Interview Questions.

Q1. How To Declare Aspect In Spring Aop?

In XML.

<bean class="com.Doj.Aop.LoggingAspect" id="loggingAspect">

<!-- configure properties of aspect here -->

</bean>

In Java

@Aspect

@Component

class LoggingAspect

//advice

//pointcut 

Q2. Which Are The Limitations Of The Two Proxy-sorts?

Spring will create either JDK or CGLib proxies

JDK Proxy

Also known as dynamic proxies

API is constructed into the JDK

Requirements: Java interface(s)

All interfaces proxied

CGLib Proxy

NOT built into JDK

Included in Spring jars

Used when interface now not available

Cannot be implemented to very last classes or technique

Q3. What Is Aspect Oriented Programming (aop) In Spring?

Aspect Oriented Programming works like Object Oriented Programming. In Object Oriented Programming, the unit of modularity is Object But in Aspect Oriented Programming the unit of modularity is Aspect. Aspect works because the modularization of concerns called crosscutting issues in AOP. AOP framework is pluggable in spring. AOP provides declarative organisation service and permits users to put in force custom elements.

Q4. What Are The Five Advice Types Called?

Before

After

AfterThrowing

AfterReturning

Around

Q5. What Are The Supported Aspectj Pointcut Designators In Spring Aop?

Execution

This

Target

Args

@goal

@args

@inside

@annotation

Q6. What Is A Pointcut, A Join Point, An Advice, An Aspect, Weaving, Introduction, Target Object, Aop Proxy?

Pointcut

An expression that selects one or extra Join Points

Join Point

A factor within the execution of a application along with a technique call or exception thrown

Advice

Code to be completed at every decided on Join Point

Aspect

A module that encapsulates pointcuts and recommendation

Weaving

Technique with the aid of which elements are blended with important code

Introduction

Spring AOP permits to introduce new interfaces (and a corresponding application) to any item advises. 

Target Object

An object is assisted through one or more respects. Also known as the object advised. 

AOP Proxy

AOP proxy is an object used to carry out the settlement vicinity. This object is created with the aid of the AOP framework. In Spring AOP proxy is a part of JDK dynamic proxy or proxy CGLIB.

Q7. How Many Advice Types Does Spring Support. What Are They Used For?

Before recommendation: Advice that executes earlier than a be part of point, however which does not have the ability to save you execution glide proceeding to the be a part of point (except it throws an exception).

After returning advice: Advice to be carried out after a be part of factor completes commonly: for instance, if a method returns without throwing an exception.

After throwing advice: Advice to be accomplished if a technique exits by way of throwing an exception.

After recommendation: Advice to be carried out no matter the method by means of which a join point exits (normal or excellent go back).

Around recommendation: Advice that surrounds a be a part of point inclusive of a technique invocation. This is the most powerful kind of recommendation. Around advice can perform custom conduct before and after the approach invocation. It is likewise accountable for selecting whether or not to proceed to the join factor or to shortcut the suggested approach execution via returning its personal go back fee or throwing an exception.

Q8. What Is A Named Pointcut?

A named pointcut may be declared inner an <aop:config> element, permitting the pointcut definition to be shared throughout several components and advisors.

<aop:config>

    <aop:pointcut id="businessService" expression="execution(* com.Xyz.Myapp.Service.*.*(..))"/>

</aop:config>

Q9. What Are The Required Libraries To Run Aspectj Ltw In Spring?

Spring-aop.Jar

aspectjrt.Jar

aspectjweaver.Jar

Q10. What Do You Have To Do To Enable The Detection Of The

To use @AspectJ elements in a Spring configuration you need to enable Spring assist for configuring Spring AOP based on @AspectJ elements, and autoproxying beans based on whether or now not they are counseled by way of the ones factors.

Enabling @AspectJ Support with Java configuration

To permit @AspectJ assist with Java @Configuration upload the @EnableAspectJAutoProxy annotation:

@Configuration

@EnableAspectJAutoProxy

public class AppConfig 

Enabling @AspectJ Support with XML configuration

To allow @AspectJ assist with XML primarily based configuration use the <aop:aspectj-autoproxy/> element:

<aop:aspectj-autoproxy/>

Q11. What Do You Understand By Load-time Weaving (ltw) In Spring?

