Top Xx Confine Remainder Interview Questions Answers For Coffee Programmers To Develop Good Inwards 2018
Thursday, May 31, 2018
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Hello guys, I receive got been sharing around REST alongside Spring tutorials from concluding a span of weeks too today, I am going to portion around of the often asked Spring too REST interview questions to Java developers applying for Web developer roles. Since Spring Framework is the most pop too the touchstone framework for developing Java spider web application too RESTful Web Services, a skillful cognition of Spring centre too Spring MVC is expected from whatever senior Java developer, but if the labor description advert nearly REST too Web Services, yous too demand to hold upwards aware of how to develop RESTful Web Services using Spring Framework. From Spring 3.1, the framework has been enhanced a lot to back upwards many features needed for RESTFul API out-of-the-box e..g HTTPMessageConverter tin convert your HTTP response to JSON or XML past times merely detecting relevant library inwards classpath e.g. Jackson too JAXB.
Spring too provides customized annotations for RESTful Web Services e.g. @RestController which tin brand your Controller REST aware, so that yous don't demand to do mutual materials required past times every unmarried REST API e.g. converting the response to JSON.
Influenza A virus subtype H5N1 skillful cognition of Spring Security is too mandatory for developing too safety RESTful Web Services inwards the existent world. Since yous cannot brand life a non-trivial REST API without security, a skillful cognition of safety basics e.g. HTTP basic authentication, digest authentication, OAuth, too JWT is really important.
Btw, If yous are non familiar alongside that concept, I propose yous become through REST alongside Spring too Learn Spring Security Course to gain around sense before your Interview. These 2 courses are specially designed to supply yous around real-world sense to boost both your cognition too sense alongside Spring MVC, REST, too Spring Security.
What does REST stand upwards for? (answer)
REST stands for REpresentational State Transfer, which uses HTTP protocol to ship information from customer to server e.g. a mass inwards the server tin hold upwards delivered to the customer using JSON or XML.
What is a resource? (answer)
Influenza A virus subtype H5N1 resources is how information is represented inwards REST architecture. By exposing entities every bit the resources it allows a customer to read, write, modify, too create resources using HTTP methods e.g. GET, POST, PUT, DELETE etc.
What are prophylactic REST operations? (answer)
REST API uses HTTP methods to perform operations. Some of the HTTP operations which doesn't alteration the resources at the server is known every bit prophylactic operations e.g. GET too HEAD. On the other hand, PUT, POST, too DELETE are dangerous because they alteration the resources on the server.
What are idempotent operations? Why is idempotency important? (answer)
There are around HTTP methods e.g. GET which hit same response no thing how many times yous usage them e.g. sending multiple GET asking to the same URI volition final result inwards same response without whatever side-effect thus it is known every bit idempotent.
On the other hand, the POST is non idempotent because if yous ship multiple POST request, it volition final result inwards multiple resources creation on the server, but again, PUT is idempotent if yous are using it to update the resource.
Even, multiple PUT asking to update a resources on a server volition give same halt result. You tin farther accept RESTful Web Services to acquire to a greater extent than nearly REST.
What are the advantages of the RestTemplate? (answer)
The RestTemplate shape is an implementation of Template method pattern inwards Spring framework. Similar to other pop template classes e.g. JdbcTemplate or JmsTempalte, it too simplifies the interaction alongside RESTful Web Services on the customer side. You tin usage it to eat a RESTful Web Servicer really easily every bit shown inwards this example.
Which HTTP methods does REST use? (answer)
REST tin usage whatever HTTP methods but the most pop ones are GET for retrieving a resource, POST for creating a resource, PUt for updating resources too DELETE for removing a resources from the server.
What is an HttpMessageConverter inwards Spring REST? (answer)
An HttpMessageConverter is a Strategy interface that specifies a converter that tin convert from too to HTTP requests too responses. Spring REST uses this interface to convert HTTP response to diverse formats e.g. JSON or XML.
Each HttpMessageConverter implementation has i or several MIME Types associated alongside it. Spring uses the "Accept" header to decide the content type customer is expecting.
It volition too so elbow grease to let on a registered HTTPMessageConverter that is capable of treatment that specific content-type too usage it to convert the response into that format before sending to the client.
