D-Net

<workflow-app xmlns="uri:oozie:workflow:0.4" name="union">

	<parameters>

        <property>

			<name>origin_1</name>

			<description>origin of the first port</description>

		</property>

		<property>

			<name>input_1</name>

			<description>first port</description>

		</property>

        <property>

			<name>origin_2</name>

			<description>origin of the second port</description>

		</property>

		<property>

			<name>input_2</name>

			<description>second port</description>

		</property>

        <property>

			<name>origin_3</name>

            <value>$UNDEFINED$</value>

			<description>origin of the third port; optional</description>

		</property>

		<property>

			<name>input_3</name>

            <value>$UNDEFINED$</value>

			<description>third port; optional</description>

		</property>

        <property>

			<name>schema_input</name>

			<description>input schema</description>

		</property>

        <property>

			<name>output</name>

			<description>output port</description>

		</property>

        <property>

			<name>schema_output</name>

			<description>output schema</description>

		</property>

	</parameters>

    <global>

        <job-tracker>${jobTracker}</job-tracker>

        <name-node>${nameNode}</name-node>

        <configuration>

            <property>

                <name>mapred.job.queue.name</name>

                <value>${queueName}</value>

            </property>

        </configuration>

    </global>

    <start to="generate-schema"/>

    <action name="generate-schema">

	    <java>

	        <main-class>eu.dnetlib.iis.core.javamapreduce.hack.AvroSchemaGenerator</main-class>

	        <arg>${schema_input}</arg>

	        <arg>${schema_output}</arg>

	        <capture-output />

	    </java>

	    <ok to="union_origin_fork" />

	    <error to="fail" />

	</action>

    <fork name="union_origin_fork">

        <path start="union_origin_1"/>

        <path start="union_origin_2"/>

        <path start="decision_union_origin_3"/>

    </fork>

    <action name="union_origin_1">

        <pig>

			<!-- The data generated by this node is deleted in this section -->

			<prepare>

				<delete path="${nameNode}${workingDir}/union_origin_1" />

				<delete path="${nameNode}${output}" />

				<mkdir path="${nameNode}${workingDir}/union_origin_1" />

			</prepare>

            <!-- Path to PIG script the workflow executes. -->

            <script>lib/scripts/origin_add.pig</script>

            <param>input=${input_1}</param>

            <param>schema_input=${wf:actionData('generate-schema')[wf:conf('schema_input')]}</param>

            <param>output=${workingDir}/union_origin_1/output</param>

            <param>schema_output=${wf:actionData('generate-schema')[wf:conf('schema_output')]}</param>

            <param>origin_value=${origin_1}</param>

        </pig>

        <ok to="union_origin_join"/>

        <error to="fail"/>

    </action>

    <action name="union_origin_2">

        <pig>

			<!-- The data generated by this node is deleted in this section -->

			<prepare>

				<delete path="${nameNode}${workingDir}/union_origin_2" />

				<delete path="${nameNode}${output}" />

				<mkdir path="${nameNode}${workingDir}/union_origin_2" />

			</prepare>

            <!-- Path to PIG script the workflow executes. -->

            <script>lib/scripts/origin_add.pig</script>

            <param>input=${input_2}</param>

            <param>schema_input=${wf:actionData('generate-schema')[wf:conf('schema_input')]}</param>

            <param>output=${workingDir}/union_origin_2/output</param>

            <param>schema_output=${wf:actionData('generate-schema')[wf:conf('schema_output')]}</param>

            <param>origin_value=${origin_2}</param>

        </pig>

        <ok to="union_origin_join"/>

        <error to="fail"/>

    </action>

    <decision name="decision_union_origin_3">

        <switch>

            <case to="union_origin_join">${origin_3 eq "$UNDEFINED$"}</case>

            <default to="union_origin_3"/>

        </switch>

    </decision>

    <action name="union_origin_3">

        <pig>

			<!-- The data generated by this node is deleted in this section -->

			<prepare>

				<delete path="${nameNode}${workingDir}/union_origin_3" />

				<delete path="${nameNode}${output}" />

				<mkdir path="${nameNode}${workingDir}/union_origin_3" />

			</prepare>

            <!-- Path to PIG script the workflow executes. -->

            <script>lib/scripts/origin_add.pig</script>

            <param>input=${input_3}</param>

            <param>schema_input=${wf:actionData('generate-schema')[wf:conf('schema_input')]}</param>

            <param>output=${workingDir}/union_origin_3/output</param>

            <param>schema_output=${wf:actionData('generate-schema')[wf:conf('schema_output')]}</param>

            <param>origin_value=${origin_3}</param>

        </pig>

        <ok to="union_origin_join"/>

        <error to="fail"/>

    </action>

    <join name="union_origin_join" to="decision_union_merge"/>

    <decision name="decision_union_merge">

        <switch>

            <case to="union_merge_2">${origin_3 eq "$UNDEFINED$"}</case>

            <default to="union_merge_3"/>

        </switch>

    </decision>

    <action name="union_merge_2">

        <pig>

			<!-- The data generated by this node is deleted in this section -->

			<prepare>

				<delete path="${nameNode}${output}" />

			</prepare>

            <!-- Path to PIG script the workflow executes. -->

            <script>lib/scripts/union2.pig</script>

            <param>input_1=${workingDir}/union_origin_1/output</param>

            <param>input_2=${workingDir}/union_origin_2/output</param>

            <param>schema_input=${wf:actionData('generate-schema')[wf:conf('schema_output')]}</param>

            <param>output=${output}</param>

            <param>schema_output=${wf:actionData('generate-schema')[wf:conf('schema_output')]}</param>

        </pig>

        <ok to="end"/>

        <error to="fail"/>

    </action>

    <action name="union_merge_3">

        <pig>

			<!-- The data generated by this node is deleted in this section -->

			<prepare>

				<delete path="${nameNode}${output}" />

			</prepare>

            <!-- Path to PIG script the workflow executes. -->

            <script>lib/scripts/union3.pig</script>

            <param>input_1=${workingDir}/union_origin_1/output</param>

            <param>input_2=${workingDir}/union_origin_2/output</param>

            <param>input_3=${workingDir}/union_origin_3/output</param>

            <param>schema_input=${wf:actionData('generate-schema')[wf:conf('schema_output')]}</param>

            <param>output=${output}</param>

            <param>schema_output=${wf:actionData('generate-schema')[wf:conf('schema_output')]}</param>

        </pig>

        <ok to="end"/>

        <error to="fail"/>

    </action>

    <kill name="fail">

		<message>Unfortunately, the workflow failed -- error message:

			[${wf:errorMessage(wf:lastErrorNode())}]</message>

    </kill>

    <end name="end"/>

</workflow-app>