Overview

This section highlights critical edge cases and operational pitfalls observed in real-world SIBS Payment Gateway (SPG) integrations.

It focuses on non-obvious scenarios that can lead to:

• Incorrect transaction states
• Duplicate processing
• Inconsistent business actions

The goal is to ensure integrations remain robust under imperfect conditions, without duplicating patterns already covered in previous sections.

Delayed or Missing Webhooks

Scenario

• A transaction remains in Pending
• No webhook is received within the expected timeframe

Risk

• Transactions remain unresolved
• Business processes stall

Handling

• Do not rely exclusively on webhooks
• Use the Status API (GET <ROOT_URL>/api/v2/payments/{transactionID}/status) as fallback
• Include all non-final transactions in reconciliation routines

Out-of-Order State Updates

Scenario

• A Success state is processed
• A delayed webhook or internal process later reintroduces a Pending state

Risk

• Final states are overwritten
• Incorrect rollback of business actions

Handling

• Enforce forward-only state transitions
• Prevent overwriting of final states (Success, Declined)
• Maintain an explicit state hierarchy in the persistence layer

Duplicate Event Processing

Scenario

• The same webhook is delivered multiple times
• Status checks return identical states repeatedly

Risk

• Duplicate business actions (e.g., double fulfillment)
• Data inconsistencies

Handling

• Implement idempotent processing
• Track processed events using:
  • transactionID
  • Event identifiers (e.g., notification ID)
• Ensure downstream operations are safe to re-execute

Premature Business Actions

Scenario

• Business logic is triggered on:
  • Initial response
  • Pending state

Risk

• Orders fulfilled without confirmed payment
• Financial inconsistencies

Handling

• Trigger business actions only when paymentStatus = "Success"
• Treat Pending as a non-final state
• Explicitly separate:
  • Transaction creation
  • Transaction confirmation

Timeout Misinterpretation

Scenario

• A transaction reaches Timeout

Risk

• Treated as final failure
• Duplicate retry attempts

Handling

• Treat Timeout as an uncertain state, not a final failure
• Always confirm via Status API (GET <ROOT_URL>/api/v2/payments/{transactionID}/status)
• Include in reconciliation workflows

Duplicate Transaction Submission

Scenario

• Same logical transaction is submitted multiple times
• Network retries or client-side duplication

Risk

• Multiple transactions for the same intent
• Financial duplication

Handling

• Enforce uniqueness of merchantTransactionId
• Implement idempotent request logic
• Use Status API to retrieve existing transaction instead of recreating

Partial Completion in Multi-Step Flows

Scenario

• AUTH succeeds
• CAPTURE is delayed, retried, or fails

Risk

• Funds reserved but not collected
• Inconsistent financial state

Handling

• Track each phase independently
• Reconcile outstanding authorizations
• Implement clear lifecycle management for:
  • AUTH
  • CAPTURE

Long-Lived Pending Transactions

Scenario

• Transactions remain in Pending for extended periods (e.g., reference-based payments)

Risk

• Accumulation of unresolved transactions
• Operational blind spots

Handling

• Implement expiration or review policies
• Periodically reconcile all pending transactions
• Ensure business processes tolerate delayed completion

Inconsistent State Across Systems

Scenario

• Internal system state diverges from SPG state

Risk

• Incorrect reporting
• Reconciliation failures

Handling

• Treat SPG (via Status API GET <ROOT_URL>/api/v2/payments/{transactionID}/status) as source of truth
• Periodically reconcile internal data
• Log all state transitions for traceability

Summary

Edge cases in SPG integrations are primarily driven by:

• Asynchronous behavior
• Event delivery uncertainty
• Distributed system characteristics

Robust integrations must:

• Assume non-deterministic timing
• Enforce idempotency and state consistency
• Continuously reconcile and validate transaction state

Handling these scenarios correctly ensures:

• Reliable financial operations
• Consistent business outcomes
• Resilience under real-world conditions