How to create a custom implementation of HttpMessageConverter to back upwards a novel type of request/responses? (answer)
You merely demand to create an implementation of AbstractHttpMessageConverter too register it using the WebMvcConfigurerAdapter#extendMessageConverters() method alongside the classes which generate a novel type of request/response.
Is REST unremarkably stateless? (answer)
Yes, REST API should hold upwards stateless because it is based on HTTP which is too stateless. Influenza A virus subtype H5N1 Request inwards REST API should comprise all the details required it to procedure i.e. it should non rely on previous or adjacent asking or around information maintained at the server halt e.g. Sessions. REST specification seat a constraint to become far stateless too yous should proceed that inwards heed spell designing your REST API.
What does @RequestMapping notation do? (answer)
The @RequestMapping notation is used to map spider web requests to Spring Controller methods. You tin map asking based upon HTTP methods e.g. GET too POST too diverse other parameters. For examples, if yous are developing RESTful Web Service using Spring too so yous tin usage produces too consumes holding along alongside media type notation to dot that this method is exclusively used to hit or consumers JSON every bit shown below:
Is @Controller a stereotype? Is @RestController a stereotype? (answer)
Yes, both @Controller too @RestController are stereotypes. The @Controller is truly a specialization of Spring's @Component stereotype annotation. This way that shape annotated with @Controller volition too hold upwards automatically hold upwards detected past times Spring container every bit business office of container's constituent scanning process.
And, @RestController is a specialization of @Controller for RESTful spider web service. It non exclusively combines @ResponseBody too @Controller notation but too gives to a greater extent than pregnant to your controller shape to clearly dot that it deals alongside RESTful requests.
Spring Framework may too usage this notation to supply around to a greater extent than useful features related to REST API evolution inwards future.
What is the departure betwixt @Controller too @RestController? (answer)
There are many differences between @Controller too @RestController every bit discussed inwards my before article (see the answer) but the most of import i is that with @RestController yous acquire the @ResponseBody notation automatically, which way yous don't demand to separately annotate your handler methods with @ResponseBody annotation. This makes the evolution of RESTful spider web service easier using Spring. You tin run into hither to learn
When do yous demand @ResponseBody notation inwards Spring MVC? (answer)
The @ResponseBody notation tin hold upwards seat on a method to indicates that the render type should hold upwards written straight to the HTTP response trunk (and non placed inwards a Model, or interpreted every bit a sentiment name).
For example:
@RequestMapping(path = "/hello", method = RequestMethod.PUT)
@ResponseBody
public String helloWorld() {
return "Hello World";
}
Alternatively, yous tin too usage @RestController notation instead of @Controller annotation. This volition take away the demand for using @ResponseBody because every bit discussed inwards the previous answer, it comes automatically alongside @RestController annotation.
What does @PathVariable do inwards Spring MVC? Why it's useful inwards REST alongside Spring? (answer)
It's i of the useful annotations from Spring MVC which allows yous to read values from URI similar query parameter. It's peculiarly useful inwards illustration of creating RESTful spider web service using Spring because inwards REST resources identifiers are business office of URI.This questions is unremarkably asked to experienced Spring MVC developers e.g. iv to half dozen years of experience.
For example, inwards the URL http://myapp.com/books/101 if yous desire to extract 101 the id, too so yous tin use @PathVariable notation of Spring MVC. If yous are non familiar alongside Spring MVC annotations then Spring MVC For Beginners: Build Java Web App inwards 25 Steps is a skillful house to get-go with.
What is the HTTP condition render code for a successful DELETE statement? (answer)
There is no strict dominion alongside honour to what condition code your REST API should render afterward a successful DELETE i.e it tin render 200 Ok or 204 No Content. In general, if the DELETE functioning is successful too the response trunk is empty render 204. If the DELETE asking is successful too the response trunk is NOT empty, render 200
What does CRUD mean? (answer)
CRUD is a curt shape of Create, Read, Update too Delete. In REST API, the POST is used to create a resource, GET is used to read a resource, PUT is used to updated a resources too DELETE is used to take away a resources from the server.This i is around other beginner degree Spring MVC questions for 1 to iii years experienced programmers
Where do yous demand @EnableWebMVC? (answer)
The @EnableWebMvc notation is required to enable Spring MVC when Java configuration is used to configure Spring MVC instead of XML. It is equivalent to <mvc: annotation-driven>
It enables back upwards for @Controller-annotated classes that usage @RequestMapping to map incoming requests to handler methods non already familiar alongside Spring's back upwards for Java configuration, Spring Master Class on Udemy is a skillful house to start.
