Projects

Verifiable implementation and operating decisions

Selected company contributions, decisions, and evidence within a verifiable scope.

Public Facility Reservations: Payment and Data Integrity

Improved application states, refunds, revenue aggregation, and supporting-document handling in a shared platform for parking passes, classes, and facility reservations.

Verified contribution window: Jul. - Sep. 2026

Role and scope

Backend and administration maintenance within a company team. These cases describe my verified changes, not sole ownership of the entire service.

A company-team contribution that strengthened server-side refund guards, narrow update paths, and aggregate calculations. No operational performance metric is disclosed.

Workflow

1. Application and state
2. Payment and refund
3. Reporting and cleanup

Key decisions

A shared boundary for refunds and cancellations

Added checks that lock the target record and revalidate existing refund requests, application state, and refundable amounts. Applied transaction rules to the relevant service methods and added rejection paths for duplicate requests.

Narrow updates to protect unrelated data

Separated vehicle edits into a dedicated service and SQL path so payment fields are not overwritten by that operation. Also added capacity checks before assignment confirmation.

Aggregation and document lifecycle

Aligned tax and net-amount calculations with aggregated payments and refunds. Connected document and preview-file cleanup to successful state updates and attachment-reference checks.

Verification: Reviewed my Java service, MyBatis SQL, and administration changes and confirmed their presence on the default branch. Refund guards, vehicle-only updates, and aggregate calculations are supported by code changes.
Limits: Company tests and production deployments were not rerun during this review. No throughput improvement or incident-reduction percentage is claimed without measurement.
Takeaway: State checks and amount calculations need a consistent server-side boundary. Database updates and file deletion have different failure behavior and require separate follow-up checks.

JavaSpringMyBatisMariaDBJSP

Public Parking: Applications, Draws, and Payment Workflows

Implemented parking features spanning applications, allocation draws, payments, and refunds, translating administration rules into server-side validation and payment-state handling.

Verified contribution window: Aug. - Sep. 2026

Role and scope

New parking functionality within a company team. Implementation and added test code are verified on development branches, not presented as a completed production rollout.

A development-branch contribution with rejection paths for applications, draws, and refunds plus mocked-payment tests. It is not represented as a completed production rollout.

Workflow

1. Application and draw
2. Ledger and validation
3. Refund and reconciliation

Key decisions

Make applications and draws verifiable

Applied dedicated transactions to applications and cancellations. Draw execution checks configuration and preparation, then rejects mismatched update counts, winner totals, or audit-record writes.

Validate external payment results

Recorded refund requests before external calls and compared transaction identifiers, amounts, and response states. Ambiguous results remain flagged for review instead of triggering unconditional refund retries.

Separate test behavior from real transactions

Required explicit runtime and enablement conditions for live payments. Added JUnit and Mockito rejection-path tests for environment confusion, amount mismatches, and missing refund configuration.

Verification: Reviewed my application, draw, refund, and payment-policy changes alongside the added JUnit and Mockito tests. External payment interactions are mocked in the reviewed test code.
Limits: The verified features are on development branches. Company CI and tests were not executed during this review, and production deployment, live-payment success rates, and load performance are not claimed.
Takeaway: A database transaction cannot make an external payment atomic. Request persistence, response validation, and reconciliation of uncertain outcomes need distinct handling.

JavaSpringMyBatisJSPJUnitMockito

Facility Contracts and Billing in a Legacy ASP System

Improved preallocated virtual-account assignment and deposit notifications in an existing Classic ASP contract and billing system, preserving compatibility with established business flows.

Verified contribution window: Jul. - Aug. 2026

Role and scope

Legacy web maintenance within a company team, focused on my account-assignment, deposit-date, and management-fee billing changes.

A legacy-maintenance contribution that improved account assignment and transaction-date validation while preserving existing contract and receipt records.

Workflow

1. Contract and assignment
2. Billing and notification
3. Deposit-date recording

Key decisions

Separate account reuse from new issuance

Restricted automatic issuance and connected reserve-and-finalize handling for a preallocated account pool. Reused existing assignments and added a release call when finalization fails.

Make database calls explicit

Used parameterized ADO commands and stored-procedure calls for account assignment, separating the target, purpose, and operator inputs and handling failures by processing stage.

Distinguish notification time from transaction date

Validated the transaction date in deposit notifications and used it when valid. Adjusted billing so the preallocated-account path does not repeatedly request new account issuance.

Verification: Reviewed my ASP changes for account assignment, ADO calls, and transaction-date validation, and confirmed default-branch presence. Bulk file moves and merges were not counted as new feature delivery.
Limits: This review covers application changes. Stored procedures on the company database, real deposit tests, and production deployment were not revalidated.
Takeaway: In a legacy system, continuity of contracts and receipt records can matter more than a rewrite. Distinguishing processing time from the actual transaction date is a small change with accounting consequences.

Classic ASPVBScriptADOSQL ServerPayment Integration