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Serverless Workflow runtimes are dedicated environments for executing workflows defined using the Serverless Workflow DSL. These runtimes ensure seamless deployment and operation within diverse runtime environments. Runtimes provide the infrastructure and execution engines necessary to run your workflows in production, handling orchestration, state management, and integration with external services.

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Available Runtimes

Apache KIE SonataFlow

Production-Ready Enterprise RuntimeApache KIE SonataFlow is a tool for building cloud-native workflow applications. Use it for services and events orchestration and choreography.
  • Cloud-native architecture
  • Kubernetes integration
  • Event-driven orchestration
  • Enterprise support

Java SDK Reference Implementation

Fully Compliant Java RuntimeFull compliant Java implementation of the Serverless Workflow specification, providing a reference runtime for testing and development.
  • Complete specification compliance
  • Reference implementation
  • Testing and validation
  • Educational resource

Lemline

Highly Scalable Messaging RuntimeLemline is a highly scalable runtime running on top of your existing messaging infrastructure.
  • Messaging-based architecture
  • High scalability
  • Existing infrastructure integration
  • Event-driven workflows

Synapse

Cross-Platform Workflow PlatformSynapse is a scalable, cross-platform, fully customizable platform for managing and running Serverless Workflows.
  • Cross-platform support
  • Fully customizable
  • Scalable architecture
  • Workflow management

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Runtime Capabilities

Serverless Workflow runtimes typically provide:

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Execution Engine

  • Parse and execute workflow definitions
  • Manage workflow state and context
  • Handle task orchestration and coordination
  • Support for concurrent and parallel execution

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Integration

  • HTTP/HTTPS service invocation
  • gRPC protocol support
  • OpenAPI and AsyncAPI integration
  • Event consumption and emission
  • Function invocation (FaaS)

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Reliability

  • Error handling and retry mechanisms
  • Timeout management
  • Transaction support
  • State persistence and recovery

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Observability

  • Workflow execution logging
  • Metrics and monitoring
  • Distributed tracing
  • Debugging capabilities

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Scalability

  • Horizontal scaling
  • Load balancing
  • Resource optimization
  • High availability

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Choosing a Runtime

When selecting a runtime for your workflows, consider:
FactorConsideration
Deployment TargetCloud, on-premises, Kubernetes, serverless platforms
Scale RequirementsExpected throughput, concurrency needs, resource constraints
Integration NeedsRequired protocols, service dependencies, existing infrastructure
Operational RequirementsMonitoring, logging, debugging, support needs
CustomizationExtensibility, plugin support, custom task types
ComplianceSpecification version support, conformance testing

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Getting Started

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Apache KIE SonataFlow

SonataFlow provides comprehensive documentation for getting started: 
# Install the SonataFlow CLI
npm install -g @kie/sonataflow-cli

# Create a new workflow project
sonataflow create my-workflow

# Run the workflow
sonataflow run my-workflow
Visit sonataflow.org for detailed guides and tutorials.

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Synapse

Synapse can be deployed as a standalone application or in container environments: 
# Run with Docker
docker run -p 8080:8080 ghcr.io/serverlessworkflow/synapse

# Deploy to Kubernetes
kubectl apply -f https://raw.githubusercontent.com/serverlessworkflow/synapse/main/deploy/kubernetes.yaml

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Conformance Testing

All runtimes can be tested for conformance using the Conformance Test Kit (CTK). The CTK ensures that runtime implementations adhere to the Serverless Workflow specification. See the Conformance Testing guide for details on validating your runtime implementation.

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Contributing a Runtime

Want to contribute a new runtime to the ecosystem?
  1. Implement the Serverless Workflow specification
  2. Validate with the CTK conformance tests
  3. Document your runtime implementation
  4. Submit a PR to add your runtime to this page
Join the community on Slack (#serverless-workflow) to discuss runtime development and get support from maintainers.

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