File2

File Component - Camel 2.0 onwards

The File component provides access to file systems, allowing files to be processed by any other Camel Components or messages from other components to be saved to disk.

URI format

file:directoryName[?options]

or

file://directoryName[?options]

Where directoryName represents the underlying file directory.

You can append query options to the URI in the following format, ?option=value&option=value&...

URI Options

Common

Consumer only

Default behavior for file consumer

• By default the file is locked for the duration of the processing.
• After the route has completed, files are moved into the .camel subdirectory, so that they appear to be deleted.
• The File Consumer will always skip any file whose name starts with a dot, such as ., .camel, .m2 or .groovy.
• Only files (not directories) are matched for valid filename, if options such as: include or exclude are used.

Producer only

Default behavior for file producer

• By default it will override any existing file, if one exist with the same name.

  Override is now default

  In Camel 1.x the Append is the default for the file producer. We have changed this to Override in Camel 2.0 as this is also the default file operation using java.io.File.
  And also the default for the FTP library we use in the camel-ftp component.

Move and Delete operations

Any move or delete operations is executed after (post command) the routing has completed; so during processing of the Exchange the file is still located in the inbox folder.

Lets illustrate this with an example:

    from("file://inbox?move=.done").to("bean:handleOrder");

When a file is dropped in the inbox folder, the file consumer notices this and creates a new FileExchange that is routed to the handleOrder bean. The bean then processes the File object. At this point in time the file is still located in the inbox folder. After the bean completes, and thus the route is completed, the file consumer will perform the move operation and move the file to the .done sub-folder.

The move and preMove options should be a directory name, which can be either relative or absolute. If relative, the directory is created as a sub-folder from within the folder where the file was consumed.

By default, Camel will move consumed files to the .camel sub-folder relative to the directory where the file was consumed.

If you want to delete the file after processing, the route should be:

    from("file://inobox?delete=true").to("bean:handleOrder");

We have introduced a pre move operation to move files before they are processed. This allows you to mark which files have been scanned as they are moved to this sub folder before being processed.

    from("file://inbox?preMove=inprogress").to("bean:handleOrder");

You can combine the pre move and the regular move:

    from("file://inbox?preMove=inprogress&move=.done").to("bean:handleOrder");

So in this situation, the file is in the inprogress folder when being processed and after it's processed, it's moved to the .done folder.

Fine grained control over Move and PreMove option

The move and preMove option is Expression-based, so we have the full power of the File Language to do advanced configuration of the directory and name pattern.
Camel will, in fact, internally convert the directory name you enter into a File Language expression. So when we enter move=.done Camel will convert this into: ${file:parent}/.done/${file:onlyname}. This is only done if Camel detects that you have not provided a ${ } in the option value yourself. So when you enter a ${ } Camel will not convert it and thus you have the full power.

So if we want to move the file into a backup folder with today's date as the pattern, we can do:

move=backup/${date:now:yyyyMMdd}/${file:name}

About moveFailed

The moveFailed option allows you to move files that could not be processed succesfully to another location such as a error folder of your choice. For example to move the files in an error folder with a timestamp you can use moveFailed=/error/${file:name.noext}-${date:now:yyyyMMddHHmmssSSS}.${file:ext}.

See more examples at File Language

Message Headers

The following headers are supported by this component:

File producer only

File consumer only

Batch Consumer

This component implements the Batch Consumer.

Exchange Properties, file consumer only

As the file consumer is BatchConsumer it supports batching the files it polls. By batching it means that Camel will add some properties to the Exchange so you know the number of files polled the current index in that order.

This allows you for instance to know how many files exists in this batch and for instance let the Aggregator aggregate this number of files.

Common gotchas with folder and filenames

When Camel is producing files (writing files) there are a few gotchas affecting how to set a filename of your choice. By default, Camel will use the message ID as the filename, and since the message ID is normally a unique generated ID, you will end up with filenames such as: ID-MACHINENAME-2443-1211718892437-1-0. If such a filename is not desired, then you must provide a filename in the CamelFileName message header. The constant, Exchange.FILE_NAME, can also be used.

The sample code below produces files using the message ID as the filename:

from("direct:report").to("file:target/reports");

To use report.txt as the filename you have to do:

from("direct:report").setHeader(Exchange.FILE_NAME, constant("report.txt")).to( "file:target/reports");

... the same as above, but with CamelFileName:

from("direct:report").setHeader("CamelFileName", constant("report.txt")).to( "file:target/reports");

And a syntax where we set the filename on the endpoint with the fileName URI option.

from("direct:report").to("file:target/reports/?fileName=report.txt");

Filename Expression

Filename can be set either using the expression option or as a string-based File Language expression in the CamelFileName header. See the File Language for syntax and samples.

