MongoRiver.NET

A library for writing .NET MongoDB oplog tailers.

Description

MongoRiver.NET is a library to monitor updates to your MongoDB databases in near-realtime. It provides a simple interface for you to take actions when records are inserted, updated, or deleted.

Code Quality Rank: L5

Programming language: C#

License: MIT License

Tags: MongoDB     ORM     Oplog     Tailer     Mongo     River     Mongoriver    

Latest version: v1.0.0

README

MongoRiver.NET

MongoRiver.NET is a library to monitor updates to your MongoDB databases in near-realtime. It provides a simple interface for you to take actions when records are inserted, updated, or deleted.

MongoRiver.NET was inspired by Stripe's Mongoriver library written in Ruby.

How it works

MongoDB has an oplog, a log of all write operations. MongoRiver.NET monitors updates to this oplog and exposes a simple interface for each operation. See the MongoDB documentation for its oplog for more info.

How to use it

Step 1: Install and use

You can install MongoRiver.NET from nuget:

PM> Install-Package MongoRiver.NET

Or download and build the source from here and reference the MongoRiver.dll.

Then add using statements:

using MongoRiver;

Step 2: Create an outlet

You'll need to write a class that implements the MongoRiver.IOutlet interface.

The IOutlet interface exposes the following methods that you can implement in your class:

void UpdateOptime(BsonTimestamp timestamp);

void Insert(string databaseName, string collectionName, BsonDocument insertedDocument);
void Update(string databaseName, string collectionName, BsonDocument filterDocument, BsonDocument updatedDocument);
void Delete(string databaseName, string collectionName, BsonDocument filterDocument);

void CreateIndex(string databaseName, string collectionName, BsonDocument indexKeyDocument, BsonDocument optionsDocument);
void DeleteIndex(string databaseName, string collectionName, string indexName);

void CreateCollection(string databaseName, string collectionName, BsonDocument optionsDocument);
void RenameCollection(string databaseName, string collectionName, string newCollectionName);
void DeleteCollection(string databaseName, string collectionName);

void DeleteDatabase(string databaseName);

You should think of these methods like callbacks -- if you want to do something every time a document is inserted into the MongoDB database, implement the Insert method.

Step 3: Create and run a stream

Once you've written your class, you can start tailing the MongoDB oplog! Here's the code you'll need to use:

var client = new MongoClient(YourMongoConnectionString);
var tailer = new Tailer(client);
IOutlet output = new YourOutlet(); // Your class that implements IOutlet here
var stream = new Stream(tailer, output);
stream.RunForever(startOplog);

startOplog here is the oplog you want the tailer to start at. We use this to resume interrupted tailers so that no information is lost.

You should save the oplog timestamp each time the UpdateOptime method is called. This allows you to retreive the startOplog when resuming a previous running tailer that was interrupted:

The tailer object exposes methods that you can use to get the start oplog.

Oplog startOplog = await tailer.GetMostRecentOplog();

// or
Oplog startOplog = await tailer.GetMostRecentOplog(lastKnowProcessedOplogTimestamp);

// or
Oplog startOplog = await tailer.GetMostRecentOplog(lastKnowProcessedOplogDateTime);

Changelog

1.1.0

• Upgrade to support MongoDB SDK v2.5

1.0.0

Initial release.