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Fency

Idempotency barrier for RabbitMQ consumers.

License

License
Categories

Categories

Redis Data Databases
GroupId

GroupId

io.fency
ArtifactId

ArtifactId

fency-redis
Last Version

Last Version

0.1.2
Release Date

Release Date
Type

Type

jar
Description

Description

Fency
Idempotency barrier for RabbitMQ consumers.
Project URL

Project URL

https://github.com/fencyio/fency
Source Code Management

Source Code Management

https://github.com/fencyio/fency

Download fency-redis

Filename Size
fency-redis-0.1.2.pom
fency-redis-0.1.2.jar 2 KB
fency-redis-0.1.2-sources.jar 1 KB
fency-redis-0.1.2-javadoc.jar 19 KB
Browse

How to add to project

<!-- https://jarcasting.com/artifacts/io.fency/fency-redis/ -->
<dependency>
    <groupId>io.fency</groupId>
    <artifactId>fency-redis</artifactId>
    <version>0.1.2</version>
</dependency>
// https://jarcasting.com/artifacts/io.fency/fency-redis/
implementation 'io.fency:fency-redis:0.1.2'
// https://jarcasting.com/artifacts/io.fency/fency-redis/
implementation ("io.fency:fency-redis:0.1.2")
'io.fency:fency-redis:jar:0.1.2'
<dependency org="io.fency" name="fency-redis" rev="0.1.2">
  <artifact name="fency-redis" type="jar" />
</dependency>
@Grapes(
@Grab(group='io.fency', module='fency-redis', version='0.1.2')
)
libraryDependencies += "io.fency" % "fency-redis" % "0.1.2"
[io.fency/fency-redis "0.1.2"]

Dependencies

runtime (2)

Group / Artifact Type Version
io.fency : fency-core jar 0.1.2
org.springframework.boot : spring-boot-starter-data-redis jar 2.1.4.RELEASE

Project Modules

There are no modules declared in this project.

Build Status codecov Codacy Badge Released Version License

Fency: an idempotency barrier for RabbitMQ consumers

Theoretical concept

Even when a sender application sends a message only once, the receiver application may receive the message more than once.

The term idempotent is used in mathematics to describe a function that produces the same result if it is applied to itself: f(x) = f(f(x)). In Messaging this concepts translates into a message that has the same effect whether it is received once or multiple times. This means that a message can safely be resent without causing any problems even if the receiver receives duplicates of the same message.

The recipient can explicitly de-dupe messages by keeping track of messages that it already received. A unique message identifier simplifies this task and helps detect those cases where two legitimate messages with the same message content arrive.

In order to detect and eliminate duplicate messages based on the message identifier, the message recipient has to keep a list of already received message identifiers.

Technical implementation

In order to store the processed message metadata, we have to be in a transactional context. If something goes wrong, the transaction has to be roll backed.

  1. The MessageInterceptor creates an MessageContext and stores it in a ThreadLocal

  2. The IdempotencyBarrier is an aspect around the @IdempotentConsumer annotation. It retrieves the MessageContext and checks if the message already exists. The unique message key is composed by the messageId and the consumerQueueName.

If the message does not exist, the target method is invoked and the message metadata is stored in a datastore.

If the message already exists, an error message is logged and the target method is not invoked.

Usage

  • Maven
<dependency>
  <groupId>io.fency</groupId>
  <artifactId>fency-spring-boot-starter-redis</artifactId>
  <version>0.1.1</version>
</dependency>
  • Gradle
implementation 'io.fency:fency-spring-boot-starter-redis:+'

Annotate your consumers with @IdempotentConsumer.

See sample app: fency-spring-boot-sample-app

Note for spring integration users

If you are already using spring integration, have a look here

References

io.fency

Fency

Idempotency barrier for RabbitMQ consumers

Versions

Version
0.1.2
0.1.1
0.1.0