Five Safes TES executors

Five Safes TES supports different technical execution models. Tasks can either execute a single container directly or use an orchestration layer to reproduce and run complex computational workflows.

• Standalone containers: This is suited for analyses whose execution depends on software from a single container image, or software from several containers in sequence. The execution is described with a single TES message with the explicit list of containers and commands within them to be run one after another.

• Orchestrated containers (WfExS): As the TES model is designed on either single or linear tasks, non-linear workflows, which depend on software from other containers, require an orchestration layer with some nesting. Workflow-based analyses are run using the WfExS-backend as an orchestrator, which runs both the corresponding workflow engine and the needed container instances. Nested containarisation (e.g. Singularity within Docker or Singularity within Singularity) enables this orchestration while remaining compatible with the TES environment.