cqrs

Many to many relationship with axon framework

只谈情不闲聊 提交于 2020-04-30 06:37:11
问题 Hi I'm new to axon framework. I've a table with many to many relationship and another table with one to many based on the query result of one to many table I want to update many to many table now how do I create a command model for this in axon framework? 来源: https://stackoverflow.com/questions/61349489/many-to-many-relationship-with-axon-framework

为什么要使用MVC+REST+CQRS架构

守給你的承諾、 提交于 2020-04-07 19:39:31
具体来说,前端浏览器:angular.js等MVC框架;后端: REST + CQRS 。 angular.js等MVC框架是指前端浏览器的MVC框架,而不是类似Struts 或SpringMVC之类的服务器端后端MVC框架。 关于后端MVC框架的问题可见《MVC模式已死 》 http://www.jdon.com/38448 和 基于任务的UI(Task-Based UI) 。 服务器端的MVC框架主要问题是粒度太粗,只能适合传统的CRUD简单粗放的应用,当我们的软件系统转向以用户体验为主,而不是以企业自身资源管理为主的模式时,响应式设计必然拥有良好的用户感受,而传统后端MVC固定的框架针对大量客户端并发事件处理无疑是力不从心,想象一下,用户鼠标一移动就可能发出一个事件,这么多事件如果每个都走Model-View-Controller这样一个流程,仅Controller就要编制多少?编程成本极高,维护拓展起来很不方便。 将MVC框架移植到浏览器前端(Rich Client),则可以巧妙回避以上问题,javascript的函数风格使得其处理事件来得更简单,对于围绕模型的操作则可以使用MVC实现。见: JavaScript大型可扩展的 设计模式 ,而模型则是从后端领域层以JSON方式推送过来。 后端架构是:REST+CQRS,将 REST 和 CQRS 组合在一起成为CQREST架构

CQRS实践(2): Command的实现

只愿长相守 提交于 2020-03-23 10:07:21
概述 继续引用上篇文章中的图片(来源于Udi Dahan博客),UI中的写入操作都将被封装为一个命令中,发送给Domain Model来处理。 我们遵循 Domain Driven Design 的设计思想,因此所有的业务逻辑都只在Domain Model中处理,Command中将不会带有业务逻辑。Command中的代码无非是通过Repository获取某些个聚合根(Aggregate Root),然后将操作委托给相应的领域对象或领域服务来处理,仅此而已。 实现 实现上,我们会涉及三个东西: (1) Command对象 Command对象的作用是用来封装命令数据,所以这类对象以属性为主,少量简单方法,但注意这些方法中不能包含业务逻辑。 举个用户注册的例子,用户注册是一个命令,所以我们需要一个RegisterCommand类,这个类定义如下: public class RegisterCommand : ICommand{ public string Email { get; set; } public string NickName { get; set; } public string Password { get; set; } public string ConfirmPassword { get; set; } public Gender Gender { get; set

How to replay in a deterministic way in CQRS / event-sourcing?

会有一股神秘感。 提交于 2020-03-01 06:44:07
问题 In CQRS / ES based systems, you store events in an event-store. These events refer to an aggregate, and they have an order with respect to the aggregate they belong to. Furthermore, aggregates are consistency / transactional boundaries, which means that any transactional guarantees are only given on a per-aggregate level. Now, supposed I have a read model which consumes events from multiple aggregates (which is perfectly fine, AFAIK). To be able to replay the read model in a deterministic way

How to replay in a deterministic way in CQRS / event-sourcing?

岁酱吖の 提交于 2020-03-01 06:43:19
问题 In CQRS / ES based systems, you store events in an event-store. These events refer to an aggregate, and they have an order with respect to the aggregate they belong to. Furthermore, aggregates are consistency / transactional boundaries, which means that any transactional guarantees are only given on a per-aggregate level. Now, supposed I have a read model which consumes events from multiple aggregates (which is perfectly fine, AFAIK). To be able to replay the read model in a deterministic way

How to replay in a deterministic way in CQRS / event-sourcing?

て烟熏妆下的殇ゞ 提交于 2020-03-01 06:43:09
问题 In CQRS / ES based systems, you store events in an event-store. These events refer to an aggregate, and they have an order with respect to the aggregate they belong to. Furthermore, aggregates are consistency / transactional boundaries, which means that any transactional guarantees are only given on a per-aggregate level. Now, supposed I have a read model which consumes events from multiple aggregates (which is perfectly fine, AFAIK). To be able to replay the read model in a deterministic way

Event sourcing infrastructure implementation

非 Y 不嫁゛ 提交于 2020-01-31 04:31:47
问题 I implement Event Sourcing and CQRS pattern in my application. I inspired by CQRS journey where I downloaded sample code. There I found whole infrastructure for Event sourcing (CommandHandlers, EventHandlers, Events, Envelopes ... etc.), but it is quite big amount of code and I can't imagine that I need all of code for my simple Event sourcing. Do you know some common tested library/nuget package/project containing all infrastructure for sending/registering commands, events and everything

Aggregate or entity without business attributes

梦想与她 提交于 2020-01-25 01:21:17
问题 Regarding below excerpt, concerning cqrs and ddd, from Patterns, Principles, and Practices of Domain-Driven Design by Nick Tune, Scott Millett Does it mean that domain model on command side can omit most of business attributes ? How would it look like for eg Customer Entity? Could Customer entity omit FirstName, Surname etc? If so, where would these business attributes be? Only in read model in CustomerEntity? Or maybe apart from CustomerEntity containing all business attributes there would

【原理】你知道 Change Data Capture 是什么吗?

懵懂的女人 提交于 2020-01-23 14:09:29
Change Data Capture(缩写为 CDC)——大概可以机翻为 “变动数据捕获”——你可以将它视为和数据库有关的架构设计模式的一种。它的核心思想是,监测并捕获数据库的变动(包括数据或数据表的插入,更新,删除等),将这些变更按发生的顺序完整记录下来,写入到消息中间件中以供其他服务进行订阅及消费。 适用场景 我们可以把 CDC 认为是数据库事件驱动的一种数据 / 信息分发系统,CDC 主要适用于以下的场景: 异构数据库之间的数据同步或备份 / 建立数据分析计算平台 在 MySQL,PostgreSQL,MongoDB 等等数据库之间互相同步数据,或者把这些数据库的数据同步到 Elasticsearch 里以供全文搜索,当然也可以基于 CDC 对数据库进行备份。而数据分析系统可以通过订阅感兴趣的数据表的变更,来获取所需要的分析数据进行处理,不需要把分析流程嵌入到已有系统中,以实现解耦。 微服务之间共享数据状态 在微服务大行其道的今日,微服务之间信息共享一直比较复杂,CDC 也是一种可能的解决方案,微服务可以通过 CDC 来获取其他微服务数据库的变更,从而获取数据的状态更新,执行自己相应的逻辑。 更新缓存 / CQRS 的 Query 视图更新 通常缓存更新都比较难搞,可以通过 CDC 来获取数据库的数据更新事件,从而控制对缓存的刷新或失效。 而 CQRS

How to handle transaction in event driven architecture?

*爱你&永不变心* 提交于 2020-01-14 05:21:12
问题 I'm currently playing with DDD & CQRS, and I moved forward a legacy application. Let's say I have an Article entity, on which I can cast votes. When a Vote is casted on an Article, I want to increment or decrement a counter accordingly to the value of the vote. This counter is part of my Query model and thus I don't think it fits the Domain Model, for such reasons, I decided to write a CastArticleVoteService in which I put the business logic about a vote, and I dispatch an Event to be handle