This may operate for a human user but non for REST clients. You demand to ship them proper condition code e.g. 404 if the resources is non found. That's where yous tin usage @ResponseStatus annotation, which allows yous to ship custom HTTP condition code along alongside proper fault message inwards illustration of Exception.
In lodge to usage it, yous tin create custom exceptions too annotated them using @ResponseStatus notation too proper HTTP condition code too reason.
When such exceptions are thrown from controller's handler methods too non handled anywhere else, too so appropriate HTTP response alongside the proper HTTP condition code, which yous receive got laid is sent to the client.
For example, if yous are writing a RESTful Web Service for a library which provides mass information too so yous tin use @ResponseStatus to create Exception which returns HTTP response code 404 when a mass is non constitute instead of Internal Server Error (500), every bit shown below:
@ResponseStatus(value=HttpStatus.NOT_FOUND, reason="No such Book") // 404
public shape BookNotFoundException extends RuntimeException {
// ...
}
If this Exception is thrown from whatever handler method too so HTTP fault code 404 alongside argue "No such Book" volition hold upwards returned to the client.
Is REST secure? What tin yous do to secure it? (answer)
This interrogation is generally asked alongside experienced Java programmers e.g. 2 to five years sense alongside both REST too Spring. Security is a wide term, it could hateful safety of message which is provided past times encryption or access restriction which is provided using authentication too authorization. REST is unremarkably non secure but yous tin secure it past times using Spring security.
At the really to the lowest degree yous tin enable HTTP basic authentication past times using HTTP inwards your Spring safety configuration file. Similarly, yous tin expose your REST API using HTTPS if the underlying server supports HTTPS.
Does REST operate alongside carry layer safety (TLS)? (answer)
TLS or Transport Layer Security is used for secure communication betwixt customer too server. It is the successor of SSL (Secure Socket Layer). Since HTTPS tin operate alongside both SSL too TLS, REST tin too operate alongside TLS.
Actually, REST says anything nearly Security, it's upwards to the server which implements that. Same RESTful Web Service tin hold upwards accessed using HTTP too HTTPS if the server supports SSL.
If yous are using Tomcat, yous tin run into hither to acquire to a greater extent than nearly how to enable SSL inwards Tomcat.
Do yous demand Spring MVC inwards your classpath for developing RESTful Web Service? (answer)
This interrogation is often asked to Java programmers alongside 1 to 2 years of sense inwards Spring. Short reply is Yes, yous demand Spring MVC inwards your Java application's classpath to develop RESTful spider web services using Spring framework. It's truly Spring MVC which provides all useful annotations e.g. @RestController, @ResponseCode, @ResponseBody, @RequestBody, and @PathVariable, thus yous must spring-mvc.jar or appropriate Maven entry inwards your pom.xml
That's all nearly around frequently asked Spring REST Interview questions for beginners too experienced Java JEE developers. These questions are too really useful to brush upwards your cognition nearly Spring REST if yous are going to accept Spring Certification. If yous demand to a greater extent than questions from Spring certification perspective, yous volition let on a lot of interrogation on this topic on David Mayer's Core Spring Simulator, i of the best simulator to exceed Spring certification at the moment.
Other Spring tutorials too Resources yous may like
Spring Master Class - Beginner to Expert
Spring Framework 5: Beginner to Guru
5 Free Courses to acquire Core Spring too Spring Boot
How Spring MVC Frameworks works?
How Basic Authentication industrial plant inwards Spring Security?
What is the Role of DispatcherServlet inwards Spring?
What is departure between @Service, @Controller, too @Component inwards Spring
REST With Spring Certification Course past times Baeldung
Thanks for reading this article, if yous similar this article too so delight portion alongside your friends too colleagues. If yous receive got whatever interrogation which is non answered on this listing too so delight driblet a comment too I'll elbow grease my best to let on an reply for you.
