For demonstration purposes, we have instrumented a commercial network management platform (IBM NetView for AIX 4.1 with TMN Support Facility) and a CMIP/SNMP MG developed by us [12] with CORBA-based management agents implemented in Java. The left part of Figure 4 depicts a CORBA/Java-based management environment: CORBA agents (here: for DNS and WWW servers and AIX SMIT) are remotely administered by means of a CORBA-enabled WWW browser. CORBAservices such as Events, Notification, Topology, Managed Sets and Policy (see e.g. [23]) provide the required management functionality in a location-independent way. However, only a small part of these important management services have been implemented until now. Fortunately, current management platforms (right part of Figure 4) contain components that have a very similar functionality to the CORBAservices mentioned above. We therefore decided to make the main platform components (Event Dispatcher, Topology Manager, State and Performance Monitors) accessible from CORBA and use them as a temporary replacement for currently specified, but not yet available CORBAservices. We have encapsulated the APIs of the MS with IDL wrappers (dark grey shaded arcs with black dots in Figure 4) which gives us the opportunity of reusing a large part of the MS functionality (e.g., event filtering, topology). By doing so, we create a conceptually integrated management information base on the platform where management-related information is collected and evaluated independent of the originating base architecture. This multiarchitectural manager is able to access managed objects in OSI/TMN, SNMP and CORBA environments.
On the other hand, the IDL wrappers also provide us with the management instrumentation of the MS and the MG via CORBA. Furthermore, the representation of AIX SMIT as CORBA objects gives us access to the static management information described in section 3.3. Together, they represent the managed objects identified in the previous sections. Our approach is in accordance with the TINA (Universal Service Component Model (USCM) [2]. The core of the MS and MG access layers are accessible either through the usage sector or through the server interfaces of the management sector; the latter has been provided by us. We are then able to manage the MS and MG via CORBA.
As we wanted to manage these systems from a web-based interface, we implemented the management application prototype as Java applets and used a commercial Java-ORB, VisiBroker for Java v. 3.0 (by Visigenic/Inprise). VisiBroker is also contained in the Netscape Communicator v. 4.5 web browser; we therefore expected that the application would load reasonably fast due to its modular design and the small size of the resulting Java classes (less than 10 kbyte per class). Unfortunately, Netscape Communicator contains only an earlier version of the Java-ORB we used, namely VisiBroker 2.5. Consequently, the Java classes for the ORB itself and its bundled CORBAservices (in total: a Java archive of 2.5 MB code size) always have to be loaded once per session into the browser first before any applet can be started.
On the other hand, the access to IBM NetView is only possible through C Application Programming Interfaces. We therefore had to build wrappers based on the Java Native Interface (JNI) around the C APIs in order to access them from Java. JNI has been developed for that purpose, thus enabling programs running under the control of the Java Virtual Machine to access other programs or libraries that have been written in C. The reason for choosing Java instead of C++ stems from the fact that we intend to copy parts of the management instrumentation between different MS at runtime.
