Answer.

History of the Issue

With the transition to microservices architectures and distributed systems, the likelihood of errors occurring during interaction between services, as well as the complexity of handling them, has sharply increased. Early approaches often overlooked the instability of network interaction, resulting in large-scale incidents in production.

The Problem

The key issue is that complex failure scenarios, service degradations, and integration errors are insufficiently formalized in requirements. As a result, developers are forced to make decisions about error handling at their discretion, leading to a diversity of cases and difficulties in testing them.

The Solution

Effective error handling descriptions should include:

• Identification of error types (network failures, timeouts, failure of third-party services, business logic errors, data inconsistencies).
• Specification of response options for each type of error: retries, transaction rollbacks, functionality degradation, alerts, user messages.
• Introduction of clear scenarios for failover testing and graceful degradation, including non-specific and chain incidents.
• Documentation of contracts and error formats (e.g. standard JSON error response contract).

Key Features:

• Standardization of error handling templates across services.
• Validation of degradation scenarios and their alignment with the business.
• Provision of error tracing and logging for subsequent incident analysis.

Trick Questions.

Is it mandatory to describe technical error handling in requirements — isn’t this the developer's task?

It is mandatory. An unreflected error-handling policy often leads to operational errors and misunderstandings. A system analyst must discuss the behavior in case of errors.

Should cases that occur very rarely (e.g., partial loss of communication between services) be described?

Yes, because rarely occurring errors lead to the most complex incidents. Their consequences can be critical for the business.

Is it required to coordinate with the business the messages displayed to users in case of errors?

Yes. Correct, informative, but not excessive or alarming messages should be coordinated with the business; otherwise, the user experience and loyalty suffer.

Common Errors and Anti-patterns

• Describing only the happy path, ignoring failure scenarios.
• Not taking into account system degradation (fallback scenarios are not described).
• Uncoordinated or technically complex error messages for the user.

Real-life Example

Negative case: The project did not describe timeout handling scenarios between services. As a result of an unstable network, services "hung" without a response. Pros: Fast execution of main scenarios. Cons: Massive failures in production, negative feedback from clients, "manual" closure of incidents.

Positive case: The analyst described degradation and restart scenarios, retries, and correct messages. Pros: High service stability during failures, reduced number of incidents. Cons: More time spent on scenario architecture development.