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Chapter 43. File2
File Component - Apache Camel 2.0 onwards
The File component provides access to file systems, allowing files to be processed by any other Apache 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&...
Note
Apache Camel only supports endpoints configured with a starting directory. So the directoryName must be a directory. If you want to consume a single file only, you can use the fileName option, e.g. by setting
fileName=thefilename
. Also, the starting directory must not contain dynamic expressions with ${ } placeholders. Again use the fileName
option to specify the dynamic part of the filename.
Avoid reading files currently being written by another application
Beware the JDK File IO API is a bit limited in detecting whether another application is currently writing/copying a file. And the implementation can be different depending on OS platform as well. This could lead to that Apache Camel thinks the file is not locked by another process and start consuming it. Therefore you have to do you own investigation as to what suits your environment. To help with this, Apache Camel provides different
readLock
options and the doneFileOption
option that you can use. See also the section the section called “Consuming files from folders where others drop files directly”.
URI Options
Name | Default Value | Description |
---|---|---|
autoCreate
|
true
|
Automatically create missing directories in the file's pathname. For the file consumer, that means creating the starting directory. For the file producer, it means the directory where the files should be written. |
bufferSize
|
128kb | Write buffer sized in bytes. |
fileName
|
null
|
Use Expression such as File Language to dynamically set the filename. For consumers, it's used as a filename filter. For producers, it's used to evaluate the filename to write. If an expression is set, it take precedence over the CamelFileName header. (Note: The header itself can also be an Expression). The expression options support both String and Expression types. If the expression is a String type, it is always evaluated using the File Language. If the expression is an Expression type, the specified Expression type is used - this allows you, for instance, to use OGNL expressions. For the consumer, you can use it to filter filenames, so you can for instance consume today's file using the File Language syntax: mydata-${date:now:yyyyMMdd}.txt . From Camel 2.11 onwards the producers support the CamelOverruleFileName header which takes precedence over any existing CamelFileName header; the CamelOverruleFileName is a header that is used only once, and makes it easier as this avoids to temporary store CamelFileName and have to restore it afterwards.
|
flatten
|
false
|
Flatten is used to flatten the file name path to strip any leading paths, so it's just the file name. This allows you to consume recursively into sub-directories, but when you eg write the files to another directory they will be written in a single directory. Setting this to true on the producer enforces that any file name recived in CamelFileName header will be stripped for any leading paths.
|
charset
|
null
|
Camel 2.5: this option is used to specify the encoding of the file, and camel will set the Exchange property with Exchange.CHARSET_NAME with the value of this option. |
copyAndDeleteOnRenameFail
|
true
|
Camel 2.9: whether to fallback and do a copy and delete file, in case the file could not be renamed directly. This option is not available for the FTP component. |
renameUsingCopy
|
false
|
Camel 2.13.1: Perform rename operations using a copy and delete strategy. This is primarily used in environments where the regular rename operation is unreliable (e.g. across different file systems or networks). This option takes precedence over the
copyAndDeleteOnRenameFail parameter that will automatically fall back to the copy and delete strategy, but only after additional delays.
|
Consumer only
Name | Default Value | Description |
---|---|---|
initialDelay
|
1000
|
Milliseconds before polling the file/directory starts. |
delay
|
500
|
Milliseconds before the next poll of the file/directory. |
useFixedDelay
|
true
|
Set to true to use fixed delay between pools, otherwise fixed rate is used. See ScheduledExecutorService in JDK for details.
|
runLoggingLevel
|
TRACE
|
Camel 2.8: The consumer logs a start/complete log line when it polls. This option allows you to configure the logging level for that. |
recursive
|
false
|
If a directory, will look for files in all the sub-directories as well. |
delete
|
false
|
If true , the file will be deleted after it is processed successfully.
|
noop
|
false
|
If true , the file is not moved or deleted in any way. This option is good for readonly data, or for ETL type requirements. If noop=true , Apache Camel will set idempotent=true as well, to avoid consuming the same files over and over again.
|
preMove
|
null
|
Use Expression such as File Language to dynamically set the filename when moving it before processing. For example to move in-progress files into the order directory set this value to order .
