How can reactive systems benefit from using Event Store Cloud for event sourcing and stream processing architectures in TypeScript

Question

Pulumi · Accepted Answer

Reactive systems can significantly benefit from using Event Store Cloud because this platform is specifically designed to manage streams of events, an essential concept in event sourcing and stream processing architectures.

**Event Sourcing** relies on storing the state changes as a sequence of events. Each action is immutable and can be replayed to restore the state of an application, which is critical for reactive systems that thrive on consistent state management, resilience, and event-driven scalability.

**Stream Processing** involves consuming, processing, and reacting to continuous streams of data in real-time. Event Store Cloud provides durable storage and enables real-time stream processing, which is crucial for reactive systems that need to make immediate decisions based on the latest data.

By utilizing Event Store Cloud in a TypeScript Pulumi project, you can effectively model, deploy, and manage the infrastructure required for such reactive systems through Infrastructure as Code (IaC) practices. Below is a TypeScript Pulumi program that demonstrates how to create the relevant Event Store Cloud resources securely and scalably:

```typescript
import * as pulumi from "@pulumi/pulumi";
import * as eventstorecloud from "@pulumi/eventstorecloud";

// Create an Event Store Cloud project to organize resources
const project = new eventstorecloud.Project("my-project", {
    // Resource properties
    name: "my-eventstore-project",
});

// Define a network within Event Store Cloud which your managed clusters will run within
const network = new eventstorecloud.Network("my-network", {
    // Resource properties
    name: "my-vpc-network",
    projectId: project.id,
    region: "us-east1",
    cidrBlock: "10.0.0.0/16", // Define an appropriate CIDR block for your network
    resourceProvider: "aws", // Specify your cloud provider (aws, gcp, or azure)
});

// Deploy a managed cluster inside your Event Store Cloud network
const cluster = new eventstorecloud.ManagedCluster("my-cluster", {
    // Resource properties
    name: "my-eventstore-cluster",
    projectId: project.id,
    networkId: network.id,
    topology: "single-node", // Choose a topology that fits your needs: single-node, small, medium,...
    instanceType: "F1", // Choose an instance type based on your requirements
    serverVersion: "20.10", // Specify the Event Store server version
    diskType: "gp2", // Disk type can be set based on performance requirements
    diskSize: 100, // Define the disk size in GB
});

// Set up scheduled backups for your Event Store Cloud managed cluster
const backup = new eventstorecloud.ScheduledBackup("my-backup", {
    // Resource properties
    projectId: project.id,
    sourceClusterId: cluster.id,
    description: "Daily Backup",
    schedule: "@daily", // Use cron format to specify the backup schedule
    maxBackupCount: 7, // Configure the maximum number of backups to retain
});

// Export necessary URLs which might be needed to access the event store cluster
export const eventStoreClusterId = cluster.id;
export const eventStoreNetworkId = network.id;

```

In the above program, you're using Pulumi to define resources as simple TypeScript classes with typed properties. Here's a breakdown of each step:

1. **Project Creation**: Setting up a dedicated project in Event Store Cloud serves as an organizational container for all related resources.

2. **Network Creation**: For the managed cluster to operate, it needs to run within a virtual private cloud; hence, a network resource is instantiated with the necessary configuration.

3. **Managed Cluster**: This is the core of Event Store Cloud, which runs Event Stores you can connect to from your applications. You select the topology, instance type, version, disc type, and size to meet your reactive system's requirements.

4. **Scheduled Backup**: To ensure the resilience of your reactive system, regular backups of your event store are necessary. Scheduling them helps maintain business continuity.

5. **Outputs**: Finally, exporting ids like `eventStoreClusterId` might be useful for other parts of your Pulumi stack or for accessing your Event Store Cloud resources.

This infrastructure setup using Pulumi allows for a resilient, event-driven architecture, central to building reactive systems. It automates provisioning and management, letting you focus on reactive system development rather than infrastructure configuration.