Several months after publishing the SOS 4.x developments, the Sensor Web community is pleased to announce the

52°North SOS 4.1 Release

A downloadable zip archive of the release contains the sources, as well as the binaries. Release requirements, installation and configuration information are documented in the 52°North wiki.

Many thanks to all 52°North SOS contributors for their enhancements and improvements, but also to all users for their feedback!

Core features and improvements

We have implemented the following additional features (NEW) and improvements.

• Binding selection by content type at /sos and /service
  • Binding a specific endpoint like /pox and /soap is no longer necessary but still supported. More infomation can be found in the SOS Wiki.
• Microsoft SQL Server support (NEW)
  • Requirements and installation instructions are documented in the Wiki.
• GetObservation with multiple temporal filters and different value references (NEW).
  • How the filters and value references are used is described in the SOS Wiki.
• Streaming (NEW)
  • The SOS provides two types of streaming. For more information, please visit the SOS Wiki.
  • XML response streaming
    • XML response streaming means that no DOM tree is created, but the data is written directly into the output stream.
    • The 52°North SOS implements a hybrid solution which is a combination of streaming and DOM tree creation with XmlBeans. For example, the SOAP envelope or the response document envelope are streaming encoded while the content, e.g. OM_Observation in a GetObservationResponse, is encoded using of XMLBeans (default encoding implementation).
    • This allows larger response documents.
    • There is less memory usage compared to the DOM tree solution.
  • Streaming datasource for GetObservation (Hibernate datasource)
    • This is only available for the GetObservation operation.
    • Unique static observation metadata (e.g. procedure, observerProperty, FoI) are queried for the resulting observations from the database.
    • The variable observation values (e.g. measured value, time stamp) are queried from the database in the encoders.
    • There are two datasource streaming solutions:
      • Scrollable: Uses Hibernate ScrollableResult
      • Chunk: The SOS queries a configurable number of values, processes these values and then queries the next values chunk.
    • There is less memory usage.
    • In combination with an XML response,  the streaming has very low latency.
  • A detailed description about the streaming implementations of the 52°North SOS and the performance differences compared to the default implementation will be described in a future blog post.
• Adapted GetDataAvailability to OGC Discussion paper
  • The OGC Sensor Observation Service 2.0 Hydrology Profile Discussion paper was published in April 2014 and contains, inter alia, the definition of the GetDataAvailability operation requests and responses.
  • The XML schema definition is available here: http://waterml2.org/schemas/gda/1.0/gda.xsd
• Reduced number of Maven profiles
  • Before the admin interface existed, Maven profiles were used to build the SOS with the required bindings, encodings, and operations. Due to the possibility to de-/activate the bindings, encodings, and operations via the admin interface, most of the Maven profiles are now obsolete. Now the mvn package command build includes all SOS modules.
  • Exception: Two profiles still exist, the oracle and sqlserver profiles, due to license restrictions with the required JDBC driver.
• Improved SQL exception handling
  • Instead of throwing only the topmost exception, a composite exception is created which contains all Throwables as a single exception.
  • All exceptions now contain sufficient information if a problem arises,  e.g. if the observation already exists.
    
• Changed samplingGeometry handling (SOS 2.0 Spatial Filtering Profile)
  • Instead of using a separate table, a geometry column was added to the observation table to store the samplingGeometry.
  • If samplingGeometries are contained in the database, GetObservation performance improves because no additional join (spatial filter) is necessary and the samplingGeometries must not be queried separately.
  • The SOS still supports the old concept with the separate table, but offers scripts to update the database model.
• Requirement for Java 7 and Java 8 support
  • The SOS now requires Java 7. There has been no more public support for Java 6 since April 2013. Using it could lead to security issues.
  • The 52°North SOS now also supports Java 8.
• Asynchronous cache serialization
  • This change fixes the issue that insert requests were getting slower when more data is available.

For further information about the functionality, improvements and fixed issues, please read the RELEASE-NOTES or visit the SOS GitHub issue page and the 52°North SOS 4.x wiki page.

A short outlook on future work

• Integrate work performed in the INSPIRE SOS context
  • coordinate transformation
  • multilingualism
• Implement support for SensorML 2.0
• Integration of the RESTful API and the Sensor Web JavaScript client
• Integration of sos.js for SOS 1.0.0 operations.
• …