optionchain_simulator 0.1.0

OptionChain-Simulator is a lightweight REST API service that simulates an evolving option chain with every request. It is designed for developers building or testing trading systems, backtesters, and visual tools that depend on option data streams but want to avoid relying on live data feeds.
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OptionChain-Simulator API and Architecture

System Architecture

flowchart TD
Client[Client Applications] --> API[API Layer]
API --> SM[Session Management]
SM --> App[Application Layer]
App --> Domain[Domain Layer]
App --> Infra[Infrastructure Layer]
Domain --> SimEngine[Simulation Engine]
Infra --> ClickHouse[(ClickHouse DB)]
Infra --> Redis[(Redis)]
Infra --> MongoDB[(MongoDB)]

Session State Transitions

stateDiagram-v2
[*] --> Initialized: POST /api/v1/chain
Initialized --> InProgress: POST /api/v1/chain/step
InProgress --> InProgress: POST /api/v1/chain/step
InProgress --> Modified: PATCH
Modified --> InProgress: POST /api/v1/chain/step
InProgress --> Reinitialized: PUT
Modified --> Reinitialized: PUT
Reinitialized --> InProgress: POST /api/v1/chain/step
Initialized --> [*]: DELETE
InProgress --> [*]: DELETE
Modified --> [*]: DELETE
Reinitialized --> [*]: DELETE

GET /api/v1/chain is a safe, repeatable peek and does not appear here because it never changes the session state — only POST /api/v1/chain/step advances the cursor.

API Request Flow

sequenceDiagram
participant Client
participant API as REST API
participant SM as Session Manager
participant SS as Simulator Service

Client->>API: POST /api/v1/chain
API->>SM: Create new session
SM->>SS: Initialize simulation
SS-->>SM: Initial state
SM-->>API: Session created (id: abc123)
API-->>Client: 201 Created (session details)

Client->>API: POST /api/v1/chain/step
API->>SM: Advance one step
SM->>SS: Advance simulation
SS-->>SM: Step data
SM-->>API: Chain data
API-->>Client: 200 OK (Chain data)

Client->>API: GET /api/v1/chain
API->>SM: Peek current step
SM->>SS: Read current snapshot
SS-->>SM: Step data (no advance)
SM-->>API: Chain data
API-->>Client: 200 OK (same snapshot, repeatable)

REST API Endpoints

The OptionChain-Simulator exposes the following REST API endpoints:

Method Endpoint Action Description
POST /api/v1/chain Create Session Creates a new simulation session
GET /api/v1/chain Read Current Step Returns the snapshot the next advance will serve (safe, repeatable)
POST /api/v1/chain/step Advance Step Serves the snapshot at the cursor (index 0 first), then advances
PUT /api/v1/chain Replace Session Completely replaces session parameters
PATCH /api/v1/chain Update Parameters Updates specific session parameters
DELETE /api/v1/chain Delete Session Terminates and removes a session

Step cursor semantics (serve-then-advance): current_step is the 0-based index of the NEXT snapshot to serve. POST /api/v1/chain/step serves the snapshot at the cursor and then advances it, so a session with steps = N serves EXACTLY indices 0..N-1 over N advances. The advance that serves the last snapshot persists the Completed state, and any further advance returns 410 Gone. GET /api/v1/chain peeks the snapshot the next advance would serve without moving the cursor.

Migration (breaking, issue #21): GET /api/v1/chain used to advance the session and consume a step. It is now a read-only, repeatable peek that returns the current snapshot without mutating state. To advance the cursor, clients must now call POST /api/v1/chain/step (same response shape, same 200/404/410/500 status codes as the old GET). Downstream consumers such as IronCondor must switch their step-advancing call from GET /api/v1/chain to POST /api/v1/chain/step.

Request/Response Models

1. Create Session (POST /api/v1/chain)

Request Body:

{
  "symbol": "AAPL",
  "steps": 10,
  "initial_price": 185.5,
  "days_to_expiration": 45.0,
  "volatility": 0.25,
  "risk_free_rate": 0.04,
  "dividend_yield": 0.005,
  "method": {
    "GeometricBrownian": {
      "dt": 0.004,
      "drift": 0.05,
      "volatility": 0.25
    }
  },
  "time_frame": "Day",
  "chain_size": 15,
  "strike_interval": 5.0,
  "smile_curve": 0.0005,
  "spread": 0.02
}

Response (201 Created):

