Understanding Asynchronous and Synchronous Services in ThingWorx

ThingWorx offers two primary service execution models: synchronous and asynchronous. Choosing the right model for your service impacts performance and user experience. This article explores the differences between these models and provides an example to illustrate their functionalities.

Synchronous vs. Asynchronous Services

Synchronous Services: These are the default service type in ThingWorx. When a client (like a mashup or another service) calls a synchronous service, the execution blocks until the service finishes processing. The client waits for a response before continuing.

Asynchronous Services: In contrast, asynchronous services run in a separate thread after being called. The client receives immediate control flow back, allowing it to continue execution without waiting for the complete service operation. The client can potentially handle other tasks while the asynchronous service runs in the background.

Here’s a table summarizing the key differences:

Feature	Synchronous Service	Asynchronous Service
Execution	Blocks caller	Doesn’t block caller
Client Control Flow	Waits for service completion	Continues execution
Use Cases	Simple tasks, immediate response needed	Long-running tasks, improved responsiveness

Example: Temperature Sensor Reading with Alerts

Imagine a scenario where a temperature sensor sends readings to ThingWorx every minute. We can implement this logic using both synchronous and asynchronous services.

Synchronous Service:

1. The sensor calls a synchronous service to submit the reading.
2. The service logic validates and stores the reading.
3. If the reading exceeds a threshold, the service triggers an alert.
4. Once everything is complete, the service returns control to the sensor, which can now send the next reading.

Asynchronous Service:

1. The sensor calls an asynchronous service to submit the reading.
2. The service logic is queued for background execution.
3. The sensor immediately continues sending the next reading.
4. In the background thread, the asynchronous service validates and stores the reading.
5. If the reading exceeds a threshold, the service triggers an alert independently.

Choosing the Right Approach

• Use synchronous services when the operation is quick and a response is needed immediately, for example, fetching a simple configuration value.
• Choose asynchronous services for long-running tasks like sending emails, performing complex calculations, or triggering alerts based on sensor data. This improves the overall responsiveness of your ThingWorx platform.

Extra Considerations:

• Asynchronous services often require additional logic to notify the client about the completion or potential failure of the operation. You can achieve this through callbacks, events, or persistent storage of execution status.
• While asynchronous services improve responsiveness, extensive use can introduce complexity and potential for race conditions.

Understanding these differences and carefully choosing between synchronous and asynchronous services is crucial for designing efficient and user-friendly ThingWorx applications.