<\/div>\n
Merhaba,<\/p>\n
Bu i\u00e7eri\u011fimizde bir \u00f6nceki kaleme ald\u0131\u011f\u0131m\u0131z Event Sourcing Nedir? Haydi Gelin Hep Beraber \u0130nceleyelim<\/a> ba\u015fl\u0131kl\u0131 makalemize basit bir somut \u00f6rnek te\u015fkil edecek \u015fekilde \u00e7al\u0131\u015fma ger\u00e7ekle\u015ftirece\u011fiz. Amac\u0131m\u0131z Event Sourcing’in pratikte ucundan k\u0131y\u0131s\u0131ndan tad\u0131na bakmak ve konuya dair sonradan kaleme alaca\u011f\u0131m\u0131z Event Store gibi bir tool’un \u015fimdiden k\u0131ymetini anlamak \ud83d\ude42 Evet… O halde haz\u0131rsan\u0131z ba\u015flayal\u0131m…<\/p>\n
Kurgu<\/h3>\n
\u0130lk olarak yapaca\u011f\u0131m\u0131z \u00e7al\u0131\u015fmaya dair genel kurgudan bahsetmek istiyorum. \u00d6rneklendirmemiz bir console uygulamas\u0131 \u00fczerinde var olan ‘Person’ nesnesine dair ‘Command’ ve ‘Query’lerin ayr\u0131m\u0131 \u00fczerinden seyredecektir. Haliyle buradan anla\u015f\u0131l\u0131yor ki, temel CQRS pattern<\/a> e\u015fli\u011finde basit bir Event Sourcing yakla\u015f\u0131m\u0131 sergileyece\u011fiz.<\/p>\n
\r\n    record Person\r\n    {\r\n        public int Id { get; init; }\r\n        public string Name { get; private set; }\r\n        public int Age { get; private set; }\r\n\r\n        public Person(int id, string name, int age)\r\n        {\r\n            Id = id;\r\n            Name = name;\r\n            Age = age;\r\n        }\r\n\r\n        public void ChangeName(string name)\r\n        => Name = name;\r\n        public void ChangeAge(int age)\r\n        => Age = age;\r\n    }\r\n\r\n    class PersonSource\r\n    {\r\n        public static List<Person> PersonList { get; } = new()\r\n        {\r\n            new(1, "Gen\u00e7ay", 28),\r\n            new(2, "Hilmi", 30),\r\n            new(3, "Co\u015fgun", 42),\r\n            new(4, "R\u0131fk\u0131", 32)\r\n        };\r\n    }\r\n<\/pre>\nCQRS Temelinin Olu\u015fturulmas\u0131<\/h4>\n\u00d6ncelikle CQRS temelini atarak uygulamay\u0131 in\u015fa etmeye ba\u015flayabiliriz.
\nQuery<\/strong>
\nRequest nesneleri:<\/p>\n\r\n    class GetPersonQueryRequest\r\n    {\r\n        public int Id { get; set; }\r\n    }\r\n<\/pre>\n\r\n    class GetAllPersonQueryRequest\r\n    {\r\n\r\n    }\r\n<\/pre>\nResponse nesneleri:<\/p>\n\r\n    class GetPersonQueryResponse\r\n    {\r\n        public Person Person;\r\n    }\r\n<\/pre>\n\r\n    class GetAllPersonQueryResponse\r\n    {\r\n        public int Id { get; set; }\r\n        public string Name { get; set; }\r\n        public int Age { get; set; }\r\n    }\r\n<\/pre>\nHandler nesneleri:<\/p>\n\r\n    class GetPersonQueryHandler\r\n    {\r\n        public GetPersonQueryResponse GetPerson(GetPersonQueryRequest request)\r\n        {\r\n            Person person = PersonSource.PersonList.FirstOrDefault(p => p.Id == request.Id);\r\n            return new GetPersonQueryResponse\r\n            {\r\n                Person = person\r\n            };\r\n        }\r\n    }\r\n<\/pre>\n\r\n    class GetAllPersonQueryHandler\r\n    {\r\n        public List<GetAllPersonQueryResponse> GetAll(GetAllPersonQueryRequest request)\r\n        {\r\n            return PersonSource.PersonList.Select(person => new GetAllPersonQueryResponse\r\n            {\r\n                Id = person.Id,\r\n                Age = person.Age,\r\n                Name = person.Name\r\n            }).ToList();\r\n        }\r\n    }\r\n<\/pre>\nCommand<\/strong>
