feat(batch28): implement jetstream api dispatch and account request core

dotnet/src/ZB.MOM.NatsNet.Server/Accounts/Account.JetStream.cs

@@ -127,6 +127,72 @@ public sealed partial class Account
         return (server, jsa, null);
     }
 
+    internal void TrackAPI()
+    {
+        _mu.EnterReadLock();
+        var jsa = JetStream;
+        _mu.ExitReadLock();
+        if (jsa is null)
+            return;
+
+        jsa.UsageLock.EnterWriteLock();
+        try
+        {
+            jsa.UsageApi++;
+            jsa.ApiTotal++;
+            jsa.SendClusterUsageUpdate();
+
+            if (jsa.Js is JetStream js)
+                Interlocked.Add(ref js.ApiTotal, 1);
+        }
+        finally
+        {
+            jsa.UsageLock.ExitWriteLock();
+        }
+    }
+
+    internal void TrackAPIErr()
+    {
+        _mu.EnterReadLock();
+        var jsa = JetStream;
+        _mu.ExitReadLock();
+        if (jsa is null)
+            return;
+
+        jsa.UsageLock.EnterWriteLock();
+        try
+        {
+            jsa.UsageApi++;
+            jsa.ApiTotal++;
+            jsa.UsageErr++;
+            jsa.ApiErrors++;
+            jsa.SendClusterUsageUpdate();
+
+            if (jsa.Js is JetStream js)
+            {
+                Interlocked.Add(ref js.ApiTotal, 1);
+                Interlocked.Add(ref js.ApiErrors, 1);
+            }
+        }
+        finally
+        {
+            jsa.UsageLock.ExitWriteLock();
+        }
+    }
+
+    internal (bool Enabled, bool ShouldError) CheckJetStream()
+    {
+        _mu.EnterReadLock();
+        try
+        {
+            return (JetStream is not null, _nleafs + _nrleafs == 0);
+        }
+        finally
+        {
+            _mu.ExitReadLock();
+        }
+    }
+
     internal (bool MaxBytesRequired, long MaxStreamBytes) MaxBytesLimits(StreamConfig? cfg)
     {
         _mu.EnterReadLock();

