nts in time. The differences are mainly due to how they view MOs. While CMIS/CMIP identifies the operations to be performed on MOs, SNMP defines only read and write operations on variables, for example: Get-request, an operation that requests the value of one or more variables. Set-request, updates one or more variables. Note that these are SNMP messages (not primitives) since SNMP defines no SNMP-SAG. 5 Management and Traffic Systems One thing they all have in common, however, is that they define and handle spontaneous reports from the traffic system in ways that are different from how they define any other MO and operations. The reason is: the view that standards take on interactions between distributed objects is confused with how objects com- municate in OO software systems. In AMLs we have no problems with that, since AMLs objects are abstract objects that are not restricted to being software objects. AMLs operation classes can therefore comprise several forms of operations where an object spontaneously generates events (se Appendix D). Figure 5.9 shows an AMLn scenario of this kind. Alarm alarmReport(...) threshholdReport(..) Remote Fig. 5.9 Spontaneous events, the REPORT operation in AMLn. MS=management system; TS=traffic system In this model we have assumed that the AMF autonomously monitors and main- tains some resource R. In an earlier phase (not shown here), the OSF has told the AF that if a certain threshold value on some property of R is reached, the AF must send an alarmReport to the OSF. As a result, the AF informs AMF about the thresh- old value (also not shown here). The following scenario tells what happens then: 1. Every time the AMF changes R, or detects a state change of R, it compares the new state to the stored threshold value. 2. If the threshold value is reached, the AMF will alert the AF via a local threshold- Report event. 3. The AF may realize a special alarm MO, or define a REPORT operation as part of an MO that represents R. In any case, the MO generates an alarmReport event to the O