pattern   inter-service communication   service api   service design  

Pattern: Remote Procedure Invocation (RPI)

Context

You have applied the Microservice architecture pattern. Services must handle requests from the application’s clients. Furthermore, services must sometimes collaborate to handle those requests. They must use an inter-process communication protocol.

Forces

  • Services often need to collaborate
  • Synchronous communicate results in tight runtime coupling, both the client and service must be available for the duration of the request

Problem

How do services in a microservice architecture communicate?

Solution

Use RPI for inter-service communication. The client uses a request/reply-based protocol to make requests to a service.

Examples

There are numerous examples of RPI technologies

RegistrationServiceProxy from the Microservices Example application is an example of a component, which is written in Scala, that makes a REST request using the Spring Framework’s RestTemplate:

@Component
class RegistrationServiceProxy @Autowired()(restTemplate: RestTemplate) extends RegistrationService {

  @Value("${user_registration_url}")
  var userRegistrationUrl: String = _

  @HystrixCommand(commandProperties=Array(new HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds", value="800")))
  override def registerUser(emailAddress: String, password: String): Either[RegistrationError, String] = {
    try {
      val response = restTemplate.postForEntity(userRegistrationUrl,
        RegistrationBackendRequest(emailAddress, password),
        classOf[RegistrationBackendResponse])
      response.getStatusCode match {
        case HttpStatus.OK =>
          Right(response.getBody.id)
      }
    } catch {
      case e: HttpClientErrorException if e.getStatusCode == HttpStatus.CONFLICT =>
        Left(DuplicateRegistrationError)
    }
  }
}

The value of user_registration_url is supplied using Externalized configuration.

Resulting context

This pattern has the following benefits:

  • Simple and familiar
  • Request/reply is easy
  • Simpler system since there in no intermediate broker

This pattern has the following drawbacks:

  • Usually only supports request/reply and not other interaction patterns such as notifications, request/async response, publish/subscribe, publish/async response
  • Reduced availability since the client and the service must be available for the duration of the interaction

This pattern has the following issues:

  • Client needs to discover locations of service instances

pattern   inter-service communication   service api   service design  


Copyright © 2024 Chris Richardson • All rights reserved • Supported by Kong.

About Microservices.io

Microservices.io is brought to you by Chris Richardson. Experienced software architect, author of POJOs in Action, the creator of the original CloudFoundry.com, and the author of Microservices patterns.

Chris helps organizations improve agility and competitiveness through better software architecture. Learn more about his consulting engagements, and training workshops.

PREMIUM CONTENT

Premium content and office hours is now available for paid subscribers at premium.microservices.io.

MICROSERVICES WORKSHOPS

Chris teaches comprehensive workshops for architects and developers that will enable your organization use microservices effectively.

Avoid the pitfalls of adopting microservices and learn essential topics, such as service decomposition and design and how to refactor a monolith to microservices.

Learn more

LEARN about microservices

Chris offers numerous other resources for learning the microservice architecture.

Get the book: Microservices Patterns

Read Chris Richardson's book:

Example microservices applications

Want to see an example? Check out Chris Richardson's example applications. See code

Remote consulting session

Got a specific microservice architecture-related question? For example:

  • Wondering whether your organization should adopt microservices?
  • Want to know how to migrate your monolith to microservices?
  • Facing a tricky microservice architecture design problem?

Consider signing up for a two hour, highly focussed, consulting session.

Virtual bootcamp: Distributed data patterns in a microservice architecture

My virtual bootcamp, distributed data patterns in a microservice architecture, is now open for enrollment!

It covers the key distributed data management patterns including Saga, API Composition, and CQRS.

It consists of video lectures, code labs, and a weekly ask-me-anything video conference repeated in multiple timezones.

The regular price is $395/person but use coupon ILFJODYS to sign up for $95 (valid until March 12, 2024). There are deeper discounts for buying multiple seats.

Learn more

Learn how to create a service template and microservice chassis

Take a look at my Manning LiveProject that teaches you how to develop a service template and microservice chassis.

Signup for the newsletter


BUILD microservices

Ready to start using the microservice architecture?

Consulting services

Engage Chris to create a microservices adoption roadmap and help you define your microservice architecture,


The Eventuate platform

Use the Eventuate.io platform to tackle distributed data management challenges in your microservices architecture.

Eventuate is Chris's latest startup. It makes it easy to use the Saga pattern to manage transactions and the CQRS pattern to implement queries.

ASSESS your architecture

Assess your application's microservice architecture and identify what needs to be improved.

Consulting services

Engage Chris to conduct an architectural assessment.



Join the microservices google group

Topics

Note: tagging is work-in-process

DDD   ·  GitOps   ·  Microservices adoption   ·  ancient lore   ·  anti-patterns   ·  application api   ·  application architecture   ·  architecting   ·  architecture   ·  architecture documentation   ·  assemblage   ·  beer   ·  books   ·  containers   ·  dark energy and dark matter   ·  deployment   ·  deployment pipeline   ·  design-time coupling   ·  developer experience   ·  development   ·  devops   ·  docker   ·  eventuate platform   ·  generative AI   ·  glossary   ·  health   ·  hexagonal architecture   ·  implementing commands   ·  implementing queries   ·  inter-service communication   ·  kubernetes   ·  loose coupling   ·  microservice architecture   ·  microservice chassis   ·  microservices adoption   ·  microservices rules   ·  microservicesio updates   ·  modular monolith   ·  multi-architecture docker images   ·  observability   ·  pattern   ·  refactoring to microservices   ·  resilience   ·  sagas   ·  security   ·  service api   ·  service architecture   ·  service blueprint   ·  service collaboration   ·  service design   ·  service discovery   ·  service granularity   ·  service template   ·  software delivery metrics   ·  success triangle   ·  tacos   ·  team topologies   ·  testing   ·  transaction management   ·  transactional messaging

All content