Consuming files from folders where others drop files directly

Beware if you consume files from a folder where other applications write files directly. Take a look at the different readLock options to see what suits your use cases. The best approach is however to write to another folder and after the write move the file in the drop folder. However if you write files directly to the drop folder then the option changed could better detect whether a file is currently being written/copied as it uses a file changed algorithm to see whether the file size / modification changes over a period of time. The other read lock options rely on Java File API that sadly is not always very good at detecting this.

Samples

Read from a directory and write to another directory

from("file://inputdir/?delete=true").to("file://outputdir")

Listen on a directory and create a message for each file dropped there. Copy the contents to the outputdir and delete the file in the inputdir.

Reading recursive from a directory and write the another

from("file://inputdir/?recursive=true&delete=true").to("file://outputdir")

Listen on a directory and create a message for each file dropped there. Copy the contents to the outputdir and delete the file in the inputdir. Will scan recursively into sub-directories. Will lay out the files in the same directory structure in the outputdir as the inputdir, including any sub-directories.

inputdir/foo.txt
inputdir/sub/bar.txt

Will result in the following output layout:

outputdir/foo.txt
outputdir/sub/bar.txt

Using flatten

If you want to store the files in the outputdir directory in the same directory, disregarding the source directory layout (e.g. to flatten out the path), you just add the flatten=true option on the file producer side:

from("file://inputdir/?recursive=true&delete=true").to("file://outputdir?flatten=true")

Will result in the following output layout:

outputdir/foo.txt
outputdir/bar.txt

Reading from a directory and the default move operation

Camel will by default move any processed file into a .camel subdirectory in the directory the file was consumed from.

from("file://inputdir/?recursive=true&delete=true").to("file://outputdir")

Affects the layout as follows:
before

inputdir/foo.txt
inputdir/sub/bar.txt

after

inputdir/.camel/foo.txt
inputdir/sub/.camel/bar.txt
outputdir/foo.txt
outputdir/sub/bar.txt

Read from a directory and process the message in java

from("file://inputdir/").process(new Processor() {
  public void process(Exchange exchange) throws Exception {
    Object body = exchange.getIn().getBody();
    // do some business logic with the input body
  }
});

The body will be a File object that points to the file that was just dropped into the inputdir directory.

Read files from a directory and send the content to a jms queue

from("file://inputdir/").convertBodyTo(String.class).to("jms:test.queue")

By default the file endpoint sends a FileMessage which contains a File object as the body. If you send this directly to the JMS component the JMS message will only contain the File object but not the content. By converting the File to a String, the message will contain the file contents what is probably what you want.

The route above using Spring DSL:

   <route>
      <from uri="file://inputdir/"/>
      <convertBodyTo type="java.lang.String"/>
      <to uri="jms:test.queue"/>
   </route>

Writing to files

Camel is of course also able to write files, i.e. produce files. In the sample below we receive some reports on the SEDA queue that we processes before they are written to a directory.

Write to subdirectory using Exchange.FILE_NAME

Using a single route, it is possible to write a file to any number of subdirectories. If you have a route setup as such:

  <route>
    <from uri="bean:myBean"/>
    <to uri="file:/rootDirectory"/>
  </route> 

You can have myBean set the header Exchange.FILE_NAME to values such as:

Exchange.FILE_NAME = hello.txt => /rootDirectory/hello.txt
Exchange.FILE_NAME = foo/bye.txt => /rootDirectory/foo/bye.txt 

This allows you to have a single route to write files to multiple destinations.

Using expression for filenames

In this sample we want to move consumed files to a backup folder using today's date as a sub-folder name:

from("file://inbox?move=backup/${date:now:yyyyMMdd}/${file:name}").to("...");

See File Language for more samples.

Avoiding reading the same file more than once (idempotent consumer)

Camel supports Idempotent Consumer directly within the component so it will skip already processed files. This feature can be enabled by setting the idempotent=true option.

from("file://inbox?idempotent=true").to("...");

By default Camel uses a in memory based store for keeping track of consumed files, it uses a least recently used cache storing holding up to 1000 entries. You can plugin your own implementation of this store by using the idempotentRepository option using the # sign in the value to indicate it's a referring to a bean in the Registry with the specified id.

   <!-- define our store as a plain spring bean -->
   <bean id="myStore" class="com.mycompany.MyIdempotentStore"/>

  <route>
    <from uri="file://inbox?idempotent=true&amp;idempotentRepository=#myStore"/>
    <to uri="bean:processInbox"/>
  </route>

Camel will log at DEBUG level if it skips a file because it has been consumed before:

DEBUG FileConsumer is idempotent and the file has been consumed before. Will skip this file: target\idempotent\report.txt

Using a file based idempotent repository

In this section we will use the file based idempotent repository org.apache.camel.processor.idempotent.FileIdempotentRepository instead of the in-memory based that is used as default.
This repository uses a 1st level cache to avoid reading the file repository. It will only use the file repository to store the content of the 1st level cache. Thereby the repository can survive server restarts. It will load the content of the file into the 1st level cache upon startup. The file structure is very simple as it store the key in separate lines in the file. By default, the file store has a size limit of 1mb when the file grew larger Camel will truncate the file store be rebuilding the content by flushing the 1st level cache in a fresh empty file.

