How to check if file exists in Mule esb

Question

I want to use choice flow control which will chose one route when file named #[function:dateStamp:dd-MM-yyyy].xml exists and other route when this file does not exist.

Is it possible to write 'when' part of choice to check for file existence?

Answer 1

You could use MEL:

<configuration>
    <expression-language>
        <import class="java.text.SimpleDateFormat" />
        <global-functions><![CDATA[
          def xmlFileExists() {
            filePath = '/tmp/' + new SimpleDateFormat('dd-MM-yyyy').format(new Date()) + '.xml';
            new File(filePath).isFile();
          }
        ]]></global-functions>
    </expression-language>
</configuration>

...

    <choice>
        <when expression="#[xmlFileExists()]">
            ...
        </when>
        <otherwise>
            ...
        </otherwise>
    </choice>

Answer 2

Not sure what that would look like but, you could always do it in plain Java. Place a Java component in front of the choice:

<component doc:name="CheckFileExists">
        <singleton-object class="com.example.CheckFileExist">
        </singleton-object>
</component>

Check for the file in the Java code and add a message property to the invocation scope.

Then do the choice on the invocation property:

<choice doc:name="Choice">
        <when expression="message.getInvocationProperty('thevariable')" evaluator="groovy">
            <processor-chain>
               ....
            </processor-chain>
        </when>
<choice>

Answer 3

If you want to check for the files existence at a certain time or interval you can use quartz with the requester module

<flow name="filePollQuartzFlow1" doc:name="filePollQuartzFlow1">
    <quartz:inbound-endpoint jobName="job" repeatInterval="60000" startDelay="1000" responseTimeout="10000" doc:name="Quartz">
        <quartz:event-generator-job/>
    </quartz:inbound-endpoint>
    <mulerequester:request config-ref="Mule_Requester" resource="file://#[function:dateStamp:dd-MM-yyyy].xml" doc:name="Request a message from a directory"/>

    <choice doc:name="Choice">
        <when expression="#[message.payload==null]">
            <logger message="NO FILE FOUND" level="ERROR" doc:name="Log Null Payload"/>
        </when>
        <otherwise>
            <byte-array-to-string-transformer doc:name="Byte Array to String"/>
            <logger message="FILE FOUND: #[message.payload]" level="ERROR" doc:name="Log Payload"/>
        </otherwise>
    </choice>
</flow>

Answer 4

This is how I ended up doing this:

<flow name="stateFileFlow" doc:name="stateFileFlow">
    <file:inbound-endpoint connector-ref="input" path="/path" doc:name="File">
        <file:filename-regex-filter pattern="(^ABC).xml" caseSensitive="true"/>
    </file:inbound-endpoint>
    <choice doc:name="Choice">
        <when expression="#[message.outboundProperties['filename'] == null]">
            <logger level="WARN" doc:name="Logger" message="NO FILE"/>
        </when>
         <otherwise>
             <logger level="WARN" doc:name="Logger" message="FILE EXISTS"/>
            <file:outbound-endpoint connector-ref="output" path="/path" doc:name="File"/>
         </otherwise>
    </choice>
</flow>

And this is yet another which make sit easier to work with an existing message:

<sub-flow name="stateFileFlow" doc:name="stateFileFlow">
    <message-properties-transformer scope="invocation" overwrite="true" doc:name="Message Properties">
        <add-message-property key="path" value="/path" />
        <add-message-property key="format" value="dd-MM-yyyy" />
        <add-message-property key="extension" value="flag" />
    </message-properties-transformer>

    <scripting:component doc:name="asdf">
       <scripting:script engine="groovy">
         <scripting:text>
            def format = message.getInvocationProperty('format');
            def path = message.getInvocationProperty('path');
            def fileName = new Date().format(format) + "." + message.getInvocationProperty('extension');
            def filePath = path + File.separator + fileName;
            def exists = new File(filePath).isFile();
            message.setProperty('exists',exists, org.mule.api.transport.PropertyScope.OUTBOUND);
            message.setProperty('filename',fileName, org.mule.api.transport.PropertyScope.OUTBOUND);
            return message.payload;
        </scripting:text>
       </scripting:script>
    </scripting:component>

    <choice doc:name="Choice">
        <when expression="#[message.outboundProperties['exists'].toString() == 'true']">
            <logger level="INFO" doc:name="Logger" message="FILE EXISTS"/>
        </when>
         <otherwise>
            <logger level="INFO" doc:name="Logger" message="CREATING FILE #[message]"/>
            <file:outbound-endpoint connector-ref="output" path="/path" doc:name="File"/>
         </otherwise>
    </choice>

</sub-flow>