{
    "id": "6af613b6-569c-5c22-9c37-2ed93f31d3af",
    "created_at": "2025-04-21T15:37:30.518022+00:00",
    "updated_at": "2025-04-21T15:37:30.518022+00:00",
    "parameters": {
        "symbol": "AAPL",
        "initial_price": 185.5,
        "volatility": 0.25,
        "risk_free_rate": 0.04,
        "method": "GeometricBrownian { dt: 0.004, drift: 0.05, volatility: 0.25 }",
        "time_frame": "day",
        "dividend_yield": 0.005,
        "smile_curve": 0.0005,
        "spread": 0.02
    },
    "current_step": 0,
    "total_steps": 10,
    "state": "Initialized"
}

2. Peek Current Step (GET /api/v1/chain?sessionid=6af613b6-569c-5c22-9c37-2ed93f31d3af)

Safe and repeatable: returns the session's current snapshot without advancing the cursor or persisting anything. To advance the session and consume a step, use POST /api/v1/chain/step?sessionid=... (issue #21) — it takes the same query parameter and returns the same body shown below.

Response (200 OK):

{
    "underlying": "AAPL",
    "timestamp": "2025-04-21T15:33:03.597061+00:00",
    "price": 185.299430466522,
    "contracts": [
        {
            "strike": 160.0,
            "expiration": "2025-06-05",
            "call": {
                "bid": 26.08,
                "ask": 26.1,
                "mid": 26.09,
                "delta": 0.9993778215543331
            },
            "put": {
                "bid": null,
                "ask": null,
                "mid": null,
                "delta": -4.2479708093406946e-6
            },
            "implied_volatility": 0.09731095458186256,
            "gamma": 3.121236702609213e-6
        },
        {
            "strike": 165.0,
            "expiration": "2025-06-05",
            "call": {
                "bid": 21.14,
                "ask": 21.16,
                "mid": 21.15,
                "delta": 0.9888998386575956
            },
            "put": {
                "bid": 0.03,
                "ask": 0.05,
                "mid": 0.04,
                "delta": -0.010482230867546823
            },
            "implied_volatility": 0.15077922021760087,
            "gamma": 0.0028266289100911603
        },
        {
            "strike": 170.0,
            "expiration": "2025-06-05",
            "call": {
                "bid": 16.62,
                "ask": 16.64,
                "mid": 16.63,
                "delta": 0.9153696474659715
            },
            "put": {
                "bid": 0.49,
                "ask": 0.51,
                "mid": 0.5,
                "delta": -0.08401242205917087
            },
            "implied_volatility": 0.1927733286389461,
            "gamma": 0.012279670056243013
        },
        {
            "strike": 175.0,
            "expiration": "2025-06-05",
            "call": {
                "bid": 12.87,
                "ask": 12.89,
                "mid": 12.88,
                "delta": 0.7964192920937592
            },
            "put": {
                "bid": 1.71,
                "ask": 1.73,
                "mid": 1.72,
                "delta": -0.2029627774313833
            },
            "implied_volatility": 0.22329327984589836,
            "gamma": 0.019409579420062936
        },
        {
            "strike": 180.0,
            "expiration": "2025-06-05",
            "call": {
                "bid": 9.76,
                "ask": 9.78,
                "mid": 9.77,
                "delta": 0.6700429413591044
            },
            "put": {
                "bid": 3.57,
                "ask": 3.59,
                "mid": 3.58,
                "delta": -0.3293391281660381
            },
            "implied_volatility": 0.24233907383845762,
            "gamma": 0.022910122989513254
        },
        {
            "strike": 185.0,
            "expiration": "2025-06-05",
            "call": {
                "bid": 7.09,
                "ask": 7.11,
                "mid": 7.1,
                "delta": 0.5468721177394451
            },
            "put": {
                "bid": 5.87,
                "ask": 5.89,
                "mid": 5.88,
                "delta": -0.45250995178569736
            },
            "implied_volatility": 0.24991071061662393,
            "gamma": 0.024315069945191076
        },
        {
            "strike": 190.0,
            "expiration": "2025-06-05",
            "call": {
                "bid": 4.68,
                "ask": 4.7,
                "mid": 4.69,
                "delta": 0.4237521134194814
            },
            "put": {
                "bid": 8.45,
                "ask": 8.47,
                "mid": 8.46,
                "delta": -0.5756299561056611
            },
            "implied_volatility": 0.24385078722742481,
            "gamma": 0.024638652336979393
        },
        {
            "strike": 195.0,
            "expiration": "2025-06-05",
            "call": {
                "bid": 2.62,
                "ask": 2.64,
                "mid": 2.63,
                "delta": 0.29452137751494756
            },
            "put": {
                "bid": 11.36,
                "ask": 11.38,
                "mid": 11.37,
                "delta": -0.7048606920101947
            },
            "implied_volatility": 0.22617927813392658,
            "gamma": 0.023389127623181388
        },
        {
            "strike": 200.0,
            "expiration": "2025-06-05",
            "call": {
                "bid": 1.03,
                "ask": 1.05,
                "mid": 1.04,
                "delta": 0.15952905609846607
            },
            "put": {
                "bid": 14.75,
                "ask": 14.77,
                "mid": 14.76,
                "delta": -0.8398530134266764
            },
            "implied_volatility": 0.19703361182603538,
            "gamma": 0.01891326128023662
        },
        {
            "strike": 205.0,
            "expiration": "2025-06-05",
            "call": {
                "bid": 0.16,
                "ask": 0.18,
                "mid": 0.17,
                "delta": 0.04271051015963935
            },
            "put": {
                "bid": 18.85,
                "ask": 18.87,
                "mid": 18.86,
                "delta": -0.9566715593655031
            },
            "implied_volatility": 0.15641378830375124,
            "gamma": 0.008916660747165772
        },
        {
            "strike": 210.0,
            "expiration": "2025-06-05",
            "call": {
                "bid": null,
                "ask": null,
                "mid": null,
                "delta": 0.0005597778266970925
            },
            "put": {
                "bid": 23.66,
                "ask": 23.68,
                "mid": 23.67,
                "delta": -0.9988222916984453
            },
            "implied_volatility": 0.10431980756707404,
            "gamma": 0.0002902662707065403
        }
    ],
    "session_info": {
        "id": "6af613b6-569c-5c22-9c37-2ed93f31d3af",
        "current_step": 1,
        "total_steps": 10
    }
}

