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@@ -11,39 +11,44 @@ connect? This is the map an engineer needs before touching anything.
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## What to produce
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Write a one-off analysis script (Python or shell — your choice) that parses
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-the source under `legacy/$1` and extracts the four datasets below. Cover
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-the parse targets that are real for the stack you're looking at — these are
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-the ones LLMs reliably miss:
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-
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-- **Program/module call graph** — who calls whom.
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- - COBOL/CICS: `CALL '...'` and `EXEC CICS LINK/XCTL PROGRAM(...)`. Most
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- `PROGRAM(...)` targets are **data-names, not literals** — resolve them
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- against working-storage `VALUE` clauses and any menu/route copybooks
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- before declaring an edge unresolvable.
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- - Java: class-level imports/invocations. Node: `require`/`import`.
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-- **Data dependency graph** — which programs read/write which data stores.
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- - COBOL batch: `SELECT ... ASSIGN TO <ddname>` joined with JCL `DD`
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- statements (this is the *only* way to attribute file I/O to a program).
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- - COBOL/CICS online: `EXEC CICS READ/WRITE/REWRITE/DELETE/STARTBR/READNEXT/
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- READPREV ... FILE(...)` joined with `DEFINE FILE` in the CSD.
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- - DB2: `EXEC SQL ... END-EXEC` table references — *not* JCL DD; DB2 access
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- is via plan/package binds.
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- - BMS: `SEND MAP`/`RECEIVE MAP` ↔ map source under `bms/` and copybooks
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- under `cpy-bms/` (or wherever the maps live).
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- - Java: JPA/MyBatis entities & tables. Node: model files.
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-- **Entry points** — whatever the stack's outermost invokers are. Mainframe:
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- JCL `EXEC PGM=` steps **and** CICS `DEFINE TRANSACTION ... PROGRAM(...)`
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- from the CSD — without the CSD, every online program looks unreachable.
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- Web: HTTP routes. CLI: argv parsing.
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-- **Dead-end candidates** — modules with no inbound edges. **Only trust this
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- once the entry-point and call-edge types above are all in the graph**, and
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- suppress the dead claim for any module that could be the target of an
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- unresolved dynamic call. A naive grep-only graph will mark most CICS
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- programs dead.
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-
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-For COBOL fixed-format, slice columns 8-72 and skip `*` indicator lines
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-(column 7) before regex matching, or you'll match sequence numbers and
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-commented-out code.
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+the source under `legacy/$1` and extracts the four datasets below. Three
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+principles apply across stacks; getting them wrong produces a misleading map:
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+
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+1. **Edges live in two places** — direct calls in source, *and* dispatcher/
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+ router calls whose targets are variables (config tables, route maps,
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+ dependency injection, dynamic dispatch). Resolve variables against config
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+ before declaring an edge unresolvable.
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+2. **The code↔storage join is usually external configuration**, not source —
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+ job/deployment descriptors map logical names to physical stores.
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+3. **Entry points usually live in deployment config**, not source — without
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+ parsing it, every top-level module looks unreachable.
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+
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+Extract:
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+
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+- **Program/module call graph** — direct calls (`CALL`, method invocations,
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+ `import`/`require`) *and* dispatcher calls (`EXEC CICS LINK/XCTL`, DI
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+ container wiring, framework routing, reflection/factory). Resolve variable
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+ call targets against route tables, copybooks, config, or constant pools.
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+- **Data dependency graph** — which modules read/write which data stores,
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+ joined through the relevant config: `SELECT…ASSIGN TO` ↔ JCL `DD` (batch
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+ COBOL), `EXEC CICS READ/WRITE…FILE()` ↔ CSD `DEFINE FILE` (CICS online),
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+ `EXEC SQL` table refs (embedded SQL), ORM annotations/mappings (Java/.NET),
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+ model files (Node/Python/Ruby). Include UI/screen bindings (BMS maps, JSPs,
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+ templates) — they're dependencies too.
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+- **Entry points** — whatever the stack's outermost invoker is, read from
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+ where it's defined: JCL `EXEC PGM=` and CICS CSD `DEFINE TRANSACTION`
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+ (mainframe), `web.xml`/route annotations/route files (web), `main()`/argv
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+ parsing (CLI), queue/scheduler subscriptions (event-driven).
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+- **Dead-end candidates** — modules with no inbound edges. **Only meaningful
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+ once all the entry-point and call-edge types above are in the graph.**
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+ Suppress the dead claim for anything that could be the target of an
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+ unresolved dynamic call. A grep-only graph will mark most dispatcher-driven
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+ modules (CICS programs, Spring controllers, ORM-bound DAOs) dead when they
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+ aren't.
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+
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+If the source is fixed-column (COBOL columns 8–72, RPG, etc.), slice the
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+code area and strip comment lines before regex matching, or you'll match
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+sequence numbers and commented-out code.
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Save the script as `analysis/$1/extract_topology.py` (or `.sh`) so it can be
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re-run and audited. Have it write a machine-readable
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Morgan Lunt