Load-time weaving (LTW) or Run time weaving is a process of weaving AspectJ elements into the training of the software whilst the instructions are being loaded in JVM.

Q12. What Is The Concept Of Aop? Which Problem Does It Solve?

Aspect-Oriented Programming (AOP) is some other manner of element to some areas of utility i.E. Go slicing problem like safety, logging and transaction. AOP is easy complement of OOP programming for special issues. In OOP, the key unit of modularity is the class, whereas in AOP the unit of modularity is the thing.

Aspect-Oriented Programming (AOP) enables modularization of go-reducing issues to solve following issues.

To keep away from tangling

To put off scattering.

Q13. Name Three Typical Cross Cutting Concerns?

Logging

Security

Transaction

Q14. How Do You Externalize Pointcuts? What Is The Advantage Of Doing This?

Externalize the pointcut to a named pointcut. Avoid to writing complex pointcut expression across the software.

Q15. How To Enable

Include the under XML code in utility XML

<aop:aspectj-autoproxy/>

Q16. What Is A Proceedingjoinpoint?

An round advice is a unique advice that can manage while and if a method (or other join point) is accomplished. This is actual for around advices most effective, so they require an issue of kind ProceedingJoinPoint, whereas other advices simply use a plain JoinPoint. ProceedingJoinPoint is used as a controversy of the techniques which tips for before, after, after throwing and around. ProceedingJoinPoint has the methods like getKind, getTarget, proceed and many others.

Q17. Define Aop Terminologies In Spring?

Aspect: In more than one lessons, the modularization of concerns that acts as crosscutting issues.

Example :Transaction management

Join Point: Join Point is a factor all through the execution of the method. 

Advice: At a join factor, the movement taken with the aid of factor is Advice. 

Pointcut: Those predicates which suits join point is referred to as Pointcut.

Weaving: Other software kind may be linked with issue and that is known as weaving.

Introduction: Introduction is defining additional techniques fields for a kind. 

Target item: Those objects which are suggested by way of aspects are Target Object. 

AOP proxy: AOP framework creates an object to fulfill thing agreement, that object is AOP proxy.

Q18. How Does Spring Solve (enforce) A Cross Cutting Concern?

Implement your mainline application good judgment:

Focusing on the middle problem

Write aspects to put in force your go-reducing worries

Spring offers many elements out-of-the-box Weave the components into your application

Adding the cross-reducing behaviors to the proper locations.

Q19. What Is The Joinpoint Argument Used For?

Context furnished via the JoinPoint parameter and Context approximately the intercepted point.

Q20. Define The Types Of Advice In Spring Aop.

In Spring AOP, kinds of advice are 

Before: Advice that runs before a be a part of factor. 

After returning: Advice that runs after a be part of factor ordinary finishing touch. 

After throwing: Advice which runs while a techniques exits through throwing an exception. 

After: Advice that runs after the be part of point go out via any manner. 

Around: Advice that runs surrounding to sign up for point. Example :approach invocation. 

Q21. How To Declare A Pointcut In Spring Aop?

Find the below code snippet.

@Pointcut("execution(* shop(..))")

private void dataSave 

Q22. What Does

To enable @AspectJ aid with Java @Configuration add the @EnableAspectJAutoProxy annotation:

@Configuration

@EnableAspectJAutoProxy

public magnificence AppConfig 

Q23. When To Use Spring Aop And When To Use Full Aspectj?

If we simplest need to recommendation the execution of operations on Spring beans then we ought to use Spring AOP. Spring AOP is easier than AspectJ. Full AspectJ calls for the AspectJ complier inside the build procedure. 

In case if we advice objects no longer to be controlled by way of Spring Container, use AspectJ.

Q24. What Are The Limitations Of Spring Aop?

Can simplest advocate non-personal strategies

Can simplest apply factors to Spring Beans

Limitations of weaving with proxies

When the use of proxies, assume technique a() calls method b() on the same magnificence/interface

advice will in no way be achieved for technique b()