Pull model of microservice interaction — what is it, pros and cons?

Pull-based interaction model of microservices is an approach where one service independently requests ("pulls") data or events from another service as needed.

How it works: Service A periodically or upon an event makes a request to Service B to get up-to-date information.

Advantages:

• Simplicity of implementation and control: the service decides when and what to request.
• Avoids redundant data, as data is requested on demand.
• Easier to control load by regulating the request frequency.

Disadvantages:

• Delays in data retrieval if requests are made at intervals.
• Possible overload with frequent requests.
• More difficult to implement reactive behavior, where services must respond instantly to changes.

Example: a reporting service periodically requests current metrics from data services instead of receiving them via push events.