|
move
|
.camel
|
Use Expression such as File Language to dynamically set the filename when moving it after processing. To move files into a .done subdirectory just enter .done .
|
moveFailed
|
null
|
Use Expression such as File Language to dynamically set the filename when moving failed files after processing. To move files into a error subdirectory just enter error . Note: When moving the files to another location it can/will handle the error when you move it to another location so Apache Camel cannot pick up the file again.
|
include
|
null
|
Is used to include files, if filename matches the regex pattern. |
exclude
|
null
|
Is used to exclude files, if filename matches the regex pattern. |
antInclude
|
null
|
Camel 2.10: Ant style filter inclusion, for example antInclude=\* {}*/*{} .txt . Multiple inclusions may be specified in comma-delimited format. See below for more details about ant path filters.
|
antExclude
|
null
|
Camel 2.10: Ant style filter exclusion. If both antInclude and antExclude are used, antExclude takes precedence over antInclude . Multiple exclusions may be specified in comma-delimited format. See below for more details about ant path filters.
|
antFilterCaseSensitive
|
true
|
Camel 2.11: Ant style filter which is case sensitive or not. |
idempotent
|
false
|
Option to use the Idempotent Consumer EIP pattern to let Apache Camel skip already processed files. Will by default use a memory based LRUCache that holds 1000 entries. If noop=true then idempotent will be enabled as well to avoid consuming the same files over and over again.
|
idempotentKey
|
Expression
|
Camel 2.11: To use a custom idempotent key. By default the absolute path of the file is used. You can use the File Language, for example to use the file name and file size, you can do: idempotentKey=$-$ . |
idempotentRepository
|
null
|
Pluggable repository as a org.apache.camel.processor.idempotent.MessageIdRepository class. Will by default use MemoryMessageIdRepository if none is specified and idempotent is true .
|
inProgressRepository
|
memory
|
Pluggable in-progress repository as a org.apache.camel.processor.idempotent.MessageIdRepository class. The in-progress repository is used to account the current in progress files being consumed. By default a memory based repository is used. |
filter
|
null
|
Pluggable filter as a org.apache.camel.component.file.GenericFileFilter class. Will skip files if filter returns false in its accept() method. Apache Camel also ships with an ANT path matcher filter in the camel-spring component. More details in section below.
|
sorter
|
null
|
Pluggable sorter as a java.util.Comparator<org.apache.camel.component.file.GenericFile> class. |
sortBy
|
null
|
Built-in sort using the File Language. Supports nested sorts, so you can have a sort by file name and as a 2nd group sort by modified date. See sorting section below for details. |
readLock
|
markerFile
|
Used by consumer, to only poll the files if it has exclusive read-lock on the file (i.e. the file is not in-progress or being written). Apache Camel will wait until the file lock is granted.
The
readLock option supports the following built-in strategies:
|
readLockTimeout
|
0 (for FTP, 2000 )
|
Optional timeout in milliseconds for the read-lock, if supported by the read-lock. If the read-lock could not be granted and the timeout triggered, then Apache Camel will skip the file. At next poll Apache Camel, will try the file again, and this time maybe the read-lock could be granted. Currently fileLock , changed and rename support the timeout.
|
readLockCheckInterval
|
1000 (for FTP, 5000 )
|
Camel 2.6: Interval in millis for the read-lock, if supported by the read lock. This interval is used for sleeping between attempts to acquire the read lock. For example when using the changed read lock, you can set a higher interval period to cater for slow writes. The default of 1 sec. may be too fast if the producer is very slow writing the file.
|
readLockMinLength
|
1
|
Camel 2.10.1: This option applied only for readLock=changed . This option allows you to configure a minimum file length. By default Camel expects the file to contain data, and thus the default value is 1. You can set this option to zero, to allow consuming zero-length files.
|
readLockLoggingLevel
|
WARN
|
Camel 2.12: Logging level used when a read lock could not be acquired. By default a WARN is logged. You can change this level, for example to OFF to not have any logging. This option is only applicable for readLock of types: changed , fileLock , rename .
|
readLockMarkerFile
|
true
|
Camel 2.14: Whether to use marker file with the changed, rename, or exclusive read lock types. By default a marker file is used as well to guard against other processes picking up the same files. This behavior can be turned off by setting this option to false. For example if you do not want to write marker files to the file systems by the Camel application.