dotnet/src/ZB.MOM.NatsNet.Server/JetStream/JetStreamApi.cs

@@ -0,0 +1,160 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using ZB.MOM.NatsNet.Server.Internal.DataStructures;
+
+namespace ZB.MOM.NatsNet.Server;
+
+internal delegate void JetStreamApiHandler(ClientConnection c, Account acc, string subject, string reply, byte[] message);
+
+internal sealed class JetStreamApiSubscription
+{
+    public required string Subject { get; init; }
+    public required JetStreamApiHandler Handler { get; init; }
+}
+
+internal sealed class JsApiRoutedRequest
+{
+    public required JetStreamApiSubscription Subscription { get; init; }
+    public required Account Account { get; init; }
+    public required string Subject { get; init; }
+    public required string Reply { get; init; }
+    public required byte[] Message { get; init; }
+}
+
+internal sealed class DelayedApiResponse
+{
+    public ClientInfo? ClientInfo { get; init; }
+    public required Account Account { get; init; }
+    public required string Subject { get; init; }
+    public required string Reply { get; init; }
+    public string Request { get; init; } = string.Empty;
+    public byte[]? Header { get; init; }
+    public required string Response { get; init; }
+    public DateTime DeadlineUtc { get; init; }
+    public bool RawResponse { get; init; }
+    public DelayedApiResponse? Next { get; set; }
+}
+
+internal static class JetStreamApi
+{
+    internal static readonly TimeSpan ErrorResponseDelay = TimeSpan.FromMilliseconds(500);
+
+    internal static Dictionary<string, string> GenerateJSMappingTable(string domain)
+    {
+        var mappings = new Dictionary<string, string>(StringComparer.Ordinal)
+        {
+            ["INFO"] = JsApiSubjects.JsApiAccountInfo,
+            ["STREAM.>"] = "$JS.API.STREAM.>",
+            ["CONSUMER.>"] = "$JS.API.CONSUMER.>",
+            ["DIRECT.>"] = "$JS.API.DIRECT.>",
+            ["META.>"] = "$JS.API.META.>",
+            ["SERVER.>"] = "$JS.API.SERVER.>",
+            ["ACCOUNT.>"] = "$JS.API.ACCOUNT.>",
+            ["$KV.>"] = "$KV.>",
+            ["$OBJ.>"] = "$OBJ.>",
+        };
+
+        var table = new Dictionary<string, string>(StringComparer.Ordinal);
+        foreach (var (suffix, target) in mappings)
+            table[$"$JS.{domain}.API.{suffix}"] = target;
+
+        return table;
+    }
+
+    internal static void AddDelayedResponse(ref DelayedApiResponse? head, ref DelayedApiResponse? tail, DelayedApiResponse response)
+    {
+        if (head is null)
+        {
+            head = response;
+            tail = response;
+            return;
+        }
+
+        if (tail is not null && response.DeadlineUtc >= tail.DeadlineUtc)
+        {
+            tail.Next = response;
+            tail = response;
+            return;
+        }
+
+        DelayedApiResponse? previous = null;
+        for (var current = head; current is not null; current = current.Next)
+        {
+            if (response.DeadlineUtc < current.DeadlineUtc)
+            {
+                response.Next = current;
+                if (previous is null)
+                    head = response;
+                else
+                    previous.Next = response;
+                return;
+            }
+
+            previous = current;
+        }
+
+        if (tail is not null)
+            tail.Next = response;
+        tail = response;
+    }
+
+    internal static string StreamNameFromSubject(string subject) =>
+        SubscriptionIndex.TokenAt(subject, 5);
+
+    internal static string ConsumerNameFromSubject(string subject) =>
+        SubscriptionIndex.TokenAt(subject, 6);
+
+    internal static bool IsJSONObjectOrArray(ReadOnlySpan<byte> payload)
+    {
+        for (var i = 0; i < payload.Length; i++)
+        {
+            var ch = payload[i];
+            if (ch is (byte)' ' or (byte)'\t' or (byte)'\r' or (byte)'\n')
+                continue;
+
+            return ch is (byte)'{' or (byte)'[';
+        }
+
+        return false;
+    }
+
+    internal static bool SubjectMatches(string pattern, string subject)
+    {
+        var p = pattern.Split('.', StringSplitOptions.None);
+        var s = subject.Split('.', StringSplitOptions.None);
+
+        for (var i = 0; i < p.Length; i++)
+        {
+            if (i >= s.Length)
+                return p[i] == ">";
+
+            var token = p[i];
+            if (token == ">")
+                return true;
+            if (token == "*")
+                continue;
+            if (!string.Equals(token, s[i], StringComparison.Ordinal))
+                return false;
+        }
+
+        return p.Length == s.Length;
+    }
+
+    internal static T? DeserializeStrict<T>(byte[] payload, bool strictMode)
+    {
+        var strictOptions = new JsonSerializerOptions
+        {
+            PropertyNameCaseInsensitive = true,
+            UnmappedMemberHandling = JsonUnmappedMemberHandling.Disallow,
+        };
+
+        try
+        {
+            return JsonSerializer.Deserialize<T>(payload, strictOptions);
+        }
+        catch when (!strictMode)
+        {
+            return JsonSerializer.Deserialize<T>(payload);
+        }
+    }
+}

dotnet/src/ZB.MOM.NatsNet.Server/JetStream/JetStreamEngine.cs

@@ -1,3 +1,6 @@
+using System.Text;
+using ZB.MOM.NatsNet.Server.Internal;
+
 namespace ZB.MOM.NatsNet.Server;
 
 internal sealed class JetStreamEngine(JetStream state)
@@ -7,6 +10,7 @@ internal sealed class JetStreamEngine(JetStream state)
     private const string JsWillExtend = "will_extend";
     private const string JsNoExtend = "no_extend";
     private const string JsDomainApiTemplate = "$JS.{0}.API.>";
+    private const string JsApiAccountPrefix = "$JS.API.ACCOUNT.";
 
     internal void SetStarted()
     {
@@ -21,6 +25,91 @@ internal sealed class JetStreamEngine(JetStream state)
         }
     }
 
