Apache Empire-db: Difference between revisions

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{{Short description|Open-source Java library}}

{{Unreferenced|date=May 2011}}

{{adNotability|Products|date=MayMarch 20112022}}

{{ Infobox Softwaresoftware

| name = Apache Empire-db

| logo = Apache_Empire-db_Logo.svg

| logo = [[File:Empire-db.gif|200px]]

| logo size = 300px

| screenshot =

| caption =

| developer = [[Apache Software Foundation]]

| status = incubation

| latest release version = 23.20.0

| latest release date = {{releaseStart date and age|20112022|03|11|02}}

| latest preview version =

| latest preview date =

| operating system = [[Cross-platform]]

| repo = {{URL|https://gitbox.apache.org/repos/asf?p{{=}}empire-db.git|EmpireDB Repository}}

| programming language = [[Java (programming language)|Java]]

| genre = [[Persistence Framework]]

| license = [[Apache License]] 2.0]]

| website = http://incubator.apache.org/empire-db

| website = {{URL|//empire-db.apache.org/}}

}}

'''Apache Empire-db''' is a Java library that provides a high level object -oriented API for accessing [[Relationalrelational database management system]]s (RDBMS) through [[JDBC]]. Apache Empire-db is Openopen Sourcesource and provided under the [[Apache License 2.0 license]] from the [[Apache Software Foundation]].

Compared to [[Object-relational mapping]] (ORM) or other data persistence solutions such as [[Hibernate (Java)|Hibernate]], [[iBATIS]] or [[TopLink]] Empire-db does not use XML files or Java annotations to provide a mapping of plain (old) javaJava object ([[POJO]]'s) to database tables, views and columns. Instead Empire-db uses a Java object model to describe the underlying data model and an API that works almost solely with object references rather than [[string literalsliteral]]s.

'''Apache Empire-db''' is a Java library that provides a high level object oriented API for accessing [[Relational database management system]]s (RDBMS) through [[JDBC]]. Apache Empire-db is Open Source and provided under the Apache 2.0 license from the [[Apache Software Foundation]].

Empire-db's aim is to provide better software quality and improved maintainability through increased compile-time safety and reduced redundancy of metadata. Additionally applications may benefit from better performance due to full control over [[SQL]] statements and their execution by the developer compared to most OR-Mappingmapping solutions.<ref>{{Cite web |title=Apache Empire-db |url=https://empire-db.apache.org/pages/home.html |access-date=2022-03-21 |website=empire-db.apache.org}}</ref>

Compared to [[Object-relational mapping]] (ORM) or other data persistence solutions such as [[Hibernate (Java)|Hibernate]], [[iBATIS]] or [[TopLink]] Empire-db does not use XML files or Java annotations to provide a mapping of plain (old) java object ([[POJO]]'s) to database tables, views and columns. Instead Empire-db uses a Java object model to describe the underlying data model and an API that works almost solely with object references rather than string literals.

Empire-db's aim is to provide better software quality and improved maintainability through increased compile-time safety and reduced redundancy of metadata. Additionally applications may benefit from better performance due to full control over [[SQL]] statements and their execution by the developer compared to most OR-Mapping solutions.

== Major benefits ==

Empire-db’sdb's key strength is its API for dynamic SQL generation for arbitrary select, update, insert or delete statements, purely by using Java methods which reference the model objects. This provides type-safety and almost entirely eliminates the use of string literals for names or expressions in code. Additionally DBMS independence is achieved through a pluggable driver model.

Using references to table and column objects significantly improves compile-time safety and thus reduces the amount of testing. As a positive side effect the IDE’sIDE's code completion can be used to browse the data model, increases productivity and eliminates the need for other external tools or IDE-plugins.

Empire-db’s key strength is its API for dynamic SQL generation for arbitrary select, update, insert or delete statements, purely by using Java methods which reference the model objects. This provides type-safety and almost entirely eliminates the use of string literals for names or expressions in code. Additionally DBMS independence is achieved through a pluggable driver model.

Further the object model also provides safe and easy access to meta-information of the data model such as field data type, maximum field length, whether a field is mandatory and a finite choice of options for a field’sfield's values. Metadata is user-extensible and not limited to DBMS related metadata. Availability of meta-information encourages more generic code and eliminates redundancies throughout application layers.

