what is the purpose of @Component in OSGI factory implementations?

Question

I am trying to implement servicefactory using apache felix scr annotations.

@Component
@Service(serviceFactory = true)
@Properties(value = { @Property(name = "className", value = "interface1") })
public class Tinterfaceimpl1 implements Tinterface {

    @Override
    public void consumeService() {
        System.out.println("tinterfaceimpl1");
    }
}

Above code is working fine. But what is the purpose of @Component? Because i am trying to expose it as a service instead of both Component & Service. If i remove the @Component state is unsatisfied. IS it really mandatory for a factory to use both component and service? pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>TinterfaceImpl</groupId>
    <artifactId>TinterfaceImpl</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <build>
        <sourceDirectory>src</sourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.apache.felix</groupId>
                <artifactId>maven-bundle-plugin</artifactId>
                <extensions>true</extensions>
                <version>2.3.5</version>
                <!-- <configuration>
                    <instructions>
                        <Import-Package>com.java.serviceeg.tinterface.Tinterface</Import-Package>
                    </instructions>
                </configuration> -->
            </plugin>
            <plugin>
                <groupId>org.apache.felix</groupId>
                <artifactId>maven-scr-plugin</artifactId>
                <version>1.14.0</version>
                <executions>
                    <execution>
                        <id>generate-scr-scrdescriptor</id>
                        <goals>
                            <goal>scr</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
        </build>
        <dependencies>
            <!-- Felix SCR annotations -->
            <dependency>
                <groupId>org.apache.felix</groupId>
                <artifactId>org.apache.felix.scr.annotations</artifactId>
                <version>1.9.6</version>
            </dependency>
            <dependency>
                <groupId>org.apache.felix</groupId>
                <artifactId>org.apache.felix.scr</artifactId>
                <version>1.6.0</version>
            </dependency>
            <dependency>
                <groupId>Tinterface</groupId>
                <artifactId>Tinterface</artifactId>
                <version>0.0.1-SNAPSHOT</version>
                <type>bundle</type>
            </dependency>
        </dependencies>
        <packaging>bundle</packaging>

</project>

Answer 1

Yes this is mandatory. It declares your class as a Component according to the Declarative Services specifcation. Without the @Component annotation, it is merely some class hanging around in your bundle.

Components may also be published as services, as in this example. But components do not have to be services -- instead they might expose some kind of external interface like a server socket or a GUI.