+    internal void ApiDispatch(ClientConnection c, Account acc, string subject, string reply, byte[] rawMessage)
+    {
+        // These meta/system directives are handled elsewhere.
+        if (subject == JsApiSubjects.JsApiLeaderStepDown ||
+            subject == JsApiSubjects.JsApiRemoveServer ||
+            subject.StartsWith(JsApiAccountPrefix, StringComparison.Ordinal))
+        {
+            return;
+        }
+
+        if (_state.Server is not NatsServer server)
+            return;
+
+        var route = server.MatchJetStreamApiSubscription(subject);
+        var (header, payload) = c.MsgParts(rawMessage);
+        var requestBody = Encoding.UTF8.GetString(payload);
+
+        if (NatsMessageHeaders.GetHeader(AccountEventConstants.ClientInfoHeader, header) is not { Length: > 0 })
+        {
+            var systemAccount = server.SystemAccount();
+            if (!ReferenceEquals(systemAccount, acc))
+                return;
+
+            if (subject != JsApiSubjects.JsApiAccountInfo)
+            {
+                if (c.Kind is ClientKind.Client or ClientKind.Leaf)
+                {
+                    var response = new ApiResponse
+                    {
+                        Type = JsApiSubjects.JsApiSystemResponseType,
+                        Error = JsApiErrors.NewJSNotEnabledForAccountError(),
+                    };
+                    server.SendAPIErrResponse(null, acc, subject, reply, requestBody, server.JsonResponse(response));
+                }
+
+                return;
+            }
+        }
+
+        if (route is null)
+        {
+            if (c.Kind is ClientKind.Client or ClientKind.Leaf)
+            {
+                var (_, requestAcc, _, _, _) = server.GetRequestInfo(c, rawMessage);
+                if (requestAcc is not null && !ReferenceEquals(requestAcc, server.SystemAccount()))
+                {
+                    var response = new ApiResponse
+                    {
+                        Type = JsApiSubjects.JsApiSystemResponseType,
+                        Error = JsApiErrors.NewJSBadRequestError(),
+                    };
+                    server.SendAPIErrResponse(null, requestAcc, subject, reply, requestBody, server.JsonResponse(response));
+                }
+            }
+
+            return;
+        }
+
+        Interlocked.Add(ref _state.ApiInflight, 1);
+
+        var request = new JsApiRoutedRequest
+        {
+            Subscription = route,
+            Account = acc,
+            Subject = subject,
+            Reply = reply,
+            Message = rawMessage.ToArray(),
+        };
+
+        var (queued, dropped) = server.EnqueueJSApiRequest(_state, request);
+        if (!queued)
+        {
+            if (dropped > 0)
+            {
+                server.PublishAdvisory(
+                    server.SystemAccount(),
+                    JsApiSubjects.JsAdvisoryApiLimitReached,
+                    new { Type = "io.nats.jetstream.advisory.v1.api_limit_reached", Dropped = dropped, Time = DateTime.UtcNow });
+            }
+
+            route.Handler(c, acc, subject, reply, rawMessage);
+            Interlocked.Add(ref _state.ApiInflight, -1);
+        }
+    }
+
     internal bool IsEnabled() => Interlocked.CompareExchange(ref _state.Disabled, 0, 0) == 0;
 
     internal void SetJetStreamStandAlone(bool isStandAlone)

