Market-wide analysis subscription

Production environment: https://stream.valuescan.ai

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1. Overview

Market-wide analysis is ValueAgent's synthesized view of BTC/ETH markets using multi-dimensional data. Market subscription is a server-initiated push mechanism: after the user subscribes, when broad-market conditions change, the server pushes analysis text to the client over SSE.

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2. Subscription URL

GET https://stream.valuescan.ai/stream/market/subscribe

Authentication parameters (query string):

Parameter	Type	Required	Description
apiKey	string	Yes	ValueScan Access Key
sign	string	Yes	HMAC-SHA256 signature
timestamp	long	Yes	Unix timestamp in milliseconds
nonce	string	Yes	Random string (replay protection)

Signing algorithm:

sign = HMAC-SHA256(SK, timestampMs + nonce)

Where timestampMs is the millisecond Unix timestamp as a string concatenated with nonce.

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3. SSE event format

Connected

event: connected
data: subscribed

Heartbeat (keep-alive)

: heartbeat

event: heartbeat
data: ping

The server sends a heartbeat every 20 seconds.

Market analysis push

event: market
data: {"ts":1775604300144,"uniqueId":"market_analysis_20260408103000","content":"BTC dominates the market with high capital concentration; watch BTC price action."}

market event payload fields:

Field	Type	Description
ts	long	Push time (millisecond timestamp)
uniqueId	string	Unique id (for deduplication)
content	string	Plain-text market analysis

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4. Subscription examples

Python

import hashlib
import hmac
import json
import time
import uuid
import urllib.request
from urllib.parse import urlencode

AK = "your-access-key"
SK = "your-secret-key"

ts = int(time.time() * 1000)
nonce = uuid.uuid4().hex
sign = hmac.new(
    SK.encode(),
    (str(ts) + nonce).encode(),
    hashlib.sha256,
).hexdigest()

params = urlencode({
    "apiKey": AK,
    "sign": sign,
    "timestamp": ts,
    "nonce": nonce,
})

url = f"https://stream.valuescan.ai/stream/market/subscribe?{params}"
req = urllib.request.Request(url, headers={"Accept": "text/event-stream"})

with urllib.request.urlopen(req, timeout=300) as resp:
    event_name = ""
    data_str = ""
    for raw in resp:
        line = raw.decode("utf-8").rstrip("\r\n")

        if line.startswith(":"):
            print("♥ Heartbeat")
            continue

        if line == "":
            if data_str:
                handle_event(event_name, data_str)
            event_name = ""
            data_str = ""
        elif line.startswith("event:"):
            event_name = line[6:].strip()
        elif line.startswith("data:"):
            data_str = line[5:].strip()


def handle_event(event_name: str, data_str: str) -> None:
    if event_name == "connected":
        print(f"[Connected] {data_str}")
    elif event_name == "market":
        payload = json.loads(data_str)
        ts = payload["ts"]
        content = payload["content"]
        dt = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime(ts / 1000))
        print(f"[Market analysis {dt}] {content}")

cURL (quick check)

python3 -c "
import hashlib, hmac, time, uuid, urllib.parse
SK='your-secret-key'
ts=int(time.time()*1000)
nonce=uuid.uuid4().hex
sign=hmac.new(SK.encode(), (str(ts)+nonce).encode(), hashlib.sha256).hexdigest()
params=urllib.parse.urlencode({'apiKey':'your-access-key','sign':sign,'timestamp':ts,'nonce':nonce})
print(f"curl -N 'https://stream.valuescan.ai/stream/market/subscribe?{params}' -H 'Accept: text/event-stream'")
'"

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5. Reconnect on disconnect

Same as signal subscription: use exponential backoff when reconnecting:

def listen_with_retry(url: str, max_retries: int = 10) -> None:
    retries = 0
    while retries <= max_retries:
        try:
            req = urllib.request.Request(url, headers={"Accept": "text/event-stream"})
            with urllib.request.urlopen(req, timeout=300) as resp:
                _read_sse(resp)
                break
        except KeyboardInterrupt:
            print("Interrupted by user, exiting.")
            break
        except Exception as e:
            retries += 1
            wait = min(2 ** retries, 60)
            print(f"Connection lost ({e}), reconnect attempt {retries} in {wait}s...")
            time.sleep(wait)
    else:
        print("Max retries reached, exiting.")

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6. Error codes

HTTP status	Description
200	Connected successfully
400	Missing or invalid parameters
401	Signature verification failed or timestamp out of range
404	Wrong subscription URL
503	Service unavailable (auth backend connection failed)