Week-1.txt

1-10-2023
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1. for(int i=2;i<=Math.sqrt(n);    ---> Prime Number or Not

2. max = (a>b)?(a>c?a:c):(b>c?b:c); --> Max of 3 Numbers

02-10-2023 :
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3. Synchronous(All at a time) vs Asynchronous Communication(one after another) :(Conference,1:1 Chat vs Email)

4. REST VS SOAP :
   a.Lack of Security(Security Compromises) vs WS High Security -ATOMICITY - Payments
   b.Data Driven vs Function Driven
   c.Stateless vs By Default stateless,we can make stateful.
   d.Api call can be cached vs cannot be Cached.
   f.HTML,XML,JSON,YAML VS XML
   g.HTTP VS HTTP,SMTP,UDP.

5.starter web services ---> SOAP.
  Starter web -------------> REST

6. @SpringBootApplication ---> @EnableAutoConfiguration + @ComponentScan + @Configuration

7. Autoconfiguration works on conditions that are associated with particular dependencies.
      
  * AutoConfigurations --> DataSourceAutoConfig --> need to add Starter JPA
  * By Default, Spring boot enables Auto-configurations for certain Classes.Enough though we have not added those Dependencies in Pom.xml.
     Ex: AopAutoConfiguration
  * To disable --> Appli.Prop : spring.autoconfigure.exclude=org.sprinf.boot.autoconfigure.aop.AopAutoConfigure

8. Application.level.org.springframework=debug.
   - You can see all positive(enabled AutoConfig) and negative. 


9. Customize or override default Configurations ---> default port=8080
    server.port=8085


10.run() method works Internally ---> 1. Create ApplicationContext.
                                      2. Register bean into Context.
                                      3. Kicked up embedded tomcat Container to run Jar file

11.  Command line runner --> interface. it has abstract run() method.(@PostConstrct)
           Ex: class config extends CommandLineRunner{
                   run(){
                      //DB Connections,Pre processing Logic
                        }
              }


12. Stereotype Annotations ---> specified detailing of annotations.
         @Controller, @Service , @Repository
    We can shuffle annotations and it runs successfully.But it doesnot make Sense.

13. Alternative for Stereotype Annotation ---> Java Base Config.

    @Configuration
    public class Config{
     
        @Bean
       public DemoService demoService(){
        return new DemoService()
       }
}


14. Dependency Injection is a Design pattern use to achieve Loose Coupling btw Classes by removing direct dependency btw them.
          

15. Setter vs Constructor Injection :
    a.Obj creation is Optional vs Mandatory.
    b. Can Achieve Circular Dependency vs Cannot Achieve.
    c. Mutable in Nature vs Immutable in Nature.

16. @PostConstructor Real World Use Cases : DB Connection, Kafka Prod-consumer Instantiate,Spring batch.

    @Value("${discount.offer.price}")
17. private int price;                    ----> Hardcoding value.

    Sout(price);

    Appli.Prop:
     discount.offer.price=98


             (or)

    @Autowired
    private Environment env;

     Sout(env.getProperty("discount.offer.price"));


18.YAML VS App.Prop :
   a.Syntax Structure
   b.Hierarchy
   c.Arrays,List - myList=apple,banana
                   myList:
                    -apple
                    -banana

   d.Readability
   e. More Precedence to Appl.prop

19.Externally Loading Properties from File rather than Applic.prop,application YAML.
    1.Create a file(test.properties) in Desktop Folder.
    2. In Appl.Prop --> spring.config.import = c://users/desktop/javalessons/test.properties


20. How to map or Bind Config Prop to Java Object?

     @Configuration
     @ConfigurationProperties(prefix="spring.properties")
     public class Credentials{

     private String username;
     private String password;

     }