\nRequest nesneleri:<\/p>\n\r\n    class ChangeNamePersonCommandRequest\r\n    {\r\n        public int Id { get; set; }\r\n        public string Name { get; set; }\r\n    }\r\n<\/pre>\n\r\n    class ChangeAgePersonCommandRequest\r\n    {\r\n        public int Id { get; set; }\r\n        public string Age { get; set; }\r\n    }\r\n<\/pre>\n\r\n    class CreatePersonCommandRequest\r\n    {\r\n        public int Id { get; set; }\r\n        public string Name { get; set; }\r\n        public int Age { get; set; }\r\n    }\r\n<\/pre>\nResponse nesneleri:<\/p>\n
\r\n    class ChangeNamePersonCommandResponse\r\n    {\r\n        public bool Register = true;\r\n    }\r\n<\/pre>\n\r\n    class ChangeAgePersonCommandResponse\r\n    {\r\n        public bool Register = true;\r\n    }\r\n<\/pre>\n\r\n    class CreatePersonCommandResponse\r\n    {\r\n        public Person Person { get; set; }\r\n    }\r\n<\/pre>\nHandler nesneleri:<\/p>\n
\r\n    class ChangeNamePersonCommandHandler\r\n    {\r\n        public ChangeNamePersonCommandResponse ChangeName(ChangeNamePersonCommandRequest request)\r\n        {\r\n            Person person = PersonSource.PersonList.FirstOrDefault(p => p.Id == request.Id);\r\n            person.ChangeName(request.Name);\r\n            return new ChangeNamePersonCommandResponse\r\n            {\r\n                Register = true\r\n            };\r\n        }\r\n    }\r\n<\/pre>\n\r\n        public ChangeAgePersonCommandResponse ChangeAge(ChangeAgePersonCommandRequest request)\r\n        {\r\n            Person person = PersonSource.PersonList.FirstOrDefault(p => p.Id == request.Id);\r\n            person.ChangeAge(request.Age);\r\n            return new ChangeAgePersonCommandResponse\r\n            {\r\n                Register = true\r\n            };\r\n        }\r\n<\/pre>\n\r\n    class CreatePersonCommandHandler\r\n    {\r\n        public CreatePersonCommandResponse CreatePerson(CreatePersonCommandRequest request)\r\n        {\r\n            PersonSource.PersonList.Add(new Person(request.Id, request.Name, request.Age));\r\n            return new CreatePersonCommandResponse\r\n            {\r\n                Person = PersonSource.PersonList.Last()\r\n            };\r\n        }\r\n    }\r\n<\/pre>\nEvet… G\u00f6r\u00fcld\u00fc\u011f\u00fc \u00fczere CQRS pattern’a uygun bir \u015fekilde gelecek istekleri ay\u0131rm\u0131\u015f olduk. Bundan sonra herhangi bir ‘Person’ nesnesine yap\u0131lan ‘Command’ isteklerini event olarak tutabilmemiz i\u00e7in \u00f6ncelikle ‘Event’ tasar\u0131mlar\u0131nda bulunmamam\u0131z gerekmektedir.<\/p>\n
