Aura Bot databases

Introduction

Currently, aura-bot uses two databases, described below:

• Mongo DB
• Redis + MongoDB

MongoDB

In order to reuse the code, and clarify the development, all classes related with MongoDB connections are stored in the mongodb-storage.ts file within aura-bot-platform repository.

Here it can be found generic “connection” class, that is mongodb-connection.ts, that will handle the connection request, pooling them and configuring according the configuration (config is mandatory when initializing).

We can find also several “DAO” files, that will couple with a specific MongoDB database and collection, and will create optionally indexes or any other thing required in a specific domain.

MongoDbConnection

There will be only one instance of MongoDbConnection, creating it in the first call to getInstance (requiring config param) and returning the same instance in subsequent calls (where the config param is not required).

To create the instance properly, the following configuration variables are used:

This singleton module should be loaded the first time automatically by the system, and then could be accessed just by calling getInstance method, like:

const connection = await MongoDbConnection.getInstance();
const db = connection.dbConnect(DATABASE);
const collection = db.collection(COLLECTION);

MongoDbStorage

This DAO class will be used by Bot Builder v4 to store the conversation and user data. An index is created to delete documents older than 24 hours (specified by config var AURA_MONGODB_BOT_COLLECTION_CONTEXT_INDEX_TTL).

Following config variables are used to initialize this class:

To create and initialize a MongoDbStorage, a code like following could be used:

const storage = await new MongoDbStorage().init(configuration);

Cache module

The cache module allows the generation of different types of cache:

• AuraCacheLocal: only used for local data.
• AuraCacheRemote: only used for remote data.
• AuraCacheRemoteLocal: used for remote and local data, with priority for remote.
• AuraCacheLocalRemote: used for local and remote data, with priority for local.

How to use cache module

It is possible to use any of the caches through the following commands:

// cache local.
const auraCacheLocal = new AuraCacheLocal('nameCacheLocal');
// cache remote.
const auraCacheRemote = new AuraCacheRemote('nameCacheRemote');
// cache local-remote
const auraCacheLocalRemote = new AuraCacheLocalRemote('nameCacheLocalRemote');
// cache remote-local.
const auraCacheRemoteLocal = new AuraCacheRemoteLocal('nameCacheRemoteLocal');

Variables for AuraCacheLocal

Only for local cache (AuraCacheLocal), it is possible to define a series of options:

• stdTTL: standard TTL as number in seconds for every generated cache element. By default, 0 (0 = unlimited).
• compressedData: data is to be compressed in remote cache. By default, false.
• deleteOnExpire: boolean value that indicates whether variables will be deleted automatically when they expire or not. If true, the variable will be deleted. If false, the variable will remain. By default, true. You are encouraged to handle the variable upon the event expired by yourself.

const options = { stdTTL: 100, encryptData: true };
const auraCacheLocal = new AuraCacheLocal('nameCacheLocal', options);

Store a key

The following code sets a key value pair. It is possible to define a TTL (in seconds). It returns true on success.

const auraCacheLocal = new AuraCacheLocal('nameCacheLocal');
auraCacheLocal.set('key', 'value');

const auraCacheRemote = new AuraCacheRemote('nameCacheRemote');
await auraCacheRemote.set('key', 'value', 1800); // -> data expire at 30m.

Retrieve a key

The following code gets a saved value from the cache. It returns undefined if the value is not found or has expired. If the value is found, it returns an object with the corresponding key value pair.

const auraCacheLocal = new AuraCacheLocal('nameCacheLocal');
auraCacheLocal.set('key', 'value');
auraCacheLocal.get('key'); // -> value.

const auraCacheRemote = new AuraCacheRemote('nameCacheRemote');
await auraCacheRemote.set('key', 'value');
await auraCacheRemote.get('key'); // -> value.

For caches such as AuraCacheLocalRemote and AuraCacheRemoteLocal, it is possible to force it to obtain data different from the priority:

// cache local-remote
const auraCacheLocalRemote = new AuraCacheLocalRemote('nameCacheLocalRemote');
await auraCacheLocalRemote.set('key', 'value');
await auraCacheLocalRemote.getRemote('key'); // -> value.
auraCacheRemote.getLocal('key');
// cache remote-local.
const auraCacheRemoteLocal = new AuraCacheRemoteLocal('nameCacheRemoteLocal');
await auraCacheRemoteLocal.set('key', 'value');
auraCacheRemoteLocal.getLocal('key'); // -> value.
await auraCacheRemoteLocal.getRemote('key'); // -> value.

Delete a key

The following code deletes a key. It returns the number of deleted entries. A delete will never fail.

const auraCacheLocal = new AuraCacheLocal('nameCacheLocal');
auraCacheLocal.set('key', 'value');
auraCacheLocal.get('key'); // -> value.
auraCacheLocal.del('key'); // -> 1.
auraCacheLocal.get('key'); // -> undefined.

const auraCacheRemote = new AuraCacheRemote('auraCacheRemote');
await auraCacheRemote.set('key', 'value');
await auraCacheRemote.get('key'); // -> value.
await auraCacheRemote.del('key'); // -> 1.
await auraCacheRemote.get('key'); // -> undefined.

Flush all data

The following code deletes all data from a store.

const auraCacheLocal = new AuraCacheLocal('nameCacheLocal');
auraCacheLocal.set('key', 'value');
auraCacheLocal.get('key'); // -> value.
auraCacheLocal.flush(); // -> true.
auraCacheLocal.get('key'); // -> undefined.

const auraCacheRemote = new AuraCacheRemote('auraCacheRemote');
await auraCacheRemote.set('key', 'value');
await auraCacheRemote.get('key'); // -> value.
await auraCacheRemote.flush(); // -> true.
await auraCacheRemote.get('key'); // -> undefined.

Redis + MongoDB

If the configuration variable AURA_BOT_CONTEXT_DATABASE is set to REDIS-MONGODB, aura-bot uses a two-level cache to store the context through Aura Redis Mongo Synchronizer.

The following environment variables must be set for the two databases.

Variables