|
directoryMustExist
|
Camel 2.5: Similar to
startingDirectoryMustExist but this applies during polling recursive sub directories.
|
|
doneFileName
|
null
|
Camel 2.6: If provided, Camel will only consume files if a done file exists. This option configures what file name to use. Either you can specify a fixed name. Or you can use dynamic placeholders. The done file is always expected in the same folder as the original file. See using done file and writing done file sections for examples. |
exclusiveReadLockStrategy
|
null
|
Pluggable read-lock as a org.apache.camel.component.file.GenericFileExclusiveReadLockStrategy implementation.
|
maxMessagesPerPoll
|
0
|
An integer that defines the maximum number of messages to gather per poll. By default, no maximum is set. Can be used to set a limit of e.g. 1000 to avoid having the server read thousands of files as it starts up. Set a value of 0 or negative to disabled it. |
eagerMaxMessagesPerPoll
|
true
|
Camel 2.9.3: Allows for controlling whether the limit from
maxMessagesPerPoll is eager or not. If eager then the limit is during the scanning of files. Where as false would scan all files, and then perform sorting. Setting this option to false allows for sorting all files first, and then limit the poll. Mind that this requires a higher memory usage as all file details are in memory to perform the sorting.
|
minDepth
|
0 |
Camel 2.8: The minimum depth to start processing when recursively processing a directory. Using minDepth=1 means the base directory. Using minDepth=2 means the first sub directory. This option is not supported by FTP consumer.
|
maxDepth
|
Integer.MAX_VALUE
|
Camel 2.8: The maximum depth to traverse when recursively processing a directory. This option is not supported by FTP consumer. |
processStrategy
|
null
|
A pluggable org.apache.camel.component.file.GenericFileProcessStrategy allowing you to implement your own readLock option or similar. Can also be used when special conditions must be met before a file can be consumed, such as a special ready file exists. If this option is set then the readLock option does not apply.
|
startingDirectoryMustExist
|
false
|
Whether the starting directory must exist. Mind that the autoCreate option is default enabled, which means the starting directory is normally auto-created if it doesn't exist. You can disable autoCreate and enable this to ensure the starting directory must exist. Will throw an exception, if the directory doesn't exist.
|
pollStrategy
|
null
|
A pluggable
org.apache.camel.spi.PollingConsumerPollStrategy allowing you to provide your custom implementation to control error handling usually occurred during the poll operation before an Exchange have been created and being routed in Camel. In other words, the error occurred while the polling was gathering information, for instance access to a file network failed so Camel cannot access it to scan for files. The default implementation will log the caused exception at WARN level and ignore it.
|
sendEmptyMessageWhenIdle
|
false
|
Camel 2.9: If the polling consumer did not poll any files, you can enable this option to send an empty message (no body) instead.
|
consumer.bridgeErrorHandler
|
false
|
Camel 2.10: Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while trying to pick up files, or the like, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the
org.apache.camel.spi.ExceptionHandler to deal with exceptions, that by default will be logged at WARN /ERROR level and ignored. See further below on this page fore more details, at section How to use the Camel error handler to deal with exceptions triggered outside the routing engine.
|
scheduledExecutorService
|
null
|
Camel 2.10: Allows for configuring a custom/shared thread pool to use for the consumer. By default each consumer has its own single threaded thread pool. This option allows you to share a thread pool among multiple file consumers.
|
scheduler
|
null
|
Camel 2.12: To use a custom scheduler to trigger the consumer to run. See more details at Polling Consumer, for example there is a Quartz2, and Spring based scheduler that supports CRON expressions. |
backoffMultiplier
|
0
|
Camel 2.12: To let the scheduled polling consumer backoff if there has been a number of subsequent idles/errors in a row. The multiplier is then the number of polls that will be skipped before the next actual attempt is happening again. When this option is in use then backoffIdleThreshold and/or backoffErrorThreshold must also be configured. See more details at Polling Consumer.
|
backoffIdleThreshold
|
0
|
Camel 2.12: The number of subsequent idle polls that should happen before the backoffMultipler should kick-in.
|
backoffErrorThreshold
|
0
|
Camel 2.12: The number of subsequent error polls (failed due some error) that should happen before the backoffMultipler should kick-in.
|
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:
includeNamePrefix
,includeNamePostfix
,excludeNamePrefix
,excludeNamePostfix
,regexPattern
are used.
