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sms-gateway

SMS gateway / OTP delivery

Twilio

SystemTechniques · 12Primitives · 46 sms-gateway Deterministic simulation testingdistributed · medium: Run the whole system in one thread under a seeded scheduler with simulated network, disk and clock, so every failure replays from its seed.›Durable job queuedistributed · medium: Persisted tasks that workers lease for a visibility timeout, ack on success and retry with backoff; at-least-once execution that survives worker and queue crashes.›Primary-backup replicationdistributed · medium: One node orders all writes and ships them to standbys; the acknowledgement rule (none, one, all) sets what a crash loses, and an external arbiter decides who takes over.›Least cost routingnetworking · medium: Pick carrier routes by prefix, price, quality and failoverWebhook deliverynetworking · medium: Reliable server-to-server HTTP callbacks: signed POSTs, 2xx-means-done, retries over days with jitter, endpoint disabling, SSRF guards and idempotent receivers.›Coverage-guided fuzzingsecurity · medium: Mutate inputs, run an instrumented target, and keep any input that reaches a new code edge; feedback turns blind guessing into incremental search.›Point-in-time recoverystorage · medium: Periodic base backups plus a continuously archived change log let you rebuild the state as of any instant, then branch from there.›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.›Exponential backoff with jittersystems · low: Retry after delays that grow geometrically and are randomized, so failed clients spread out instead of hammering a recovering service in synchronized waves.›E164 number parsingdata-structures · low: Parse, validate and normalize phone numbers to E.164Longest prefix matchnetworking · low: IP prefix lookup structures (DIR-24-8, Poptrie, LC-trie) for routes, ACLs and geo-IPCircuit breakersystems · low: Stop calling a failing dependency for a while, probe it with trial calls, and resume on recovery: fail fast instead of piling up timeouts.›Sliding-window counterssystems · low: Count events in the last W seconds with a ring of sub-bucket counters; the two-bucket weighted estimate gives rate limits in 16 bytes per key.›Hdr histogramdata-structures · low: Log-linear bucketed histograms with bounded relative error for latency percentilesProcess supervisionhardware-os · low: A parent process starts services, reaps their exits and restarts them under a delay and burst-limit policy, then stops them with SIGTERM before SIGKILL.›Smpp protocolnetworking · low: SMPP binds, submit_sm, delivery receipts and windowingSms encoding segmentationnetworking · low: GSM-7/UCS-2 encoding and concatenated SMS segmentation with UDHMessage authentication codes (HMAC,…security · low: A keyed short tag proving a message is unmodified and came from a key holder; pick HMAC, CMAC, KMAC or a one-time polynomial MAC by what primitive you already have.›Mutual TLSsecurity · low: TLS where the client also proves a certificate key, so every connection carries a verified, rotatable machine identity.›One-time codes (HOTP, TOTP)security · low: Short numeric codes derived from a shared secret plus a counter or the clock (HOTP, TOTP), or random codes sent by SMS or email; safe only with expiry, single use and attempt limits.›Graceful drainingsystems · low: On a termination signal, stop taking new work, finish in-flight work until a deadline, tell clients to reconnect elsewhere, then exit; clients resume from a token.›Token bucketsystems · low: A bucket of up to b tokens refilled at rate r; requests spend tokens, enforcing an average rate while allowing bursts of b.›Cooperative schedulingconcurrency · low: Green threads/coroutines yielding at await points on a user-space scheduler+ 5 more techniques+ 30 more primitives

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