic one. The username / password are encoded with Base64 and sent in the header.
Token-based one. You could have a look at this link for more details: https://templth.wordpress.com/2015/01/05/implementing-authentication-with-tokens-for-restful-applications/
OAuth2. See this link: http://www.bubblecode.net/en/2013/03/10/understanding-oauth2/.
Regarding file upload, you can leverage multipart contents. See this link: http://restlet.com/blog/2015/10/27/implementing-file-upload-with-restlet-framework/. We use the Restlet framework but you might pick up some generic hints...
Hope it helps you,
Thierry
In my opinion the concept of a Rest-full API is a little blurry, I would advise you to take a look at this article http://martinfowler.com/articles/richardsonMaturityModel.html
Not many public rest-full api's actually achive the discussed level 3. The general idea it to model your api around the "resources" your application deals in and respect the proper http verbs.
As for tools I kinda like https://apiary.io/ it helps you build an API and can provide mock responses as well
I am a bit confused about the difference between the two.
What I have been making till now is just deploying a web application that gets invoked by a URL and returns a response(json/XML) .
what I have read about rest web services
Its a way to communicate with web applications and to reveal your methods to the world.
Question 1
But in my case I did the same revealing the URL .
Platform independent
The rest features say that its Language-independent (C# can talk to Java)
Question 2
But in traditional approach also any language can invoke any web service by simple request (get/post) which ever implemented.
Question 3
What is rest and how to get started with it (specifically in terms of django) if possible.?
You are doing REST.
REST is not a library, or a format, it's simply a technique. What you call the "traditional approach" is exactly what REST is: simple requests via GET and POST (as well as PUT and DELETE) to an endpoint that returns JSON or XML.
That is in contrast to the previously-dominant way of making API requests, ie SOAP, which requires all sorts of up-front configuration of WSDL files and service discovery, along with particularly specified request formats.
Thanks for looking!
Background
I am building a strictly machine-to-machine web-service (restful) application. The application will listen for requests, retrieve data, construct objects, serialize to JSON and return the JSON object.
This application will ultimately be used by other web applications as well as iOS apps, Android apps, and even desktop apps.
The existing code that I have inherited makes a distinction based on how the service was called in terms of HTTP verbs (GET, POST, etc).
Question
In this day and age of machine-to-machine communication, is the HTTP verb even relevant any longer? Could it in fact be constraining for future adoption of the service API to base the code around HTTP verbs?
Update
fmgp provides a clear answer to "why" these verbs are used, but I feel should I clarify my concern:
Will other platforms such as iOS or Android (for example) be able to originate HTTP verb-based calls like GET and POST? If the answer is "no" then I assume that we should stay away from relying on these verbs and instead build the desired action into the request URL as a parameter.
In RestFul applications, you have a verb foreach CRUD operation:
Create: POST
Read: GET
Update: PUT
Delete: DELETE
Everything claimed "restful" will work the same way according to this philosophy.
There's nothing standard in that, just a clean, good designed, easy to understand programming style. Of course you may want to do all operation with only GET and some query parameters as soon as your client and server can handle it.
This question already has answers here:
Representational state transfer (REST) and Simple Object Access Protocol (SOAP)
(14 answers)
Closed 9 years ago.
I currently figure out the similar is both using internet protocol (HTTP) to exchange data between consumer and provider.
The difference is:
SOAP is a XML-based message protocol, while REST is an architectural style
SOAP uses WSDL for communication between consumer and provider, whereas REST just uses XML or JSON to send and receive data
SOAP invokes services by calling RPC method, REST just simply calls services via URL path
SOAP doesn't return human readable result, whilst REST result is readable with is just plain XML or JSON
SOAP is not just over HTTP, it also uses other protocols such as SMTP, FTP, etc, REST is over only HTTP
That's everything I know as the differences between them. Could anyone correct me and add more.
SOAP uses WSDL for communication btw consumer and provider, whereas
REST just uses XML or JSON to send and receive data
WSDL defines contract between client and service and is static by its nature. In case of REST contract is somewhat complicated and is defined by HTTP, URI, Media Formats and Application Specific Coordination Protocol. It's highly dynamic unlike WSDL.
SOAP doesn't return human readable result, whilst REST result is readable with is just plain XML or JSON
This is not true. Plain XML or JSON are not RESTful at all. None of them define any controls(i.e. links and link relations, method information, encoding information etc...) which is against REST as far as messages must be self contained and coordinate interaction between agent/client and service.
With links + semantic link relations clients should be able to determine what is next interaction step and follow these links and continue communication with service.
It is not necessary that messages be human readable, it's possible to use cryptic format and build perfectly valid REST applications. It doesn't matter whether message is human readable or not.
Thus, plain XML(application/xml) or JSON(application/json) are not sufficient formats for building REST applications. It's always reasonable to use subset of these generic media types which have strong semantic meaning and offer enough control information(links etc...) to coordinate interactions between client and server.
For more details regarding control information I highly recommend to
read this: http://www.amundsen.com/hypermedia/hfactor/
Web Linking: https://www.rfc-editor.org/rfc/rfc5988
Registered link relations:
http://www.iana.org/assignments/link-relations/link-relations.xml
REST is over only HTTP
Not true, HTTP is most widely used and when we talk about REST web services we just assume HTTP. HTTP defines interface with it's methods(GET, POST, PUT, DELETE, PATCH etc) and various headers which can be used uniformly for interacting with resources. This uniformity can be achieved with other protocols as well.
P.S.
Very simple, yet very interesting explanation of REST: http://www.looah.com/source/view/2284
In day to day, practical programming terms, the biggest difference is in the fact that with SOAP you are working with static and strongly defined data exchange formats where as with REST and JSON data exchange formatting is very loose by comparison. For example with SOAP you can validate that exchanged data matches an XSD schema. The XSD therefore serves as a 'contract' on how the client and the server are to understand how the data being exchanged must be structured.
JSON data is typically not passed around according to a strongly defined format (unless you're using a framework that supports it .. e.g. http://msdn.microsoft.com/en-us/library/jj870778.aspx or implementing json-schema).
In-fact, some (many/most) would argue that the "dynamic" secret sauce of JSON goes against the philosophy/culture of constraining it by data contracts (Should JSON RESTful web services use data contract)
People used to working in dynamic loosely typed languages tend to feel more comfortable with the looseness of JSON while developers from strongly typed languages prefer XML.
http://www.mnot.net/blog/2012/04/13/json_or_xml_just_decide
SOAP brings it’s own protocol and focuses on exposing pieces of application logic (not data) as services. SOAP exposes operations. SOAP is focused on accessing named operations, each implement some business logic through different interfaces.
Though SOAP is commonly referred to as “web services” this is a misnomer. SOAP has very little if anything to do with the Web. REST provides true “Web services” based on URIs and HTTP.
By way of illustration here are few calls and their appropriate home with commentary.
getUser(User);
This is a rest operation as you are accessing a resource (data).
switchCategory(User, OldCategory, NewCategory)
REST permits many different data formats where as SOAP only permits XML. While this may seem like it adds complexity to REST because you need to handle multiple formats, in my experience it has actually been quite beneficial. JSON usually is a better fit for data and parses much faster. REST allows better support for browser clients due to it’s support for JSON.