org.lappsgrid.annotations

Java annotations that can be applied to services to automatically generate JSON metadata files.

Build Status

Maven

<dependency>
    <groupId>org.lappsgrid</groupId>
    <artifactId>annotations</artifactId>
    <version>${see.above}</version>
</dependency>

Annotations

There are three annotation types that can be used to generate JSON metadata.

1. org.lappsgrid.annotations.CommonMetadata
   Use this on super classes to provide common metadata for all sub-classes. This annotation only works in conjunction with the @ServiceMetadata annotation.
2. org.lappsgrid.annotations.ServiceMetadata
   Used to declare metadata for org.lappsgrid.api.WebService objects.
3. org.lappsgrid.annotations.DataSourceMetadata
   Used to declare metadata for org.lappsgrid.api.DataSource objects.

Examples

@CommonMetadata(
    vendor="http://www.anc.org",
    license="apache2",
    format="gate",
    encoding="UTF-8"
)
public abstract class ParentClass implements WebService { ... }

@ServiceMetadata(
    requires = "token",
    produces = "sentence"
)
public class ServiceClass extends ParentClass { ... }

Note that you can use a discriminator's short name as defined in http://vocab.lappsgrid.org/discriminators.html any time a discriminator URI is required.

Generated Files

To generate the JSON metadata files the Java compiler must be configured to use the LAPPS annotation processor.

<plugins>
    <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
            <annotationProcessors>
                <annotationProcessor>org.lappsgrid.annotation.processing.MetadataProcessor</annotationProcessor>
            </annotationProcessors>
        </configuration>
    </plugin>
    ...
</plugins>
<dependencies>
    <dependency>
        <groupId>org.lappsgrid</groupId>
        <artifactId>annotations</artifactId>
        <version>1.0.1</version>
    </dependency>
</dependencies>

The generated JSON files will be created in src/main/resources/metadata and will use the fully qualified class name of the service class. For example, if the above SeviceClass is in the org.anc.examples package the name of the generated metadata file will be org.anc.examples.ServiceClass.json.

Tips and Troubleshooting

Cleaning up

Since the metadata files are automatically generated during the compile phase it makes sense to delete them during the clean phase. To do this we need to configure the maven-clean-plugin to delete the metadata directory.

    <plugin>
        <artifactId>maven-clean-plugin</artifactId>
        <configuration>
            <filesets>
                <fileset>
                    <directory>src/main/resources/metadata</directory>
                </fileset>
            </filesets>
        </configuration>
    </plugin>