Currently, we are using this library to listen to push topics whenever there is a change in salesforce. We are using this library as follows.
Code for registering an event and configuring the Salesforce Streaming Client in Program.cs is:
public static void Main(string[] args)
{
var builder = WebApplication.CreateBuilder(args);
builder.Host.ConfigureServices((hostContext, services) =>
{
var salesforceConfiguration = services.BuildServiceProvider().GetRequiredService<IOptions>().Value;
services.AddResilientStreamingClient("", "", (conf) =>
{
conf.ClientId = salesforceConfiguration.ClientId;
conf.ClientSecret = salesforceConfiguration.ClientSecret;
conf.RefreshToken = salesforceConfiguration.RefreshToken;
conf.LoginUrl = salesforceConfiguration.BaseUrl;
conf.OAuthUri = Constants.OAuthUriConfig;
conf.EventOrTopicUri = Constants.EventOrTopicConfig;
conf.CometDUri = salesforceConfiguration.CometdUrl;
});
services.AddSingleton<IEventBus, EventBus>();
services.AddHostedService();
services.AddTransient<IMessageListener, UpdatedListener>();
services.AddTransient<IMessageListener, DeletedListener>();
});
var app = builder.Build();
app.Run();
}
Code for subscribing to events is:
public class SalesforceEventBusHostedService:IHostedService
{
private readonly ILogger _logger;
private readonly IEventBus _eventBus;
private readonly ICacheService _cacheService;
//Make a list of push topics that we created in salesforce
private readonly List<Tuple<string,int,Type>> _eventsMapping = new()
{
new Tuple<string,int,Type>("topic/Updated",-1,typeof(UpdatedListener)),
new Tuple<string, int, Type>("topic/Deleted", -1, typeof(DeletedListener))
};
public SalesforceEventBusHostedService(ILogger<SalesforceEventBusHostedService> logger,IEventBus eventBus, ICacheService<ReplayIdDto> cacheService)
{
_logger = logger;
_eventBus = eventBus;
_cacheService = cacheService;
_cacheService.CacheRegion = $"{Constants.MessageListenerCacheRegion}";
}
private static object[] GetPlatformEventObject(string eventName,int replayId,Type eventType)
{
var platformEvent = Activator.CreateInstance(typeof(PlatformEvent<>).MakeGenericType(eventType));
platformEvent?.GetType().GetProperty("Name")?.SetValue(platformEvent, eventName);
platformEvent?.GetType().GetProperty("ReplayId")?.SetValue(platformEvent, replayId);
return new[] {platformEvent};
}
private async Task SubscribeToEvent(string eventName,int replayId,Type eventType)
{
var platformEvent = GetPlatformEventObject(eventName, replayId, eventType);
var subscribeMethod = typeof(IEventBus).GetMethod("Subscribe")?.MakeGenericMethod(eventType);
await ((Task) subscribeMethod?.Invoke(_eventBus, platformEvent))!;
}
private async Task UnSubscribeToEvent(string eventName,int replayId,Type eventType)
{
var platformEvent = GetPlatformEventObject(eventName, replayId, eventType);
var subscribeMethod = typeof(IEventBus).GetMethod("Unsubscribe")?.MakeGenericMethod(eventType);
await ((Task) subscribeMethod?.Invoke(_eventBus, platformEvent))!;
}
public async Task StartAsync(CancellationToken cancellationToken)
{
_logger.LogInformation($"{nameof(SalesforceEventBusHostedService)} starting.");
for (var i = 0; i < _eventsMapping.ToList().Count; i++)
{
var (originalEventName, originalReplayId, originalEventType) = _eventsMapping[i];
var replayIdFromCache = (await _cacheService.GetItemAsync(StreamingApiHelper.RemoveEventOrTopicPrefix(originalEventName)))?.ReplayId??originalReplayId;
var (eventName, replayId, eventType) = _eventsMapping[i] = new Tuple<string, int, Type>(originalEventName, replayIdFromCache, originalEventType);
await SubscribeToEvent(eventName, replayId, eventType);
}
}
public async Task StopAsync(CancellationToken cancellationToken)
{
_logger.LogInformation($"{nameof(SalesforceEventBusHostedService)} stopped.");
foreach (var (eventName,replayId, eventType) in _eventsMapping)
{
await UnSubscribeToEvent(eventName, replayId, eventType);
}
}
}
But I face an issue like:
System.NullReferenceException: Object reference not set to an instance of an object.
at CometD.NetCore.Salesforce.ResilientStreamingClient.ErrorExtension_ConnectionError(Object sender, String e) in C:\projects\cometd-netcore-salesforce\src\CometD.NetCore.Salesforce\ResilientStreamingClient.cs:line 210
at CometD.NetCore.Client.Extension.ErrorExtension.ReceiveMeta(IClientSession session, IMutableMessage message) in C:\projects\cometd-netcore\src\CometD.NetCore\Client\Extension\ErrorExtension.cs:line 74
at CometD.NetCore.Common.AbstractClientSession.ExtendReceive(IMutableMessage message) in C:\projects\cometd-netcore\src\CometD.NetCore\Common\AbstractClientSession.cs:line 188
at CometD.NetCore.Common.AbstractClientSession.Receive(IMutableMessage message) in C:\projects\cometd-netcore\src\CometD.NetCore\Common\AbstractClientSession.cs:line 155
at CometD.NetCore.Client.BayeuxClient.PublishTransportListener.OnMessages(IList`1 messages) in C:\projects\cometd-netcore\src\CometD.NetCore\Client\BayeuxClient.cs:line 769
at CometD.NetCore.Client.Transport.LongPollingTransport.GetResponseCallback(IAsyncResult asynchronousResult) in C:\projects\cometd-netcore\src\CometD.NetCore\Client\Transport\LongPollingTransport.cs:line 310
Can anyone please guide me on why this error is received and if there is something I should be updating on our end?
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