Producer only
Name | Default Value | Description |
---|---|---|
fileExist
|
Override
|
What to do if a file already exists with the same name. The following values can be specified: Override, Append, Fail, Ignore, Move, and TryRename (Camel 2.11.1). Override , which is the default, replaces the existing file. Append adds content to the existing file. Fail throws a GenericFileOperationException , indicating that there is already an existing file. Ignore silently ignores the problem and does not override the existing file, but assumes everything is okay. The Move option requires Camel 2.10.1 onwards, and the corresponding moveExisting option to be configured as well. The option eagerDeleteTargetFile can be used to control what to do if an moving the file, and there exists already an existing file, otherwise causing the move operation to fail. The Move option will move any existing files, before writing the target file. TryRename Camel 2.11.1 is only applicable if tempFileName option is in use. This allows to try renaming the file from the temporary name to the actual name, without doing any exists check. This check may be faster on some file systems and especially FTP servers.
|
tempPrefix
|
null
|
This option is used to write the file using a temporary name and then, after the write is complete, rename it to the real name. Can be used to identify files being written and also avoid consumers (not using exclusive read locks) reading in progress files. Is often used by FTP when uploading big files. |
tempFileName
|
null
|
Camel 2.1: The same as tempPrefix option but offering a more fine grained control on the naming of the temporary filename as it uses the File Language.
|
keepLastModified
|
false
|
Camel 2.2: Will keep the last modified timestamp from the source file (if any). Will use the Exchange.FILE_LAST_MODIFIED header to located the timestamp. This header can contain either a java.util.Date or long with the timestamp. If the timestamp exists and the option is enabled it will set this timestamp on the written file. Note: This option only applies to the file producer. You cannot use this option with any of the ftp producers.
|
eagerDeleteTargetFile
|
true
|
Camel 2.3: Whether or not to eagerly delete any existing target file. This option only applies when you use fileExists=Override and the tempFileName option as well. You can use this to disable (set it to false) deleting the target file before the temp file is written. For example you may write big files and want the target file to exists during the temp file is being written. This ensure the target file is only deleted until the very last moment, just before the temp file is being renamed to the target filename. From Camel 2.10.1 on this option is also used to control whether to delete any existing files when fileExist=Move is enabled, and an existing file exists. If the option copyAndDeleteOnRenameFail is false , an exception will be thrown if an existing file existed; if it's true , the existing file is deleted before the move operation.
|
doneFileName
|
null
|
Camel 2.6: If provided, then Camel will write a 2nd done file when the original file has been written. The done file will be empty. This option configures what file name to use. Either you can specify a fixed name. Or you can use dynamic placeholders. The done file will always be written in the same folder as the original file. See writing done file section for examples. |
allowNullBody
|
false
|
Camel 2.10.1: Used to specify if a null body is allowed during file writing. If set to true then an empty file will be created, when set to false, and attempting to send a null body to the file component, a GenericFileWriteException of 'Cannot write null body to file.' will be thrown. If the `fileExist` option is set to 'Override', then the file will be truncated, and if set to `append` the file will remain unchanged. |
forceWrites
|
true
|
Camel 2.10.5/2.11: Whether to force syncing writes to the file system. You can turn this off if you do not want this level of guarantee, for example if writing to logs / audit logs etc; this would yield better performance. |
Default behavior for file producer
- By default it will override any existing file, if one exist with the same name. In Apache Camel 1.x the
Append
is the default for the file producer. We have changed this toOverride
in Apache Camel 2.0 as this is also the default file operation usingjava.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 is considered as a directory name (though if you use an expression such as File Language, or Simple then the result of the expression evaluation is the file name to be used - eg if you set
move=../backup/copy-of-${file:name}
then that's using the File Language which we use return the file name to be used), 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, Apache 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. Apache Camel will, in fact, internally convert the directory name you enter into a File Language expression. So when we enter
move=.done
Apache Camel will convert this into: ${file:parent}/.done/${file:onlyname}
. This is only done if Apache Camel detects that you have not provided a ${ }
in the option value yourself. So when you enter an expression containing ${ }
, the expression is interpreted as a File Language expression.
