The DSpace Spring Service Manager supports overriding configuration at many levels.
Configuring Addons to Support Spring Services
Configuring Addons to support Spring happens at two levels. Default Spring configuration is available in the DSpace JAR or WAR resources directory and allows the addon developer to inject configuration into the service manager at load time. The second level is in the deployed [dspace]/config/spring directory where configurations can be provided on a addon module by addon module basis.
This latter method requires the addon to implement a SpringLoader to identify the location to look for Spring configuration and a place configuration files into that location. This can be seen inside the current [dspace-source]/config/modules/spring.cfg
The ordering of the loading of Spring configuration is the following:
- configPath = "spring/spring-dspace-applicationContext.xml" relative to the current classpath
- addonResourcePath = "classpath*:spring/spring-dspace-addon-*-services.xml" relative to the current classpath
- coreResourcePath = "classpath*:spring/spring-dspace-core-services.xml" relative to the current classpath
- Finally, an array of SpringLoader API implementations that are checked to verify "config/spring/module" can actually be loaded by its existence on the classpath. The configuration of these SpringLoader API classes can be found in dspace.dir/config/modules/spring.cfg.
Configuring a new Addon
There are 2 ways to create a new Spring addon: a new Spring file can be located in the resources directory or in the configuration [dspace]/config/spring directory. A Spring file can also be located in both of these locations but the configuration directory gets preference and will override any configurations located in the resources directory.
Addon located as resource in jar
In the resources directory of a certain module, a Spring file can be added if it matches the following pattern: "spring/spring-dspace-addon-*-services.xml". An example of this can be found in the dspace-discovery-solr block in the DSpace trunk. (
Wherever this jar is loaded (JSPUI module, XMLUI module, DSpace command line, ...) the Spring files will be processed into services.
Addon located in the [dspace]/config/spring directory
This directory has the following subdirectories in which Spring files can be placed:
- api: when placed in this module the Spring files will always be processed into services (since all of the DSpace modules are dependent on the API).
- discovery: when placed in this module the Spring files will only be processed when the discovery library is present (in the case of discovery in the xmlui & in the command line interface).
- jspui: only processed for the JSPUI.
- xmlui: only processed for the XMLUI (example: the configurable workflow).
The reason why there is a separate directory is that if a service cannot be loaded, which would the case for the configurable workflow (the JSPUI would not be able to retrieve the XMLUI interface classes), the kernel will crash and DSpace will not start.
Configuring an additional subdirectory for a custom module
So you need to indeed create a new directory in [dspace]/config/spring. Next you need to create a class that inherits from the "org.dspace.kernel.config.SpringLoader". This class only contains one method named getResourcePaths(). What we do now at the moment is implement this in the following manner:
After the class has been created you will also need to add it to the "springloader.modules" property located in the [dspace]/config/modules/spring.cfg.
The Spring service manager will check this property to ensure that only the interface implementations which it can find the class for are loaded in.
By doing this way we give some flexibility to the developers so that they can always create their own Spring modules and then Spring will not crash when it can't find a certain class.
The Core Spring Configuration
Utilizing Autowiring to minimize configuration complexity.
Please see the following tutorials:
Accessing the Services Via Service Locator / Java Code
Please see the following tutorials:
Please see Architectural Overview here: DSpace Services Framework
Service Manager Startup in Webapplications and CLI
Please see the DSpace Services Framework
Several good Spring / DSpace Services Tutorials are already available: