PHP SDK developer's guide - Observability

The observability section of the Temporal Developer's guide covers the many ways to view the current state of your Temporal Application—that is, ways to view which Workflow Executions are tracked by the Temporal Platform and the state of any specified Workflow Execution, either currently or at points of an execution.

This section covers features related to viewing the state of the application, including:

• Metrics
• Tracing
• Logging
• Visibility

How to use Visibility APIs

The term Visibility, within the Temporal Platform, refers to the subsystems and APIs that enable an operator to view Workflow Executions that currently exist within a Cluster.

How to use Search Attributes

The typical method of retrieving a Workflow Execution is by its Workflow Id.

However, sometimes you'll want to retrieve one or more Workflow Executions based on another property. For example, imagine you want to get all Workflow Executions of a certain type that have failed within a time range, so that you can start new ones with the same arguments.

You can do this with Search Attributes.

• Default Search Attributes like WorkflowType, StartTime and ExecutionStatus are automatically added to Workflow Executions.
• Custom Search Attributes can contain their own domain-specific data (like customerId or numItems).
  • A few generic Custom Search Attributes like CustomKeywordField and CustomIntField are created by default in Temporal's Docker Compose.

The steps to using custom Search Attributes are:

• Create a new Search Attribute in your Cluster using tctl search-attribute create or the Cloud UI.
• Set the value of the Search Attribute for a Workflow Execution:
  • On the Client by including it as an option when starting the Execution.
  • In the Workflow by calling UpsertSearchAttributes.
• Read the value of the Search Attribute:
  • On the Client by calling DescribeWorkflow.
  • In the Workflow by looking at WorkflowInfo.
• Query Workflow Executions by the Search Attribute using a List Filter:
  • In tctl.
  • In code by calling ListWorkflowExecutions.

Here is how to query Workflow Executions:

How to set custom Search Attributes

After you've created custom Search Attributes in your Cluster (using tctl search-attribute createor the Cloud UI), you can set the values of the custom Search Attributes when starting a Workflow.

Use the WorkflowOptions::withSearchAttributes() method to provide Search Attributes when you start a Workflow.

$workflow = $this->workflowClient->newWorkflowStub(
    GreetingWorkflowInterface::class,
    WorkflowOptions::new()
        ->withWorkflowExecutionTimeout(CarbonInterval::minute())
        ->withSearchAttributes(
            [
                'CustomKeywordField' => 'value',
                'CustomIntField' => 123,
            ]
        )
);

How to upsert Search Attributes

You can upsert Search Attributes to add or update Search Attributes from within Workflow code.

To upsert Search Attributes within a Workflow, use Workflow::upsertSearchAttributes().

class GreetingWorkflow implements GreetingWorkflowInterface
{
    public function getGreeting(string $name)
    {
        Workflow::upsertSearchAttributes(
            [
                'CustomKeywordField' => 'attr1-value',
                'CustomIntField' => 123,
            ]
        );

        // ...
    }
}

How to remove a Search Attribute from a Workflow

To remove a Search Attribute that was previously set, set it to an empty array: [].

To remove a Search Attribute that was previously set, set it to an empty array [].