Creating a Process Instance

Technical Preview

The C# SDK is a technical preview available from Camunda 8.9. It will become fully supported in Camunda 8.10. Its API surface may change in future releases without following semver.

The recommended pattern is to obtain keys from a prior API response (e.g. a deployment) and pass them directly — no manual conversion needed:

using Camunda.Orchestration.Sdk;

using var client = CamundaClient.Create();

var deployment = await client.DeployResourcesFromFilesAsync(["process.bpmn"]);
var processKey = deployment.Processes[0].ProcessDefinitionKey;

var result = await client.CreateProcessInstanceAsync(
    new ProcessInstanceCreationInstructionByKey
    {
        ProcessDefinitionKey = processKey,
    });

Console.WriteLine($"Process instance key: {result.ProcessInstanceKey}");

If you need to restore a key from external storage (database, message queue, config file), wrap the raw value with the domain key constructor:

using Camunda.Orchestration.Sdk;

using var client = CamundaClient.Create();

var storedKey = "2251799813685249"; // from a DB row or config
var result = await client.CreateProcessInstanceAsync(
    new ProcessInstanceCreationInstructionByKey
    {
        ProcessDefinitionKey = ProcessDefinitionKey.AssumeExists(storedKey),
    });

Console.WriteLine($"Process instance key: {result.ProcessInstanceKey}");

You can also start a process instance by BPMN process ID (which uses the latest deployed version):

var result = await client.CreateProcessInstanceAsync(
    new ProcessInstanceCreationInstructionById
    {
        ProcessDefinitionId = ProcessDefinitionId.AssumeExists("order-process"),
    });