Abstract. The German Indonesian Tsunami Early Warning System (GITEWS) is built upon a complex sensor data infrastructure. To best fulfill the demand for a long living system, the underlying software and hardware architecture of GITEWS must be prepared for future modifications both of single sensors and entire sensors systems. The foundation for a flexible integration and for stable interfaces is a result of following the paradigm of a Service Oriented Architecture (SOA). The Tsunami Service Bus (TSB) -our integration platform in GITEWS -realizes this SOA approach by implementing the Sensor Web Enablement (SWE) standards and services. This paper focuses on architectural and implementation aspects of the TSB. Initially, the general architectural approach in GITEWS by SOA and SWE is presented. Based on this conception, the concrete system architecture of GITEWS is introduced. The sensor integration platform TSB is then discussed in detail, following by its primary responsibilities and components. Special emphasis is laid on architectural transparency, comprehensible design decisions, and references to the applied technology. The Tsunami Service Bus (TSB) is the sensor integration platform of the German Indonesian Tsunami Early Warning System (Rudloff et al., 2009 ). Due to the geological situation in Indonesia, the primary goal of GITEWS is to deliver a reliable tsunami warning message as quickly as possible. This is achieved using several sensor systems: the seismological system, the near real time GPS deformation monitoring sysCorrespondence to: J. Fleischer (jens.fleischer@gfz-potsdam.de) tem, several tide gauges, and buoy systems. Together they provide the fundamental data necessary to support the prediction of a tsunami wave performed by the warning center. But all these sensors use their own rather fixed proprietary data formats and specific behaviors (Fig. 1) . This is complicated by the fact that GITEWS is a long running system, which has to cope with changing requirements over time: new sensor types might be added while old sensors will be replaced by newer ones. Additionally, new algorithms by experts or including foreign sensor networks are assumed to change interfaces and quantity structures even during the implementation phase. In order to manage this multitude of sensors over time, an additional intermediate layer has to be introduced to provide both the required flexibility for sensor integration as well as a stable and uniform interface for the warning system. Thus, seen from an architectural viewpoint, GITEWS is a typical integration project. Although the overall functional requirements for the integration platform TSB could have been stated at project start, the non-functional requirements for system operations were uncertain: -The TSB shall provide a standardized interface for accessing sensor data as well as for tasking the sensors. The time for accessing sensor data shall be in a range of less than seconds. -The TSB shall provide midterm storage (weeks) of all incoming sensor data, including post processing and quality checks. Long-term sensor data is not meaningful for an early warning system. The time for processing incoming sensor data shall be in a range of seconds or less. Published by Copernicus Publications on behalf of the European Geosciences Union.
Another contribution comes from REF , a framework developed with the target to deliver a reliable tsunami warning message as quickly as possible, a critical activity especially in zones, such as the Asiatic south-east, in which these events happen with a higher likelihood.
An integration platform for heterogeneous sensor systems in GITEWS – Tsunami Service
Natural Hazards and Earth System Sciences
Engineering