# **XXL System 20 — Distributed Configuration Snapshot & Time‑Travel Platform** (version snapshots • diffs • rollback • time‑travel queries)
# **Step 1 — Architecture Map (XXL Config Snapshot Platform)**
### **1. Config Model**
- config ID
- config value
- metadata
- version
### **2. Snapshot Model**
- snapshot ID
- config version
- timestamp
- diff
### **3. Diff Engine**
- line‑by‑line diff
- structural diff
- JSON diff
### **4. Time‑Travel Engine**
- get config at timestamp
- get config at version
- diff between versions
### **5. Rollback Engine**
- restore version
- restore snapshot
- restore timestamp
### **6. Promotion Engine**
- promote config from dev → staging → prod
### **7. Audit Engine**
- config changes
- snapshot creation
- rollback events
### **8. Storage Engine**
- version store
- snapshot store
- diff store
### **9. API Layer**
- set config
- get config
- diff versions
- snapshot
- rollback
### **10. System Orchestrator**
- start diff engine
- start snapshot engine
- start audit engine
- unified MAIN
---
# **Step 2 — Core Types & Shared Primitives**
```nxd
MODULE cfg.types
TYPE RESULT UNION { OK(any), ERR(string) }
TYPE OPTION UNION { SOME(any), NONE }
TYPE TIMESTAMP int
TYPE CONFIG {
ID: string,
VALUE: string,
VERSION: int,
TS: TIMESTAMP
}
TYPE SNAPSHOT {
ID: string,
CFG: string,
VERSION: int,
DIFF: string,
TS: TIMESTAMP
}
TYPE AUDIT {
KIND: string,
CFG: string,
MESSAGE: string,
TS: TIMESTAMP
}
TYPE CHANNEL_STRING CHANNEL<string>
```
---
# **Step 3 — Shared Utilities**
```nxd
MODULE cfg.util
FUNC NOW(): TIMESTAMP:
RETURN CURRENT_TIME()
FUNC LOG(MSG: string):
PRINTLN("[CFG] " ADD MSG)
FUNC GEN_ID(P: string): string:
RETURN P ADD "-" ADD RANDOM_STRING(8)
```
---
# **Step 4 — Config Store**
```nxd
MODULE cfg.store
IMPORT cfg.types
IMPORT cfg.util
LET CONFIGS SET MAP<string,LIST<CONFIG>> {}
FUNC SET_CFG(ID: string, VAL: string):
LET V SET 1
IF CONFIGS HAS ID:
V SET CONFIGS[ID][LEN(CONFIGS[ID])-1].VERSION ADD 1
LET C SET CONFIG {
ID: ID,
VALUE: VAL,
VERSION: V,
TS: NOW()
}
IF NOT (CONFIGS HAS ID):
CONFIGS[ID] SET []
PUSH CONFIGS[ID], C
LOG("config updated: " ADD ID ADD " v" ADD TO_STRING(V))
RETURN C
FUNC GET_CFG(ID: string): OPTION:
IF NOT (CONFIGS HAS ID): RETURN NONE
RETURN SOME(CONFIGS[ID][LEN(CONFIGS[ID])-1])
```
---
# **Step 5 — Diff Engine**
```nxd
MODULE cfg.diff
IMPORT cfg.types
IMPORT cfg.util
FUNC DIFF(A: string, B: string): string:
LET LA SET SPLIT(A,"\n")
LET LB SET SPLIT(B,"\n")
LET OUT SET ""
LET MAX SET MAX(LEN(LA),LEN(LB))
LOOP I IN RANGE(0,MAX):
LET L1 SET ""
LET L2 SET ""
IF I LT LEN(LA): L1 SET LA[I]
IF I LT LEN(LB): L2 SET LB[I]
IF L1 NE L2:
OUT SET OUT ADD "- " ADD L1 ADD "\n"
OUT SET OUT ADD "+ " ADD L2 ADD "\n"
RETURN OUT
```
---
# **Step 6 — Snapshot Engine**
```nxd
MODULE cfg.snap
IMPORT cfg.types
IMPORT cfg.util
IMPORT cfg.store
IMPORT cfg.diff
LET SNAPS SET LIST<SNAPSHOT> []
FUNC SNAPSHOT(ID: string): RESULT:
MATCH GET_CFG(ID):
CASE NONE: RETURN ERR("no such config")
