← Back
Home › Systems › Payments and commerce

ach

ACH batch payment clearing and netting

FedACH, The Clearing House EPN, EBA STEP2

SystemTechniques · 6Primitives · 36 ach Batch checkpoint restartdistributed · medium: Large batch jobs (end-of-day, settlement, payroll runs) that checkpoint and restart idempotentlyMultilateral nettingfinance · medium: Netting obligations across many parties into one net position per participant per currencyPayment state machinefinance · medium: Persisted state machine for a payment lifecycle (authorize, capture, void, refund) that treats timeouts as unknown, retries with the same key and applies webhooks idempotently.›Real time gross settlementfinance · medium: Per-payment final settlement against prefunded central-bank or settlement-bank balancesExternal merge sortsearch-sort · medium: Sort data larger than RAM: write memory-sized sorted runs, then k-way merge them with large sequential buffers; terabytes in one merge pass.›Hardware security module (HSM)security · medium: A tamper-resistant device or service that generates keys, signs, decrypts and wraps with them internally, and releases a key only as ciphertext.›Idempotency keysfinance · low: Client-chosen unique key per logical operation, stored with a request fingerprint and the final response, so retries replay the first result instead of acting twice.›Double-entry ledgerfinance · low: Append-only journal of transactions whose postings sum to zero per currency; balances are derived, so money can only move, never appear or vanish.›Iso 20022 messagesfinance · low: ISO 20022 XML payment and securities messages (pacs, pain, camt, sese): structure and validationGapless sequence numbersstorage · low: Gap-free, monotonic numbering (invoices, journal entries) under concurrency and rollbacksMoney representationfinance · low: Store money as integer minor units with an explicit currency exponent, compute in wider integers, and round once with a named rounding mode.›Reconciliationfinance · low: Match internal ledger records against bank and processor statements by reference, then amount and date window; every unmatched or mismatched item becomes an exception.›Fuzzy string matchingsearch-sort · low: Edit distance, Jaro-Winkler and trigram indexes for approximate name and address matchingDigital signatures (Ed25519)security · low: Small, fast, deterministic public-key signatures that prove who produced a message; the default for tokens, releases and protocols.›Mutual TLSsecurity · low: TLS where the client also proves a certificate key, so every connection carries a verified, rotatable machine identity.›Fixed width record parsingstorage · low: Parse fixed-column records by field offset and length: padding, implied decimals, packed decimal, record-type discriminators, batch control totalsBusiness day calendarssystems · low: Holiday calendars, business-day adjustment rules (following, modified following) and settlement cyclesCalendar date arithmeticsystems · low: Civil dates, time zones (tzdb), DST gaps, month-end anchoring and duration mathWrite-ahead logstorage · low: Append each change to a checksummed sequential log and fsync it before touching data pages; the basis of crash durability in nearly every database.›Cron schedulingsystems · low: Cron expression parsing and next-fire-time computation, with catch-up and time-zone rulesHash aggregationstorage · low: GROUP BY via hash tables with partitioning and spill to diskEvent sourcingfinance · low: Persist state changes as an append-only stream of immutable events per entity; current state is a fold over them, guarded by expected-version appends.›+ 20 more primitives

Similar systems

Share the most building blocks with this one.

realtime-payments 46 %rtgs 41 %payroll 36 %treasury 35 %securities-settlement 33 %