Choosing which AOP declaration style to use
11.4 Choosing which AOP declaration style to use
Once you have decided that an aspect is the best approach for implementing a given requirement, how do you decide between using Spring AOP or AspectJ, and between the Aspect language code style, AspectJ annotation style, or the Spring XML style? These decisions are influenced by a number of factors including application requirements, development tools, and team familiarity with AOP. Spring AOP or full AspectJ? Use the simplest thing that can work. Spring AOP is simpler than using full AspectJ as there is no requirement to introduce the AspectJ compiler weaver into your development and build processes. If you only need to advise the execution of operations on Spring beans, then Spring AOP is the right choice. If you need to advise objects not managed by the Spring container such as domain objects typically, then you will need to use AspectJ. You will also need to use AspectJ if you wish to advise join points other than simple method executions for example, field get or set join points, and so on. When using AspectJ, you have the choice of the AspectJ language syntax also known as the code style or the AspectJ annotation style. Clearly, if you are not using Java 5+ then the choice has been made for you… use the code style. If aspects play a large role in your design, and you are able to use the AspectJ Development Tools AJDT plugin for Eclipse, then the AspectJ language syntax is the preferred option: it is cleaner and simpler because the language was purposefully designed for writing 4.3.9.RELEASE Spring Framework 248 aspects. If you are not using Eclipse, or have only a few aspects that do not play a major role in your application, then you may want to consider using the AspectJ style and sticking with a regular Java compilation in your IDE, and adding an aspect weaving phase to your build script. AspectJ or XML for Spring AOP? If you have chosen to use Spring AOP, then you have a choice of AspectJ or XML style. There are various tradeoffs to consider. The XML style will be most familiar to existing Spring users and it is backed by genuine POJOs. When using AOP as a tool to configure enterprise services then XML can be a good choice a good test is whether you consider the pointcut expression to be a part of your configuration you might want to change independently. With the XML style arguably it is clearer from your configuration what aspects are present in the system. The XML style has two disadvantages. Firstly it does not fully encapsulate the implementation of the requirement it addresses in a single place. The DRY principle says that there should be a single, unambiguous, authoritative representation of any piece of knowledge within a system. When using the XML style, the knowledge of how a requirement is implemented is split across the declaration of the backing bean class, and the XML in the configuration file. When using the AspectJ style there is a single module - the aspect - in which this information is encapsulated. Secondly, the XML style is slightly more limited in what it can express than the AspectJ style: only the singleton aspect instantiation model is supported, and it is not possible to combine named pointcuts declared in XML. For example, in the AspectJ style you can write something like: Pointcutexecution get public void propertyAccess {} Pointcutexecutionorg.xyz.Account+ .. public void operationReturningAnAccount {} PointcutpropertyAccess operationReturningAnAccount public void accountPropertyAccess {} In the XML style I can declare the first two pointcuts: aop:pointcut id = propertyAccess expression = execution get aop:pointcut id = operationReturningAnAccount expression = executionorg.xyz.Account+ .. The downside of the XML approach is that you cannot define the accountPropertyAccess pointcut by combining these definitions. The AspectJ style supports additional instantiation models, and richer pointcut composition. It has the advantage of keeping the aspect as a modular unit. It also has the advantage the AspectJ aspects can be understood and thus consumed both by Spring AOP and by AspectJ - so if you later decide you need the capabilities of AspectJ to implement additional requirements then it is very easy to migrate to an AspectJ-based approach. On balance the Spring team prefer the AspectJ style whenever you have aspects that do more than simple configuration of enterprise services.11.5 Mixing aspect types
Parts
» Dependency Injection and Inversion of Control Framework Modules
