Microservices (eDR PSD)
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Microservices are small, independent services that work together to perform a larger task. Each service has a specific function and communicates through an API using a defined interface and protocols. This allows services to be developed and deployed independently while still working together. Some key advantages of microservices include scalability, flexibility, and easier maintenance compared to monolithic applications. However, microservices also increase complexity and overhead due to the distributed nature.
![Advantages
• Scalable
• Decoupled
• Better control over development, testing and deployment
• Easier maintenance
• and theoretically is costs less for the business [once it’s up and running]](https://image.slidesharecdn.com/edrpsdmicroservices-170210154514/85/Microservices-eDR-PSD-7-320.jpg)
Microservices (eDR PSD)
- 1. Microservices A brief introduction to services and microservices
- 2. What is a service? “a mechanism to enable access to one or more capabilities, where the access is provided using a prescribed interface and is exercised consistent with constraints and policies as specified by the service description. “ OASIS Reference Model for Service Oriented Architecture
- 3. What is a service? “enable access to one or more capabilities” • Delegated functionality to specialists (no general specialist) “access is provided using a prescribed interface ” • Enforces a distributed architecture, communicating by: • REST, SOAP, AMQP, MSQM, JMS, etc.. ” is exercised consistent with constraints and policies as specified by the service description. ” • Abides by the Service Contract
- 4. Service contract Agreement between a service and its consumer that specifies inbound and outbound data as well as the format.
- 5. Service contract We have to consider: • Service availability • Service responsiveness • Circuit breaker pattern (if service is not in-memory/remote) • Versioning (heterogeneous or homogeneous) • Security (e.g. authentication) • Transactions (ACID compliance)
- 6. Example • Sys AV Scanner • Enables access to a virus scanning service • Access is provided using REST • Responds using JSON • Sys understands the communication protocol “inbound data” • Sys understands the response “outbound data”
- 7. Advantages • Scalable • Decoupled • Better control over development, testing and deployment • Easier maintenance • and theoretically is costs less for the business [once it’s up and running]
- 8. Heterogeneous & Homogeneous Versioning Homogeneous versioning uses version numbers across the same contract. Heterogeneous versioning uses different types of the same contract.
- 9. Disadvantages • Increased complexity • Increased cost • Service contracts can be difficult • What happens if a service I need to connect to is no longer available?
- 11. Characteristics: Taxonomy Two types of classification: • Service Type Type of role the service plays in the overall architecture • Business Area Type of role the service plays in the business application
- 12. Characteristics: Taxonomy Many functional services and private-shared infrastructure services
- 13. Characteristics: Granularity Microservices are small, fine-grained services. They do one thing, and they do it well. • Granularity affects performance! • Service Contract overhead can add 100ms to the total response time • Can impede ACID compliance if services are too granular
- 14. Characteristics: Choreography / Orchestration Orchestration: coordination with a central mediator Choreography: coordination without a central mediator Microservices favour orchestration over choreography Too much choreography can lead to higher efferent coupling • The degree to which one component is dependent on other components to complete a single business request
- 15. Characteristics: Choreography / Orchestration Don’t be afraid to redefine services in a more coarsely-grained manner!
- 16. Characteristics: Topology Microservices have an API layer • Mediator in service orchestration • Server-access façade • Introduces abstraction • Context awareness • Each service can share or have its own access to the infrastructure layer.
- 17. Capabilities: Application scope • Microservices are suited to well-partitioned systems
- 18. Capabilities: Heterogeneous Interoperability The ability to integrate different programming languages and platforms • Microservices support protocol-aware-heteronegeous-interopability • Protocol between API layer and service MUST be the same • SOA also supports protocol-agnostic-heterogeneous-interopability • Hallelujah for that protocol-transforming middleware
- 19. What else can’t Microservices do? Contract decoupling Mediation / Routing Protocol Transformation
- 20. Contract decoupling • Allow services to consume a message that does not abide to the service contract • Message Transformation • Convert XML to JSON • Message Enhancement • Normalise date/time format
- 21. Mediation / Routing • Provides the ability to mediate (discover services) and route a request • A service registry typically acts as the central service configuration repository
- 22. Protocol Transformation • Enables protocol agnostic heterogenous interopability • Potentially allows service optimisation • Service A can only communicate in SOAP, Service B is much faster at accepting requests in REST