## 2 Review of Literature
### The Proposal to Assess the Logistics Process Based on Five Steps  
The assessment of the reliability of the logistics process in any engineering system requires making five steps presented in the algorithm shown in Figure 3.  
The developed method allows for the assessment of reliability, taking into consideration the timeliness of the performed operations as well as the quality analysis of the messages transferred. In the first step of the method developed, the analyzed process should be characterized, thereby defining its purpose. Then, the sub-processes that make up this process should be identified by decomposing the process at Level I. In the Level II decomposition, individual activities should be identified, where operations (a set of activities or a single activity) and messages (containing data) that must be delivered to carry out certain operations are distinguished. Then, experimental studies should be carried out, which allow for determining the timely execution of all operations within the activities. The analysis of these activities consists of the analysis of the timely execution of individual operations, as well as the quality of the messages received. In the final step, on the basis of the studies carried out, the process reliability should be determined and assessed. The developed method is based on the model shown in Figure 4, which demonstrates that a message confirming the performance of this operation is needed before each operation is performed. In the model (Figure 5), the execution of the action depends on the correctness of the message. Should the data contained in this message be correct, the operation can be executed. However, if the message is incorrect or the message is missing important data, clarifying procedures must be performed. Only after these irregularities have been clarified can the operation continue. Figure 4: Operational model in any engineering system. Figure 5: Structure of an activity. Figure 3: Algorithm of the process reliability assessment method. Step 1-Characterization of the process  
The achievement of the intended goals by the system requires the implementation of several coordinated activities and the execution of a certain process [44; 45; 46; 47]. In the analyzed engineering system, the main process should be singled out and given a name. The purpose of the process should result from the tasks of the entire system, in line with the customer's requirements. The process input may comprise tangible resources, data and all other elements necessary for the functioning of the process. The process output comprises all the tangible and intangible elements that arise as a result of the functioning of this process. The supplier and customer may be a natural person or an institution supplying the process or collecting the result of its outcome. The owner of the process is most often the decision-maker who supervises the course and functioning of the entire process. The basic parameters for the assessment of the process under examination may include process duration, timely execution of the process, process quality and cost [48]. Step 2-Process decomposition--level I  
The process decomposition on level I consists of the decomposition of a process into sub-processes. The number of sub-processes depends on the characteristics of the analyzed process in the studied engineering system. In this step of the suggested method, it is assumed that the process decomposition at level I can contain merely verbal descriptions. Step 3-Process decomposition--level II  
In step 3, the sub-processes should be decomposed into actions necessary for the execution of the sub-processes. In this step, a process map should be developed, utilizing any process mapping tool (e.g., block process flow sheet, BPMN, etc.) that will allow for the identification of these actions. After their identification, operations (collection of activities) and messages (data set) should be distinguished as part of the execution of individual activities.