Using references to table and column objects significantly improves compile-time safety and thus reduces the amount of testing. As a positive side effect the IDE’s code completion can be used to browse the data model, increases productivity and eliminates the need for other external tools or IDE-plugins.

Further the object model also provides safe and easy access to meta-information of the data model such as field data type, maximum field length, whether a field is mandatory and a finite choice of options for a field’s values. Metadata is user-extensible and not limited to DBMS related metadata. Availability of meta-information encourages more generic code and eliminates redundancies throughout application layers.

== Features at a glance ==

* Data model definition through a Java object model omits the need to learn XML schemas or annotations and easily allows user interceptions and extensions.

* Portable RDBMS independent record handling and command definition with support for a variety of relational databases such as [[Oracle Database|Oracle]], [[Microsoft SQL Server]], [[MySQL]], [[Apache Derby|Derby]], [[H2 (DBMS)|H2]] and [[HSQLDB]] (as of version 2.0.5)

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* Automatic tracking of record state and field modification (aka "dirty checking") to only insert/ update modified fields.

* Support for optimistic locking through timestamp column.

* No need to always work with full database entities. Build queries to provide you with the data exactly as you need itneeded, and obtain the result for example as a list of any type of POJO with matching property setters or constructor.

* Lightweight and passive library with zero configuration footprint that allows simple integration with any architecture or framework.

== Example ==

As an example consider a database with two tables called ''Employees'' and ''Departments'' for which a list of employees in a particular format, with certain constraints and a given order should be retrieved.

The corresponding Oracle syntax SQL statement is assumed to be as follows:

<sourcesyntaxhighlight lang="sql">

SELECT t1.EMPLOYEE_ID,

t1.LASTNAME || ', ' || t1.FIRSTNAME AS NAME,

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AND t1.RETIRED=0

ORDER BY t1.LASTNAME, t1.FIRSTNAME

</syntaxhighlight>

</source>

This SQL statement can be created using Empire-db's command API using object model references like this:

<sourcesyntaxhighlight lang="java">

SampleDB db = getDatabase();

// Declare shortcuts (not necessary but convenient)

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cmd.orderBy(EMP.LASTNAME);

cmd.orderBy(EMP.FIRSTNAME);

</syntaxhighlight>

</source>

In order to execute the query and retrieve a list of POJO's holding the query result the following code may be used:

<sourcesyntaxhighlight lang="java">

// Class definition for target objects

public class EmployeeInfo {

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private String name;

private String department;

// GettterGetter's and Setters for all properties

// or a public Constructor using fields

public get...

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DBReader reader = new DBReader();

try {

reader.open(cmd, getConnection());

List<EmployeeInfo> empList = reader.getBeanList(EmployeeInfo.class);

} finally {

reader.close()

}

</syntaxhighlight>

</source>

Empire-db also supports field access through object references or obtaining query results as XML.

== History ==

Empire-db was originally developed at ESTEAM Software a German software development company which used Empire-db to develop various applications for a variety of different branches.

In January 2008 Empire-db was made officially Openopen Sourcesource and first published though SourceForge.Netnet.

In June 2008 a proposal was submitted to the Apache Software Foundation for Empire-db to become an Apache Incubator project. In July 2008 Empire-db got accepted for incubation and all rights over the Software were transferred to the Apache Foundation.

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In October 2008 Empire-db 2.0.4 was the first official Apache incubator release with all package names changed to begin with org.apache.empire.

== See also ==

{{Portal|JavaComputer programming}}

* [[Java Database Connectivity]] (JDBC)

* [[Object-relational mapping]]

* [[Hibernate (Java)|Hibernate]]

* [[iBATIS]]

* [[TopLink]]

* [[Apache Struts]]

==References==

{{reflist}}

== External links ==

* {{official website|//empire-db.apache.org/}}

*[http://incubator.apache.org/empire-db Empire-db project page at the Apache Foundation]

{{apache}}

[[Category:{{Apache Software Foundation|Empire-db]]}}

[[Category:Computer languages]]

[[esCategory:Apache Software Foundation projects|Empire-db]]

[[Category:Java (programming language) libraries]]