Temporal Client

Overview

To initialize a Workflow Client, create an instance of a Workflow client with temporal.client.core/create-client, create a Workflow stub with temporal.client.core/create-workflow, and invoke the Workflow with temporal.client.core/start). Finally, gather the results of the Workflow with temporal.client.core/get-result.

Details

To start a Workflow Execution, your Temporal Server must be running, and your front-end service must be accepting gRPC calls.

You can provide options to (create-client) to establish a connection to the specifics of the Temporal front-end service in your environment.

(create-client {:target "temporal-frontend:7233" :namespace "my-namespace"})

After establishing a successful connection to the Temporal Frontend Service, you may perform operations such as:

• Starting Workflows: See temporal.client.core/start and temporal.client.core/signal-with-start
• Signaling Workflows: See temporal.client.core/>! and temporal.client.core/signal-with-start
• Gathering Results: See temporal.client.core/get-result
• Cancelling Workflows: See temporal.client.core/cancel and temporal.client.core/terminate

As a simple example, for the following Workflow implementation:

(require '[temporal.workflow :refer [defworkflow]])
(require '[temporal.activity :refer [defactivity] :as a])

(defactivity greet-activity
  [ctx {:keys [name] :as args}]
  (log/info "greet-activity:" args)
  (str "Hi, " name))

(defworkflow greeter-workflow
  [ctx {:keys [args]}]
  (log/info "greeter-workflow:" args)
  @(a/invoke greet-activity args))

We can create a client to invoke our Workflow as follows:

(require '[temporal.client.core :as c])

(def task-queue "MyTaskQueue")

(let [client (c/create-client)
      workflow (c/create-workflow client greeter-workflow {:task-queue task-queue})]
  (c/start workflow {:name "Bob"})
  (println @(c/get-result workflow)))

Evaluating this code should result in Hi, Bob appearing on the console. Note that (get-result) returns a promise, thus requiring a dereference.