Performance, Scalability & Throughput

Latency SLOs · Throughput · HPA/VPA · Auto-scaling · Caching · Technical Debt

API / Operation	P50 SLO	P95 SLO	P99 SLO	Throughput Scale	Design Notes
Product Catalog Query	Very Low	Low	Sub-100ms	High — scale horizontally	In-Memory Cache-cached; cache TTL (configurable)
Subscriber Profile API	Very Low	Low	Sub-200ms	High — scale horizontally	DB read replica + In-Memory Cache L1 cache
Order Placement	Sub-500ms	Sub-second	<1 sec	Moderate — async capable	Async provisioning; sync validation only
Real-time Rating (CDR)	Very Low	Very Low	Low	Very High — stream processing	In-memory rate table; no DB on critical path
Invoice Generation	<2 sec	<5 sec	<10 secec	Batch — parallel per bill run	Async PDF generation; batch processing
Authentication (Token)	Very Low	Very Low	Low	High — scale horizontally	JWT validation cached; no DB lookup
Notification Dispatch	Sub-second	<2 sec	<5 sec	High — scale horizontally	Async event-driven; SLA is delivery time not dispatch

Auto-Scaling — HPA & VPA

Horizontal · Vertical · Event-driven · Predictive

HPAHorizontal Pod Autoscaler scales replica count based on CPU (target 60%), memory (target 70%), and custom metrics (queue depth, RPS). Scale-out: seconds (configurable). Scale-in: cool-down window (configurable) to prevent thrashing.

VPAVertical Pod Autoscaler recommends optimal resource requests/limits based on observed usage. Applied in "recommend" mode — actual requests set by platform team per sprint. Prevents right-sizing drift.

Event-driven autoscalingAutoscaling driven by event backlog for event-consumer services. Scale to zero when no events. Scale from zero rapidly on first event arrival. Mediation and notification services scale on event-stream consumer lag.

Predictive ScalingScheduled HPA rules pre-scale billing pods 30 min before month-end bill run. CDR ingestion pods pre-scale before known high-traffic windows (month-end, campaigns).

HPA VPA Event-driven autoscaling Scale-to-Zero

Technical Debt Management

Debt Registry · Fitness Functions · Code Quality Platform · DORA

Technical debt is a first-class engineering concern — not a backlog item to be deferred indefinitely. Unmanaged debt compounds: the cost of deferral increases non-linearly as systems scale.

Debt RegistryEvery known technical debt item is recorded with: description, impact assessment, estimated remediation effort, and owner. Registry reviewed in monthly architecture forum.

Fitness FunctionsAutomated architectural tests run on every CI build: no cross-service database calls, no shared libraries with circular dependencies, no deprecated API versions in use, test coverage ≥80%.

Code Quality GatesCode Quality Platform quality gate: 0 new critical bugs, 0 new security hotspots, <5% code duplication on new code, coverage ≥80% on new code. Pipeline fails if gate not met.

DORA MetricsDeploy frequency, Lead time for changes, MTTR and Change failure rate tracked per service. Shared dashboard visible to engineering and leadership. Targets reviewed quarterly.

Remediation BudgetMinimum 20% of each sprint allocated to technical debt remediation. This is non-negotiable — not traded away for feature velocity. Enforced at planning.

Debt Registry Fitness Functions Code Quality Platform DORA Metrics

Non-Functional Requirements — Summary Reference

NFR Category	Requirement	Target / Standard	Status
Availability	Platform availability SLO	99.99% (≈ minutes per year)	Mandatory
Latency	API P99 latency (tier-1 services)	< Sub-second P99	Mandatory
Throughput	CDR processing rate	Very High — stream processing sustained	Mandatory
RTO	Revenue-critical service recovery	<Minutes (Tier 0 — near-zero)	Mandatory
RPO	Maximum data loss window	Near-zero (Tier 0 — synchronous replication)	Mandatory
Security	Encryption in transit	TLS 1.3+ on external traffic, mTLS on all inter-service communication	Mandatory
Security	Encryption at rest	AES-256-GCM all data stores	Mandatory
Identity	Authentication protocol	OAuth 2.0 / OIDC + Workload Identity Standard workload identity	Mandatory
PII Compliance	GDPR — Right to Erasure SLA	Confirmed deletion within the regulatory SLA window	Mandatory
Resilience	Circuit breaker on all external calls	Error rate >50% in 10 s window triggers open	Mandatory
Idempotency	All financial mutation endpoints	Idempotency key + 24 h dedup store	Mandatory
Scalability	HPA on all stateless services	CPU target 60%, scale within a short cool-down window	Mandatory
Anti-Affinity	Pod distribution	Required: no two replicas on same node; Preferred: spread across AZs	Mandatory
Technical Debt	Sprint debt remediation allocation	Minimum 20% per sprint	Recommended
Observability	Distributed tracing coverage	100% of requests carry traceId; 10% sampled	Mandatory
CI/CD Security	SAST + SCA in every pipeline	Critical/High CVEs block merge	Mandatory

Performance & Scalability

Telecom

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