Asynchronous Processes using UML Activity Diagrams

Concepts

Threading

A thread is a path of execution within a program. It allows a program to operate more efficiently by performing multiple operations simultaneously. Each thread can run parts of the program code independently from other threads.

Asynchronous Processing

Asynchronous operations allow a program to initiate a task and move on to another without waiting for the task completion. The program's flow doesn't get blocked, and other operations can continue running in parallel.

Modeling Asynchronous Concepts in the UML Activity Diagram

We show the essence of threading and asynchronous processing in the provided UML activity diagram. These concepts are modeled:

• Threads using Swimlanes: Swimlanes help in segregating the actions performed by different actors. We use them here to model the threads. Each swimlane represents a separate path of execution (thread).

• Initial Node: It marks the start of the process in the activity diagram. From here, control flows into the first action.

• Action: An operation within a thread, signifying a step in the process.

• Fork Node: This node splits the control flow into two or more concurrent flows, indicating the creation of new threads or asynchronous actions.

• Asynchronous Actions: These are tasks initiated by the thread that can run independently of the thread's main flow.

• Acquire Lock Action: Before entering a critical section, a thread must acquire a lock to ensure mutual exclusion. This action represents an attempt by a thread to enter a protected section of code.

• syncObject (Object): This object is a synchronization mechanism (like a mutex or semaphore) that controls access to the critical section.

• Decision Node: This represents a point where the control flow is decided based on the condition of lock acquisition.

• Wait N ms Action: If the lock is not acquired, the thread waits for a specified time before retrying.

• Critical Section Activity: This activity is where the actual processing happens and cannot be executed by more than one thread simultaneously.

• Release Lock Action: Once the critical section activity is completed, the thread releases the lock, allowing other threads to enter the critical section.

• Join Node: This node brings together the concurrent flows, synchronizing the threads.

• Activity Final Node: This marks the end of the process modeled in the activity diagram.

Activity Diagram with Modeled Threads

Threads and asynchonous processing using UML activity diagrams

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