Author Archives: khiem

About khiem

I am a fan of Java ecosystem. Love reading books, and sharing.

Hibernate cache in theory

The note will follow: 1. Introduction. Hibernate has a two-level cache architecture: first-level cache and second-level cache. Figure 1: Hibernate’s two levels cache (source: Manning) The first-level cache is the persistence context cache (scope of Session). The cache ensures that when the application requests the same persistent object twice in a particular session, it gets back… Read More »

Advantages and Disadvantages of Microservices

To begin with an interesting question, is a microservice architecture a good choice for the system you’re working on? Basically, micro-service often deals with large team, multi-tenancy, supporting many user interaction models, allowing different business functions to evolve independently, and scaling. However, the best answer is it depends on complexity and productivity. If a system… Read More »

Liquibase notes

1. Generate Change Logs from an existing database Generate change logs from an existing database. For instance, copy postgresSQL driver to %LINQUIBASE_HOME%/postgresql-8.3-603.jdbc3.jar. Run a following line command in console (single line). If successful, liquibase will show a message “Liquibase ‘generateChangeLog’ Successful” 2. Check a table already presents Using preCondition tag which follows some form of… Read More »

Model Mapper for data response

1. Fund Adaptor Suppose that Fund Adaptor executes a service to search the response data- a monthly or daily (depending on the schedule). This example is to show how the customer details response data is mapped. There are two data transfer objects (DTO) namely CustomerDTO (maybe to present in UI) and CustomerSvcDTO (from executing store procedures… Read More »

Summary of OO hierarchy inheritance mapping strategies

1. Pre-requisites Should read first there types of mapping below: Single-table strategy Joined-tables strategy Table-per-class strategy 2. Summary mapping strategies Table 1: Summary of OO hierarchy inheritance mapping strategies (source: EJB3 in Action) References: D. Pan, R. Rahman, R. Cuprak, M. Remijan, “Mapping inheritance”, In EJB3 in Action,pp.292-293, Manning, Second Edition, 2014

Table-per-class strategy for mapping inheritance with JPA

1. Table-per-class strategy Table-per-class strategy is similar to  joined-tables strategy because each entity in domain model gets its own table. One significant difference is no relationship between the tables, which doesn’t take advantage of power of relational database at all. Following the stock market example in join-table-strategy and single-table-strategy , we are there different tables namely product, bonds, shares but product_code, description, version… Read More »