» Usage scenarios Introduction to the Spring Framework
» Java EE 6 and 7 Groovy Bean Definition DSL
» Core Container Improvements General Web Improvements
» WebSocket, SockJS, and STOMP Messaging Testing Improvements
» JMS Improvements Caching Improvements
» Web Improvements New Features and Enhancements in Spring Framework 1
» WebSocket Messaging Improvements Testing Improvements
» Core Container Improvements New Features and Enhancements in Spring Framework 4.2
» Data Access Improvements JMS Improvements Web Improvements
» Core Container Improvements Data Access Improvements Caching Improvements
» JMS Improvements Web Improvements WebSocket Messaging Improvements Testing Improvements
» Introduction to the Spring IoC container and beans
» Container overview The IoC container
» Bean overview The IoC container
» Dependencies The IoC container
» y.Baz beans The IoC container
» driverClassName = username = The IoC container
» email = spouse-ref = The IoC container
» y.Bar bean y.Foo constructor-arg y.Foo c:bar-ref baz-ref = y.Foo c:_0-ref _1-ref =
» y.z.MyValueCalculator b.c.ReplacementComputeValue Bean scopes
» y.Foo property Customizing the nature of a bean
» Bean definition inheritance The IoC container
» Container Extension Points The IoC container
» Annotation-based container configuration The IoC container
» Classpath scanning and managed components
» Using JSR 330 Standard Annotations
» Java-based container configuration The IoC container
» Environment abstraction The IoC container
» Registering a LoadTimeWeaver Additional Capabilities of the ApplicationContext
» The BeanFactory The IoC container
» Introduction The Resource interface
» Built-in Resource implementations Resources
» The ResourceLoaderAware interface Resources
» Resources as dependencies Application contexts and Resource paths
» Introduction Validation, Data Binding, and Type Conversion
» Validation using Spring’s Validator interface
» Resolving codes to error messages Bean manipulation and the BeanWrapper
» Spring Type Conversion Validation, Data Binding, and Type Conversion
» Spring Field Formatting Validation, Data Binding, and Type Conversion
» Configuring a global date time format
» Spring Validation Validation, Data Binding, and Type Conversion
» Introduction Feature Overview Spring Expression Language SpEL
» Expression Evaluation using Spring’s Expression Interface
» Expression support for defining bean definitions
» Language Reference Spring Expression Language SpEL
» 3e0 4 .getValueDouble. 4e0 2 .getValueDouble.
» Classes used in the examples
» Introduction Aspect Oriented Programming with Spring
» Schema-based AOP support Aspect Oriented Programming with Spring
» y.service.DefaultFooService y.SimpleProfiler aop:config
» Choosing which AOP declaration style to use
» Mixing aspect types Proxying mechanisms
» Introduction Pointcut API in Spring
» Advisor API in Spring Using the ProxyFactoryBean to create AOP proxies
» Concise proxy definitions Spring AOP APIs
» Creating AOP proxies programmatically with the ProxyFactory Manipulating advised objects
» Using the auto-proxy facility
» Using TargetSources Spring AOP APIs
» Mock Objects Unit Testing support Classes
» Overview Goals of Integration Testing
» JDBC Testing Support Annotations
» Spring TestContext Framework Integration Testing
» loginAction-ref = username = userPreferences-ref = theme =
» PetClinic Example Integration Testing
» Understanding the Spring Framework transaction abstraction
» Synchronizing resources with transactions
» Declarative transaction management Transaction Management
» y.service.DefaultFooService Transaction Management
» y.service.DefaultFooService y.SimpleProfiler y.service.DefaultFooService
» y.SimpleProfiler Transaction Management
» Programmatic transaction management Transaction Management
» Choosing between programmatic and declarative transaction management Transaction bound event
» Application server-specific integration Transaction Management
» Introduction Consistent exception hierarchy
» Annotations used for configuring DAO or Repository classes
» Introduction to Spring Framework JDBC
» Using the JDBC core classes to control basic JDBC processing and error handling
» Controlling database connections Data access with JDBC
» JDBC batch operations Data access with JDBC
» Simplifying JDBC operations with the SimpleJdbc classes
» Modeling JDBC operations as Java objects
» Common problems with parameter and data value handling
» Embedded database support Data access with JDBC
» Initializing a DataSource Data access with JDBC
