Logistics Based Business Modelling

To understand and measure existing processes and to design the new processes Logistics Based Business Modelling (LBBM ) can be used (Gerrits [4]). LBBM takes a time based view of business processes, focusing on showing the product lead time  in information processing production processes. Gerrits defines product lead time as `the time that passes between the moment a customer orders a product and the moment the product is delivered'. A process is composed of operations . Each operation executes (sequentially  or parallel ) a part of the process. Operations need resources  to be executed. These resources, like employee's, computers, etc. have a limited capacity.

The production lead time consists of the following components:

• processing time , the time actually worked on a job, i.e. a customer order;
• queue time , the time a job waits for a resource to become available. Gerrits distinguishes two kinds of queue time: (1) capacity oriented queue time and (2) batch oriented queue time. The first is caused by the unbalance of demand and supply of capacity, the second by the periodic availability of resources that are operated in batch mode;
• setup time , the time that passes between the moment a resource comes available and the moment it is able to start the next job. When the setup time is relatively large it becomes efficient to combine similar jobs into larger jobs, leading to batch production. In information production the setup time of machines is much less important than the setup times of employees, that is, the employee needs time to assimilate to the case at hand;
• wait time , wait time occurs in processes with parallel operations  that at some point have to synchronize;
• transport time , time needed to move a job from a resource at a certain location to another resource at another location.

The modelling language of LBBM  uses the following objects to model business processes:

  
Figure 1: Operation, task and transport


• operation, an operation  processes data, it reflects the processing component of an information production process. An operation is atomic in the sense that wait time, queue time and transport time may not be part of an operation. Only setup time and process time are part of an operation. Furthermore, it is possible to define the pre- and post-conditions of an operation. The pre-condition describes the needed input data, the post-condition describes the produced output. Operations are represented as in figure 1;

• task, a task  is a series of consecutive operations that are executed by the same employee. Note that there is no wait time, queue time or transport time between the operations. The name or the function of the employee is written in the lower right corner of the rectangle. See figure 1;

• transport, information transport  between resources is denoted as in figure 1. Data flows are needed when information flows from one resource to another. The flow of data depicts the determinants of transport time and defines the sequence of operations in a process. Duplication  of data is denoted by splitting the arrow;

    
  Figure 2: Queue and wait time and organization unit
  

• queue and wait time, the same symbol for queue time  and wait time  is used, see figure 2. Conceptually, both represent a state of non-activity: no work is done on the case. If one information flow comes into a triangle, it is a queue, otherwise it is a combination of wait time and queue time.

• organization unit, figure 2 depicts the grouping of employees in organization units . This makes it possible to depict the different departments, involved in the execution of the process. That way boundaries between departments, often responsible for extra transport time, become visible;

    
  Figure 3: Choice, external agent, means and archive
  

• choice, points in the process where decisions  are made that result in different information flows are depicted as in figure 3;

• external agent, an external agent   is an external organization or person that acts as source or destination of data. Agents can either be external to the organization or to the business process at hand. Agents are denoted as in figure 3;

• means, means  are used by employees to perform operations. They are depicted because they influence the queue and set up times. Each time an employee has to change means to handle the case, a new operation is performed. See figure 3;

• archive, especially for describing paper flow processes, the archive  symbol is necessary. The availability of data is one of the sources of wait time . See figure 3;