Entities can have attributes associated with them. Attribute names must be unique, are case sensitive, and cannot contain spaces or blanks. Attribute values can be strings, numbers, or Java objects.

Each entity has two default attributes named Id and BirthTime. The Id value is a unique integer assigned (in sequence) when the entity is created, and the BirthTime value is the simulation clock time when the entity was created. You can add additional default attributes (along with their default values) to an entity type by using the Entity Types dialog box at design time. (See Figure 8.1.) Each new entity created of that type automatically has all the attributes defined on that entity type as shown in the Entity Types dialog box.

The Modifier block in your simulation model can also be used to add or modify entity attributes at simulation time. Other blocks are provided in Simulation Studio to read entity attribute values and use this information in their processing. Individual blocks are discussed in Appendix A: Templates.

As a simple example of using entity attributes, consider the scenario where you want to model an electronics repair shop. Your entities could represent customers coming into the repair shop. You could assign attributes to each of these customers to represent (i) what type of equipment the customer needs to have repaired; (ii) an indicator of the severity of the problem; and (iii) warranty information. You could then use these attributes to route customer entities to different technicians in the shop depending on the values of the attributes. You could use the severity attribute to calculate a time-to-repair value.

Attributes are intended to give your entities unique characteristics that you can use to make your simulation model more representative of the system that you are investigating.