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Cratis

Architecture

Prologue is deliberately self-contained and has no dependency on Studio. The Extractor and Receiver are ordinary services, while the Interpreter supports two hosting shapes: a run-to-completion batch process and a resumable HTTP service. Only the resumable service mode embeds an Orleans silo; file-based capture and batch interpretation do not require Orleans.

The pieces

Section titled “The pieces”
cratis/prologue-interpreter
cratis/prologue-receiver
cratis/prologue-extractor
reverse proxy
JSON capture files
HTTP POST
Extractor
Receiver
Batch mode
Service mode

Orleans silo
Your system
Mounted folder
MongoDB
extraction-result.json

+ .play
SessionResult over HTTP
  • Extractor — a reverse proxy plus a database and telemetry watcher, all in one process. It’s the only piece that has to run continuously, next to the system it’s watching.
  • Receiver — a thin HTTP endpoint (POST /captures, POST /prologues/{id}/captures) that stores whatever the Extractor posts to it in MongoDB via Cratis.Prologue.Storage. It’s optional — the Extractor can write JSON files to a mounted folder instead, with no Receiver or MongoDB involved at all.
  • Interpreter — a job, not a service, by default. It reads a folder of capture files, interprets them, and exits. A second mode embeds Orleans and keeps interpretation running as resumable session grains with state backed by MongoDB.

The shared Cratis.Prologue.Contracts, Cratis.Prologue.Configuration, and Cratis.Prologue.Interpreter.Contracts packages define the canonical capture, configuration, and extraction-result formats. Cratis.Prologue.Interpretation contains the interpretation engine, and Cratis.Prologue.Screenplay converts an extraction result into a .play document.

Two ways to run the Interpreter

Section titled “Two ways to run the Interpreter”
yes
no
Batch mode (default)

run-to-completion job
Reads /captures folder
Writes extraction-result.json + .play

to /output, then exits
Service mode

--serve or PROLOGUE_MODE=service
Resumable HTTP session

state persisted in MongoDB
Idle beyond timeout,

or awaiting an answer

past the grace period?
Container exits cleanly

— an orchestrator restarts it to resume

Batch mode is what you get from the image by default, and what the Cratis CLI’s cratis prologue interpret drives — a folder of captures in, an ExtractionResult and a Screenplay .play file out, then the container exits. See Running the Interpreter.

Service mode embeds an Orleans silo and hosts interpretation as resumable session grains over HTTP. Session state persists in MongoDB, so a session waiting for answers can resume after the process restarts. This mode is intended for interactive integrations; use batch mode when you only need file-based input and output.

No dependency on Studio

Section titled “No dependency on Studio”

Nothing here requires Studio to be running. If you only want an ExtractionResult and .play file, the Extractor and batch Interpreter are the complete Prologue pipeline; the Cratis CLI provides the corresponding command workflow.

Next

Section titled “Next”