es: 1. The slave-CNPC could just record that information in its own object resource model. Later, when the master-CNPC requests that a connection be set up to the CNU that uses that route, the slave-CNPC can just refuse to do so, referring to the blocking state of that route. No harm is done to system integrity. 2. Considering that blocking of resources is a rare phenomena, a more efficient method is to let the slave-CNPC report blocking and deblocking conditions of all the resources it manages to the master-CNPC as soon as it happens. This means that the master-CNPC will have to manage some knowledge of resource states even on the slave side. However, it also means that the master-CNPC need not bother the slave-CNPC with connection requests, in case it cannot succeed due to blocked resources. This reduces the need for communication between the two parts, without harming system integrity. As soon as an object resource model is partitioned to some extent, and each part handled by a part of the controlling object, we have a decentralized control solu- tion The solution in Fig. 6.29 means that a special substructure is defined for 6 Process Control System Modelling CNPC, where CNPC is divided into two service objects. These objects become abstract machines in the D-dimension, and communicate by a special abstract pro- tocol. The object resource model for CNPC is partitioned in some way, one part being handled by each of the objects. The service relation to TEPC will be handled by the master-CNPC alone. This means that TEPC, except for processing charac- teristics, will not be affected by whether the CNPC solution represents a central- ized or a decentralized control function. This also implies that, in an abstraction hierarchy, each service object can define its own solution to how control is shared between objects in its substructure. The CNPC is a service object of type agent. When an agent is given a substruc- ture based on fragmentation of its object resource model, we call the parts distrib- uted agents. A dist