@conference {, title = {The Template Task Graph (TTG) - An Emerging Practical Dataflow Programming Paradigm for Scientific Simulation at Extreme Scale}, booktitle = { 2020 IEEE/ACM 5th International Workshop on Extreme Scale Programming Models and Middleware (ESPM2)}, year = {2020}, month = {2020-11}, publisher = {IEEE}, organization = {IEEE}, abstract = {We describe TESSE, an emerging general-purpose, open-source software ecosystem that attacks the twin challenges of programmer productivity and portable performance for advanced scientific applications on modern high-performance computers. TESSE builds upon and extends the ParsecDAG/-dataflow runtime with a new Domain Specific Languages (DSL) and new integration capabilities. Motivating this work is our belief that such a dataflow model, perhaps with applications composed in domain specific languages, can overcome many of the challenges faced by a wide variety of irregular applications that are poorly served by current programming and execution models. Two such applications from many-body physics and applied mathematics are briefly explored. This paper focuses upon the Template Task Graph (TTG), which is TESSE{\textquoteright}s main C++ Api that provides a powerful work/data-flow programming model. Algorithms on spatial trees, block-sparse tensors, and wave fronts are used to illustrate the API and associated concepts, as well as to compare with related approaches.}, keywords = {dag, dataflow, exascale, graph, High-performance computing, workflow}, doi = {https://doi.org/10.1109/ESPM251964.2020.00011}, author = {George Bosilca and Robert Harrison and Thomas Herault and Mohammad Mahdi Javanmard and Poornima Nookala and Edward Valeev} }