What the terms added into the AOP, so that we are calling it Cross Cutting Concern.
Difference between Interceptor and AOP.
-This question is for lil bit discussion on AOP and Interceptor but please elobarate.
Interceptors are part of Spring framework which allow you to write logic by intercepting requests/calls in between the route. There are mainly 2 kinds of Interceptors in Spring.
Handler Interceptors, present in Spring MVC framework, are used to include your interceptor logic for web requests, whereas Method Interceptors, within Spring AOP framework, are generic in nature and not just limited to intercept HTTP requests.
When comparing AOP with Interceptors, I can say, in one line, that these Method Interceptors are the base understanding behind writing aspects in AOP.
AOP, aka Aspect Oriented Programing, is a bit complex subject to be explained in a StackOverflow answer. I would suggest you to read for it on internet and make yourself comfortable with the basics & AOP terminology before entering into Aspect Oriented Programing.
Below is one good resource to understand the dynamic proxy in Spring AOP and fundamentals of it.
Understanding Dynamic Proxy: Spring AOP Basics
Update
Wikipedia has a very simple yet effective definition & example for Cross-Cutting Concern.
In Aspect-oriented software development, cross-cutting concerns are
aspects of a program that affect other concerns. These concerns often
cannot be cleanly decomposed from the rest of the system in both the
design and implementation, and can result in either scattering (code
duplication), tangling (significant dependencies between systems), or
both.
For instance, if writing an application for handling medical records,
the indexing of such records is a core concern, while logging a
history of changes to the record database or user database, or an
authentication system, would be cross-cutting concerns since they
touch more parts of the program.
AOP with Spring Framework is described in a very simple manner at this article of TutorialsPoint which would help you get familiar with all the basic terminologies of Spring AOP.
Related
I am reading spring docs this site.
and I already have knowledge IoC(or DI) and AOP a little bit.
While reading docs, I read this phrase.
Foremost amongst these is the Spring Framework’s Inversion of Control (IoC) container. A thorough treatment of the Spring Framework’s IoC container is closely followed by comprehensive coverage of Spring’s Aspect-Oriented Programming (AOP) technologies.
As far as I know, IoC is how Container creates instances and injects them when needed, and AOP is perspective-oriented programming;How you can focus on what you want to do.
However, I understand the above phrase that AOP works well thanks to IoC.
I'm not sure what's the relationship between the two.
Wait for a good answer.
An IoC framework allows injection of an implementation through an external influence, typically configuration.
AOP's purpose is to enable loose weaving of other concerns into business logic code without direct modification of the code.
Spring is a framework that extensively uses AOP to enable implementation of IoC.
There is a whole lot of reading material on both patterns available on the web.
For IoC start here. For AOP, I found this helpful.
AOP concerned mainly with abstracting functionality that applies across the board to many components of your application. for example logging and security. These have little or nothing to do with actual business functionality but are essential system-wide functions
IOC or Di is mainly loose coupling and managing the dependencies between the component of an application.
Both IOC and AOP are made possible through having your code managed by some sort of run-time container.
The container injects dependencies into your constructors and property setters, instead of you doing it manually. The motto for Spring is/was: "Creating objects so you don't have to."
Once your code is running in a container, it's a simple enough matter to introduce AOP concepts which boil down to executing code before or after what's being managed by the container.
IOC and AOP are sibling practices made possible by a run-time container. Start with a IOC container and it's easy to introduce AOP features. Start with an AOP container and IOC features easily follow.
It's seems both looking same. Interceptor are like filter and even AOP(Aspect Oriented Programming in Spring) also will work as filter. My doubt what's difference between them.
Spring Interceptors
Spring Interceptors has the ability to pre-handle and post-handle the
web requests. Each interceptor class should extend the
HandlerInterceptorAdapter class
Aspect-Oriented Programming (AOP)
Aspect-Oriented Programming (AOP) complements Object-Oriented
Programming (OOP) by providing another way of thinking about program
structure. The key unit of modularity in OOP is the class, whereas in
AOP the unit of modularity is the aspect.
