LOTOS

LOTOS (Language of Temporal Ordering Specifications) is a formal specification language that allows expressing processes and process compositions.

There is a wide set of operators with which very interesting behaviors and process interactions can be obtained. But first, we'll start from the basics.

The basic process is an event, and an event is a communication through a gate, for instance, receiving through a gate g an integer value x

g?x:int

or providing as output "hello" through the gate h

h!"hello"

Notice that we represent input with a question mark and output with an exclamation mark. In addition, when g receives the value within x, the variable x is locally accessible to the following events.. but now we ask ourselves, how to add events?

The simplest case is the sequential composition, obtained with the semicolon (;)

for instance

g?x:int; g!x

this process receives an int value, and then outputs it through the same gate

Different gates and variables could be involved. For instance

g?x:int; g?y: string; h!concat(y, " world"); f!x+2

In the next LOTOS post I will discuss choice (choosing between enabled behaviors)

A Lotus flower