Event Tasar\u0131mlar\u0131n\u0131 Ger\u00e7ekle\u015ftirmek<\/h4>\n\r\n    interface IEvent\r\n    {\r\n    }\r\n<\/pre>\n\r\n    class NameChangedEvent : IEvent\r\n    {\r\n        public Person Person { get; set; }\r\n        public string oldName, newName;\r\n        public NameChangedEvent(Person person, string oldName, string newName)\r\n        {\r\n            Person = person;\r\n            this.oldName = oldName;\r\n            this.newName = newName;\r\n        }\r\n        public override string ToString()\r\n        => $"Id de\u011feri {Person.Id} olan personelin ad\u0131 de\u011fi\u015ftirilmi\u015ftir.\\nEski ad\u0131 : {oldName}\\nYeni ad\u0131 : {newName}";\r\n    }\r\n<\/pre>\nYukar\u0131daki kod blo\u011funu incelerseniz e\u011fer bir ‘Person’ nesnesinin ‘Name’ de\u011ferinin de\u011fi\u015fti\u011fini ifade eden ‘NameChangedEvent’ isminde bir s\u0131n\u0131f tasarlanm\u0131\u015ft\u0131r. Ayn\u0131 \u015fekilde ‘Age’ de\u011ferinin de\u011fi\u015fti\u011fini ve yeni bir ‘Person’ eklendi\u011fini ifade eden ‘AgeChangedEvent’ ve ‘PersonCreatedEvent’ isimli event s\u0131n\u0131flar\u0131 da a\u015fa\u011f\u0131dad\u0131r.<\/p>\n
\r\n    class AgeChangedEvent : IEvent\r\n    {\r\n        public Person Person { get; set; }\r\n        public int oldAge, newAge;\r\n\r\n        public AgeChangedEvent(Person person, int oldAge, int newAge)\r\n        {\r\n            Person = person;\r\n            this.oldAge = oldAge;\r\n            this.newAge = newAge;\r\n        }\r\n        public override string ToString()\r\n            => $"Id de\u011feri {Person.Id} olan personelin ya\u015f\u0131 de\u011fi\u015ftirilmi\u015ftir.\\nEski ya\u015f : {oldAge}\\nYeni ya\u015f : {oldAge}";\r\n    }\r\n<\/pre>\n\r\n    class PersonCreatedEvent : IEvent\r\n    {\r\n        public Person Person { get; set; }\r\n\r\n        public PersonCreatedEvent(Person person)\r\n        {\r\n            Person = person;\r\n        }\r\n\r\n        public override string ToString()\r\n        => $"Yeni personel {Person.Id} id de\u011ferinde eklenmi\u015ftir.";\r\n    }\r\n<\/pre>\nEvent Broker Tasar\u0131m\u0131n\u0131 Ger\u00e7ekle\u015ftirmek<\/h4>\nVe son olarak ‘Person’ nesnesi \u00fczerinde yarat\u0131lacak olan t\u00fcm event’leri toplayacak olan ve gerekli aksiyonlar\u0131 alacak olan ‘Event Broker’ nesnesini olu\u015fturmam\u0131z gerekmektedir.<\/p>\n
\r\n    class EventBroker\r\n    {\r\n        \/\/Olu\u015fan event'leri depolayaca\u011f\u0131m\u0131z koleksiyon.\r\n        public List<IEvent> allEvents = new();\r\n        \/\/Uygulamada gelen Command isteklerinde devreye girecek event tan\u0131mlan\u0131yor.\r\n        public event EventHandler<object> Commands;\r\n        \/\/Uygulamada gelen Query isteklerinde devreye girecek event tan\u0131mlan\u0131yor.\r\n        public event EventHandler<object> Queries;\r\n        public EventBroker()\r\n        {\r\n            \/\/'Commands' isimli 'EventHandler'a a\u015fa\u011f\u0131daki metot tan\u0131mlan\u0131yor.\r\n            this.Commands += (sender, command) =>\r\n            {\r\n                \/\/E\u011fer gelen Command 'ChangeAgePersonCommandRequest' t\u00fcr\u00fcndense\r\n                if (command is ChangeAgePersonCommandRequest req1)\r\n                {\r\n                    ChangeAgePersonCommandHandler handler = new ChangeAgePersonCommandHandler();\r\n                    ChangeAgePersonCommandResponse response = handler.ChangeAge(req1);\r\n                    \/\/\u0130lgili iste\u011fe uygun event olan 'AgeChangedEvent' nesnesi event deposuna at\u0131l\u0131yor.