跳到主要內容

Install K8S on VM and spring boot integration.

Installation Environment Vmware Workstation pro  It is recommended to use the  snapshot  to store the state of each installation stage to avoid installation failures and causing the installation to start from scratch. Ubuntu 22.04 windows 11 Hardware settings  create 3 VM: 4 cores and 4G memory and 100G capacity Before installing K8s (All use the root user) set host: 192.168.47.135 master 192.168.47.131 node1 192.168.47.132 node2 set root ssh connection: sudo su - echo "PermitRootLogin yes" >> /etc/ssh/sshd_config systemctl restart sshd sudo passwd ssh-keygen for i in {master,node1,node2}; do  ssh-copy-id root@$i; done set Ipvs and conf  create conf file: for i in {master,node1,node2}; do ssh root@$i 'cat << EOF > /etc/modules-load.d/containerd.conf overlay br_netfilter EOF'; done execute conf: for i in {master,node1,node2}; do ssh root@$i 'modprobe overlay;modprobe br_netfilter;'; done create 99-kubernetes-cri.conf file: for i in {maste...

Composition and Inheritance


Composition vs Inheritance

In "Effective JAVA" or if you search the Internet, you will find that everyone says that composition is better than inheritance.

We know the composition has the advantages of the following:

  • Composition is loosely coupled.
  • The composition has better access control. 
  • Composition is more flexible.
  • Unit test easier.

Is this really true? usually yes, but let's back to thinking about it, what are we programmed for, methods are just tools, and people are the core.

Let's see what the advantage is of inheritance before we choose the methods. here.

Choosing the best fit method for the program is the most important thing, not just avoiding inheritance.


reference:

https://www.digitalocean.com/community/tutorials/composition-vs-inheritance

https://github.com/hollischuang/toBeTopJavaer


留言

這個網誌中的熱門文章

Install K8S on VM and spring boot integration.

Installation Environment Vmware Workstation pro  It is recommended to use the  snapshot  to store the state of each installation stage to avoid installation failures and causing the installation to start from scratch. Ubuntu 22.04 windows 11 Hardware settings  create 3 VM: 4 cores and 4G memory and 100G capacity Before installing K8s (All use the root user) set host: 192.168.47.135 master 192.168.47.131 node1 192.168.47.132 node2 set root ssh connection: sudo su - echo "PermitRootLogin yes" >> /etc/ssh/sshd_config systemctl restart sshd sudo passwd ssh-keygen for i in {master,node1,node2}; do  ssh-copy-id root@$i; done set Ipvs and conf  create conf file: for i in {master,node1,node2}; do ssh root@$i 'cat << EOF > /etc/modules-load.d/containerd.conf overlay br_netfilter EOF'; done execute conf: for i in {master,node1,node2}; do ssh root@$i 'modprobe overlay;modprobe br_netfilter;'; done create 99-kubernetes-cri.conf file: for i in {maste...

Mongo DB

Table of contents [ hide ] Mongo DB An open-source NoSQL file database. Due to the use of JSON document data storage structure, MongoDB has three advantages: flexibility, easy expansion, and high performance. Compared with traditional relational databases, users do not need to define the data structure in advance when using MongoDB to store data, and can freely add the Key/Value of the data. Basic concept SQL vs MongoDB Database vs Database Table vs Collection Row vs Document Column vs Field Index vs Index Primary key vs _id View vs View Table Joins vs $lookup Query Syntax Example SQL vs MongoDB a = 1 vs {a: 1} a<> 1 vs {a: {$ne: 1}} a > 1 vs {a: {$gt: 1}} a >= 1 vs {a: {$gte: 1}} a < 1 vs {a: {$lt: 1}} a <= 1 vs {a: {$lte: 1}} Aggregation  Pipeline Stages Description: Mongo DB vs SQL Filter criteria: $match vs where Projection: $project vs as Left outer join: $lookup vs left outer join Sort: $sort vs order by Group: $group vs group by Pagination: $skip/$limi...

OS basic

Table of contents [ hide ] OS architecture The operating system architecture consists of three parts, user mode, kernel mode, and hardware. User mode is for the application to execute the user's program. Kernel mode is to control all the I/O devices and system stability. Storage device hierarchy System call The system call is a kind of software interrupt, including six categories. Process control. File management. Device management. Information maintenance. Communication. Protection. System calls use three methods to pass parameters. Registers. The table in memory. Push onto the stack. A view of operating system services reference: https://www.amazon.com/-/zh_TW/Operating-System-Concepts-Abraham-Silberschatz/dp/1119800366/ref=sr_1_1?keywords=Operating-System-Concepts&qid=1669538704&s=books&sr=1-1