After file uploads (1 Oct), this post covers CDN/edge caching: why PoPs exist, Cache-Control, HTML vs fingerprinted assets, purge, Vary/privacy, TLS, origin shield, metrics and deploy interactions.

सिमान्तसञ्चयः: A Metrical Codification of Edge and CDN Caching (with English glosses)

What this post is about

Edge/CDN caching stores cacheable HTTP responses near users to cut latency and origin load. It is a different tier from in-process caches.

Topics covered

1. Origin offload and latency
2. Cache-Control / s-maxage
3. Immutable assets vs HTML
4. Purge and tags
5. Private responses and Vary
6. TLS at edge
7. Origin protection
8. Edge metrics
9. Blue-green / release interaction
10. Link to app-cache treatise

Sanskrit title

सिमान्तसञ्चयः = sīmānta-sañcayaḥ “cache at the boundary/edge”.

ग्राह्यम् / Keep

१. सत्यशीर्षाणि: correct Cache-Control
२. अङ्गुलिचिह्नसंपत्तिः: hashed static assets long TTL
३. purgeपथः: emergency invalidation
४. Varyगोप्यता: never cache one user for another
५. मूलगोपनम्: hide/protect origin
६. hitमापनम्: hit ratio and origin latency
७. HTML ह्रस्वTTL: short HTML cache on appshell

त्याज्यम् / Avoid

• cache personalized JSON publicly
• year-long HTML without fingerprint plan
• no purge tool for incidents

पदच्छेदः
दूरजनं यदि मूलं नित्यं स्पृशेत् तदा विलम्बो दाहश्च । सिमान्तसञ्चयस्तस्माद् समीपस्मृतिः ॥१॥

Word-for-word

Gloss table

English sense
A CDN or edge cache serves static and cacheable responses from points of presence near users so origin is not on every request path.

Context / topic
Topic: why edge cache. Distinct from app-memory cache (7 Sep).

वृत्तमिति: ८-८-८-८।

पदच्छेदः
Cache-Control सत्यं लेख्यं max-age s-maxage च । मौनकैशे जीर्णराज्यम् ॥२॥

Word-for-word

Gloss table

English sense
Origins must emit correct cache headers. Shared caches honor s-maxage; browsers honor max-age. Missing headers often mean accidental private caching or never caching.

Context / topic
Topic: cache headers as contract.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
विविक्तं HTML API पृथक् नीत्या । एकं year cache HTML भङ्गाय ॥३॥

Word-for-word

Gloss table

English sense
Fingerprinted static assets can be immutable long TTL. HTML entrypoints and personalized API JSON usually cannot. Mixing policies causes users to stick on old appshells.

Context / topic
Topic: asset fingerprint vs HTML.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
अमान्यकरणं purge tag version pathैः । केवलTTL आशा मन्दा ॥४॥

Word-for-word

Gloss table

English sense
Plan active invalidation (purge by URL or tag) for sudden content fixes. TTL-only is too slow for emergency corrections.

Context / topic
Topic: purge and surrogate keys.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
गोप्यं Cookie Authorization मा साझकैशे लिख्यताम् । Vary शीर्षं सत्यं वदेत् ॥५॥

Word-for-word

Gloss table

English sense
Authenticated or cookie-varying responses must be private or correctly Vary-keyed. Caching one user’s JSON for another is a privacy incident.

Context / topic
Topic: private vs public cache.

वृत्तमिति: एकादशाक्षराः पादाः।

पदच्छेदः
TLS समाप्तिः सिमान्ते मूलपथे वा स्पष्टा । मिश्रनीतिः प्रमाणपत्रभ्रमे ॥६॥

Word-for-word

Gloss table

English sense
Know where TLS ends and whether origin uses mTLS. Edge cert lifecycle still follows प्रमाणपत्रचक्रः.

Context / topic
Topic: TLS at edge. Links to certs (14 Sep).

वृत्तमिति: ८-८-८-८।

पदच्छेदः
मूलरक्षां shield rate limit WAF युक्तं कुर्यात् । CDN मा केवलं आशाकवचम् ॥७॥

Word-for-word

Gloss table

English sense
CDN is not a full security program. Still protect origin IPs, rate-limit and watch app authz.

Context / topic
Topic: origin hardening.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
मापनं hit ratio origin latency purge errors । अदृश्यसिमान्तः मिथ्याशान्तिः ॥८॥

Word-for-word

Gloss table

English sense
Monitor hit ratio, origin offload, purge failures and TLS errors at the edge.

Context / topic
Topic: CDN observability.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
नीलाहरितस्विचे cache bust नीतिं स्मर । जीर्णHTML स्विचं हन्ति ॥९॥

Word-for-word

Gloss table

English sense
On releases bump asset hashes and avoid long HTML cache so users are not stuck mid-deploy.

Context / topic
Topic: deploy interaction. Links to blue-green (19 Aug).

वृत्तमिति: ८-८-८-८।

पदच्छेदः
सञ्चयधर्मः अनुप्रयोगस्मृतिं वदति सिमान्तः जालसमीपं वदति । उभौ स्मृती भिन्नस्तराः ॥१०॥

Word-for-word

Gloss table

English sense
Application caches and edge caches are different tiers with different invalidation tools. Do not tune one and ignore the other.

Context / topic
Topic: link to सञ्चयधर्मः (7 Sep).

सन्धिः: सञ्चयः अन्तः; सिमान्तः बहिः।

वृत्तमिति: एकादशाक्षराः पादाः।

पदच्छेदः
शीर्षम् अमान्यं गोप्यं मूलरक्षा मापनं पञ्चकम् । एभिः सिमान्तसञ्चयः समीपसत्यसमन्वितः ॥११॥

Word-for-word

Gloss table

English sense
Five limbs: correct headers, active purge, private/public rules, origin protection and edge metrics.

Context / topic
Topic: checklist.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
इति सिमान्तसञ्चयसारः समीपसत्यसमन्वितः । मितं स्मरणं क्रियायोग्यं तन्त्रधर्मः स उच्यते ॥१२॥

Word-for-word

Gloss table

English sense
Closing: remember at the edge what is safe to remember and forget on purpose when truth changes.

Context / topic
Topic: close.

उपसंहारन्यायः: समीपं स्मर; गोप्यं मा; अमान्यं शीघ्रं कुरु।

वृत्तमिति: ८-८-८-८।

१. Why edge
२. Headers
३. HTML vs assets
४. Purge
५. Privacy/Vary
६. TLS
७. Origin guard
८. Metrics
९. Deploy link
१०. App-cache link
११. Five limbs
१२. Close

1. Prior: caching 2026-09-07; blue-green 2026-08-19; certs 2026-09-14; gateway 2026-08-12.
2. Domain: CDN and HTTP edge caching.
3. Bilingual word-for-word + sense.
4. Style: no em dash; no Oxford comma in English clauses.