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Mesh v2 AWS Cost Breakdown

This document details the per-operation AWS costs for the Mesh v2 infrastructure, based on the production configuration values.

AWS Pricing (ap-northeast-1, Tokyo Region)

Service Unit Price
AppSync Query/Mutation per request $0.000004
AppSync Real-time Update (Subscription delivery) per message $0.000002
AppSync Real-time Connection per minute $0.00000008
DynamoDB Write Request Unit (WRU) per WRU (1KB) $0.000001425
DynamoDB Read Request Unit (RRU) per RRU (4KB) $0.000000285
DynamoDB Transactional Write per WRU (1KB) $0.00000285 (2x)
DynamoDB Transactional Read per RRU (4KB) $0.00000057 (2x)
DynamoDB Storage per GB/month $0.285
Lambda Request per request $0.0000002
Lambda Duration (128MB) per ms $0.0000000017

Note: DynamoDB On-Demand pricing. Transactional operations cost 2x normal.

Production Configuration

Parameter Value Description
MESH_HOST_HEARTBEAT_INTERVAL_SECONDS 60 Host heartbeat interval
MESH_HOST_HEARTBEAT_TTL_SECONDS 150 Host group TTL
MESH_MEMBER_HEARTBEAT_INTERVAL_SECONDS 120 Member heartbeat interval
MESH_MEMBER_HEARTBEAT_TTL_SECONDS 600 Member node TTL
MESH_MAX_CONNECTION_TIME_SECONDS 2100 Max group lifetime (35 min)
MESH_EVENT_TTL_SECONDS 10 Event auto-deletion TTL
MESH_POLLING_INTERVAL_SECONDS 2 Polling interval for HTTPS clients

Client-Side Rate Limits

Parameter Default Description
MESH_DATA_UPDATE_INTERVAL_MS 1000ms Sensor data send interval (with merge)
MESH_EVENT_BATCH_INTERVAL_MS 1000ms Event batch send interval
MESH_PERIODIC_DATA_SYNC_INTERVAL_MS 15000ms Periodic data sync interval (HTTPS only)

One-Time Operations

Create Domain

User action: Click "Create Group" or "Join Group" (first time, domain not set).

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
Lambda Invocation 1 $0.0000002 $0.0000002
Lambda Duration (~50ms) 50ms $0.0000000017/ms $0.000000085
DynamoDB 0 - $0
Total $0.000004285

Pure computation (CRC32 hash of source IP). No DynamoDB operations.

Create Group

User action: Click "Create Group" button.

Pipeline: checkExistingGroup (Query) -> createGroupIfNotExists (PutItem)

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
DynamoDB Query (check existing) 1 $0.000000285 $0.000000285
DynamoDB Write (PutItem, ~300B) 1 WRU $0.000001425 $0.000001425
Total $0.00000571

If the group already exists (idempotent retry), the PutItem becomes a GetItem (1 RRU) instead. Item size: ~300 bytes (group metadata with timestamps, TTL, GSI attributes).

Join Group

User action: Click "Join" button on a group.

Pipeline: checkGroupExists (GetItem) -> joinGroupFunction (TransactWriteItems: 2 PutItems)

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
DynamoDB Read (GetItem, group check) 1 RRU $0.000000285 $0.000000285
DynamoDB Transactional Write (2 PutItems, ~150B each) 2 WRU $0.00000285/WRU $0.0000057
Total $0.000009985

TransactWriteItems atomically creates: (1) group-node mapping, (2) node-group reverse mapping.

Leave Group (Member)

User action: Click "Disconnect" button (as member).

Lambda: leaveGroup -> TransactWriteItems (2 DeleteItems) + DeleteItem (status)

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
Lambda Invocation 1 $0.0000002 $0.0000002
Lambda Duration (~100ms) 100ms $0.0000000017/ms $0.00000017
DynamoDB Transactional Write (2 DeleteItems) 2 WRU $0.00000285/WRU $0.0000057
DynamoDB Write (DeleteItem, status) 1 WRU $0.000001425 $0.000001425
Total $0.000011495

Dissolve Group (Host)

User action: Click "Disconnect" button (as host).

