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ApplicationContext context = new ClassPathXmlApplicationContext(
new String[] {"example.xml"});
Example myExample = applicationContext.getBean("my-example");
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But its important to note that as a user of the DSpace Service Manager, this code is "action" is handled for you and encapsulated within the ServiceManager API.
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/* Go on to do something interesting with the service */
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The Case For Spring
This tutorial focuses on adoption of Spring as a best practice for many aspects of DSpace development, from Core Library definition and instantiation to Application Developer implementation of customizations and addons.
- Spring focuses around providing a way to manage your business objects. (DSpace currently lacks this capability).
- Spring is both comprehensive and modular. Spring has a layered architecture, you can choose to use just about any part of it in isolation.
- It is easy to introduce Spring incrementally into existing projects. (The Latest DSpace WebMVC, REST and XMLUI development efforts already leverage Spring WebMVC in the application tier).
- Spring is designed from the ground up to help you write code that's easy to test. Spring is an ideal framework for test driven projects. (DSpace has only just introduced a JUnit Test Suite, which does not leverage Spring in its solution. However, the DSpace Service Manager already delivers a testing suite leverages Spring to support testing configuration).
- Spring is an increasingly important integration technology, its role recognized by several large vendors. By utilizing Spring, DSpace will be able to incrementally improve its architecture to be more robust, and more "enterprise grade".
The Service Manager
The ServiceManager provides the DSpace Application with the above Spring ApplicationContext so that the developer does not need to be responsible for its creation when developing against DSpace. Thus, to extend the pervious example, the DSpace class and its underlying Service Manager can be utilized to get at any object that has been instantiated as a service bean by core or addon application code.Example example = new DSpace().getSingletonService("my-example", Example.class);
/* Go on to do something interesting with the service */
The DSpace Service Manager implementation manages the entire lifecycle of a running DSpace application and provides access to services by Applications that may be executing external to this "kernel" of DSpace Services. Via Spring and loading of individual dspace.cfg properties the ServiceManager manages a developer API of service lookups and manages the overall lifecycle control for the DSpace Application. During this Lifecycle it also manages the configuration of those services, (either through providing those properties to the Spring Application Context injecting those properties directly into the defined classes, or by providing those properties directly in the by allowing properties to be pushed into the services as they start up (mostly from the ConfigurationService).where they can be injected in Spring definition xml files and/or "annotations" or by exposing those properties via the injection of the DSpace ConfigurationService.
DSpace ConfigurationService
The ServiceManagerSystem abstraction allows the DSpace ServiceManager to use different systems to manage its services. The current implementation is Spring Framework based. The original design intent of the Service Manager was to support more than one IoC/DI Solution, however, as work has progressed with DSpace, it has become clear that there are trade offs to consider in its usage.
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