Dapr: Simplifying the development of distributed systems

In the past, software developers struggled with the complex requirements of distributed systems. They had to develop individual solutions for things like state management or messaging, resulting in long development times and high costs. 

Dapr, a platform of abstract tools and services, makes developers' work easier. They can now focus on application development, saving time and resources. Dapr works independently of programming languages and cloud platforms, making the application more flexible.

Dapr's building blocks offer a wide range of functionality that developers can select according to their needs. This modular approach allows them to use the building blocks according to the requirements of their application without adding unnecessary complexity. 

Service-to-service invocation: A robust service-oriented call structure enables method calls, including retries, to remote services.

State Management: State management for storing and querying key-value pairs allows you to easily implement stateful services alongside stateless services in your application.

Publish and Subscribe: Publishing events and subscribing to topics between services enables event-driven architectures.

Resource Binding: Resource Binding with Triggers builds on event-driven architectures by receiving and sending events to and from any external sources such as databases, queues, file systems, etc.

Actors: Dapr provides many features in its actor runtime environment, including concurrency, state and lifecycle management for activating/deactivating actors, as well as timers and reminders for activating actors.

Secrets: The secret management API integrates with public Cloud and local secret stores to retrieve the secrets for use in the application code.

Configuration: The configuration API allows you to retrieve and subscribe to the application configuration.

Distributed Lock: The Distributed Lock API allows your application to obtain a lock on any resource, giving it exclusive access until the lock is either released by the application or a lease timeout occurs. 

Workflows: The workflow API can be combined with other Dapr building blocks to define long-running processes or data flows that traverse multiple microservices.

Cryptography: The Cryptography API provides an abstraction layer for cryptographic operations, such as encrypting and decrypting messages, without having to share keys with your applications.

Dapr uses a modular structure where functionality is provided in the form of components. Every component has an interface definition. All components are interchangeable, i.e. one component can be replaced by another with the same interface.