worker

Cadence Worker

Cadence Worker is a new role for Cadence service used for hosting any components responsible for performing background processing on the Cadence cluster.

Replicator

Replicator is a background worker responsible for consuming replication tasks generated by remote Cadence clusters and pass it down to processor so they can be applied to local Cadence cluster.

Quickstart for local development with multiple Cadence clusters and replication

1. Start dependency using docker if you don't have one running:

docker-compose -f docker/dev/cassandra.yml up

Then install the schemas:

make install-schema-xdc

1. Start Cadence development server for cluster0, cluster1 and cluster2:

./cadence-server --zone xdc_cluster0 start
./cadence-server --zone xdc_cluster1 start
./cadence-server --zone xdc_cluster2 start

1. Create a global Cadence domain that replicates data across clusters

cadence --do sample domain register --ac cluster0 --cl cluster0 cluster1 cluster2

Then run a helloworld from Go Client Sample or Java Client Sample

1. Failover a domain between clusters:

Failover to cluster1:

cadence --do samples-domain domain update --ac cluster1

or failover to cluster2:

cadence --do samples-domain domain update --ac cluster2

Failback to cluster0:

cadence --do sample samples-domain update --ac cluster0

Multiple region setup

In a multiple region setup, use another set of config instead.

./cadence-server --zone cross_region_cluster0 start
./cadence-server --zone cross_region_cluster1 start
./cadence-server --zone cross_region_cluster2 start

Right now the only difference is at clusterGroupMetadata.clusterRedirectionPolicy. In multiple region setup, network communication overhead between clusters is high so should use "selected-apis-forwarding". workflow/activity workers need to be connected to each cluster to keep high availability.

Archiver

Archiver is used to handle archival of workflow execution histories. It does this by hosting a cadence client worker and running an archival system workflow. The archival client gets used to initiate archival through signal sending. The archiver shards work across several workflows.