\r\n                    this.allEvents.Add(new AgeChangedEvent(response.Person, response.OldAge, req1.Age));\r\n                }\r\n                \/\/E\u011fer gelen Command 'ChangeNamePersonCommandRequest' t\u00fcr\u00fcndense\r\n                else if (command is ChangeNamePersonCommandRequest req2)\r\n                {\r\n                    ChangeNamePersonCommandHandler handler = new ChangeNamePersonCommandHandler();\r\n                    ChangeNamePersonCommandResponse response = handler.ChangeName(req2);\r\n                    \/\/\u0130lgili iste\u011fe uygun event olan 'NameChangedEvent' nesnesi event deposuna at\u0131l\u0131yor.\r\n                    this.allEvents.Add(new NameChangedEvent(response.Person, response.OldName, req2.Name));\r\n                }\r\n                \/\/E\u011fer gelen Command 'CreatePersonCommandRequest' t\u00fcr\u00fcndense\r\n                else if (command is CreatePersonCommandRequest req3)\r\n                {\r\n                    CreatePersonCommandHandler handler = new CreatePersonCommandHandler();\r\n                    CreatePersonCommandResponse response = handler.CreatePerson(req3);\r\n                    \/\/\u0130lgili iste\u011fe uygun event olan 'PersonCreatedEvent' nesnesi event deposuna at\u0131l\u0131yor.\r\n                    this.allEvents.Add(new PersonCreatedEvent(response.Person));\r\n                }\r\n            };\r\n            \/\/'Queries' isimli 'EventHandler'a a\u015fa\u011f\u0131daki metot tan\u0131mlan\u0131yor.\r\n            this.Queries += (sender, query) =>\r\n            {\r\n                \/\/E\u011fer gelen Query 'GetPersonQueryRequest' t\u00fcr\u00fcndense\r\n                if (query is GetPersonQueryRequest req1)\r\n                {\r\n                    GetPersonQueryHandler handler = new GetPersonQueryHandler();\r\n                    GetPersonQueryResponse response = handler.GetPerson(req1);\r\n                    Console.WriteLine($"Id\\tName\\tAge");\r\n                    Console.WriteLine($"{response.Person.Id}\\t{response.Person.Name}\\t{response.Person.Age}\\n***********");\r\n                }\r\n                \/\/E\u011fer gelen Query 'GetAllPersonQueryRequest' t\u00fcr\u00fcndense\r\n                else if (query is GetAllPersonQueryRequest req2)\r\n                {\r\n                    GetAllPersonQueryHandler handler = new GetAllPersonQueryHandler();\r\n                    List<GetAllPersonQueryResponse> response = handler.GetAll(req2);\r\n                    Console.WriteLine($"Id\\tName\\tAge");\r\n                    response.ForEach(person => Console.WriteLine($"{person.Id}\\t{person.Name}\\t{person.Age}"));\r\n                    Console.WriteLine("***********");\r\n                }\r\n            };\r\n        }\r\n        \/\/Client'\u0131n 'Command' g\u00f6nderebilmesi i\u00e7in kullanaca\u011f\u0131 metot.\r\n        public void Command(object command)\r\n            => Commands(this, command);\r\n        \/\/Client'\u0131n 'Query' g\u00f6nderebilmesi i\u00e7in kullanaca\u011f\u0131 metot.