1. Workflow Validation Kerstin Kleese van Dam Michela Taufer

2. Discussion Topics Identify State of the Art, Gaps and Future Research Topics for: Validating Performance Validation and Reproducibility Validating Accuracy

3. Performance Validation (1) State of the Art: No tools, just one off studies. Single application performance tools are available, but not necessarily applicable to workflows as is. Different vision of performance in Cloud computing - i.e., latency driven. Cloud deploys the concept of enough accurate service within a certain time /amount of resources Gaps: Tools to model and predict workflow performance, tools to monitor performance to validate and improve future predictions and models (importance of factors) Information flow between system, application and workflow How to express and achieve performance goals - for a facility versus for a specific workflow Do we know what metrics we need to capture for different performance goals? Who is capturing them and which granularity

4. Performance Validation (2) Future Research Topics: Tools to monitor, model and predict performance Performance information capture at runtime - workflow and system, capture information about events, capture at different levels - provenance In-situ analysis of performance data Intelligent schedulers at different levels to optimize performance according to set goals

5. Reproducibility and Validation (1) State of the Art: Definition of “reproducibility” depends on community and single scientist; it ranges from stringent bit-to-bit reproducibility to reproducibility of the science with different methods. Some disagreements on who is responsible for reproducibility: the application, the workflow, the system? In the end in complex applications, the workflow has major role on domain decompositions. Gaps: Not clear role of the workflow in tracking aspects related to reproducibility. Hidden information that if revealed can be overwhelming. How can you track everything at exascale, especially when you have unexpected events? What is the responsibility of the workflow system and what it needs to track? Provenance should be viewed from the point of view of the consumer of the information The level of resolution to keep provenance need to be define Need to define the lifespam of validation/provenance data

6. Reproducibility and Validation (2) Future Research Topics: Integration of application, programming models, and run-time systems to pursue reproducibility Pursue reproducibility of results to identify incorrect science. When publishing results, we need to provide provenance, so that others can reproduce the results Automatic annotation embedded in multi-layer or modular workflows

7. Validating Accuracy (1) State of the Art: Who is responsible for which part of accuracy? Application responsible to guarantee accuracy No test suite to check for workflow and system accuracy regularly No one is watching the correctness of the workflow manager establish accuracy of components a priori, workflow system can monitor specific variables to see if application/workflow is progressing to plan and present to user. First research in using data mining and machine learning to identify deviation and correct for it - challenge its black box - so how to convey it to the user, trade offs of between workflow completion and accuracy observed Gaps: Link to reproducibility - can we reproduce to validate accuracy Can we use accuracy measure to determine what data to keep or through away, can accuracy metrics trigger capture of more system information to inform later debugging Investigate human in the loop role in determining accuracy (what deviation is acceptable), and decide on suitable actions.

8. Validating Accuracy (2) Future Research Topics: We cannot always get exact numbers, but the numbers need to be within a certain range For a given problem, can you capture what the best settings are?