Aspects enable the modularization of concerns such as transaction
management that cut across multiple types and objects. (Such concerns
are often termed crosscutting concerns in AOP literature.).AOP aspects are a complex subject
We are analyzing different concepts for one of my projects. We decided to use Spring Boot & Microservices architecture.
After further discussions, we came to a query whether we CAN/SHOULD use Spring AOP to resolve cross cutting concerns of various microservices?
If not how can we address common concerns of microservices like logging, transaction mgmt, etc?
I have googled this topic extensively (even went to 5 pages for same search), but no luck. Any help appreciated.
Use Spring interceptors. They have interceptors and factories for just about anything. Lets you add instrumentation and common code to all aspects.
UPDATE: samples interceptors and factories.
ClientHttpRequestInterceptor
FilterRegistrationBean
SimpleClientHttpRequestFactory
ChannelInterceptor
I don't think that there is anything to worry about using AOP. This is how Spring does things usually under the hood.
I'd just be careful with logging method invocations, especially parameters which is the common use (abuse) of AOP.
Ususally the less code you write the better. If you can use standard, proven way of doing things - use it.
What are the enumerated benefits to using the Spring template classes such as RestTemplate, JdbcTemplate, JpaTemplate, JdoTemplate, JndiTemplate JdoTemplate etc?
I'm looking for the general benefits of using these classes as best practice design, for example the thread safeness of these classes. Or if someone could point me to the section of the Spring documentation that discusses the same I would accept that as well.
Less boilerplate code
More cohesive exceptions handling (e.g. JDBC drivers checked exceptions are translated to meaningful runtime exceptions)
Easier and uniform configuration (almost everything can be configured in Spring context files)
Automatized resource management (like, for instance, closing DB connections)
Note, that not all templates are equally useful. For instance jdbcTemplate is a pure gem, I can't live without that (mostly because JDBC is not the best interface one can imagine), on the other hand jpaTemplate does not bring so many advantages.
Note, that if you use given template, your code becomes dependent on Spring interfaces, so Spring is not only dependency mechanism for your application, but becomes also part of it - Spring is no longer easily replacable with something else (Google Guice, CDI). However, given the fact Spring is a pretty good peace of code, I would not be worried about that aspect.
What is the Difference between Spring IOC and Spring AOP and their Importance ?
Have you searched the web for IoC and AOP? There are a lot of references to both.
In a nutshell, IoC allows an external force to determine what implementation will be used by code rather than the code determining the implementation. The "external force" might be a configuration file, a unit test, other different code, etc.
AOP allows cross-cutting concerns to be implemented outside of the code affected by those concerns.
The "purpose" of Spring includes IoC and AOP, but goes quite a ways beyond that in its scope.
For more details please check.
Inversion of Control Containers and the Dependency Injection pattern and
Aspect-oriented programming
Also check this
What is AOP, Dependency Injection and Inversion Of Control in Simple English
IoC, AOP and more
Spring IOC: In simple answer normally you create object with new operator and set yourself for getter and setter. So, yes we use new operator in Java to create object. There is no any bad in doing this. But, when your project size grows and lots of developers are working, and you want to achieve POJO-based programming, you can use DI. So then maybe your question arises - why I can not code it myself? Of course you can use the power of reflection, annotation, and XML. But, some other had already coded this then why not reuse the third party one? There are lots of options for you to choose; Spring can be the best one. It manages your object life cycle from object creation to its destruction. You use the objects created and set by Spring DI container but you do not create them yourself.
Spring AOP: It is related to cross cutting concern. What it mean is in large system the common functionality is scattered throughout different modules. So AOP provides an easiest way to take out a common implementation in the form of 'aspect'. You can also in this case write own implementation using proxy concept but you can reuse the code of proxy based that is implementation of APO alliance using Spring.
Objective of Spring IOC is to reduce explicit dependencies between components, while purpose of Spring AOP is to wire components together possibly by enforcing certain common behavior (read: NOT Interface)
Since purpose of Spring AOP is to enforce certain behavior across components.So, Spring IOC comes in handy to achieve this purpose