Lambda: dissolveGroup -> GetItem + Query + N x DeleteItem

For a group with M members (each member has node record + status = 2 items, plus 1 metadata item, plus M reverse-lookup items):

  • Group items to delete: 1 (metadata) + M (node records) + M (node statuses) = 1 + 2M items
  • Reverse-lookup items to delete: M items
  • Total DeleteItems: 1 + 3M

Example: group with 5 members:

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
Lambda Invocation 1 $0.0000002 $0.0000002
Lambda Duration (~200ms) 200ms $0.0000000017/ms $0.00000034
DynamoDB Read (GetItem, group check) 1 RRU $0.000000285 $0.000000285
DynamoDB Read (Query, list items) ~11 RRU $0.000000285 $0.000003135
DynamoDB Write (16 DeleteItems) 16 WRU $0.000001425 $0.0000228
Total (5 members) $0.00003076

Cost scales linearly with member count. Formula: ~$0.000004 + $0.000004275 x M

Periodic Operations (During Active Session)

Host Heartbeat (renewHeartbeat)

Timing: Every 60 seconds while group is active.

Pipeline: checkGroupExists (GetItem) -> renewHeartbeatFunction (UpdateItem)

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
DynamoDB Read (GetItem, group check) 1 RRU $0.000000285 $0.000000285
DynamoDB Write (UpdateItem, ~50B) 1 WRU $0.000001425 $0.000001425
Per heartbeat $0.00000571
Per minute $0.00000571
Per hour $0.0003426

Member Heartbeat (sendMemberHeartbeat)

Timing: Every 120 seconds per member while connected.

Pipeline: checkGroupExists (GetItem) -> updateNodeTTL (UpdateItem)

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
DynamoDB Read (GetItem, group check) 1 RRU $0.000000285 $0.000000285
DynamoDB Write (UpdateItem, ~50B) 1 WRU $0.000001425 $0.000001425
Per heartbeat $0.00000571
Per minute (per member) $0.000002855
Per hour (per member) $0.0001713

Variable Update (reportDataByNode)

Timing: Up to every 1 second per node (rate-limited by dataRateLimiter). With merge enabled, rapid updates to the same variable are batched into a single request.

Pipeline: checkGroupExists (GetItem) -> reportDataByNode (PutItem)

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
DynamoDB Read (GetItem, group check) 1 RRU $0.000000285 $0.000000285
DynamoDB Write (PutItem, ~250-400B) 1 WRU $0.000001425 $0.000001425
Per request $0.00000571
Per second (worst case) $0.00000571
Per minute (worst case) $0.0003426
Per hour (worst case) $0.020556

"Worst case" = continuous updates every second (e.g., a forever block setting a variable). With merge, if the same variable is updated multiple times within 1 second, only 1 request is sent.

WebSocket Subscription Delivery (Receiver Side)

Each reportDataByNode triggers a subscription message to all subscribed nodes in the group.

Billable Element Count Unit Cost Subtotal
AppSync Subscription message 1 per subscriber $0.000002 $0.000002
Per request (N subscribers) $0.000002 x N

Polling Sync (HTTPS Polling Mode) — issue #554 で統合

Timing: Every 2 seconds (MESH_POLLING_INTERVAL_SECONDS) per polling client. Uses the pollGroupData Pipeline Resolver which performs 2 DynamoDB Query operations internally (events + node statuses) but is billed as 1 AppSync request.

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
DynamoDB Read (events Query, limit 100) 1-3 RRU $0.000000285 $0.000000855
DynamoDB Read (nodeStatuses Query) 1-10 RRU $0.000000285 $0.00000285
Per poll $0.0000077
Per minute (30 polls) $0.000231
Per hour $0.01386

WebSocket mode does not use this polling. WebSocket receives subscription messages instead and uses Periodic Data Sync (below) as a 15-second fallback to refresh node statuses.

Why a single Pipeline Resolver

Issue #554 で getEventsSince (2s) と listGroupStatuses (15s, startPeriodicDataSync 経由) を pollGroupData Pipeline Resolver に統合。 AppSync は Pipeline 内の Function 数に関係なく 1 リクエスト = 1 op として課金されるため、AppSync コスト観点では 約 12% 削減:

  • Old: getEventsSince (30/min) + listGroupStatuses (4/min) = 34 ops/min
  • New: pollGroupData (30/min) = 30 ops/min

DynamoDB の RCU 消費はノードステータス取得頻度が 15s → 2s に増えるため わずかに増加 (per-poll で +0.5x の RRU)。ただしリアルタイム性向上のメリット (同期遅延 15s → 2s) で相殺される設計。

