This repository is a study in event sourcing and CQRS architectures. See this blog post for details. It is an implementation of a distributed calculator.
There are two commands availiable:
- POST
/valuesaccepts{"value" : <f64>}returnsHTTP/202and anid(UUID) of the accepted value. - PUT
/values/{id}accepts={"operation" : <OPERATION>, "value" : 3}where OPERATION can beADDorMULTIPLY, it returnsHTTP/202
There is one query path constructed from the events:
- GET
/values/{id}returns{"value" : <current-value>}
Install confluent hub client:
curl -O http://client.hub.confluent.io/confluent-hub-client-latest.tar.gz
# add to .bashrc:
export PATH="<path-to>/confluent-hub-client-latest/bin:$PATH"
# test
confluent-hub help[Client]
package "API" {
package "/queries" {
[queries]
[subscriptions]
}
package "/commands" {
[Commander]
}
}
database "Message store" {
folder "Retention: forever" {
[commands topic] as ct
}
[events topic] as et
[other topics]
}
package "Command Processor" {
[Command Handler] as CH
database "state" {
[Business model]
}
}
node "Aggregate views" {
[consumers]
database "views" {
}
}
Client .down.> Commander
Client .down.> subscriptions
Client .down.> queries
queries <.down. views
Commander .down.> ct : Commands
ct ..> CH : business logic
CH ..> et : Events
et .> subscriptions
et .> consumers
consumers .> views
Start docker containers:
docker-compose -f docker-compose.yml upStart watcher
cargo watch -s "cargo run"Send some commands:
curl -d '{"value": 2}' -H "Content-Type: application/json" -X POST http://localhost:3030/values
# => 2753b941-eb10-497c-b58c-2b3dec1eeeef
curl -d '{"operation": "ADD", "value": 2}' -H "Content-Type: application/json" -X PUT http://localhost:3030/values/2753b941-eb10-497c-b58c-2b3dec1eeeef
curl -d '{"operation": "MULTIPLY", "value": 3}' -H "Content-Type: application/json" -X PUT http://localhost:3030/values/2753b941-eb10-497c-b58c-2b3dec1eeeefQuery the materialized view:
curl -X GET -H "Content-Type: application/json" http://localhost:3030/values/2753b941-eb10-497c-b58c-2b3dec1eeeef
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