CASE SOME(C):
LET PREV SET ""
IF C.VERSION GT 1:
LET P SET CONFIGS[ID][C.VERSION-2]
PREV SET P.VALUE
LET D SET DIFF(PREV,C.VALUE)
LET S SET SNAPSHOT {
ID: GEN_ID("snap"),
CFG: ID,
VERSION: C.VERSION,
DIFF: D,
TS: NOW()
}
PUSH SNAPS, S
LOG("snapshot created: " ADD S.ID)
RETURN OK(S)
```
---
# **Step 7 — Time‑Travel Engine**
```nxd
MODULE cfg.time
IMPORT cfg.types
IMPORT cfg.util
IMPORT cfg.store
FUNC AT_VERSION(ID: string, V: int): OPTION:
IF NOT (CONFIGS HAS ID): RETURN NONE
LOOP C IN CONFIGS[ID]:
IF C.VERSION EQ V: RETURN SOME(C)
RETURN NONE
FUNC AT_TIME(ID: string, TS: TIMESTAMP): OPTION:
IF NOT (CONFIGS HAS ID): RETURN NONE
LET BEST SET NONE
LOOP C IN CONFIGS[ID]:
IF C.TS LE TS:
BEST SET SOME(C)
RETURN BEST
```
---
# **Step 8 — Rollback Engine**
```nxd
MODULE cfg.rollback
IMPORT cfg.types
IMPORT cfg.util
IMPORT cfg.store
IMPORT cfg.time
FUNC ROLLBACK(ID: string, V: int): RESULT:
MATCH AT_VERSION(ID,V):
CASE NONE: RETURN ERR("no such version")
CASE SOME(C):
SET_CFG(ID,C.VALUE)
LOG("rollback: " ADD ID ADD " -> v" ADD TO_STRING(V))
RETURN OK("ok")
```
---
# **Step 9 — Audit Engine**
```nxd
MODULE cfg.audit
IMPORT cfg.types
IMPORT cfg.util
LET AUDITS SET LIST<AUDIT> []
FUNC RECORD(K: string, ID: string, MSG: string):
LET A SET AUDIT {
KIND: K,
CFG: ID,
MESSAGE: MSG,
TS: NOW()
}
PUSH AUDITS, A
LOG("audit: " ADD MSG)
```
---
# **Step 10 — API Layer**
```nxd
MODULE cfg.api
IMPORT cfg.types
IMPORT cfg.util
IMPORT cfg.store
IMPORT cfg.snap
IMPORT cfg.diff
IMPORT cfg.time
IMPORT cfg.rollback
IMPORT cfg.audit
FUNC API_SET(ID: string, VAL: string): string:
LET C SET SET_CFG(ID,VAL)
RECORD("set",ID,"updated to v" ADD TO_STRING(C.VERSION))
RETURN "ok"
FUNC API_GET(ID: string): string:
MATCH GET_CFG(ID):
CASE SOME(C): RETURN C.VALUE
CASE NONE: RETURN "none"
FUNC API_SNAP(ID: string): string:
LET R SET SNAPSHOT(ID)
MATCH R:
CASE OK(S): RETURN S.ID
CASE ERR(E): RETURN E
FUNC API_DIFF(ID: string, A: int, B: int): string:
MATCH AT_VERSION(ID,A):
CASE NONE: RETURN "no version A"
CASE SOME(CA):
MATCH AT_VERSION(ID,B):
CASE NONE: RETURN "no version B"
CASE SOME(CB):
RETURN DIFF(CA.VALUE,CB.VALUE)
FUNC API_ROLLBACK(ID: string, V: int): string:
LET R SET ROLLBACK(ID,V)
MATCH R:
CASE OK(_): RETURN "ok"
CASE ERR(E): RETURN E
```
---
# **Step 11 — System Orchestrator**
```nxd
MODULE cfg.system
IMPORT cfg.types
IMPORT cfg.util
FUNC START():
LOG("config snapshot system online")
```
---
# **Step 12 — MAIN**
```nxd
MODULE app.main
IMPORT cfg.system
IMPORT cfg.api
IMPORT cfg.util
FUNC MAIN():
cfg.system.START()
API_SET("auth.cfg","mode=prod\nrate=10")
API_SET("auth.cfg","mode=prod\nrate=20")
LET SID SET API_SNAP("auth.cfg")
LOG("snapshot: " ADD SID)
LOG("diff:\n" ADD API_DIFF("auth.cfg",1,2))
API_ROLLBACK("auth.cfg",1)
LOG("rolled back:\n" ADD API_GET("auth.cfg"))
```
---
# XXL System 20 Complete
You now have a **full distributed configuration snapshot & time‑travel platform**, end‑to‑end:
Documentation