dotnet/src/ZB.MOM.NatsNet.Server/JetStream/JsAccount.Core.cs

@@ -218,6 +218,38 @@ internal sealed partial class JsAccount
         }
     }
 
+    internal long TieredReservation(string tier, StreamConfig cfg)
+    {
+        long reservation = 0;
+
+        Lock.EnterReadLock();
+        try
+        {
+            foreach (var stream in Streams.Values.OfType<NatsStream>())
+            {
+                var streamCfg = stream.Config;
+                if (streamCfg.MaxBytes <= 0 || string.Equals(streamCfg.Name, cfg.Name, StringComparison.Ordinal))
+                    continue;
+
+                if (string.IsNullOrEmpty(tier))
+                {
+                    if (streamCfg.Storage == cfg.Storage)
+                        reservation += Math.Max(1, streamCfg.Replicas) * streamCfg.MaxBytes;
+                    continue;
+                }
+
+                if (streamCfg.Replicas == cfg.Replicas && JetStreamEngine.IsSameTier(streamCfg, cfg))
+                    reservation += Math.Max(1, streamCfg.Replicas) * streamCfg.MaxBytes;
+            }
+
+            return reservation;
+        }
+        finally
+        {
+            Lock.ExitReadLock();
+        }
+    }
+
     internal (ulong Mem, ulong Store) StorageTotals()
     {
         UsageLock.EnterReadLock();