3. Update Session Parameters (PATCH /api/v1/chain?sessionid=6af613b6-569c-5c22-9c37-2ed93f31d3af)

Request Body:

{
  "symbol": "AAPL",
   "initial_price": 385.5,
  "steps": 8,
  "volatility": 0.2,
  "risk_free_rate": 0.03,
  "dividend_yield": 0.005,
  "days_to_expiration": 30.0,
  "time_frame": "Day"
}

Response (200 OK):

{
    "id": "6af613b6-569c-5c22-9c37-2ed93f31d3af",
    "created_at": "2025-04-21T15:32:59.551486+00:00",
    "updated_at": "2025-04-21T15:33:19.515911+00:00",
    "parameters": {
        "symbol": "AAPL",
        "initial_price": 385.5,
        "volatility": 0.2,
        "risk_free_rate": 0.03,
        "method": "GeometricBrownian { dt: 0.004, drift: 0.05, volatility: 0.25 }",
        "time_frame": "day",
        "dividend_yield": 0.005,
        "smile_curve": 0.0005,
        "spread": 0.02
    },
    "current_step": 0,
    "total_steps": 30,
    "state": "Reinitialized"
}

4. Replace Session (PUT /api/v1/chain)

Request Body:

{
  "symbol": "AAPL",
  "steps": 30,
  "initial_price": 385.5,
  "days_to_expiration": 45.0,
  "volatility": 0.25,
  "risk_free_rate": 0.04,
  "dividend_yield": 0.005,
  "method": {
    "GeometricBrownian": {
      "dt": 0.004,
      "drift": 0.05,
      "volatility": 0.25
    }
  },
  "time_frame": "Day",
  "chain_size": 15,
  "strike_interval": 5.0,
  "smile_curve": 0.0005,
  "spread": 0.02
}

Response (200 OK):

{
    "id": "6af613b6-569c-5c22-9c37-2ed93f31d3af",
    "created_at": "2025-04-21T15:37:30.518022+00:00",
    "updated_at": "2025-04-21T15:37:33.951540+00:00",
    "parameters": {
        "symbol": "AAPL",
        "initial_price": 385.5,
        "volatility": 0.25,
        "risk_free_rate": 0.04,
        "method": "GeometricBrownian { dt: 0.004, drift: 0.05, volatility: 0.25 }",
        "time_frame": "day",
        "dividend_yield": 0.005,
        "smile_curve": 0.0005,
        "spread": 0.02
    },
    "current_step": 0,
    "total_steps": 30,
    "state": "Reinitialized"
}

5. Delete Session (DELETE /api/v1/chain?sessionid=6af613b6-569c-5c22-9c37-2ed93f31d3af)

Response (200 OK):

