Distributed theory

What is a distributed system ？

A distributed system is a collection of independent computers , These computers are like a single related system to users. Distributed systems are a group of communication through the network 、 A system of computer nodes that coordinate work to accomplish common tasks . Distributed systems have emerged to use cheap 、 Ordinary machines do calculations that a single computer can't do 、 Storage tasks The aim is to use more machines , Processing more data .

Distributed systems （distributed system） It's a software system based on the network

Why do we use distributed systems

The first thing to be clear is , Only when the processing power of a single node can not meet the growing Computing 、 When storing tasks , And the improvement of hardware （ Add memory 、 Add disk 、 Use a better CPU） When it's too high to pay , When the application can't be further optimized , We need to think about distributed systems .
And because distributed systems have multiple nodes 、 The topology of communication over a network , There will be a lot of problems that single machine systems don't have

A preliminary understanding Dubbo

With the development of the Internet , Website size increases , The current architecture has been unable to meet and cope with the distributed service architecture and mobile computing architecture is imperative

Single application architecture

When website traffic is low , Just one app , Deploy all functions together , To reduce deployment nodes and costs . here , Data access framework to simplify the work of adding, deleting, modifying and querying (ORM) Is the key .

For small websites , Small management system , Deploy all functions into one function , Easy to use performance It's hard to scale
Collaborative development issues Not conducive to upgrade maintenance .

Vertical application architecture

When The number of visits is increasing , Single application increases the acceleration brought by the machine is getting smaller and smaller , Split the application into several unrelated applications , To improve efficiency . here , For accelerating front-end page development Web frame (MVC) Is the key .
Through the segmentation business to achieve each Modules are deployed independently , Reduced the difficulty of maintenance and deployment , It's easier to manage a team , Performance scaling is also more convenient , More targeted . shortcoming ： Common modules cannot be reused , Development waste

Distributed service architecture

As more and more vertical applications , Interaction between applications is inevitable , take Extract core business , As an independent service , Gradually form a stable service center , Enable front-end applications to respond more quickly to changing market demands . here , Distributed service framework for business reuse and integration (RPC) Is the key .

Flow computing architecture

When the service is more and more , Capacity assessment , Problems such as waste of small service resources are gradually emerging , At this time, it is necessary to add a dispatching center to manage the cluster capacity in real time based on the access pressure , Improve cluster utilization . here , Resource scheduling and Governance Center for improving machine utilization (SOA)[ Service Oriented Architecture] Is the key

RPC【Remote Procedure Call】 Remote procedure call , It's a kind of Interprocess communication mode , He is a technical thought , Not the norm . it Allow the program to call another address space （ Usually on another machine that shares the network ） A process or function of , Instead of programmers explicitly coding the details of this remote call . That is, whether the programmer calls local or remote functions , Essentially, the call code written is basically the same . That is to say, two servers A,B, An application is deployed in A Server , Want to call B Functions provided by the application on the server / Method , Because it's not in a memory space , Can't call directly , need Express the semantics of the call and convey the data of the call through the network . Why use RPC Well ？ Just can't be in a process , Even a computer through local calls to complete the requirements , For example, communication between different systems , Even communication between different organizations , Because computing power needs to scale out , You need to deploy applications on a cluster of multiple machines .RPC It is to call remote functions just like calling local functions ;

Dubbo Use and install

Apache Dubbo |ˈdʌbəʊ| It's a high performance 、 Lightweight open source Java RPC frame , It provides three core competencies ： Interface oriented remote method call , Intelligent fault tolerance and load balancing , And automatic service registration and discovery .
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zookeeper download

 link ：https://pan.baidu.com/s/1MQPQVUHD_FDkUNPmN6uc-Q 
 Extraction code ：wpru

Test connection

download dubbo-admin

Address ：https://github.com/apache/dubbo-admin/tree/master

Package in the project directory dubbo-admin

mvn clean package -Dmaven.test.skip=true

Because this is a front-end and back-end project, we should integrate the front-end project npm install After a while npm run dev To access the front-end visual interface