So if we want to move the file into a backup folder with today's date as the pattern, we can do:
move=backup/${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:name.ext}
.
See more examples at File Language.
Message Headers
The following headers are supported by this component:
File producer only
Header | Description |
---|---|
CamelFileName
|
Specifies the name of the file to write (relative to the endpoint directory). The name can be a String ; a String with a File Language or Simple expression; or an Expression object. If it's null then Apache Camel will auto-generate a filename based on the message unique ID.
|
CamelFileNameProduced
|
The actual absolute filepath (path + name) for the output file that was written. This header is set by Camel and its purpose is providing end-users with the name of the file that was written. |
CamelOverruleFileName
|
Camel 2.11: Is used for overruling CamelFileName header and use the value instead (but only once, as the producer will remove this header after writing the file). The value can be only be a String. Notice that if the option fileName has been configured, then this is still being evaluated.
|
File consumer only
Header | Description |
---|---|
CamelFileName
|
Name of the consumed file as a relative file path with offset from the starting directory configured on the endpoint. |
CamelFileNameOnly
|
Only the file name (the name with no leading paths). |
CamelFileAbsolute
|
A boolean option specifying whether the consumed file denotes an absolute path or not. Should normally be false for relative paths. Absolute paths should normally not be used but we added to the move option to allow moving files to absolute paths. But can be used elsewhere as well.
|
CamelFileAbsolutePath
|
The absolute path to the file. For relative files this path holds the relative path instead. |
CamelFilePath
|
The file path. For relative files this is the starting directory + the relative filename. For absolute files this is the absolute path. |
CamelFileRelativePath
|
The relative path. |
CamelFileParent
|
The parent path. |
CamelFileLength
|
A long value containing the file size.
|
CamelFileLastModified
|
A long value containing the last modified timestamp of the file.
|
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 Apache Camel will add some properties to the Exchange so you know the number of files polled the current index in that order.
Property | Description |
---|---|
CamelBatchSize
|
The total number of files that was polled in this batch. |
CamelBatchIndex
|
The current index of the batch. Starts from 0. |
CamelBatchComplete
|
A boolean value indicating the last Exchange in the batch. Is only true for the last entry.
|
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 Apache Camel is producing files (writing files) there are a few gotchas affecting how to set a filename of your choice. By default, Apache 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");
Or 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. You may also want to look at the doneFileName
option, which uses a marker file (done) to signal when a file is done and ready to be consumed.
Using done files
Available as of Camel 2.6
See also section writing done files below.
If you want only to consume files when a done file exists, then you can use the
doneFileName
option on the endpoint.
from("file:bar?doneFileName=done");
Will only consume files from the bar folder, if a file name done exists in the same directory as the target files. Camel will automatically delete the done file when it's done consuming the files.
However its more common to have one done file per target file. This means there is a 1:1 correlation. To do this you must use dynamic placeholders in the
doneFileName
option. Currently Camel supports the following two dynamic tokens: file:name
and file:name.noext
which must be enclosed in ${ }. The consumer only supports the static part of the done file name as either prefix or suffix (not both).
from("file:bar?doneFileName=${file:name}.done");
In this example only files will be polled if there exists a done file with the name file name.done. For example
hello.txt
- is the file to be consumedhello.txt.done
- is the associated done file
You can also use a prefix for the done file, such as:
from("file:bar?doneFileName=ready-${file:name}");
hello.txt
- is the file to be consumedready-hello.txt
- is the associated done file
Writing done files
Available as of Camel 2.6
After you have written af file you may want to write an additional done file as a kinda of marker, to indicate to others that the file is finished and has been written. To do that you can use the
doneFileName
option on the file producer endpoint.
.to("file:bar?doneFileName=done");
Will simply create a file named
done
in the same directory as the target file.
However its more common to have one done file per target file. This means there is a 1:1 correlation. To do this you must use dynamic placeholders in the
doneFileName
option. Currently Camel supports the following two dynamic tokens: file:name
and file:name.noext
which must be enclosed in ${ }
.