dotnet/src/ZB.MOM.NatsNet.Server/NatsServer.JetStreamApi.cs

@@ -0,0 +1,430 @@
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using ZB.MOM.NatsNet.Server.Internal;
+
+namespace ZB.MOM.NatsNet.Server;
+
+public sealed partial class NatsServer
+{
+    private readonly Lock _jsApiSubsLock = new();
+    private readonly List<JetStreamApiSubscription> _jsApiSubscriptions = [];
+    private IpQueue<JsApiRoutedRequest>? _jsApiRoutedReqs;
+    private IpQueue<DelayedApiResponse>? _delayedApiResponses;
+
+    internal void ProcessJSAPIRoutedRequests()
+    {
+        var queue = _jsApiRoutedReqs;
+        if (queue is null)
+            return;
+
+        var client = CreateInternalJetStreamClient();
+        var token = _quitCts.Token;
+
+        while (!token.IsCancellationRequested)
+        {
+            try
+            {
+                if (!queue.Ch.WaitToReadAsync(token).AsTask().GetAwaiter().GetResult())
+                    break;
+
+                while (true)
+                {
+                    var (request, ok) = queue.PopOne();
+                    if (!ok)
+                        break;
+
+                    var start = DateTime.UtcNow;
+                    request.Subscription.Handler(client, request.Account, request.Subject, request.Reply, request.Message);
+                    var elapsed = DateTime.UtcNow - start;
+                    if (elapsed >= TimeSpan.FromSeconds(1))
+                        Warnf("Internal subscription on '{0}' took too long: {1}", request.Subject, elapsed);
+
+                    var js = GetJetStreamState();
+                    if (js is not null)
+                        Interlocked.Add(ref js.ApiInflight, -1);
+                }
+            }
+            catch (OperationCanceledException)
+            {
+                return;
+            }
+            catch (Exception ex)
+            {
+                Warnf("JetStream routed API worker failed: {0}", ex.Message);
+            }
+        }
+    }
+
+    internal Exception? SetJetStreamExportSubs()
+    {
+        var js = GetJetStreamState();
+        if (js is null)
+            return new InvalidOperationException(JsApiErrors.NewJSNotEnabledError().Description ?? "jetstream not enabled");
+
+        var workers = Math.Min(Math.Max(Environment.ProcessorCount, 1), 16);
+
+        _jsApiRoutedReqs = IpQueue<JsApiRoutedRequest>.NewIPQueue("Routed JS API Requests");
+        _delayedApiResponses = IpQueue<DelayedApiResponse>.NewIPQueue("Delayed JS API Responses");
+        Interlocked.Exchange(ref js.QueueLimit, JsApiSubjects.JsDefaultRequestQueueLimit);
+
+        for (var i = 0; i < workers; i++)
+            StartGoRoutine(ProcessJSAPIRoutedRequests);
+
+        StartGoRoutine(DelayedAPIResponder);
+
+        lock (_jsApiSubsLock)
+        {
+            _jsApiSubscriptions.Clear();
+            _jsApiSubscriptions.Add(new JetStreamApiSubscription
+            {
+                Subject = JsApiSubjects.JsApiAccountInfo,
+                Handler = JsAccountInfoRequest,
+            });
+        }
+
+        var sys = SystemAccount();
+        if (sys is null)
+            return null;
+
+        var err = sys.AddServiceExport(JsApiSubjects.JsAllApi, null);
+        if (err is not null)
+            Warnf("Error setting up jetstream service exports: {0}", err.Message);
+        return err;
+    }
+
+    internal JetStreamApiSubscription? MatchJetStreamApiSubscription(string subject)
+    {
+        lock (_jsApiSubsLock)
+        {
+            foreach (var sub in _jsApiSubscriptions)
+            {
+                if (JetStreamApi.SubjectMatches(sub.Subject, subject))
+                    return sub;
+            }
+        }
+
+        return null;
+    }
+
+    internal (bool Queued, long Dropped) EnqueueJSApiRequest(JetStream js, JsApiRoutedRequest request)
+    {
+        var queue = _jsApiRoutedReqs;
+        if (queue is null)
+            return (false, 0);
+
+        var (pending, error) = queue.Push(request);
+        var limit = Interlocked.Read(ref js.QueueLimit);
+        if (limit <= 0)
+            limit = JsApiSubjects.JsDefaultRequestQueueLimit;
+
+        if (error is null && pending < limit)
+            return (true, 0);
+
+        RateLimitFormatWarnf("JetStream API queue limit reached, dropping {0} requests", pending);
+        var drained = queue.Drain();
+        if (drained > 0)
+            Interlocked.Add(ref js.ApiInflight, -drained);
+
+        return (false, drained);
+    }
+
+    internal void SendAPIResponse(ClientInfo? ci, Account acc, string subject, string reply, string request, string response)
+    {
+        acc.TrackAPI();
+        if (!string.IsNullOrWhiteSpace(reply))
+            _ = SendInternalAccountMsgWithReply(acc, reply, string.Empty, null, response, false);
+
+        SendJetStreamAPIAuditAdvisory(ci, acc, subject, request, response);
+    }
+
+    internal void SendAPIErrResponse(ClientInfo? ci, Account acc, string subject, string reply, string request, string response)
+    {
+        acc.TrackAPIErr();
+        if (!string.IsNullOrWhiteSpace(reply))
+            _ = SendInternalAccountMsgWithReply(acc, reply, string.Empty, null, response, false);
