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Pattern-based Decentralization and Run-time Adaptation Framework for Multi-site Workflow Orchestrations. Selim Kalayci, S. Masoud Sadjadi School of Computing and Information Sciences Florida International University.
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Pattern-based Decentralization and Run-time Adaptation Framework for Multi-site Workflow Orchestrations Selim Kalayci, S. Masoud Sadjadi School of Computing and Information Sciences Florida International University SEKE 2013: The 25th International Conference on Software Engineering and Knowledge Engineering
Background • Scientific workflows capture the business logic of complex applications in various fields • Directed Acyclic Graphs (DAGs) are commonly used to represent them • Basic Lifecycle of workflows: Abstract Workflow Concrete Workflow Workflow Orchestration SEKE 2013
Workflow Orchestration • Orchestration of workflows that span multiple site of resources. • e.g., XSEDE, national and international Grid infrastructures • Heterogeneous and dynamic computing environments • Centralized Orchestration Issues • Scalability • Additional overhead • Non-optimal Adaptation decisions, due to lack of detailed resource information SEKE 2013
Contributions of this Paper • Decentralized orchestration of workflows • Pattern-based generic framework • Utilizes common DAG patterns (next slide) • Run-time adaptation of workflow orchestration • Pattern-based, non-intrusive framework • Complies with ‘separation of concerns’ • Prototype Implementation based on Condor DAGMan SEKE 2013
DAG Patterns • Building blocks for most types of scientific workflows • High-level representation to describe ‘tasks’ and ‘data/control dependencies’ among them SEKE 2013
Decentralization Framework • Local workflow execution managers collaborate to orchestrate the whole workflow • Increasing scalability • Higher autonomy for local sites • Workflow specification goes through a transformation process • Each site performs locally • Pattern-based in accordance with each mapping scenario SEKE 2013
Transformations for the Sequence DAG Pattern - 1 (a) (b) SEKE 2013
Transformations for the Sequence DAG Pattern - 2 (c) (d) SEKE 2013
Transformations for the Fork/Branch DAG Pattern - 1 (a) SEKE 2013
Transformations for the Fork/Branch DAG Pattern - 2 (b) SEKE 2013
Transformations for the Join DAG Pattern - 1 (a) SEKE 2013
Transformations for the Join DAG Pattern - 2 (b) SEKE 2013
Run-time Adaptation • Problem: dynamic changes in the run-time environment • Solution: • Step 1 – Monitoring and Planning • Step 2 – Enactment of Adaptation Plan • Enactment of Adaptation Plan: basically, modifying the mapping of certain tasks. SEKE 2013
Run-time Adaptation Framework • Our Framework: • Follows the Decentralized approach • Based on DAG Adaptation patterns • Low-level of intrusiveness • At the Originating Site: • Transformation based on DAG Adaptation patterns • At the Destination Site(s): • Capture the transferred tasks and compose the corresponding ‘patch DAG’ • Orchestrate the patch DAG in isolation SEKE 2013
DAG Adaptation for the Sequence DAG Pattern - 1 (a) SEKE 2013
DAG Adaptation for the Sequence DAG Pattern - 2 (b) SEKE 2013
Patch DAG corresponding to the Adapted Sequence Pattern - 1 (a) SEKE 2013
Patch DAG corresponding to the Adapted Sequence Pattern - 2 (b) SEKE 2013
Prototype Implementation • Based on Condor DAGMan • Centralized • No native run-time support • Decentralization • Local Condor DAGMan deployed at each site • Transformations achieved through Pre/Post scripts and lightweight sync tasks • Run-time Adaptation • At originating site: utilize rescue DAGs to keep track of pre/post-adaptation specifications • At destination site: compose and then orchestrate patch DAG specification SEKE 2013
Related Work • Centralized Workflow Execution Managers: • Pegasus (underlying engine: Condor DAGMan) • Taverna • GrADS • ASKALON: hierarchical workflow management system, one master and multiple slave engines • Several studies for decentralization of business processes enacted via BPEL execution engine • Most of the existing Adaptation mechanisms are highly-intrusive SEKE 2013
Thank you! • This material is based upon work supported by the National Science Foundation under Grant Nos. OISE-0730065 and HRD-0833093. • Contact: Selim Kalayci, S. Masoud Sadjadi {skala001, sadjadi}@cs.fiu.edu School of Computing and Information Sciences Florida International University SEKE 2013