{
    "message": "Session deleted successfully: 6af613b6-569c-5c22-9c37-2ed93f31d3af",
    "session_id": "6af613b6-569c-5c22-9c37-2ed93f31d3af"
}

Domain Models

classDiagram
class SessionManager {
+createSession(params) Session
+getNextStep(id) (Session, OptionChain)
+updateSession(id, params) Session
+reinitializeSession(id, params) Session
+deleteSession(id) bool
}

class Session {
+id UUID
+createdAt DateTime
+updatedAt DateTime
+parameters SimulationParameters
+currentStep usize
+totalSteps usize
+state SessionState
+advanceStep() Result
+modifyParameters(params)
+reinitialize(params, steps)
}

class SessionState {
<<enumeration>>
Initialized
InProgress
Modified
Reinitialized
Completed
Error
}

class SimulationParameters {
+symbol String
+initialPrice Positive
+volatility Positive
+riskFreeRate Decimal
+strikes Vec~Positive~
+expirations Vec~String~
+method SimulationMethod
+timeFrame TimeFrame
}

class Simulator {
+simulateNextStep(session) OptionChain
-createRandomWalk(session) RandomWalk
}

class OptionChain {
+underlying String
+timestamp DateTime
+price Positive
+contracts Vec~OptionContract~
}

class OptionContract {
+strike Positive
+expiration String
+call OptionData
+put OptionData
+impliedVolatility Positive
+gamma Positive
}

Session --> SimulationParameters
Session --> SessionState
SessionManager --> Session: manages
SessionManager --> Simulator: uses
Simulator --> OptionChain: produces
OptionChain --> OptionContract: contains

Infrastructure Components

classDiagram
class SessionStore {
<<interface>>
+get(id) Session
+save(session) void
+delete(id) bool
+cleanup() int
}

class InMemorySessionStore {
-sessions Map~UUID, Session~
+get(id) Session
+save(session) void
+delete(id) bool
+cleanup() int
}

class RedisSessionStore {
-client RedisClient
+get(id) Session
+save(session) void
+delete(id) bool
+cleanup() int
}

class HistoricalDataRepository {
<<interface>>
+getHistoricalPrices(symbol, timeframe, startDate, endDate) Vec~Positive~
+listAvailableSymbols() Vec~String~
+getDateRangeForSymbol(symbol) (DateTime, DateTime)
}

class ClickHouseHistoricalRepository {
-client ClickHouseClient
+getHistoricalPrices(symbol, timeframe, startDate, endDate) Vec~Positive~
+listAvailableSymbols() Vec~String~
+getDateRangeForSymbol(symbol) (DateTime, DateTime)
}

SessionStore <|.. InMemorySessionStore: implements
SessionStore <|.. RedisSessionStore: implements
HistoricalDataRepository <|.. ClickHouseHistoricalRepository: implements

🚀 Deploy the project

To deploy the services defined in Docker/docker-compose.yml, run the following command:

make deploy

This will:

  • Build the Docker images (--build)
  • Force container recreation (--force-recreate)
  • Run everything in detached mode (-d)
  • Use optionchain-simulator as the project name to namespace containers and resources

Make sure Docker and Docker Compose are installed and running on your system.

Makefile Commands for Development

The project includes a Makefile with useful commands for development:

Command Description
make build Builds the project
make release Builds the project in release mode
make test Runs all tests
make fmt Formats the code using rustfmt
make lint Runs clippy for linting
make check Runs tests, formatting check, and linting
make run Runs the project
make clean Cleans build artifacts
make doc Generates documentation
make coverage Generates code coverage report
make bench Runs benchmarks
make deploy deploy the services in local

Additional commands for CI/CD and deployment:

Command Description
make pre-push Runs fixes, formatting, linting, and tests before pushing
make workflow Runs all GitHub Actions workflows locally
make publish Publishes the package to crates.io
make zip Creates a ZIP archive of the project

Contribution and Contact

We welcome contributions to this project! If you would like to contribute, please follow these steps:

  1. Fork the repository.
  2. Create a new branch for your feature or bug fix.
  3. Make your changes and ensure that the project still builds and all tests pass.
  4. Commit your changes and push your branch to your forked repository.
  5. Submit a pull request to the main repository.

If you have any questions, issues, or would like to provide feedback, please feel free to contact the project maintainer:

Joaquín Béjar García

We appreciate your interest and look forward to your contributions!

✍️ License

Licensed under MIT license