Camel MongoDB GridFS component
Available as of Camel 2.17
Maven users will need to add the following dependency to their
pom.xml for this component:
URI format ( camel < 2.19 )
GridFS endpoints support the following options, depending on whether they are acting like a Producer or as a Consumer (options vary based on the consumer type too).
Required. The name of the database to which this endpoint will be bound. All operations will be executed against this database.
The name of the GridFS bucket within the Database. The default is the GridFS.DEFAULT_BUCKET value ("fs").
The id of the operation this endpoint will execute. Pick from the following:
- Query operations:
- Write operations:
- Delete operations:
Combined with the query strategy parameters to create the query used to search for new files.
The strategy that is used to find new files. Can be one of:
TimeStamp - files that are uploaded after the Consumer starts are processed
PersistentTimestamp - Like TimeStamp, but the last timestamp used is persisted to a collection so when the Consumer restarts, it can resume where it left off
FileAttribute - finds files that do NOT have the give attribute. After processing, it adds the attribute.
TimestampAndFileAttribute - finds files that are newer than the TimeStamp and are missing the attribute
When using persistent timestamps, this is the Collection that the timestamp is stored into.
When using persistent timestamps, this is the object ID for the timestamp object. Each consumer can have it's own timestamp ID stored in a common Collection
When using FileAttribute, this is the name of the attribute that is used. When a file is about to be processed, the attribute is set to "processing" and then set to "done" when the file processing is done.
The delay between polling GridFS for new files
The initial delay before the first poll
Configuration of database in Spring XML
The following Spring XML creates a bean defining the connection to a MongoDB instance.
The following route defined in Spring XML executes the operation findOne on a collection.
GridFS operations - producer endpoint
Returns the total number of file in the collection, returning an Integer as the OUT message body.
You can provide a filename header to provide a count of files matching that filename.
Returns an Reader that lists all the filenames and their IDs in a tab separated stream.
Finds a file in the GridFS system and sets the body to an InputStream of the content. Also provides the metadata has headers. It uses Exchange.FILE_NAME from the incoming headers to determine the file to find.
Creates a new file in the GridFs database. It uses the Exchange.FILE_NAME from the incoming headers for the name and the body contents (as an InputStream) as the content.
Removes a file from the GridFS database.
The GridFS component will poll GridFS periodically for new files to process. The two parameters that control this behavior are the delay and initialDelay parameters. The delay parameter specifies how long the background tread will sleep between polling attempts. The default is 500ms. The initialDelay parameter specifies how long the consumer will wait after starting before polling the first time. This is useful if the backend service needs a bit longer to become available.
The Consumer has several strategies for determining which files within the grid have not been processed yet:
- TimeStamp - (default) when the consumer starts up, it uses the current time as the starting point. Any files currently in the grid are ignored, only files added after the consumer start are processed. After polling, the consumer updates it's timestamp with the timestamp of the newest file processed.
- PersistentTimestamp - when the consumer starts up, it queries the collection specified by the persistentTSCollection parameter for the object given by the persistentTSObject parameter to use as the starting timestamp. If the object doesn't exist, it uses the current time and creates the object. After each file processed, the timestamp in the collection is updated.
- FileAttribute - instead of timestamps, the consumer will query gridfs for files that don't have the attribute given by the fileAttributeName parameter. When the file starts to be processed by the consumer, the attribute is added to the file in the gridfs.
- TimestampAndFileAttribute - finds files that are newer than the TimeStamp and are missing the attribute. Adds the attribute to the file when processing.
- PersistentTimestampAndFileAttribute - finds files that are newer than the TimeStamp and are missing the attribute. Adds the attribute to the file when processing and updates the persistent timestamp.