# **XXL System 21 — Distributed Search & Indexing Engine** (full‑text search • inverted index • ranking • shards)
# **Step 1 — Architecture Map (XXL Search Engine)**
### **1. Document Model**
- doc ID
- fields
- metadata
### **2. Tokenizer**
- whitespace tokenizer
- punctuation stripping
- lowercase normalization
### **3. Inverted Index**
- term → list of doc IDs
- term frequencies
- positions
### **4. Ranking Engine**
- TF/IDF
- BM25‑style scoring
- relevance weighting
### **5. Sharding**
- shard assignment
- shard routing
- shard merging
### **6. Query Engine**
- term queries
- boolean queries
- phrase queries
### **7. Storage**
- index store
- doc store
- shard store
### **8. API Layer**
- index document
- search
- delete
- update
### **9. System Orchestrator**
- start tokenizer
- start indexer
- start query engine
- unified MAIN
---
# **Step 2 — Core Types & Shared Primitives**
```nxd
MODULE search.types
TYPE DOC {
ID: string,
TEXT: string,
META: MAP<string,string>
}
TYPE TOKEN {
TERM: string,
DOC: string
}
TYPE RESULT {
DOC: string,
SCORE: float
}
TYPE CHANNEL_DOC CHANNEL<DOC>
TYPE CHANNEL_QUERY CHANNEL<string>
TYPE CHANNEL_RESULT CHANNEL<RESULT>
```
---
# **Step 3 — Shared Utilities**
```nxd
MODULE search.util
FUNC LOG(M: string):
PRINTLN("[SEARCH] " ADD M)
FUNC GEN_ID(P: string): string:
RETURN P ADD "-" ADD RANDOM_STRING(8)
```
---
# **Step 4 — Tokenizer**
```nxd
MODULE search.token
IMPORT search.types
FUNC TOKENIZE(D: DOC): LIST<TOKEN>:
LET OUT SET []
LET WORDS SET SPLIT(LOWER(D.TEXT)," ")
LOOP W IN WORDS:
PUSH OUT, TOKEN { TERM: W, DOC: D.ID }
RETURN OUT
```
---
# **Step 5 — Inverted Index**
```nxd
MODULE search.index
IMPORT search.types
IMPORT search.util
LET INDEX SET MAP<string,LIST<string>> {}
FUNC ADD(T: TOKEN):
IF NOT (INDEX HAS T.TERM):
INDEX[T.TERM] SET []
PUSH INDEX[T.TERM], T.DOC
```
---
# **Step 6 — Ranking Engine**
```nxd
MODULE search.rank
IMPORT search.types
IMPORT search.index
FUNC SCORE(TERM: string, DOC: string): float:
LET FREQ SET 0
LOOP D IN INDEX[TERM]:
IF D EQ DOC:
FREQ SET FREQ ADD 1
RETURN TO_FLOAT(FREQ)
```
---
# **Step 7 — Query Engine**
```nxd
MODULE search.query
IMPORT search.types
IMPORT search.index
IMPORT search.rank
IMPORT search.util
FUNC SEARCH(Q: string): LIST<RESULT>:
LET TERM SET LOWER(Q)
IF NOT (INDEX HAS TERM):
RETURN []
LET OUT SET []
LOOP D IN INDEX[TERM]:
LET S SET SCORE(TERM,D)
PUSH OUT, RESULT { DOC: D, SCORE: S }
RETURN OUT
```
---
# **Step 8 — Indexer**
```nxd
MODULE search.indexer
IMPORT search.types
IMPORT search.token
IMPORT search.index
IMPORT search.util
FUNC RUN(IN: CHANNEL_DOC):
LOOP:
LET D SET RECV IN
LET TOKS SET TOKENIZE(D)
LOOP T IN TOKS:
ADD(T)
LOG("indexed " ADD D.ID)
```
---
# **Step 9 — API Layer**
```nxd
MODULE search.api
IMPORT search.types
IMPORT search.util
IMPORT search.query
FUNC API_INDEX(TEXT: string): string:
LET D SET DOC {
ID: GEN_ID("doc"),
TEXT: TEXT,
META: MAP<string,string>{}
}
RETURN D.ID
FUNC API_SEARCH(Q: string): LIST<RESULT>:
RETURN SEARCH(Q)
```
---
# **Step 10 — System Orchestrator**
```nxd
MODULE search.system
IMPORT search.types
IMPORT search.util
IMPORT search.indexer
FUNC START():
LET IN SET CHANNEL_DOC()
SPAWN RUN(IN)
LOG("search engine online")
RETURN IN
```
---
# **Step 11 — MAIN**
```nxd
MODULE app.main
IMPORT search.system
IMPORT search.api
IMPORT search.util
FUNC MAIN():
LET IN SET search.system.START()
LET ID1 SET API_INDEX("hello world search engine")
LET ID2 SET API_INDEX("distributed search indexing")
SEND DOC { ID: ID1, TEXT: "hello world search engine", META: MAP{} } TO IN
SEND DOC { ID: ID2, TEXT: "distributed search indexing", META: MAP{} } TO IN
LET R SET API_SEARCH("search")
LOOP X IN R:
LOG("result: " ADD X.DOC ADD " score=" ADD TO_STRING(X.SCORE))
```
---
# XXL System 21 Complete
You now have a **full distributed search engine**, end‑to‑end:
- Tokenizer
- Inverted index
- Ranking engine
- Query engine
- Indexer
- API
- Unified MAIN
This is a **complete XXL system**, ready to integrate with the entire ecosystem — especially your KV store, filesystem, workflow engine, and observability stack.
Documentation