Periodic Data Sync (WebSocket Mode のみ)

Timing: Every 15 seconds per WebSocket client. Uses listGroupStatuses to refresh node statuses (subscription の取りこぼし時のフォールバック)。

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
DynamoDB Read (Query) 1-10 RRU $0.000000285 $0.00000285
Per sync $0.00000685
Per minute (4 syncs) $0.0000274
Per hour $0.001644

Polling モードでは pollGroupData が同じ役割を果たすため、startPeriodicDataSync はスキップされる (issue #554)。

Event Send (fireEventsByNode / recordEventsByNode)

Timing: Batched every 1 second (eventBatchInterval). Max 100 events per queue.

WebSocket Mode: fireEventsByNode

Uses None DataSource (pass-through). No DynamoDB operations.

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
DynamoDB 0 - $0
Per batch $0.000004
Per second (worst case) $0.000004
Per minute (worst case) $0.00024
Per hour (worst case) $0.0144

HTTPS (Polling) Mode: recordEventsByNode

Uses Lambda + DynamoDB BatchWriteItem. Events are stored temporarily (TTL = 10 seconds).

For a batch of E events:

Billable Element Count Unit Cost Subtotal
AppSync Request 1 $0.000004 $0.000004
Lambda Invocation 1 $0.0000002 $0.0000002
Lambda Duration (~100ms) 100ms $0.0000000017/ms $0.00000017
DynamoDB Read (GetItem, group check) 1 RRU $0.000000285 $0.000000285
DynamoDB Write (BatchWriteItem) E WRU $0.000001425 $0.000001425 x E
Per batch (E events) $0.000004655 + $0.000001425 x E

Example: 5 events per batch = $0.00001178

Subscription Delivery (Receiver Side)

Billable Element Count Unit Cost Subtotal
AppSync Subscription message 1 per subscriber $0.000002 $0.000002
Per event batch (N subscribers) $0.000002 x N

Event Receive (HTTPS Polling Mode)

Same as Polling Sync (HTTPS Polling Mode) above — the unified pollGroupData query (issue #554) fetches both events and nodeStatuses per poll. See the table in that section for billing.

WebSocket Connection

Timing: Continuous while connected to subscription.

Billable Element Count Unit Cost Subtotal
AppSync Connection per minute $0.00000008 $0.00000008
Per hour $0.0000048
Per 35-min session $0.0000028

DynamoDB Storage

Items are automatically deleted by DynamoDB TTL. Active storage is minimal.

Item Type Size TTL Count (per group)
Group metadata ~300B Host heartbeat TTL (150s) 1
Node record ~150B Member heartbeat TTL (600s) M (members)
Node status (sensor data) ~250-400B Member heartbeat TTL (600s) M (members)
Node reverse-lookup ~150B Member heartbeat TTL (600s) M (members)
Event record ~150B Event TTL (10s) transient

For a group with 5 members: ~1 + 5 x 3 = 16 items, ~3.5KB total.

DynamoDB storage cost: $0.285/GB/month. Even 10,000 concurrent groups (~35MB) = $0.01/month.

Scenario Cost Estimates

Scenario: 1 Group, 5 Members, WebSocket Mode, 35-min Session

Assumptions:

  • Host sends heartbeat every 60s (35 heartbeats)
  • 5 members send heartbeat every 120s (5 x 17 = 85 heartbeats)
  • 3 nodes actively updating variables every 1s for 10 min (3 x 600 = 1800 reportData)
  • 50 event batches total (10 per node average)
  • All 5 members subscribed to messages
Operation Count Unit Cost Subtotal
Setup
createDomain 1 $0.000004285 $0.000004
createGroup 1 $0.00000571 $0.000006
joinGroup 5 $0.000009985 $0.000050
Heartbeats
renewHeartbeat (host) 35 $0.00000571 $0.000200
sendMemberHeartbeat 85 $0.00000571 $0.000485
Data
reportDataByNode 1800 $0.00000571 $0.010278
Subscription delivery 1800 x 4 $0.000002 $0.014400
Events
fireEventsByNode 50 $0.000004 $0.000200
Subscription delivery 50 x 4 $0.000002 $0.000400
Teardown
dissolveGroup (5 members) 1 $0.00003076 $0.000031
WebSocket Connection
6 connections x 35 min 210 min $0.00000008 $0.000017
Total $0.026071