We configure our repository using Spring XML creating our file idempotent repository and define our file consumer to use our repository with the idempotentRepository using # sign to indicate Registry lookup:

Using a JPA based idempotent repository

In this section we will use the JPA based idempotent repository instead of the in-memory based that is used as default.

First we need a persistence-unit in META-INF/persistence.xml where we need to use the class org.apache.camel.processor.idempotent.jpa.MessageProcessed as model.

Then we need to setup a Spring jpaTemplate in the spring XML file:

And finally we can create our JPA idempotent repository in the spring XML file as well:

And yes then we just need to refer to the jpaStore bean in the file consumer endpoint using the [[idempotentRepository}} using the # syntax option:

  <route>
    <from uri="file://inbox?idempotent=true&amp;idempotentRepository=#jpaStore"/>
    <to uri="bean:processInbox"/>
  </route>

Filter using org.apache.camel.component.file.GenericFileFilter

Camel supports pluggable filtering strategies. You can then configure the endpoint with such a filter to skip certain files being processed.

In the sample we have build our own filter that skips files starting with skip in the filename:

And then we can configure our route using the filter attribute to reference our filter (using # notation) that we have defines in the spring XML file:

   <!-- define our sorter as a plain spring bean -->
   <bean id="myFilter" class="com.mycompany.MyFileSorter"/>

  <route>
    <from uri="file://inbox?filter=#myFilter"/>
    <to uri="bean:processInbox"/>
  </route>

Filtering using ANT path matcher

The ANT path matcher is shipped out-of-the-box in the camel-spring jar. So you need to depend on camel-spring if you are using Maven.
The reasons is that we leverage Spring's AntPathMatcher to do the actual matching.

The file paths is matched with the following rules:

• ? matches one character
• * matches zero or more characters
• ** matches zero or more directories in a path

The sample below demonstrates how to use it:

Sorting using Comparator

Camel supports pluggable sorting strategies. This strategy it to use the build in java.util.Comparator in Java. You can then configure the endpoint with such a comparator and have Camel sort the files before being processed.

In the sample we have built our own comparator that just sorts by file name:

And then we can configure our route using the sorter option to reference to our sorter (mySorter) we have defined in the spring XML file:

   <!-- define our sorter as a plain spring bean -->
   <bean id="mySorter" class="com.mycompany.MyFileSorter"/>

  <route>
    <from uri="file://inbox?sorter=#mySorter"/>
    <to uri="bean:processInbox"/>
  </route>

Sorting using sortBy

Camel supports pluggable sorting strategies. This strategy it to use the File Language to configure the sorting. The sortBy option is configured as follows:

sortBy=group 1;group 2;group 3;...

Where each group is separated with semi colon. In the simple situations you just use one group, so a simple example could be:

sortBy=file:name

This will sort by file name, you can reverse the order by prefixing reverse: to the group, so the sorting is now Z..A:

sortBy=reverse:file:name

As we have the full power of File Language we can use some of the other parameters, so if we want to sort by file size we do:

sortBy=file:length

You can configure to ignore the case, using ignoreCase: for string comparison, so if you want to use file name sorting but to ignore the case then we do:

sortBy=ignoreCase:file:name

You can combine ignore case and reverse, however reverse must be specified first:

sortBy=reverse:ignoreCase:file:name

In the sample below we want to sort by last modified file, so we do:

sortBy=file:modifed

And then we want to group by name as a 2nd option so files with same modifcation is sorted by name:

sortBy=file:modifed;file:name

Now there is an issue here, can you spot it? Well the modified timestamp of the file is too fine as it will be in milliseconds, but what if we want to sort by date only and then subgroup by name?
Well as we have the true power of File Language we can use the its date command that supports patterns. So this can be solved as:

sortBy=date:file:yyyyMMdd;file:name

Yeah, that is pretty powerful, oh by the way you can also use reverse per group, so we could reverse the file names:

sortBy=date:file:yyyyMMdd;reverse:file:name

Using GenericFileProcessStrategy

The option processStrategy can be used to use a custom GenericFileProcessStrategy that allows you to implement your own begin, commit and rollback logic.
For instance lets assume a system writes a file in a folder you should consume. But you should not start consuming the file before another ready file have been written as well.

So by implementing our own GenericFileProcessStrategy we can implement this as:

• In the begin() method we can test whether the special ready file exists. The begin method returns a boolean to indicate if we can consume the file or not.
• in the commit() method we can move the actual file and also delete the ready file.

Debug logging

This component has log level TRACE that can be helpful if you have problems.

See Also

• Configuring Camel
• Component
• Endpoint
• Getting Started

• File Language
• FTP2