User:Indsin/sandbox

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Orca Framework
Developer(s)Pivotal Software
Initial release1 October 2013; 10 years ago (2013-10-01)
Preview release
4.2.3-00SNAPSHOT / October 15, 2015 (2015-10-15)
Written inJava
Operating systemCross-platform
PlatformJava Virtual Machine
TypeSoftware Production Line Framework
Websitespring.io

The "ORCA Framework" is a standalone framework for producing enterprise level software. It is written in Java, which follows the model–view–controller (mvc) architectural pattern. It solves all the major functional and nonfunctional issues of multi-customer systems. It operates on almost all the major areas of software development by combining different modules.

Version history[edit]

During 2012, Atra Vision Co. undertook some projects for developing and implementing enterprise level ERP systems for a group of factories and companies with versatility in their business perspective and employee strength, which made them understand the real time problems of software production line. This ERP contains around 60 modules, which should be implemented together accurately and must also be powerful enough to support high end feature level customization and flexibility without changing the code at the time of implementation. During the last decades of experience of many custom development projects, Atra team learned that architecture is one of the most important sections for any mission critical application. Continuous radical changes in the development process can be harmful for any development process flow. Another thing that we learned is that a bad quality in process flow and in product level can be a major cause for a project failure. It became an important necessity for us to investigate and select a proper way to solve these primary problems. In the first era of software development, the developers followed hard coded development process and rigid architecture. Where a requirement change can lead to a huge refraction in code is both time consuming and prone to bugs. During the second era, around 2000, the concept of BPMS (Business Process Management System) was introduced and made a revolution in software industry. It made the change in requirements and customization a comfort, and provided a solution to integrate legacy systems easily. But BPMS is unable to implement the core business process which makes it unsuitable for the mission. These investigations lead to stay in middle way. Because our framework should develop the core business and must integrate all the existing and new software modules, and also should have some advance features to support for future changes and customization.

Modules[edit]

The Spring Framework includes several modules that provide a range of service:

Inversion of control container (dependency injection)[edit]

Central to the Spring Framework is its inversion of control (IoC) container, which provides a consistent means of configuring and managing Java objects using reflection. The container is responsible for managing object lifecycles of specific objects: creating these objects, calling their initialization methods, and configuring these objects by wiring them together.

Objects created by the container are also called managed objects or beans. The container can be configured by loading XML files or detecting specific Java annotations on configuration classes. These data sources contain the bean definitions that provide the information required to create the beans.

Objects can be obtained by means of either dependency lookup or dependency injection.[2] Dependency lookup is a pattern where a caller asks the container object for an object with a specific name or of a specific type. Dependency injection is a pattern where the container passes objects by name to other objects, via either constructors, properties, or factory methods.

In many cases one need not use the container when using other parts of the Spring Framework, although using it will likely make an application easier to configure and customize. The Spring container provides a consistent mechanism to configure applications and integrates with almost all Java environments, from small-scale applications to large enterprise applications.

The container can be turned into a partially compliant EJB 3.0 container by means of the Pitchfork project. Some[who?] criticize the Spring Framework for not complying with standards.[3] However, SpringSource doesn't see EJB 3 compliance as a major goal, and claims that the Spring Framework and the container allow for more powerful programming models.[4] You do not create an object, but describe how they should be created, by defining it in the Spring configuration file. You do not call services and components, but tell which services and components must be called, by defining them in the Spring configuration files. This makes the code easy to maintain and easier to test through IoC.

Aspect-oriented programming framework[edit]

The Spring Framework has its own Aspect-oriented programming (AOP) framework that modularizes cross-cutting concerns in aspects. The motivation for creating a separate AOP framework comes from the belief that it would be possible to provide basic AOP features without too much complexity in either design, implementation, or configuration. The Spring AOP framework also takes full advantage of the Spring container.

The Spring AOP framework is proxy pattern-based, and is configured at run time. This removes the need for a compilation step or load-time weaving. On the other hand, interception only allows for public method-execution on existing objects at a join point.

