MongoDB GridFS

Provides MongoDB GridFS support via the Vert.x event bus keeping file chunks in a binary format. See the MongoDB site for more information on GridFS: http://docs.mongodb.org/manual/reference/gridfs/

Dependencies

This module requires a MongoDB server to be available on the network.

Configuration

The MongoDB GridFS module takes the following configuration:

{
    "address": <address>,
    "host": <host>,
    "port": <port>,
    "db_name": <db_name>,
    "pool_size": <pool_size>
}

Or for replica sets:

{
    "address": <address>,
    "seeds": [{"host":<address1>, "port":<port1>},{"host":<address2>, "port":<port2>}]
    "db_name": <db_name>,
    "pool_size": <pool_size>
}

For example:

{
    "address": "test.my_persistor",
    "host": "192.168.1.100",
    "port": 27000,
    "pool_size": 20,
    "db_name": "my_db"
}

Or for replica sets:

{
    "address": "test.my_persistor",
    "seeds": [{"host":"192.168.1.100", "port":27000},{"host":"192.168.1.101", "port":27000}]
    "pool_size": 20,
    "db_name": "my_db"
}

Let's take a look at each field in turn:

• address The main address for the module. Every module has a main address. Defaults to et.mongo.gridfs.
• host Host name or ip address of the MongoDB instance. Defaults to localhost.
• port Port at which the MongoDB instance is listening. Defaults to 27017.
• db_name Name of the database in the MongoDB instance to use. Defaults to default_db.
• pool_size The number of socket connections the module instance should maintain to the MongoDB server. Default is 10.
• seeds Use instead of host and port when connecting to a replica set.

Operations

The module supports the following operations

Get File

Returns GridFS file information for a given id.

Send a JSON message to the module main address:

{
    "action": "getFile",
    "id": <id>,
    "bucket": <bucket>
}

Where:

• id is the ObjectId of the GridFS file. This field is mandatory.
• bucket is GridFS bucket the file was saved under. The default value is "fs".

An example would be:

{
    "action": "getFile",
    "id": "51d864754728011036adc575",
    "bucket": "my_bucket"
}

When the getFile completes successfully, a reply message is sent back to the sender with the following data:

{
    "status": "ok",
    "filename": <filename>,
    "contentType": <contentType>,
    "length": <length>,
    "chunkSize": <chunkSize>,
    "uploadDate": <uploadDate>,
    "metadata": <metadata>
}

Where:

• filename is the filename provided when saving
• contentType is the content type (ex. image/jpeg)
• length is the total file length in bytes
• chunkSize is the size in bytes of each chunk
• uploadDate is the long time of the upload in milliseconds since 1 Jan 1970
• metadata is an optional json object with additional metadata

If an error occurs in saving the document a reply is returned:

{
    "status": "error",
    "message": <message>
}

Where message is an error message.

Get Chunk

Returns a GridFS file chunk

Send a JSON message to the module main address:

{
    "action": "getChunk",
    "files_id": <files_id>,
    "n": <n>,
    "bucket": <bucket>,
    "reply": <reply>
}

Where:

• files_id is the ObjectId of the file
• n is the chunk number (first chunk is 0).
• bucket is GridFS bucket the file was saved under. The default value is "fs".
• reply is a boolean flag indicating a reply message handler should be added to send the next chunk

An example would be:

{
    "action": "getChunk",
    "files_id": "51d864754728011036adc575",
    "n": 0,
    "bucket": "my_bucket",
    "reply": true
}

When the get chunk completes successfully, a reply message with the chunk data byte[] in the message body is returned.

If an error occurs when getting the chunk, a json message is returned:

{
    "status": "error",
    "message": <message>
}

Where message is an error message.

Save File

Saves the file information.

Send a JSON message to the module main address:

{
    "action": "saveFile",
    "id": <id>,
    "length": <length>,
    "chunkSize": <chunkSize>,
    "uploadDate": <uploadDate>,
    "filename": <filename>,
    "contentType": <contentType>,
    "bucket": <bucket>
}

Where:

• id is the ObjectId of the file.
• length is the total file length in bytes
• chunkSize is the size in bytes of each chunk
• uploadDate is the long time of the upload in milliseconds since 1 Jan 1970. The field is optional.
• filename is the filename provided when saving. This field is optional.
• contentType is the content type (ex. image/jpeg). This field is optional (but recommended).
• bucket is GridFS bucket the file was saved under. The default value is "fs".

An example would be:

{
    "action": "saveFile",
    "id": "51d864754728011036adc575",
    "length": 161966,
    "chunkSize": 102400,
    "contentType": "image/jpeg"
}

When the save completes successfully, a reply message is sent back to the sender with the following data:

{
    "status": "ok"
}

If an error occurs when saving the file information a reply is returned:

{
    "status": "error",
    "message": <message>
}

Where message is an error message.

Save Chunk

Saves a chunk of binary data in the GridFS format.

Send a Buffer message to the module main address + "/saveChunk".

The Buffer is made up of 3 parts:

1. The first four bytes are an int defining the length of a UTF-8 encoded json string.
2. The json bytes are next
3. The remaining bytes are the chunk to be saved

The json contains the following fields:

{
    "files_id": <files_id>,
    "n": <n>,
    "bucket": <bucket>
}

Where:

• files_id is the ObjectId of the file
• n is the chunk number (first chunk is 0).
• bucket is GridFS bucket the file was saved under. The default value is "fs".

An example would be:

{
    "files_id": "51d864754728011036adc575",
    "n": 0,
    "bucket": "my_bucket",
}

An example of generating the message would be:

public Buffer getMessage(String files_id, int chunkNumber, byte[] data) {
    JsonObject jsonObject = new JsonObject()
            .putString("files_id", files_id)
            .putNumber("n", chunkNumber);
    byte[] json = jsonObject.encode().getBytes("UTF-8");
    byte[] data = getData(chunkNumber);

    Buffer buffer = new Buffer();
    buffer.appendInt(json.length);
    buffer.appendBytes(json);
    buffer.appendBytes(data);

    return buffer;
}

When the save completes successfully, a reply message is sent back to the sender with the following data:

{
     "status": "ok"
}