\r\n        public void Query(object query)\r\n            => Queries(this, query);\r\n        \/\/T\u00fcm event'i yazd\u0131rabilmek\/okuyabilmek i\u00e7in kullan\u0131lacak metot.\r\n        public void WriteAllEvent()\r\n            => allEvents.ForEach(@event => Console.WriteLine($"{@event.ToString()}\\n***********"));\r\n    }\r\n<\/pre>\nYukar\u0131daki kod blo\u011funu incelerseniz temel d\u00fczeyde bir ‘Event Broker’ nesnesinde olmas\u0131 gereken t\u00fcm aksiyonlar tasarlanm\u0131\u015ft\u0131r. Ad\u0131m ad\u0131m kod sat\u0131rlar\u0131nda gerekli a\u00e7\u0131klamalar\u0131 yapt\u0131\u011f\u0131m i\u00e7in burada tekrardan detayland\u0131rmaya girmek istemesem de genel anlamda bir izahatte bulunman\u0131n faydas\u0131 olaca\u011f\u0131 kanaatindeyim: Dikkat ederseniz uygulamadaki t\u00fcm event’ler, yap\u0131lan ‘Command’ ve ‘Query’ isteklerine istinaden gerekli olaylar e\u015fli\u011finde, iste\u011fin t\u00fcr\u00fcne g\u00f6re ayr\u0131\u015ft\u0131rma ger\u00e7ekle\u015ftirildikten sonra ‘event’ olarak kay\u0131t alt\u0131na al\u0131nmaktad\u0131r. Ard\u0131ndan bu event’ler istek do\u011frultusunda tekrar listelenebilmekte ve hatta eldeki verinin herhangi bir T zaman\u0131ndaki halini elde edebilecek vaziyette geli\u015ftirilmeye meyletmektedir.<\/p>\n
Dolay\u0131s\u0131yla \u015fu a\u015famadan sonra art\u0131k tek yap\u0131lmas\u0131 gereken client’\u0131 tasarlamak ve test ama\u00e7l\u0131 bir ka\u00e7 ‘Command’ yahut ‘Query’ isteklerini g\u00f6ndermektir.<\/p>\n
Client<\/h4>\n\r\n    class Program\r\n    {\r\n        static void Main(string[] args)\r\n        {\r\n            EventBroker eventBroker = new EventBroker();\r\n            eventBroker.Command(new CreatePersonCommandRequest { Id = 5, Age = 21, Name = "Muiddin" });\r\n            eventBroker.Command(new CreatePersonCommandRequest { Id = 6, Age = 44, Name = "Fadi\u015f" });\r\n            eventBroker.Command(new ChangeAgePersonCommandRequest { Id = 2, Age = 55 });\r\n            eventBroker.Command(new ChangeAgePersonCommandRequest { Id = 2, Age = 66 });\r\n            eventBroker.Command(new ChangeNamePersonCommandRequest { Id = 3, Name = "Serdar" });\r\n            eventBroker.WriteAllEvent();\r\n            eventBroker.Query(new GetAllPersonQueryRequest());\r\n            eventBroker.Query(new GetPersonQueryRequest() { Id = 3 });\r\n        }\r\n    }\r\n<\/pre>\nG\u00f6r\u00fcld\u00fc\u011f\u00fc \u00fczere client ‘CreatePersonCommandRequest<\/em>‘, ‘CreatePersonCommandRequest<\/em>‘, ‘ChangeAgePersonCommandRequest<\/em>‘, ‘ChangeAgePersonCommandRequest<\/em>‘ ve ‘ChangeNamePersonCommandRequest<\/em>‘ olmak \u00fczere be\u015f adet Command iste\u011finde bulunmakta ve akabinde ‘GetAllPersonQueryRequest<\/em>‘ ve ‘GetPersonQueryRequest<\/em>‘ olmak \u00fczere iki Query iste\u011fiyle verileri okumak istemektedir. 11.<\/em><\/strong> sat\u0131rda ise ‘WriteAllEvent’ fonksiyonu ile o ana kadar olu\u015fan t\u00fcm event’leri listelemektedir. Sonu\u00e7 olarak a\u015fa\u011f\u0131daki gibi bir \u00e7\u0131kt\u0131yla kar\u015f\u0131la\u015f\u0131lmaktad\u0131r.