.to("file:bar?doneFileName=done-${file:name}");
Will for example create a file named
done-foo.txt
if the target file was foo.txt
in the same directory as the target file.
.to("file:bar?doneFileName=${file:name}.done");
Will for example create a file named
foo.txt.done
if the target file was foo.txt
in the same directory as the target file.
.to("file:bar?doneFileName=${file:name.noext}.done");
Will for example create a file named
foo.done
if the target file was foo.txt
in the same directory as the target file.
Read from a directory and write to another directory
from("file://inputdir/?delete=true").to("file://outputdir")
Read from a directory and write to another directory using a overrule dynamic name
from("file://inputdir/?delete=true").to("file://outputdir?overruleFile=copy-of-${file:name}")
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 recursively from a directory and writing to 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
Apache 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, which 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
Apache 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 process before they are written to a directory.
public void testToFile() throws Exception { MockEndpoint mock = getMockEndpoint("mock:result"); mock.expectedMessageCount(1); mock.expectedFileExists("target/test-reports/report.txt"); template.sendBody("direct:reports", "This is a great report"); assertMockEndpointsSatisfied(); } protected JndiRegistry createRegistry() throws Exception { // bind our processor in the registry with the given id JndiRegistry reg = super.createRegistry(); reg.bind("processReport", new ProcessReport()); return reg; } protected RouteBuilder createRouteBuilder() throws Exception { return new RouteBuilder() { public void configure() throws Exception { // the reports from the seda queue is processed by our processor // before they are written to files in the target/reports directory from("direct:reports").processRef("processReport").to("file://target/test-reports", "mock:result"); } }; } private static class ProcessReport implements Processor { public void process(Exchange exchange) throws Exception { String body = exchange.getIn().getBody(String.class); // do some business logic here // set the output to the file exchange.getOut().setBody(body); // set the output filename using java code logic, notice that this is done by setting // a special header property of the out exchange exchange.getOut().setHeader(Exchange.FILE_NAME, "report.txt"); } }
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.
Writing file through the temporary directory relative to the final destination
Sometime you need to temporarily write the files to some directory relative to the destination directory. Such situation usually happens when some external process with limited filtering capabilities is reading from the directory you are writing to. In the example below files will be written to the
/var/myapp/filesInProgress
directory and after data transfer is done, they will be atomically moved to the /var/myapp/finalDirectory
directory.
from("direct:start"). to("file:///var/myapp/finalDirectory?tempPrefix=/../filesInProgress/");
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}/${file:name}").to("...");
See File Language for more samples.
Avoiding reading the same file more than once (idempotent consumer)
Apache Camel supports Idempotent Consumer directly within the component so it will skip already processed files. This feature can be enabled by setting the
idempotent=true
option.
from("file://inbox?idempotent=true").to("...");
Camel uses the absolute file name as the idempotent key, to detect duplicate files. From Camel 2.11 onwards you can customize this key by using an expression in the idempotentKey option. For example to use both the name and the file size as the key
<route> <from uri="file://inbox?idempotent=true&dempotentKey=${file:name}-${file:size}"/> <to uri="bean:processInbox"/> </route>
By default Apache Camel uses an in-memory based store for keeping track of consumed files, it uses a least recently used cache 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&dempotentRepository=#myStore"/> <to uri="bean:processInbox"/> </route>
Apache 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 stores the key in separate lines in the file. By default, the file store has a size limit of 1mb and when the file grows larger, Apache Camel will truncate the file store and rebuild the content by flushing the 1st level cache into 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:
<!-- this is our file based idempotent store configured to use the .filestore.dat as file --> <bean id="fileStore" class="org.apache.camel.processor.idempotent.FileIdempotentRepository"> <!-- the filename for the store --> <property name="fileStore" value="target/fileidempotent/.filestore.dat"/> <!-- the max filesize in bytes for the file. Apache Camel will trunk and flush the cache if the file gets bigger --> <property name="maxFileStoreSize" value="512000"/> <!-- the number of elements in our store --> <property name="cacheSize" value="250"/> </bean> <camelContext xmlns="http://camel.apache.org/schema/spring"> <route> <from uri="file://target/fileidempotent/?idempotent=true&dempotentRepository=#fileStore&ove=done/${file:name}"/> <to uri="mock:result"/> </route> </camelContext>
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.