Sumber https://javarevisited.blogspot.com/
Spring too provides customized annotations for RESTful Web Services e.g. @RestController which tin brand your Controller REST aware, so that yous don't demand to do mutual materials required past times every unmarried REST API e.g. converting the response to JSON.
Influenza A virus subtype H5N1 skillful cognition of Spring Security is too mandatory for developing too safety RESTful Web Services inwards the existent world. Since yous cannot brand life a non-trivial REST API without security, a skillful cognition of safety basics e.g. HTTP basic authentication, digest authentication, OAuth, too JWT is really important.
Btw, If yous are non familiar alongside that concept, I propose yous become through REST alongside Spring too Learn Spring Security Course to gain around sense before your Interview. These 2 courses are specially designed to supply yous around real-world sense to boost both your cognition too sense alongside Spring MVC, REST, too Spring Security.
20 Spring REST Web Service Interview Questions
Here are a span of often asked questions nearly using REST Web Services inwards Spring Framework.What does REST stand upwards for? (answer)
REST stands for REpresentational State Transfer, which uses HTTP protocol to ship information from customer to server e.g. a mass inwards the server tin hold upwards delivered to the customer using JSON or XML.
What is a resource? (answer)
Influenza A virus subtype H5N1 resources is how information is represented inwards REST architecture. By exposing entities every bit the resources it allows a customer to read, write, modify, too create resources using HTTP methods e.g. GET, POST, PUT, DELETE etc.
What are prophylactic REST operations? (answer)
REST API uses HTTP methods to perform operations. Some of the HTTP operations which doesn't alteration the resources at the server is known every bit prophylactic operations e.g. GET too HEAD. On the other hand, PUT, POST, too DELETE are dangerous because they alteration the resources on the server.
What are idempotent operations? Why is idempotency important? (answer)
There are around HTTP methods e.g. GET which hit same response no thing how many times yous usage them e.g. sending multiple GET asking to the same URI volition final result inwards same response without whatever side-effect thus it is known every bit idempotent.
On the other hand, the POST is non idempotent because if yous ship multiple POST request, it volition final result inwards multiple resources creation on the server, but again, PUT is idempotent if yous are using it to update the resource.
Even, multiple PUT asking to update a resources on a server volition give same halt result. You tin farther accept RESTful Web Services to acquire to a greater extent than nearly REST.
What are the advantages of the RestTemplate? (answer)
The RestTemplate shape is an implementation of Template method pattern inwards Spring framework. Similar to other pop template classes e.g. JdbcTemplate or JmsTempalte, it too simplifies the interaction alongside RESTful Web Services on the customer side. You tin usage it to eat a RESTful Web Servicer really easily every bit shown inwards this example.
Which HTTP methods does REST use? (answer)
REST tin usage whatever HTTP methods but the most pop ones are GET for retrieving a resource, POST for creating a resource, PUt for updating resources too DELETE for removing a resources from the server.
What is an HttpMessageConverter inwards Spring REST? (answer)
An HttpMessageConverter is a Strategy interface that specifies a converter that tin convert from too to HTTP requests too responses. Spring REST uses this interface to convert HTTP response to diverse formats e.g. JSON or XML.
Each HttpMessageConverter implementation has i or several MIME Types associated alongside it. Spring uses the "Accept" header to decide the content type customer is expecting.
It volition too so elbow grease to let on a registered HTTPMessageConverter that is capable of treatment that specific content-type too usage it to convert the response into that format before sending to the client.
How to create a custom implementation of HttpMessageConverter to back upwards a novel type of request/responses? (answer)
You merely demand to create an implementation of AbstractHttpMessageConverter too register it using the WebMvcConfigurerAdapter#extendMessageConverters() method alongside the classes which generate a novel type of request/response.
Is REST unremarkably stateless? (answer)
Yes, REST API should hold upwards stateless because it is based on HTTP which is too stateless. Influenza A virus subtype H5N1 Request inwards REST API should comprise all the details required it to procedure i.e. it should non rely on previous or adjacent asking or around information maintained at the server halt e.g. Sessions. REST specification seat a constraint to become far stateless too yous should proceed that inwards heed spell designing your REST API.
What does @RequestMapping notation do? (answer)
The @RequestMapping notation is used to map spider web requests to Spring Controller methods. You tin map asking based upon HTTP methods e.g. GET too POST too diverse other parameters. For examples, if yous are developing RESTful Web Service using Spring too so yous tin usage produces too consumes holding along alongside media type notation to dot that this method is exclusively used to hit or consumers JSON every bit shown below:
@RequestMapping (method = RequestMethod.POST, consumes="application/json") public Book save(@RequestBody Book aBook) { return bookRepository.save(aBook); }You tin similarly create other handler methods to hit JSON or XML. If yous are non familiar alongside these annotations too so I propose yous bring together Spring MVC For Beginners course of educational activity on Udemy to acquire from scratch.
Is @Controller a stereotype? Is @RestController a stereotype? (answer)
Yes, both @Controller too @RestController are stereotypes. The @Controller is truly a specialization of Spring's @Component stereotype annotation. This way that shape annotated with @Controller volition too hold upwards automatically hold upwards detected past times Spring container every bit business office of container's constituent scanning process.
And, @RestController is a specialization of @Controller for RESTful spider web service. It non exclusively combines @ResponseBody too @Controller notation but too gives to a greater extent than pregnant to your controller shape to clearly dot that it deals alongside RESTful requests.
Spring Framework may too usage this notation to supply around to a greater extent than useful features related to REST API evolution inwards future.
What is the departure betwixt @Controller too @RestController? (answer)
There are many differences between @Controller too @RestController every bit discussed inwards my before article (see the answer) but the most of import i is that with @RestController yous acquire the @ResponseBody notation automatically, which way yous don't demand to separately annotate your handler methods with @ResponseBody annotation. This makes the evolution of RESTful spider web service easier using Spring. You tin run into hither to learn
When do yous demand @ResponseBody notation inwards Spring MVC? (answer)
The @ResponseBody notation tin hold upwards seat on a method to indicates that the render type should hold upwards written straight to the HTTP response trunk (and non placed inwards a Model, or interpreted every bit a sentiment name).
For example:
@RequestMapping(path = "/hello", method = RequestMethod.PUT)
@ResponseBody
public String helloWorld() {
return "Hello World";
}
Alternatively, yous tin too usage @RestController notation instead of @Controller annotation. This volition take away the demand for using @ResponseBody because every bit discussed inwards the previous answer, it comes automatically alongside @RestController annotation.
What does @PathVariable do inwards Spring MVC? Why it's useful inwards REST alongside Spring? (answer)
It's i of the useful annotations from Spring MVC which allows yous to read values from URI similar query parameter. It's peculiarly useful inwards illustration of creating RESTful spider web service using Spring because inwards REST resources identifiers are business office of URI.This questions is unremarkably asked to experienced Spring MVC developers e.g. iv to half dozen years of experience.
For example, inwards the URL http://myapp.com/books/101 if yous desire to extract 101 the id, too so yous tin use @PathVariable notation of Spring MVC. If yous are non familiar alongside Spring MVC annotations then Spring MVC For Beginners: Build Java Web App inwards 25 Steps is a skillful house to get-go with.
What is the HTTP condition render code for a successful DELETE statement? (answer)
There is no strict dominion alongside honour to what condition code your REST API should render afterward a successful DELETE i.e it tin render 200 Ok or 204 No Content. In general, if the DELETE functioning is successful too the response trunk is empty render 204. If the DELETE asking is successful too the response trunk is NOT empty, render 200
What does CRUD mean? (answer)
CRUD is a curt shape of Create, Read, Update too Delete. In REST API, the POST is used to create a resource, GET is used to read a resource, PUT is used to updated a resources too DELETE is used to take away a resources from the server.This i is around other beginner degree Spring MVC questions for 1 to iii years experienced programmers
Where do yous demand @EnableWebMVC? (answer)
The @EnableWebMvc notation is required to enable Spring MVC when Java configuration is used to configure Spring MVC instead of XML. It is equivalent to <mvc: annotation-driven>
It enables back upwards for @Controller-annotated classes that usage @RequestMapping to map incoming requests to handler methods non already familiar alongside Spring's back upwards for Java configuration, Spring Master Class on Udemy is a skillful house to start.
