SALMon

Combination of model-based and invocation-based management strategies:
Some agents apply model-based strategies to manage their systems, whereas others apply a traditional invocation-based strategy. SALMon combines both approaches in a common framework.

Passive monitoring consists on gathering the QoS information from the interaction between the service and the service client. On-line testing consists on invoking periodically the service to obtain the QoS information. SALMon combines both approaches in the same architecture in order to satisfy the needs of the different scenarios.

Extensible with new quality metrics: The broadness and heterogeneity of web services requires that any activity dealing with QoS must be extensible to fulfill the specific needs of the emerging stakeholders of the web services. To this aim, we provide SALMON with the required extensability at both the conceptual and execution levels.

Capability to monitor different types of services: The high heterogeneity of the technologies used to implement web services requires a monitoring strategy not attached to a particular technical solution. In SALMon, the core of the monitor is agnostic over the technical specifications, leading the capability to monitor other type of services.

Different mechanisms to retrieve the QoS: SALMon provides two strategies to retrieve the monitored QoS, namely push and pull strategies. In the push strategy, QoS updates are notified to the subscribed agents, which receive the data as soon as the web service is invoked and the quality metrics are computed. In the pull strategy, QoS updates are requested by the users whenever they need it.

High interoperability: The architecture of SALMon has been designed as a service oriented architecture, where the different monitoring modules are services, which facilitates the capability of each module to be easily coupled, replaced and decoupled in the monitoring system. Moreover, following the SOA principles facilitates the monitor to be easily integrated to any framework which uses SOA