The Sensor Web connects live sensors and Earth Science models (ESM). A workflow is one approach for designing, implementing, and constructing a live link between sensors and ESM. The Sensor Web consists of many individual Web services. A workflow coordinates them to enable bi-directional connectivity between sensors and ESMs. This study uses Business Process Execution Language as the base scripting language to design, author, deploy, and execute workflows. Message-level coordination mechanisms are developed, implemented, and demonstrated in two scenarios-bird migratory modeling and georeferenceable imagery workflow. The advantage of message-level coordination is short-cutting the data flow.