When do yous demand @ResponseStatus notation inwards Spring MVC? (answer)
Influenza A virus subtype H5N1 skillful questions for iii to five years experienced limit developers. The @ResponseStatus notation is required during fault treatment inwards Spring MVC too REST. Normally when an fault or exception is thrown at server side, spider web server render a blanket HTTP condition code 500 - Internal server error.This may operate for a human user but non for REST clients. You demand to ship them proper condition code e.g. 404 if the resources is non found. That's where yous tin usage @ResponseStatus annotation, which allows yous to ship custom HTTP condition code along alongside proper fault message inwards illustration of Exception.
In lodge to usage it, yous tin create custom exceptions too annotated them using @ResponseStatus notation too proper HTTP condition code too reason.
When such exceptions are thrown from controller's handler methods too non handled anywhere else, too so appropriate HTTP response alongside the proper HTTP condition code, which yous receive got laid is sent to the client.
For example, if yous are writing a RESTful Web Service for a library which provides mass information too so yous tin use @ResponseStatus to create Exception which returns HTTP response code 404 when a mass is non constitute instead of Internal Server Error (500), every bit shown below:
@ResponseStatus(value=HttpStatus.NOT_FOUND, reason="No such Book") // 404
public shape BookNotFoundException extends RuntimeException {
// ...
}
If this Exception is thrown from whatever handler method too so HTTP fault code 404 alongside argue "No such Book" volition hold upwards returned to the client.
Is REST secure? What tin yous do to secure it? (answer)
This interrogation is generally asked alongside experienced Java programmers e.g. 2 to five years sense alongside both REST too Spring. Security is a wide term, it could hateful safety of message which is provided past times encryption or access restriction which is provided using authentication too authorization. REST is unremarkably non secure but yous tin secure it past times using Spring security.
At the really to the lowest degree yous tin enable HTTP basic authentication past times using HTTP inwards your Spring safety configuration file. Similarly, yous tin expose your REST API using HTTPS if the underlying server supports HTTPS.
Does REST operate alongside carry layer safety (TLS)? (answer)
TLS or Transport Layer Security is used for secure communication betwixt customer too server. It is the successor of SSL (Secure Socket Layer). Since HTTPS tin operate alongside both SSL too TLS, REST tin too operate alongside TLS.
Actually, REST says anything nearly Security, it's upwards to the server which implements that. Same RESTful Web Service tin hold upwards accessed using HTTP too HTTPS if the server supports SSL.
If yous are using Tomcat, yous tin run into hither to acquire to a greater extent than nearly how to enable SSL inwards Tomcat.
Do yous demand Spring MVC inwards your classpath for developing RESTful Web Service? (answer)
This interrogation is often asked to Java programmers alongside 1 to 2 years of sense inwards Spring. Short reply is Yes, yous demand Spring MVC inwards your Java application's classpath to develop RESTful spider web services using Spring framework. It's truly Spring MVC which provides all useful annotations e.g. @RestController, @ResponseCode, @ResponseBody, @RequestBody, and @PathVariable, thus yous must spring-mvc.jar or appropriate Maven entry inwards your pom.xml
That's all nearly around frequently asked Spring REST Interview questions for beginners too experienced Java JEE developers. These questions are too really useful to brush upwards your cognition nearly Spring REST if yous are going to accept Spring Certification. If yous demand to a greater extent than questions from Spring certification perspective, yous volition let on a lot of interrogation on this topic on David Mayer's Core Spring Simulator, i of the best simulator to exceed Spring certification at the moment.
Other Spring tutorials too Resources yous may like
Spring Master Class - Beginner to Expert
Spring Framework 5: Beginner to Guru
5 Free Courses to acquire Core Spring too Spring Boot
How Spring MVC Frameworks works?
How Basic Authentication industrial plant inwards Spring Security?
What is the Role of DispatcherServlet inwards Spring?
What is departure between @Service, @Controller, too @Component inwards Spring
REST With Spring Certification Course past times Baeldung
Thanks for reading this article, if yous similar this article too so delight portion alongside your friends too colleagues. If yous receive got whatever interrogation which is non answered on this listing too so delight driblet a comment too I'll elbow grease my best to let on an reply for you.
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