Most feasible way to handle consistency across microservices is via eventual consistency. This model doesn’t enforce distributed ACID transactions across microservices. Event sourcing is an event-centric approach to business logic design and persistence. It favours to use some mechanisms of ensuring that the system would be eventually consistent at some...
Performing impact analysis is a crucial software development task. It is all about calculating the impact of software change.
Q1. What is an impact analysis? Is it a trivial task?
A1. An impact analysis is about being able to tell which pieces of code,
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Q. When will you use NamedParameterStatement over PreparedStatement?
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Reason 1: PreparedStatement uses anonymous parameters that are accessed by index, which is ok when you have 2 or 3 parameters,
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Q01. What is JDBC? How do you connect to a database?
A01. JDBC stands for Java DataBase Connectivity. It is an API which provides easy connection to a wide range of databases.
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Q1. What is a Transaction? What does setAutoCommit do? A1. A transaction is a set of operations that should be completed as a unit. If one operation fails then all the other operations fail as well. For example if you transfer funds between two accounts there will be two operations...
Q1. What is the difference between initial request and postback? A1. Initial request (e.g. HTTP GET) is the request that is made from a browser in order to display a page. Postback happens when the browser posts the page back to the server with form values, … Read more ›...
Q1. What are the system qualities that typically form a basis for QoS requirements? A1. Quality of service (QoS) covers Non Functional requirements such as As microservices use disparate datasources like SQL store, NoSQL store, Cache, Object store like AWS S3, … Read more ›...
This extends 15 Spring Boot interview questions & answers. Spring Boot & Spring Cloud are used for building Microservices architecture. Q1. What is Spring Cloud? A1. Spring Boot is widely used to develop MicroServices. As many organisations deploy these services on the cloud like AWS, … Read more ›...
Messaging systems are used in enterprise applications for scalability. Here is some sample code that compliments JMS interview questions and answers. JMS configuration Step 1: Add the relevant dependency jars to the pom.xml file.
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<properties> <spring.version>4.2.6.RELEASE</spring.version> <jms-api.version>2.0.1</jms-api.version> <mq-client.version>8.0.0.0</mq-client.version> </properties> <dependencies> <!-- Spring JMS --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jms</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>${spring.version}</version> </dependency> <!-- JMS API --> <dependency> <groupId>javax.jms</groupId> <artifactId>javax.jms-api</artifactId> <version>${jms-api.version}</version> </dependency> <!-- Websphere MQ Implementation --> <dependency> <groupId>com.ibm.mq</groupId> <artifactId>allclient</artifactId> <version>${mq-client.version}</version> </dependency> </dependencies> |
Note that the “com.ibm.mq.allclient.jar” … Read more ›...
This is the continuation Spring JMS with Websphere MQ
Step 1: Write a listener class to receive the message by invoking the onMessage(Message message) method.
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package com.myapp.service.impl; import javax.jms.Message; import javax.jms.MessageListener; import javax.jms.TextMessage; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.stereotype.Component; @Component //@Transactional public class MyAppListener implements MessageListener { private static Logger LOG = LoggerFactory.getLogger(MyAppListener.class); @Override public void onMessage(Message message) { LOG.info("Entered ..............."); if (message instanceof TextMessage) { try { String msg = ((TextMessage) message).getText(); LOG.debug("Message contents: {} ", msg); System.out.println(msg); } catch (Exception e) { LOG.error("Error processing the message"); } } } } |
Step 2 : Configure the Spring container and bootstrap the MyListener
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Spring security pre-authentication scenario assumes that a valid authenticated user is available via either Single Sign On (SSO) applications like Siteminder, Tivoli, etc or a X509 certification based authentication. The Spring security in this scenario will only be used for authorization.
The example shown below retrieves the user name via the HTTP headers.
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Example #1 Wiring JDBC Datasource
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public DriverManagerDataSource datasource() { DriverManagerDataSource ds = new DriverManagerDataSource(); ds.setDriverClassName(environment.getRequiredProperty("spring.datasource.driver-class-name")); ds.setUrl(environment.getRequiredProperty("spring.datasource.url")); ds.setUsername(environment.getRequiredProperty("spring.datasource.username")); ds.setPassword(environment.getRequiredProperty("spring.datasource.password")); return ds; } } |
application.yml where the datasource properties are read.
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############ # Datasource properties ############ spring: datasource: driver-class-name: com.sybase.jdbc4.jdbc.SybDataSource url: jdbc:sybase:Tds:mydbhost:5700/my_db username: user password: pwd |
Example #2 Wiring JDBC Datasource with JNDI
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public DataSource dataSource() { final JndiDataSourceLookup jndiLookup = new JndiDataSourceLookup(); final String dataSourceJndi = environment.getRequiredProperty("spring.datasource.jndi"); return jndiLookup.getDataSource(dataSourceJndi); } } |
Example #3 Wiring JDBC Embedded Datasource for integration testing
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public DataSource dataSource() { final EmbeddedDatabaseBuilder builder = new EmbeddedDatabaseBuilder(); builder.setType(EmbeddedDatabaseType.HSQL); builder.addScript("classpath:hsqldb-oracle.sql"); builder.addDefaultScripts(); // defaults are schema.sql and data.sql return builder.build(); } } |
Example #4 Wiring up the JdbcTemplate by passing in the datasource
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public JdbcTemplate jdbcTemplate() { return new JdbcTemplate(datasource()); } @Bean public DataSource dataSource() { //...... } } |
Example #5 Wiring up a DAO...