+
+        SendJetStreamAPIAuditAdvisory(ci, acc, subject, request, response);
+    }
+
+    internal void DelayedAPIResponder()
+    {
+        var queue = _delayedApiResponses;
+        if (queue is null)
+            return;
+
+        var token = _quitCts.Token;
+        DelayedApiResponse? head = null;
+        DelayedApiResponse? tail = null;
+
+        while (!token.IsCancellationRequested)
+        {
+            try
+            {
+                while (true)
+                {
+                    var (entry, ok) = queue.PopOne();
+                    if (!ok)
+                        break;
+                    JetStreamApi.AddDelayedResponse(ref head, ref tail, entry);
+                }
+
+                var now = DateTime.UtcNow;
+                if (head is not null && head.DeadlineUtc <= now)
+                {
+                    var entry = head;
+                    head = head.Next;
+                    if (head is null)
+                        tail = null;
+
+                    if (entry.RawResponse)
+                        _ = SendInternalAccountMsgWithReply(entry.Account, entry.Subject, string.Empty, entry.Header, entry.Response, false);
+                    else
+                        SendAPIErrResponse(entry.ClientInfo, entry.Account, entry.Subject, entry.Reply, entry.Request, entry.Response);
+
+                    continue;
+                }
+
+                var wait = head is null
+                    ? TimeSpan.FromSeconds(1)
+                    : head.DeadlineUtc - now;
+
+                if (wait < TimeSpan.Zero)
+                    wait = TimeSpan.Zero;
+
+                _ = Task.WhenAny(
+                    queue.Ch.WaitToReadAsync(token).AsTask(),
+                    Task.Delay(wait, token)).GetAwaiter().GetResult();
+            }
+            catch (OperationCanceledException)
+            {
+                return;
+            }
+            catch (Exception ex)
+            {
+                Warnf("Delayed JetStream API responder failed: {0}", ex.Message);
+            }
+        }
+    }
+
+    internal void SendDelayedAPIErrResponse(
+        ClientInfo? ci,
+        Account acc,
+        string subject,
+        string reply,
+        string request,
+        string response,
+        TimeSpan duration)
+    {
+        _delayedApiResponses?.Push(new DelayedApiResponse
+        {
+            ClientInfo = ci,
+            Account = acc,
+            Subject = subject,
+            Reply = reply,
+            Request = request,
+            Response = response,
+            DeadlineUtc = DateTime.UtcNow.Add(duration),
+            RawResponse = false,
+        });
+    }
+
+    internal void SendDelayedErrResponse(Account acc, string subject, byte[]? header, string response, TimeSpan duration)
+    {
+        _delayedApiResponses?.Push(new DelayedApiResponse
+        {
+            Account = acc,
+            Subject = subject,
+            Reply = string.Empty,
+            Header = header,
+            Response = response,
+            DeadlineUtc = DateTime.UtcNow.Add(duration),
+            RawResponse = true,
+        });
+    }
+
+    internal (ClientInfo? ClientInfo, Account? Account, byte[] Header, byte[] Message, Exception? Error) GetRequestInfo(ClientConnection c, byte[] raw)
+    {
+        var (hdr, msg) = c.MsgParts(raw);
+
+        ClientInfo? clientInfo = null;
+        var clientInfoBytes = NatsMessageHeaders.GetHeader(AccountEventConstants.ClientInfoHeader, hdr);
+        if (clientInfoBytes is { Length: > 0 })
+        {
+            try
+            {
+                clientInfo = JsonSerializer.Deserialize<ClientInfo>(clientInfoBytes);
+            }
+            catch (Exception ex)
+            {
+                return (null, null, hdr, msg, ex);
+            }
+        }
+
+        Account? acc = null;
+        var serviceAccount = clientInfo?.ServiceAccount();
+        if (!string.IsNullOrWhiteSpace(serviceAccount))
+            (acc, _) = LookupAccount(serviceAccount);
+
+        if (acc is null)
+        {
+            acc = c.Account() as Account;
+            acc ??= SystemAccount();
+        }
+
+        if (acc is null)
+            return (clientInfo, null, hdr, msg, ServerErrors.ErrMissingAccount);
+
+        return (clientInfo, acc, hdr, msg, null);
+    }
+
+    internal Exception? UnmarshalRequest<T>(ClientConnection c, Account acc, string subject, byte[] message, out T? value)
+    {
+        var strictMode = JetStreamConfig()?.Strict ?? true;
+        value = JetStreamApi.DeserializeStrict<T>(message, strictMode);
+        if (value is not null)
+            return null;
+
+        var err = new InvalidOperationException("unable to deserialize JetStream API request");
+        c.RateLimitWarnf("Invalid JetStream request '{0} > {1}': {2}", acc.Name, subject, err.Message);
+        return err;
+    }
+
+    internal Exception? UnmarshalRequest(ClientConnection c, Account acc, string subject, byte[] message, object destination)
+    {
+        var strictMode = JetStreamConfig()?.Strict ?? true;
+        object? parsed;
+
+        try
+        {
+            parsed = JsonSerializer.Deserialize(message, destination.GetType(), new JsonSerializerOptions
+            {
+                PropertyNameCaseInsensitive = true,
+                UnmappedMemberHandling = JsonUnmappedMemberHandling.Disallow,
+            });
+        }
+        catch (Exception ex) when (!strictMode)
+        {
+            try
+            {
+                parsed = JsonSerializer.Deserialize(message, destination.GetType());
+            }
+            catch
+            {
+                c.RateLimitWarnf("Invalid JetStream request '{0} > {1}': {2}", acc.Name, subject, ex.Message);
+                return ex;
+            }
+        }
+        catch (Exception ex)
+        {
+            c.RateLimitWarnf("Invalid JetStream request '{0} > {1}': {2}", acc.Name, subject, ex.Message);
+            return ex;
+        }
+
+        if (parsed is null)
+            return new InvalidOperationException("empty JetStream API request body");
+
+        foreach (var property in destination.GetType().GetProperties())
+        {
+            if (!property.CanRead || !property.CanWrite)
+                continue;
+            property.SetValue(destination, property.GetValue(parsed));
+        }
+
+        return null;
+    }
+
+    internal void JsAccountInfoRequest(ClientConnection c, Account acc, string subject, string reply, byte[] rawMessage)
+    {
+        if (!JetStreamEnabled())
+            return;
+
+        var (ci, requestAcc, hdr, msg, err) = GetRequestInfo(c, rawMessage);
+        if (err is not null || requestAcc is null)
+        {
+            Warnf("Malformed JetStream API Request: {0}", Encoding.UTF8.GetString(msg));
+            return;
+        }
+
+        var response = new JsApiAccountInfoResponse
+        {
+            Type = JsApiSubjects.JsApiAccountInfoResponseType,
+        };
+
+        var requiredApiLevel = NatsMessageHeaders.GetHeader(JsApiSubjects.JsRequiredApiLevel, hdr);
+        var reqApiHeader = requiredApiLevel is null ? null : Encoding.ASCII.GetString(requiredApiLevel);
+        if (JetStreamVersioning.ErrorOnRequiredApiLevel(reqApiHeader))
+        {
+            response.Error = JsApiErrors.NewJSRequiredApiLevelError();
+            SendAPIErrResponse(ci, requestAcc, subject, reply, Encoding.UTF8.GetString(msg), JsonResponse(response));
+            return;
+        }
+
+        var (hasJetStream, shouldError) = requestAcc.CheckJetStream();
+        if (!hasJetStream)
+        {
+            if (!shouldError)
+                return;
+
+            response.Error = JsApiErrors.NewJSNotEnabledForAccountError();
+            SendAPIErrResponse(ci, requestAcc, subject, reply, Encoding.UTF8.GetString(msg), JsonResponse(response));
+            return;
+        }
+
+        var stats = requestAcc.JetStreamUsage();
+        response.Memory = stats.Memory;
+        response.Store = stats.Store;
+        response.ReservedMemory = stats.ReservedMemory;
+        response.ReservedStore = stats.ReservedStore;
+        response.Streams = stats.Streams;
+        response.Consumers = stats.Consumers;
+        response.Limits = stats.Limits;
+        response.Domain = stats.Domain;
+        response.Api = stats.Api;
+        response.Tiers = stats.Tiers;
+
+        SendAPIResponse(ci, requestAcc, subject, reply, Encoding.UTF8.GetString(msg), JsonResponse(response));
+    }
+
+    internal static string StreamNameFromSubject(string subject) => JetStreamApi.StreamNameFromSubject(subject);
+
+    internal static string ConsumerNameFromSubject(string subject) => JetStreamApi.ConsumerNameFromSubject(subject);
+
+    internal string JsonResponse(object response)
+    {
+        try
+        {
+            return JsonSerializer.Serialize(response);
+        }
+        catch (Exception ex)
+        {
+            Warnf("Problem marshaling JSON for JetStream API: {0}", ex.Message);
+            return string.Empty;
+        }
+    }
+
+    internal void SendJetStreamAPIAuditAdvisory(ClientInfo? ci, Account acc, string subject, string request, string response)
+    {
+        _ = ci;
+        _ = acc;
+        _ = subject;
+        _ = request;
+        _ = response;
+    }
+
+    private Exception? SendInternalAccountMsgWithReply(Account account, string subject, string reply, byte[]? header, string response, bool trackApi)
+    {
+        _ = trackApi;
+
+        try
+        {
+            var sendQueue = account.GetSendQueue() ?? NewSendQueue(account);
+            SendQueue.Send(sendQueue, subject, reply, header ?? [], Encoding.UTF8.GetBytes(response));
+            return null;
+        }
+        catch (Exception ex)
+        {
+            return ex;
+        }
+    }
+}

dotnet/src/ZB.MOM.NatsNet.Server/NatsServer.JetStreamCore.cs

@@ -268,11 +268,7 @@ public sealed partial class NatsServer
 
     internal void SetupJetStreamExports()
     {
-        var sys = SystemAccount();
+        var err = SetJetStreamExportSubs();
-        if (sys == null)
-            return;
-
-        var err = sys.AddServiceExport(JsApiSubjects.JsAllApi, null);
         if (err != null)
             Warnf("Error setting up jetstream service exports: {0}", err.Message);
     }