Clustering

Moleculer framework supports several software architectures.

Monolith architecture

In this version, all services are running on the same node like a monolith. There is no network latency and no transporter module. The local calls are the fastest.

Monolith architecture

Microservices architecture

This is the well-known microservices architecture when all services are running on individual nodes and communicates via transporter. In this case, the network latency is not negligible. But your services can be scaled to be resilient and fault-tolerant.

Microservices architecture

Mixed architecture

In this case, we are running coherent services in a group on the same node. It combines the advantages of monolith and microservices architectures.
For example, if the posts service calls the users service multiple times, we put them to the same node, so that we can cut down the network latency between these services. If the node is overloaded, we will scale it up.

Mixed architecture

Tip

The ServiceBroker first tries to call the local instances of service (if exists) to reduce network latencies. This logic can be turned off in broker options with preferLocal: false property under the registry key.

How choose

Do you choose between monolith and microservices when developing your application? Do you choose monolith approach because its easy to develop? Do you prefer microservices architecture because it is reliable and highly scalable? With Moleculer you don’t have to choose. You can have the best of both approaches. During the development of your application load all services is single node. This way you can quickly debug and test of your application logic. When ready, simply distribute your services across multiple nodes. Don’t worry, you don’t have to change a single line of code in your services. Just select a transporter, load one service per node and you’re done. Your application is running in microservices architecture.