Compared to the AspectJ framework, Spring AOP is less powerful, but also less complicated. Spring 1.2 includes support to configure AspectJ aspects in the container. Spring 2.0 added more integration with AspectJ; for example, the pointcut language is reused and can be mixed with Spring AOP-based aspects. Further, Spring 2.0 added a Spring Aspects library that uses AspectJ to offer common Spring features such as declarative transaction management and dependency injection via AspectJ compile-time or load-time weaving. SpringSource also uses AspectJ AOP in other Spring projects such as Spring Roo and Spring Insight, with Spring Security also offering an AspectJ-based aspect library.

Spring AOP has been designed to make it able to work with cross-cutting concerns inside the Spring Framework. Any object which is created and configured by the container can be enriched using Spring AOP.

The Spring Framework uses Spring AOP internally for transaction management, security, remote access, and JMX.

Since version 2.0 of the framework, Spring provides two approaches to the AOP configuration:

  • schema-based approach and
  • @AspectJ-based annotation style.

<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:mvc="http://www.springframework.org/schema/mvc" 
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:aop="http://www.springframework.org/schema/aop" 
   xmlns:context="http://www.springframework.org/schema/context"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context-3.0.xsd
       http://www.springframework.org/schema/mvc
       http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
       http://www.springframework.org/schema/aop 
       http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

The Spring team decided not to introduce new AOP-related terminology; therefore, in the Spring reference documentation and API, terms such as aspect, join point, advice, pointcut, introduction, target object (advised object), AOP proxy, and weaving all have the same meanings as in most other AOP frameworks (particularly AspectJ).

Data access framework[edit]

Spring's data access framework addresses common difficulties developers face when working with databases in applications. Support is provided for all popular data access frameworks in Java: JDBC, iBatis/MyBatis, Hibernate, JDO, JPA, Oracle TopLink, Apache OJB, and Apache Cayenne, among others.

For all of these supported frameworks, Spring provides these features

  • Resource management - automatically acquiring and releasing database resources
  • Exception handling - translating data access related exception to a Spring data access hierarchy
  • Transaction participation - transparent participation in ongoing transactions
  • Resource unwrapping - retrieving database objects from connection pool wrappers
  • Abstraction for BLOB and CLOB handling

All these features become available when using template classes provided by Spring for each supported framework. Critics have said these template classes are intrusive and offer no advantage over using (for example) the Hibernate API directly.[5][failed verification] In response, the Spring developers have made it possible to use the Hibernate and JPA APIs directly. This however requires transparent transaction management, as application code no longer assumes the responsibility to obtain and close database resources, and does not support exception translation.

Together with Spring's transaction management, its data access framework offers a flexible abstraction for working with data access frameworks. The Spring Framework doesn't offer a common data access API; instead, the full power of the supported APIs is kept intact. The Spring Framework is the only framework available in Java that offers managed data access environments outside of an application server or container.[citation needed]

While using Spring for transaction management with Hibernate, the following beans may have to be configured:

  • A Data Source like com.mchange.v2.c3p0.ComboPooledDataSource or org.apache.commons.dbcp.BasicDataSource
  • A SessionFactory like org.springframework.orm.hibernate3.LocalSessionFactoryBean with a DataSource attribute
  • A HibernateProperties like org.springframework.beans.factory.config.PropertiesFactoryBean
  • A TransactionManager like org.springframework.orm.hibernate3.HibernateTransactionManager with a SessionFactory attribute

Other points of configuration include:

  • An AOP configuration of cutting points.
  • Transaction semantics of AOP advice[clarify].

Transaction management framework[edit]

Spring's transaction management framework brings an abstraction mechanism to the Java platform. Its abstraction is capable of:

In comparison, JTA only supports nested transactions and global transactions, and requires an application server (and in some cases also deployment of applications in an application server).

The Spring Framework ships a PlatformTransactionManager for a number of transaction management strategies:

  • Transactions managed on a JDBC Connection
  • Transactions managed on Object-relational mapping Units of Work
  • Transactions managed via the JTA TransactionManager and UserTransaction
  • Transactions managed on other resources, like object databases

Next to this abstraction mechanism the framework also provides two ways of adding transaction management to applications:

  • Programmatically, by using Spring's TransactionTemplate
  • Configuratively, by using metadata like XML or Java annotations (@Transactional, etc)

Together with Spring's data access framework — which integrates the transaction management framework — it is possible to set up a transactional system through configuration without having to rely on JTA or EJB. The transactional framework also integrates with messaging and caching engines.

