✅ Unsubscribe from Market Depth (MarketBookReleaseAsync)

Request: Unsubscribe from Depth of Market (DOM) updates for a symbol on MT5. Closes DOM subscription and frees resources.

API Information:

• SDK wrapper: MT5Account.MarketBookReleaseAsync(...) (from NuGet package MetaRPC.MT5)
• gRPC service: mt5_term_api.MarketInfo
• Proto definition: MarketBookRelease (defined in mt5-term-api-market-info.proto)

RPC

• Service: mt5_term_api.MarketInfo
• Method: MarketBookRelease(MarketBookReleaseRequest) → MarketBookReleaseReply
• Low‑level client (generated): MarketInfo.MarketInfoClient.MarketBookRelease(request, headers, deadline, cancellationToken)
• SDK wrapper (your class):

namespace mt5_term_api
{
    public class MT5Account
    {
        public async Task<MarketBookReleaseData> MarketBookReleaseAsync(
            string symbol,
            DateTime? deadline = null,
            CancellationToken cancellationToken = default);
    }
}

Request message:

MarketBookReleaseRequest { symbol }

Reply message:

MarketBookReleaseReply { data: MarketBookReleaseData }

---

🔽 Input

Parameter	Type	Description
symbol	string	Symbol name (previously subscribed via MarketBookAddAsync)
deadline	DateTime?	Absolute per‑call UTC deadline → converted to timeout
cancellationToken	CancellationToken	Cooperative cancel for the call/retry loop

---

⬆️ Output — MarketBookReleaseData

Field	Type	Description
ClosedSuccessfully	bool	true if unsubscription successful

---

💬 Just the essentials

• What it is. Closes DOM subscription for a symbol. Stops receiving order book updates and frees resources.
• Why you need it. Clean up subscriptions when done. Reduce server/terminal load by unsubscribing unused symbols.
• Sanity check. If ClosedSuccessfully == true → subscription closed. Can no longer get DOM via MarketBookGetAsync.

---

🎯 Purpose

Use it to clean up DOM subscriptions:

• Free terminal/server resources.
• Stop receiving DOM updates for unused symbols.
• Proper cleanup before shutdown.

---

🧩 Notes & Tips

• Resource management: Always unsubscribe when done to avoid resource leaks.
• Multiple symbols: Call separately for each subscribed symbol.
• Already unsubscribed: Returns true even if symbol wasn't subscribed.
• No penalty: Safe to call multiple times for same symbol.
• Cleanup order: Unsubscribe before disconnecting from MT5.

---

🔗 Usage Examples

1) Basic unsubscribe

// acc — connected MT5Account

var result = await acc.MarketBookReleaseAsync("BTCUSD");

if (result.ClosedSuccessfully)
{
    Console.WriteLine("✓ DOM subscription closed for BTCUSD");
}
else
{
    Console.WriteLine("⚠ Failed to close DOM subscription");
}

---

2) Subscribe, use, then unsubscribe pattern

var symbol = "ETHUSD";

// 1. Subscribe
var subResult = await acc.MarketBookAddAsync(symbol);
if (!subResult.OpenedSuccessfully)
{
    Console.WriteLine("DOM not available");
    return;
}

try
{
    // 2. Use DOM data
    var domData = await acc.MarketBookGetAsync(symbol);
    Console.WriteLine($"DOM entries: {domData.MqlBookInfos.Count}");

    // Process DOM data...
}
finally
{
    // 3. Always unsubscribe (cleanup)
    var releaseResult = await acc.MarketBookReleaseAsync(symbol);
    Console.WriteLine($"Cleanup: {releaseResult.ClosedSuccessfully}");
}

---

3) Unsubscribe from multiple symbols

var symbols = new[] { "BTCUSD", "ETHUSD", "XAUUSD" };

foreach (var symbol in symbols)
{
    var result = await acc.MarketBookReleaseAsync(symbol);
    Console.WriteLine($"{symbol}: {(result.ClosedSuccessfully ? "✓ Unsubscribed" : "✗ Failed")}");
}

---

4) Using statement pattern (automatic cleanup)

async Task UseDomData(MT5Account acc, string symbol)
{
    // Subscribe
    var subResult = await acc.MarketBookAddAsync(symbol);
    if (!subResult.OpenedSuccessfully)
        return;

    try
    {
        // Use DOM
        for (int i = 0; i < 5; i++)
        {
            var domData = await acc.MarketBookGetAsync(symbol);
            Console.WriteLine($"Iteration {i}: {domData.MqlBookInfos.Count} entries");
            await Task.Delay(1000);
        }
    }
    finally
    {
        // Cleanup
        await acc.MarketBookReleaseAsync(symbol);
    }
}

// Call
await UseDomData(acc, "BTCUSD");

---

5) Graceful shutdown with error handling

var subscribedSymbols = new List<string> { "ES", "NQ", "YM" };

// Subscribe to all
foreach (var symbol in subscribedSymbols)
{
    await acc.MarketBookAddAsync(symbol);
}

// ... use DOM data ...

// Graceful shutdown: unsubscribe from all
Console.WriteLine("Shutting down, cleaning up DOM subscriptions...");

foreach (var symbol in subscribedSymbols)
{
    try
    {
        var result = await acc.MarketBookReleaseAsync(
            symbol,
            deadline: DateTime.UtcNow.AddSeconds(3));

        if (result.ClosedSuccessfully)
        {
            Console.WriteLine($"✓ {symbol} unsubscribed");
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine($"⚠ {symbol} unsubscribe failed: {ex.Message}");
    }
}

Console.WriteLine("Cleanup complete");

---

6) Conditional unsubscribe (check if subscribed first)

var symbol = "BTCUSD";

// Try to get DOM data first
try
{
    var domData = await acc.MarketBookGetAsync(symbol);

    if (domData.MqlBookInfos.Count > 0)
    {
        // Has data, so was subscribed
        var result = await acc.MarketBookReleaseAsync(symbol);
        Console.WriteLine($"✓ Unsubscribed from {symbol}");
    }
    else
    {
        Console.WriteLine($"⚠ {symbol} not subscribed or no data");
    }
}
catch
{
    Console.WriteLine($"⚠ {symbol} not subscribed");
}