» Introduction to ORM with Spring
» General ORM integration considerations
» Hibernate Object Relational Mapping ORM Data Access
» JDO Object Relational Mapping ORM Data Access
» Introduction Marshaller and Unmarshaller
» Using Marshaller and Unmarshaller
» XML Schema-based Configuration JAXB
» Castor Marshalling XML using OX Mappers
» XMLBeans JiBX Marshalling XML using OX Mappers
» XStream Marshalling XML using OX Mappers
» Introduction to Spring Web MVC framework
» The DispatcherServlet Web MVC framework
» Handler mappings Web MVC framework
» Resolving views Web MVC framework
» Using flash attributes Web MVC framework
» Building URIs Web MVC framework
» Using locales Web MVC framework
» Using themes Web MVC framework
» Spring’s multipart file upload support
» Handling exceptions Web MVC framework
» Web Security Convention over configuration support
» y.RegistrationController HTTP caching support
» Code-based Servlet container initialization
» Configuring Spring MVC Web MVC framework
» simpleDateFormat = Web MVC framework
» Introduction Thymeleaf Groovy Markup Templates
» Velocity FreeMarker View technologies
» Document views PDFExcel Property
» Feed Views JSON Mapping View
» Introduction Integrating with other web frameworks
» Common configuration Integrating with other web frameworks
» JavaServer Faces 1.2 Apache Struts 2.x
» Introduction Portlet MVC Framework
» The DispatcherPortlet Portlet MVC Framework
» The ViewRendererServlet Controllers Portlet MVC Framework
» Handler mappings Portlet MVC Framework
» Views and resolving them Multipart file upload support
» Handling exceptions Annotation-based controller configuration
» absolute-ordering absolute-ordering WebSocket API
» SockJS Fallback Options WebSocket Support
» STOMP Over WebSocket Messaging Architecture
» Introduction Controller method CORS configuration
» Global CORS configuration Advanced Customization
» Introduction Remoting and web services using Spring
» Using Hessian or Burlap to remotely call services via HTTP
» Exposing services using HTTP invokers
» Web services Remoting and web services using Spring
» JMS Remoting and web services using Spring
» Accessing RESTful services on the Client
» Introduction Accessing EJBs Enterprise JavaBeans EJB integration
» Introduction JMS Java Message Service
» Using Spring JMS JMS Java Message Service
» Sending a Message JMS Java Message Service
» Receiving a message JMS Java Message Service
» Support for JCA Message Endpoints
» Annotation-driven listener endpoints JMS Java Message Service
» JMS namespace support JMS Java Message Service
» Introduction Exporting your beans to JMX
» Controlling the management interface of your beans
» Controlling the ObjectNames for your beans
» Accessing MBeans via Proxies
» Introduction Configuring CCI JCA CCI
» Using Spring’s CCI access support
» Modeling CCI access as operation objects
» Using the JavaMail MimeMessageHelper
» Introduction The Spring TaskExecutor abstraction
» The Spring TaskScheduler abstraction
» Annotation Support for Scheduling and Asynchronous Execution
» The task namespace Task Execution and Scheduling
» Introduction A first example
» y.DefaultBookingService property Defining beans that are backed by dynamic languages
» y.DefaultBookingService property Dynamic language support
» Scenarios Dynamic language support
» Bits and bobs y.DefaultBookingService property
» Introduction Understanding the cache abstraction
» Declarative annotation-based caching Cache Abstraction
» JCache JSR-107 annotations Cache Abstraction
» Declarative XML-based caching y.service.DefaultBookService
» Configuring the cache storage name =
» Classic ORM usage Classic Spring Usage
» JMS Usage Classic Spring Usage
» Concise proxy definitions Classic Spring AOP Usage
» Using the autoproxy facility
» Using TargetSources Classic Spring AOP Usage
» Introduction XML Schema-based configuration
» Introduction Authoring the schema
» Coding a NamespaceHandler Extensible XML authoring
» BeanDefinitionParser Extensible XML authoring
» Registering the handler and the schema
» Using a custom extension in your Spring XML configuration Meatier examples
» Introduction The argument tag The bind tag
» The escapeBody tag The eval tag The hasBindErrors tag
» The htmlEscape tag The message tag
» The nestedPath tag The param tag The theme tag
» The transform tag The url tag
» Introduction The button tag The checkbox tag
» The checkboxes tag The errors tag
» The option tag The options tag
» The password tag The radiobutton tag
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