Model–view–controller framework[edit]

The Spring Framework features its own MVC web application framework, which wasn't originally planned. The Spring developers decided to write their own Web framework as a reaction to what they perceived as the poor design of the (then) popular Jakarta Struts Web framework,[6] as well as deficiencies in other available frameworks. In particular, they felt there was insufficient separation between the presentation and request handling layers, and between the request handling layer and the model.[7]

Like Struts, Spring MVC is a request-based framework. The framework defines strategy interfaces for all of the responsibilities that must be handled by a modern request-based framework. The goal of each interface is to be simple and clear so that it's easy for Spring MVC users to write their own implementations, if they so choose. MVC paves the way for cleaner front end code. All interfaces are tightly coupled to the Servlet API. This tight coupling to the Servlet API is seen by some as a failure on the part of the Spring developers to offer a high-level abstraction for Web-based applications [citation needed]. However, this coupling makes sure that the features of the Servlet API remain available to developers while offering a high abstraction framework to ease working with said API.

The DispatcherServlet class is the front controller[8] of the framework and is responsible for delegating control to the various interfaces during the execution phases of an HTTP request.

The most important interfaces defined by Spring MVC, and their responsibilities, are listed below:

  • Controller: comes between Model and View to manage incoming requests and redirect to proper response. It acts as a gate that directs the incoming information. It switches between going into model or view.
  • HandlerAdapter: execution of objects that handle incoming requests
  • HandlerInterceptor: interception of incoming requests comparable, but not equal to Servlet filters (use is optional and not controlled by DispatcherServlet).
  • HandlerMapping: selecting objects that handle incoming requests (handlers) based on any attribute or condition internal or external to those requests
  • LocaleResolver: resolving and optionally saving of the locale of an individual user
  • MultipartResolver: facilitate working with file uploads by wrapping incoming requests
  • View: responsible for returning a response to the client. Some requests may go straight to view without going to the model part; others may go through all three.
  • ViewResolver: selecting a View based on a logical name for the view (use is not strictly required)

Each strategy interface above has an important responsibility in the overall framework. The abstractions offered by these interfaces are powerful, so to allow for a set of variations in their implementations, Spring MVC ships with implementations of all these interfaces and together offers a feature set on top of the Servlet API. However, developers and vendors are free to write other implementations. Spring MVC uses the Java java.util.Map interface as a data-oriented abstraction for the Model where keys are expected to be string values.

The ease of testing the implementations of these interfaces seems one important advantage of the high level of abstraction offered by Spring MVC. DispatcherServlet is tightly coupled to the Spring inversion of control container for configuring the web layers of applications. However, web applications can use other parts of the Spring Framework—including the container—and choose not to use Spring MVC.

Remote access framework[edit]

Spring's Remote Access framework is an abstraction for working with various RPC-based technologies available on the Java platform both for client connectivity and marshalling objects on servers. The most important feature offered by this framework is to ease configuration and usage of these technologies as much as possible by combining inversion of control and AOP.

The framework also provides fault-recovery (automatic reconnection after connection failure) and some optimizations for client-side use of EJB remote stateless session beans[clarify].

Spring provides support for these protocols and products out of the box

  • HTTP-based protocols
    • Hessian: binary serialization protocol, open-sourced and maintained by CORBA-based protocols
    • RMI (1): method invocations using RMI infrastructure yet specific to Spring
    • RMI (2): method invocations using RMI interfaces complying with regular RMI usage
    • RMI-IIOP (CORBA): method invocations using RMI-IIOP/CORBA
  • Enterprise JavaBean client integration
    • Local EJB stateless session bean connectivity: connecting to local stateless session beans
    • Remote EJB stateless session bean connectivity: connecting to remote stateless session beans
  • SOAP
    • Integration with the Apache Axis Web services framework

Apache CXF provides integration with the Spring Framework for RPC-style exporting of object on the server side.

Both client and server setup for all RPC-style protocols and products supported by the Spring Remote access framework (except for the Apache Axis support) is configured in the Spring Core container.

