Heiko Schuldt ( ) and Gert Brettlecker ( )

University of Basel
  

Technical Contact Point:

Gert Brettlecker ( )
  

Type of Software:

STABLE PROTOTYPE 
  

Descriptive Keywords:

Java, Data Stream Management, Process Management, Mobile Devices, Sensor Data, Telemonitoring, Reliability, Checkpointing
  

Potential Use and Applications:

Data Stream Management (DSM) addresses the continuous processing of sensor data. DSM requires the combination of stream operators, which may run on different distributed devices, into stream processes. Due to the recent advantages in sensor technologies and wireless communication, DSM is increasingly gaining importance in various application domains. Especially in healthcare, the continuous monitoring of patients at home (telemonitoring) can significantly benefit from DSM and produces data which needs to be stored in an eHealth Digital Library. A vital requirement in telemonitoring is however that the infrastructure for DSM provides a high degree of reliability. This may be achieved by a novel approach to efficient and coordinated stream operator checkpointing supporting reliable DSM while maintaining the high result quality needed for healthcare applications.
  

General Description:

OSIRIS-SE (SE for Stream-Enabled) is an extended version of the OSIRIS system (Open Service Infrastructure for Reliable and Integrated process Support). OSIRIS offers an infrastructure for reliable distributed (P2P) process execution. The development of OSIRIS-SE has been started at UMIT in Hall in Tyrol and is continued at the University of Basel. OSIRIS-SE, in addition to OSIRIS, allows for the P2P execution of stream-processes in a distributed environment. Stream processes are combinations of continuously running data stream operators, that are interconnected to perform a certain data stream processing task on incoming sensor data. OSIRIS-SE is programmed completely in Java and runs on various platforms like Windows and Linux, including also PDAs with MS Windows Mobile 2003. The nodes that are participating in an OSIRIS-SE network are also called providers, because according to the service oriented approach, each participating node provides OSIRIS-SE services to the network. Providers are equipped with a local middleware layer (the OSIRIS-SE software layer). The OSIRIS-SE layer running at each node also contains a process execution engine. Thus these providers are able to run stream processes as well as traditional processes based on discrete service calls. The process execution is based on locally replicated meta-data from core services, like service repository or process description repository. This replication allows for decoupling meta-data distribution and process execution. Therefore, processes –both streaming and traditional– can be executed without contacting any central service at runtime. Moreover, OSIRIS-SE implements a reliable and efficient operator checkpointing for data stream operators within a stream process. Since data stream operators are continuously running and aggregating a state during runtime (e.g., the average of the last 10 blood pressure measurements) one has to access and migrate this state when a failure affects a running operator instance.
  

Technical Description:

OSIRIS-SE is implemented completely in Java. At a basic level it offers a generic message oriented middleware which can deal with various pluggable transport layers, as a proprietary TCP socket transport, Web-services based transport, or a peer-to-peer based JXTA transport. Based on the messaging system, OSIRIS-SE offers a component framework which allows for configuration, lifecycle management, and service execution. Message processing at component level is done in a service based concept, where service interaction is in request-response style. Moreover, OSIRIS-SE offers a dedicated agent component, which is responsible for communication between OSIRIS-SE providers and offers pipeline-based message processing. The agent has an incoming and outgoing message processing pipeline which also supports arbitrary plugging of dedicated pipeline handlers. An example of a pipeline handler is the process execution engine running on each provider. Additional pipeline handlers are e.g., responsible for message routing and load balancing. This pipeline-based message processing allows to easily extend OSIRIS-SE. A dedicated gateway component offers the ability to integrate non-OSIRIS-SE services, like standard WSDL/SOAP services in a loosely coupled way. The data stream management functionality of OSIRIS-SE is implemented by offering an additional stream component framework, which offers the design of data stream operators. Extended functionality of the message transport system allows dealing with data streams and offering a reliable buffered first-in/first out transport of data stream elements between operators. At the level of the transport layer data stream elements are dynamically grouped into messages. Moreover, the process execution engine is able to create, maintain, and stop data stream processes. Finally, running operator instances are monitored and their state is saved at a suitable backup provider in an efficient way.
  

Required User Skills:

Fair knowledge of Java, conceptual knowledge of message oriented middleware, SOA, process management, and data stream management is recommended.
  

Pre-Requisites for Installation:

The software is based on Java. The core parts of the infrastructure are implemented to work even on Java 1.3 in order to be compatible with mobile devices. If a current Java 1.5 JVM is available full functionality is offered. The hardware requirements are very low since the software was designed to run also on mobile devices. For mobile devices 64 MB available free memory is sufficient.
  

Conditions of Use:

Contact the authors.