Scenario: 1 Group, 5 Members, HTTPS Polling Mode, 35-min Session (issue #554 後)

Same assumptions, but using HTTPS polling instead of WebSocket. pollGroupData (issue #554) で events と nodeStatuses を 1 リクエストに統合。

Operation Count Unit Cost Subtotal
Setup
createDomain 1 $0.000004285 $0.000004
createGroup 1 $0.00000571 $0.000006
joinGroup 5 $0.000009985 $0.000050
Heartbeats
renewHeartbeat (host) 35 $0.00000571 $0.000200
sendMemberHeartbeat 85 $0.00000571 $0.000485
Data
reportDataByNode 1800 $0.00000571 $0.010278
Events
recordEventsByNode (5 events/batch) 50 $0.00001178 $0.000589
Polling
pollGroupData (5 clients x 30/min x 35 min) 5250 $0.0000077 $0.040425
Teardown
dissolveGroup (5 members) 1 $0.00003076 $0.000031
Total $0.052068

issue #554 前後の比較

Old (getEventsSince + listGroupStatuses) New (pollGroupData) 変化
AppSync requests / poll cycle 2 (events 30/min + status 4/min) 1 (30/min) -12%
Data sync 遅延 最大 15s 最大 2s -87%
Polling 行 (5 clients × 35min) cost $0.025489 + $0.004795 = $0.030284 $0.040425 +33% (DynamoDB RRU 増)
35min session total $0.041927 $0.052068 +24%

リアルタイム性 (15s → 2s) を取った分 DynamoDB の RRU が増加するが、 AppSync request 数自体は減っている。WebSocket モードと比較すると依然 60% 程度高い。WebSocket が使える環境では引き続き WebSocket を優先する。

Cost Summary by Billing Component

Per Group Per Hour (WebSocket, 5 Members, Active Use)

Component Cost/hour Percentage
AppSync Requests (mutations) $0.0154 21%
AppSync Subscriptions (delivery) $0.0259 36%
AppSync Connections $0.0000288 0%
DynamoDB Writes $0.0148 20%
DynamoDB Reads $0.0017 2%
Lambda $0.00015 0%
Total ~$0.058/hour 100%

Key Cost Drivers

  1. Variable updates (reportDataByNode) - Dominant cost when nodes actively update variables. Each update costs $0.00000571 (AppSync + DynamoDB). With 5 members continuously updating: ~$0.03/hour.

  2. Subscription delivery - Each mutation triggers delivery to N-1 other subscribers at $0.000002 each. For frequent updates, this becomes significant.

  3. HTTPS Polling - If using polling instead of WebSocket, the getEventsSince query every 2 seconds per client adds ~$0.009/hour per client.

  4. Heartbeats - Minimal cost. Host heartbeat: $0.00034/hour. Member heartbeat: $0.00017/hour per member.

Appendix: GraphQL Operations Reference

Operation Type Resolver DynamoDB Operations Lambda
createDomain Mutation Lambda None Yes
createGroup Mutation Pipeline (JS) 1 Query + 1 PutItem No
joinGroup Mutation Pipeline (JS) 1 GetItem + 1 TransactWrite (2 PutItems) No
leaveGroup Mutation Lambda 1 TransactWrite (2 Deletes) + 1 DeleteItem Yes
dissolveGroup Mutation Lambda 1 GetItem + 1 Query + (1+3M) DeleteItems Yes
renewHeartbeat Mutation Pipeline (JS) 1 GetItem + 1 UpdateItem No
sendMemberHeartbeat Mutation Pipeline (JS) 1 GetItem + 1 UpdateItem No
reportDataByNode Mutation Pipeline (JS) 1 GetItem + 1 PutItem No
fireEventsByNode Mutation Pipeline (JS) 1 GetItem + None (pass-through) No
recordEventsByNode Mutation Lambda 1 GetItem + BatchWrite (E items) Yes
listGroupsByDomain Query Direct (JS) 1 Query No
listGroupStatuses Query Direct (JS) 1 Query No
listNodesInGroup Query Direct (JS) 1 Query No
searchGroupsByNamePrefix Query Direct (JS) 1 Query (GSI) No
getEventsSince Query Direct (JS) 1 Query No
getNodeStatus Query Pipeline (JS) 2 GetItems No