Communication style pattern

Question 1

Communcation style pattern

Answer 1

Remote Procedure Invocation
Messaging
Domain-specific protocol

Question 2

Remote Procedure Invocation (RPI): context

Answer 2

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.

Question 3

Remote Procedure Invocation (RPI): solution

Answer 3

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

Question 4

Remote Procedure Invocation (RPI): example

Answer 4

REST
gRPC
Apache Thrift

Question 5

Remote Procedure Invocation (RPI): result benefits

Answer 5

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

Question 6

Remote Procedure Invocation (RPI): result drawbacks

Answer 6

• 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

Question 7

Remote Procedure Invocation (RPI): result issues

Answer 7

Client needs to discover locations of service instances

Question 8

Remote Procedure Invocation (RPI): related

Answer 8

The Domain-specific protocol is an alternative pattern
The Messaging is an alternative pattern
Externalized configuration supplies the (logical) network location, e.g. URL, of the service.
A client must use either Client-side discovery and Server-side discovery to locate a service instance
A client will typically use the Circuit Breaker pattern to improve reliability

Question 9

Messaging: context

Answer 9

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.

Question 10

Messaging: solution

Answer 10

Use asynchronous messaging for inter-service communication. Services communicating by exchanging messages over messaging channels.

Question 11

Messaging: examples

Answer 11

There are numerous examples of asynchronous messaging technologies

Apache Kafka
RabbitMQ

Question 12

Messaging: result benefits

Answer 12

• Loose runtime coupling since it decouples the message sender from the consumer
• Improved availability since the message broker buffers messages until the consumer is able to process them
• Supports a variety of communication patterns including request/reply, notifications, request/async response, publish/subscribe, publish/async response etc

Question 13

Messaging: result drawback

Answer 13

Additional complexity of message broker, which must be highly available

Question 14

Messaging: result issues

Answer 14

Request/reply-style communication is more complex

Question 15

Messaging: related

Answer 15

• The Saga pattern and CQRS pattern use messaging
• The Transactional Outbox pattern enables messages to be sent as part of a database transaction
• The Externalized configuration pattern supplies the (logical) message channel names and the location of the message broker
• The Domain-specific protocol pattern is an alternative pattern
• The RPI pattern is an alternative pattern

Question 16

Messaging: related

Answer 16

Enterprise Integration Patterns - a comprehensive set of message patterns
The Event Tram framework, which implements transaction messaging for microservices

Question 17

Domain-specific protocol: context

Answer 17

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.

Question 18

Domain-specific protocol: solution

Answer 18

Use a domain-specific protocol for inter-service communication.

Question 19

Domain-specific protocol: example

Answer 19

There are numerous domain-specific protocols including:

• Email protocols such as SMTP and IMAP
• Media streaming protocols such as RTMP, HLS, and HDS

Question 20

Domain-specific protocol: related

Answer 20

• The Messaging pattern is an alternative pattern

* The RPI pattern is an alternative pattern