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Watchers

We support to use distributed messaging systems like etcd to keep consistence between multiple Casbin enforcer instances. So our users can concurrently use multiple Casbin enforcers to handle large number of permission checking requests.

Similar to policy storage adapters, we don't put watcher code in the main library. Any support for a new messaging system should be implemented as a watcher. A complete list of Casbin watchers is provided as below. Any 3rd-party contribution on a new watcher is welcomed, please inform us and I will put it in this list:)

Go

Java

Node.js

Python

.NET

Watcher	Type	Author	Description
Etcd Watcher	KV store	Casbin	Watcher for etcd
NATS Watcher	Messaging system	Soluto	Watcher for NATS
ZooKeeper Watcher	KV store	Grepsr	Watcher for Apache ZooKeeper
Redis Watcher	KV store	@billcobbler	Watcher for Redis
NATS, RabbitMQ, GCP Pub/Sub, AWS SNS & SQS, Kafka, InMemory	Messaging System	@rusenask	Watcher based on Go Cloud Dev Kit that works with leading cloud providers and self-hosted infrastructure
RocketMQ Watcher	Messaging system	@fmyxyz	Watcher for Apache RocketMQ

Watcher	Type	Author	Description
Etcd Adapter	KV store	@mapleafgo	Watcher for etcd

Watcher	Type	Author	Description
Etcd Watcher	KV store	Casbin	Watcher for etcd
Redis Watcher	KV store	Casbin	Watcher for Redis
Pub/Sub Watcher	Messaging system	Casbin	Watcher for Google Cloud Pub/Sub
Postgres Watcher	Database	Matteo Collina	Watcher for PostgreSQL

Watcher	Type	Author	Description
Redis Watcher	KV store	ScienceLogic	Watcher for Redis
PostgreSQL Watcher	Database	Casbin	Watcher for PostgreSQL

Watcher	Type	Author	Description
Redis Watcher	KV store	@Sbou	Watcher for Redis

WatcherEx

In order to support incremental synchronization between multiple instances, we provide the WatcherEx interface. We hope it can notify other instances when the policy changes, but there is currently no implementation of WatcherEx. We recommend that you use dispatcher to achieve this.

Compared with Watcher interface, with implementing WatcherEx what kind of update action can be distinguished, etc AddPolicy, RemovePolicy, etc.

WatcherEx Apis:

api	description
SetUpdateCallback(func(string)) error	SetUpdateCallback sets the callback function that the watcher will call, when the policy in DB has been changed by other instances. A classic callback is Enforcer.LoadPolicy().
Update() error	Update calls the update callback of other instances to synchronize their policy. It is usually called after changing the policy in DB, like Enforcer.SavePolicy(), Enforcer.AddPolicy(), Enforcer.RemovePolicy(), etc.
Close()	Close stops and releases the watcher, the callback function will not be called any more.
UpdateForAddPolicy(params ...string) error	UpdateForAddPolicy calls the update callback of other instances to synchronize their policy. It is called after Enforcer.AddPolicy()
UpdateForRemovePolicy(params ...string) error	UPdateForRemovePolicy calls the update callback of other instances to synchronize their policy. It is called after Enforcer.RemovePolicy()
UpdateForRemoveFilteredPolicy(fieldIndex int, fieldValues ...string) error	UpdateForRemoveFilteredPolicy calls the update callback of other instances to synchronize their policy. It is called after Enforcer.RemoveFilteredNamedGroupingPolicy()
UpdateForSavePolicy(model model.Model) error	UpdateForSavePolicy calls the update callback of other instances to synchronize their policy. It is called after Enforcer.RemoveFilteredNamedGroupingPolicy()