There is alternative open-source implementation (Cluster4Spring) of a remoting subsystem included into Spring Framework that is intended to support various schemes of remoting (1-1, 1-many, dynamic services discovering)…

Convention-over-configuration rapid application development[edit]

Spring Boot[edit]

Spring Boot is Spring's convention-over-configuration solution for creating stand-alone, production-grade Spring based Applications that you can "just run".[9] It takes an opinionated view of the Spring platform and third-party libraries so you can get started with minimum fuss. Most Spring Boot applications need very little Spring configuration. Features:

  • Create stand-alone Spring applications
  • Embed Tomcat or Jetty directly (no need to deploy WAR files)
  • Provide opinionated 'starter' POMs to simplify your Maven configuration
  • Automatically configure Spring whenever possible
  • Provide production-ready features such as metrics, health checks and externalized configuration
  • Absolutely no code generation and no requirement for XML configuration

Spring Roo[edit]

Spring Roo provides an alternative, code-generation based approach at using convention-over-configuration to rapidly build applications in Java. It currently supports Spring Framework, Spring Security and Spring Web Flow. Roo differs from other rapid application development frameworks by focusing on:

  • Extensibility (via add-ons)
  • Java platform productivity (as opposed to other languages)
  • Lock-in avoidance (Roo can be removed within a few minutes from any application)
  • Runtime avoidance (with associated deployment advantages)
  • Usability (particularly via the shell features and usage patterns)

Batch framework[edit]

Spring Batch is a framework for batch processing that provides reusable functions that are essential in processing large volumes of records, including:

  • logging/tracing
  • transaction management
  • job processing statistics
  • job restart

It also provides more advanced technical services and features that will enable extremely high-volume and high performance batch jobs through optimizations and partitioning techniques. Spring Batch is a framework for batch processing – execution of a series of jobs. In Spring Batch, A job consists of many steps and each step consists of a READ-PROCESS-WRITE task or single operation task (tasklet).

For "READ-PROCESS-WRITE" process, it means "read" data from the resources (csv, xml or database), "process" it and "write" it to other resources (csv, xml and database). For example, a step may read data from a CSV file, process it and write it into the database. Spring Batch provides many made Classes to read/write CSV, XML and database.

For "single" operation task (tasklet), it means doing single task only, like clean up the resources after or before a step is started or completed.

And the steps can be chained together to run as a job.

Integration framework[edit]

Spring Integration is a framework for Enterprise application integration that provides reusable functions that are essential in messaging, or event-driven architectures.

  • routers - routes a message to a message channel based on conditions
  • transformers - converts/transforms/changes the message payload and creates a new message with transformed payload
  • adapters - to integrate with other technologies and systems (HTTP, AMQP, JMS, XMPP, SMTP, IMAP, FTP (as well as FTPS/SFTP), file systems, etc.)
  • filters - filters message based on criteria. If the criteria are not met, message is dropped
  • service activators - invoke an operation on a service object
  • management and auditing

Spring Integration supports pipe-and-filter based architectures.

Criticisms[edit]

The Spring Framework has received some criticism for what some developers perceive to be an over-reliance on XML by Spring's container. Since version 3.0.0, however, developers have been able to specify all or part of an application context through annotations. Spring Boot makes heavy use of this to minimize the amount of configuration that must be written. Furthermore, the Spring Tool Suite (STS), built on top of Eclipse, provides code-completion, validation, contextual information, and graphical visualizations when editing Spring XML configuration files.

See also[edit]

References[edit]

  1. ^ Spring Framework documentation for the Core Container
  2. ^ What is the difference between the depencylookup and dependency injection - Spring Forum. Forum.springsource.org (2009-10-28). Retrieved on 2013-11-24.
  3. ^ Spring VS EJB3
  4. ^ "Pitchfork FAQ". Retrieved 2006-06-06.
  5. ^ Hibernate VS Spring
  6. ^ Introduction to the Spring Framework
  7. ^ Johnson, Expert One-on-One J2EE Design and Development, Ch. 12. et al.
  8. ^ Patterns of Enterprise Application Architecture: Front Controller
  9. ^ Spring Boot

Bibliography[edit]

External links[edit]

The Wikibook Java Programming has a page on the topic of: Spring framework


Category:Aspect-oriented programming Category:Java enterprise platform Category:Web frameworks

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