<persistence-unit name="idempotentDb" transaction-type="RESOURCE_LOCAL"> <class>org.apache.camel.processor.idempotent.jpa.MessageProcessed</class> <properties> <property name="openjpa.ConnectionURL" value="jdbc:derby:target/idempotentTest;create=true"/> <property name="openjpa.ConnectionDriverName" value="org.apache.derby.jdbc.EmbeddedDriver"/> <property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema"/> <property name="openjpa.Log" value="DefaultLevel=WARN, Tool=INFO"/> </properties> </persistence-unit>
Then we need to setup a Spring
jpaTemplate
in the spring XML file:
<!-- this is standard spring JPA configuration --> <bean id="jpaTemplate" class="org.springframework.orm.jpa.JpaTemplate"> <property name="entityManagerFactory" ref="entityManagerFactory"/> </bean> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean"> <!-- we use idempotentDB as the persitence unit name defined in the persistence.xml file --> <property name="persistenceUnitName" value="idempotentDb"/> </bean>
And finally we can create our JPA idempotent repository in the spring XML file as well:
<!-- we define our jpa based idempotent repository we want to use in the file consumer --> <bean id="jpaStore" class="org.apache.camel.processor.idempotent.jpa.JpaMessageIdRepository"> <!-- Here we refer to the spring jpaTemplate --> <constructor-arg index="0" ref="jpaTemplate"/> <!-- This 2nd parameter is the name (= a cateogry name). You can have different repositories with different names --> <constructor-arg index="1" value="FileConsumer"/> </bean>
And then we just need to reference the jpaStore bean in the file consumer endpoint, using the
idempotentRepository
option and the #
syntax:
<route> <from uri="file://inbox?idempotent=true&dempotentRepository=#jpaStore"/> <to uri="bean:processInbox"/> </route>
Filter using org.apache.camel.component.file.GenericFileFilter
Apache 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 built our own filter that skips files starting with
skip
in the filename:
public class MyFileFilter implements GenericFileFilter { public boolean accept(GenericFile pathname) { // we dont accept any files starting with skip in the name return !pathname.getFileName().startsWith("skip"); } }
And then we can configure our route using the filter attribute to reference our filter (using
#
notation) that we have defined in the spring XML file:
<!-- define our filter as a plain spring bean --> <bean id="myFilter" class="com.mycompany.MyFileFilter"/> <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:
<camelContext xmlns="http://camel.apache.org/schema/spring"> <template id="camelTemplate"/> <!-- use myFilter as filter to allow setting ANT paths for which files to scan for --> <endpoint id="myFileEndpoint" uri="file://target/antpathmatcher?recursive=true&ilter=#myAntFilter"/> <route> <from ref="myFileEndpoint"/> <to uri="mock:result"/> </route> </camelContext> <!-- we use the antpath file filter to use ant paths for includes and exlucde --> <bean id="myAntFilter" class="org.apache.camel.component.file.AntPathMatcherGenericFileFilter"> <!-- include and file in the subfolder that has day in the name --> <property name="includes" value="**/subfolder/**/*day*"/> <!-- exclude all files with bad in name or .xml files. Use comma to seperate multiple excludes --> <property name="excludes" value="**/*bad*,**/*.xml"/> </bean>
Sorting using Comparator
Apache 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 Apache Camel sort the files before being processed.
In the sample we have built our own comparator that just sorts by file name:
public class MyFileSorter implements Comparator<GenericFile> { public int compare(GenericFile o1, GenericFile o2) { return o1.getFileName().compareToIgnoreCase(o2.getFileName()); } }
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>
URI options can reference beans using the # syntax
Sorting using sortBy
Apache 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:modified
And then we want to group by name as a 2nd option so files with same modifcation is sorted by name:
sortBy=file:modified;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 aboolean
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.
Important when using
consumer.bridgeErrorHandler
When using
consumer.bridgeErrorHandler
, then interceptors, OnCompletion does not apply. The Exchange is processed directly by the Camel Error Handler, and does not allow prior actions such as interceptors, onCompletion to take action.
Debug logging
This component has log level TRACE that can be helpful if you have problems.
See also: