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Configuring Addons to Support Spring Services

Wiki MarkupConfiguring 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.

Wiki MarkupThis 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

Configuration Priorities

The ordering of the loading of Spring configuration is the following:

1. configPath = "spring/spring-dspace-applicationContext.xml" relative to the current classpath
2. addonResourcePath = "classpath*:spring/spring-dspace-addon-*-services.xml" relative to the current classpath
3. coreResourcePath = "classpath*:spring/spring-dspace-core-services.xml" relative to the current classpath
4. 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

Wiki MarkupThere 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. (spring-dspace-addon-discovery-services.xml)
Wherever this jar is loaded (JSPUI module, XMLUI module, DSpace command line, ...) the Spring files will be processed into services.

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Addon

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located

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in

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the

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[dspace

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]/config/spring

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directory

This directory has the following subdirectories in which Spring files can be placed:

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Configuring an additional subdirectory for a custom moduleunmigrated-wiki-markup

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:

@Override
public String[] getResourcePaths(ConfigurationService configurationService) {
     StringBuffer filePath = new StringBuffer();
     filePath.append(configurationService.getProperty("dspace.dir"));
     filePath.append(File.separator);
     filePath.append("config");
     filePath.append(File.separator);
     filePath.append("spring");
     filePath.append(File.separator);
     filePath.append("{module.name}"); //Fill in the module name in this string
     filePath.append(File.separator);
     try {

          //By adding the XML_SUFFIX here it doesn't matter if there should be some kind of spring.xml.old file in there it will only load in the active ones.
          return new String[]{new File(filePath.toString()).toURI().toURL().toString() + XML_SUFFIX};
      } catch (MalformedURLException e) {
          return new String[0];
      }
}

Wiki MarkupAfter 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.

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