Amazon Kinesis

               

Scenario: Create Amazon Kinesis client to push data stream to AWS

Solution:

      Per Amazon:

      With Amazon Kinesis, you can ingest real-time data such as video, audio, application logs, website        clickstreams, and IoT telemetry data for machine learning, analytics, and other applications.

      

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using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using Amazon;
using Amazon.Kinesis;
using Amazon.Kinesis.Model;
using Amazon.SecurityToken;
using Amazon.SecurityToken.Model;
using Timer = System.Timers.Timer;

namespace ConsoleApplication1
{
    public abstract class KinesisClient<T> : IKinesisClient where T : class
    {
        private readonly object _lock = new();
        private readonly ReaderWriterLockSlim _lockSlim = new();
        
        public void Publish(object data)
        {
            PublishData((T)data);
        }
        
        private void Send(PutRecordRequest request)
        {
            KinesisConnectionMultiplexer client;

            if (_disposed)
            {
                return;
            }

            _lockSlim.EnterReadLock();

            try
            {
                if (TryGetClient(_kinesisClients, out client))
                {
                    PublishDataStream(client, request);
                    return;
                }
            }
            finally
            {
                _lockSlim.ExitReadLock();
            }

            _lockSlim.EnterWriteLock();

            try
            {
                if (!TryGetClient(_kinesisClients, out client))
                {
                    //local
                    if (isLocal)
                    {
                        _kinesisClients = CreateClients(clientsecret, null);
                    }
                    else
                    {
                        //awsTemporaryCredentials.AccessKeyId}
                        //awsTemporaryCredentials.SecretAccessKey}
                        //awsTemporaryCredentials.SessionToken
                        //awsTemporaryCredentials.Expiration }");

                        var awsTemporaryCredentials = GetKinesisCredentials();

                        _kinesisClients = CreateClients(awsTemporaryCredentials);
                        TryGetClient(_kinesisClients, out client);
                    }
                }

                PublishDataStream(client, request);
            }
            finally
            {
                _lockSlim.ExitWriteLock();
            }
        }
        
        private void PublishData(T data)
        {
            Send(new PutRecordRequest
            {
                StreamName = "OrderStream",
                Data = new MemoryStream(Encoding.UTF8.GetBytes(json)),
                PartitionKey = DateTime.Now.ToString("yyyy-MM")
            });
        }
        
        private static KinesisConnectionMultiplexer[] CreateClients(Credentials awsCredentials)
        {
            var clients = new KinesisConnectionMultiplexer[MaxConnections];

            for (var i = 0; i < MaxConnections; i++)
            {
                clients[i] = new KinesisConnectionMultiplexer
                {
                    Client = !string.IsNullOrEmpty(ClientId)
                        ? new AmazonKinesisClient(ClientId, ClientSecret,
                            RegionEndpoint.GetBySystemName(Region) ?? RegionEndpoint.USEast1)
                        : new AmazonKinesisClient(awsCredentials?.AccessKeyId, awsCredentials?.SecretAccessKey,
                            awsCredentials?.SessionToken, RegionEndpoint.GetBySystemName(Region) ??
                                                         RegionEndpoint.USEast1),
                    ExpiryTime = awsCredentials?.Expiration ?? DateTime.MaxValue

                };
            }

            return clients;
        }

        public Credentials GetKinesisCredentials()
        {
            var roleArn = $"arn:aws:iam::{IamAccountId}:role/{IamRoleName}";

            var request = new AssumeRoleRequest
            {
                RoleArn = roleArn,
                RoleSessionName = $"{"Environment"}_kinesis_session",
                DurationSeconds = ConnectionDuration
            };

            var response =
                new AmazonSecurityTokenServiceClient(RegionEndpoint.GetBySystemName({"Region"}) ??}
                                                     RegionEndpoint.USEast1).AssumeRoleAsync(request);
        
            return response.Result.HttpStatusCode == System.Net.HttpStatusCode.OK ? response.Result.Credentials : null;
        }

        public bool TryGetClient(KinesisConnectionMultiplexer[] clients, out KinesisConnectionMultiplexer client)
        {
            if (clients == null || !clients.Any())
            {
                client = null;
                return false;
            }

            lock (clients)
            {
                client = clients.Where(k => DateTime.Now.AddSeconds(10) <= k.ExpiryTime).Min(client => client);
            }

            if (client == null)
            {
                return false;
            }

            Interlocked.Increment(ref client.Load);
            return true;
        }

        private void PublishDataStream(KinesisConnectionMultiplexer multiplexer, PutRecordRequest putRecordRequest)
        {
            ProcessPutRecordsRequest(multiplexer, putRecordRequest);
        }

        private void ProcessPutRecordsRequest(KinesisConnectionMultiplexer multiplexer,
            PutRecordRequest putRecordRequest)
        {
            var client = multiplexer.Client;
            var cts = new CancellationTokenSource();
            var ct = cts.Token;
            var task = client.PutRecordAsync(putRecordRequest, ct).Result;

            Interlocked.Decrement(ref multiplexer.Load);
        }
    }
}

Ref vs Out parameter

              

Scenario: Difference between Ref vs Out parameter

Solution:

      While creating a new object two things get created:

1. The block of memory that holds data for the object.
2. A reference  or pointer to that block of data.

      When the object is sent through a method without ref it copies the reference pointer but not 

       the data. So If we modify a property on an object, it will affect the same data pointed to by the               earlier reference. If we set the reference to null or point it to new data it will not affect the earlier        reference and also not the data referenced by it

      When it is passed with ref keyword to a method then the actual reference to the object gets                     sent to the method and so now there only one reference to the data:

using System;

namespace ConsoleAppCore
{
    public class Program
    {
        static void Main(string[] args)
        {
            var profile = new Profile
            {
                Id = 1,
                Name = "Test User",
                Address = "Los Angeles"
            };

            Console.WriteLine(
                $"Outside the Method Profile (Before Method call): {profile.Id} - {profile.Name}, {profile.Addrress}");

            ChangeAddress(profile);

            Console.WriteLine(
            $"Outside the Method Profile (After Method call w/o ref): {profile.Id} - {profile.Name}, {profile.Addrress}");
            Console.ReadLine();

            ChangeAddressRef(ref profile);

            Console.WriteLine(
                $"Outside the Method Profile (After Method call w/ ref): {profile.Id} - {profile.Name}, {profile.Addrress}");
            Console.ReadLine();
        }

        private static bool ChangeAddress(Profile data)
        {
            //data.Addrress = "New York";
            //Console.WriteLine(
            //    $"Outside the Method Profile (Before Method call): {data.Id} - {data.Name}, {data.Addrress}");

            data = null;

            return true;
        }

        private static bool ChangeAddressRef(ref Profile data)
        {
            //data.Addrress = "New York";
            //Console.WriteLine(
            //    $"Outside the Method Profile (Before Method call): {data.Id} - {data.Name}, {data.Addrress}");

            data = new Profile();

            return true;
        }
    }

    public class Profile
    {
        public int Id{ get; set; }
        public string Name { get; set; }
        public string Address { get; set; }
    }
}