If you have applications that use the REST API, you will need to make changes to certificate validation.  For information about these changes, see

http://www.ibm.com/support/knowledgecenter/SSCRJU_4.0.0/com.ibm.streams.install.doc/doc/ibminfospherestreams-migrating-applications-rest.html.

Streams 4.0 introduces a set of Java™ Management Extensions (JMX) APIs to provide programmatic access to configuration and status information for Streams objects, such as a domain and its instances, jobs, and resources. You can manage and monitor these objects by using a set of JMX beans.  For information about using these new APIs, see

http://www.ibm.com/support/knowledgecenter/SSCRJU_4.0.0/com.ibm.streams.dev.doc/doc/jmxapi-dev.html.