\n<\/a><\/p>\n
Evet… Bu sat\u0131rlara geldiysek e\u011fer art\u0131k hasbel kader bir Event Sourcing operasyonunun nas\u0131l ceyran etti\u011fini anlam\u0131\u015f, hi\u00e7 yoktan tad\u0131na bakm\u0131\u015f bulunmaktay\u0131z. Ve umuyorum ki, yo\u011fun uygulamalarda buradaki gibi event’leri in-memory’de depolaman\u0131n maliyetinin a\u011f\u0131rl\u0131\u011f\u0131n\u0131 ve y\u00f6netilebilirli\u011finin g\u00fc\u00e7l\u00fc\u011f\u00fcn\u00fc g\u00f6rd\u00fc\u011f\u00fcn\u00fcz kanaatindeyim. Haliyle event’leri g\u00fc\u00e7l\u00fc bir \u015fekilde depolayabilmenin ve y\u00f6netebilmenin k\u0131ymetinin \u00f6nemine binaen sonraki yaz\u0131mda Event Sourcing i\u00e7in olduk\u00e7a kullan\u0131\u015fl\u0131 bir tools olan Event Store<\/a>‘la sizleri tan\u0131\u015ft\u0131rmak istiyorum.<\/p>\n
O halde sizler bu makaleyi okuyup sindirene kadar ben de m\u00fcjdesini verdi\u011fim di\u011fer makaleyi klavyeye almaya ba\u015flasam iyi olacak \ud83d\ude42<\/p>\n
\u0130lgilenenlerin faydalanmas\u0131 dile\u011fiyle…
\nSonraki yaz\u0131lar\u0131mda g\u00f6r\u00fc\u015fmek \u00fczere…
\n\u0130yi \u00e7al\u0131\u015fmalar…<\/p>\n
Not : \u00d6rnek projeyi indirmek i\u00e7in buraya<\/a> t\u0131klay\u0131n\u0131z.<\/p>\n","protected":false},"excerpt":{"rendered":"
Merhaba, Bu i\u00e7eri\u011fimizde bir \u00f6nceki kaleme ald\u0131\u011f\u0131m\u0131z Event Sourcing Nedir? Haydi Gelin Hep Beraber \u0130nceleyelim ba\u015fl\u0131kl\u0131 makalemize basit bir somut \u00f6rnek te\u015fkil edecek \u015fekilde \u00e7al\u0131\u015fma ger\u00e7ekle\u015ftirece\u011fiz. Amac\u0131m\u0131z Event Sourcing’in pratikte ucundan k\u0131y\u0131s\u0131ndan tad\u0131na bakmak...<\/p>\n","protected":false},"author":1,"featured_media":21566,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2739,153,3573],"tags":[4229,4217,4228],"class_list":["post-21539","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-net-core","category-design-pattern","category-microservices","tag-event-broker","tag-event-sourcing","tag-event-sourcing-example"],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.gencayyildiz.com\/blog\/wp-json\/wp\/v2\/posts\/21539","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.gencayyildiz.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.gencayyildiz.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.gencayyildiz.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gencayyildiz.com\/blog\/wp-json\/wp\/v2\/comments?post=21539"}],"version-history":[{"count":32,"href":"https:\/\/www.gencayyildiz.com\/blog\/wp-json\/wp\/v2\/posts\/21539\/revisions"}],"predecessor-version":[{"id":21573,"href":"https:\/\/www.gencayyildiz.com\/blog\/wp-json\/wp\/v2\/posts\/21539\/revisions\/21573"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.gencayyildiz.com\/blog\/wp-json\/wp\/v2\/media\/21566"}],"wp:attachment":[{"href":"https:\/\/www.gencayyildiz.com\/blog\/wp-json\/wp\/v2\/media?parent=21539"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gencayyildiz.com\/blog\/wp-json\/wp\/v2\/categories?post=21539"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gencayyildiz.com\/blog\/wp-json\/wp\/v2\/tags?post=21539"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
CQRS Temelinin Olu\u015fturulmas\u0131<\/h4>\n\u00d6ncelikle CQRS temelini atarak uygulamay\u0131 in\u015fa etmeye ba\u015flayabiliriz.\nQuery<\/strong>\nRequest nesneleri:<\/p>\n
