ObjectDB Database Search

ObjectDB Database Explorer is a visual GUI tool for managing ObjectDB databases . It can be used to view data in ObjectDB databases , execute JPQL and JDOQL queries and edit the content of databases ... the shell file, setting the paths to the objectdb.jar file and to the JVM). Connecting to the Database

A connection to a database is represented by an EntityManager instance, which also provides functionality for performing operations on a database . Many applications require multiple database ... database connection, using a separate EntityManager instance, for every HTTP request. The main role

, the same database is managed on multiple machines (nodes), possibly in different geographic locations ... master-slave replication, the master node manages the main (master) database , which supports Read / Write operations. The other (slave) nodes in the cluster manage identical copies of the same database

The configuration element specifies back end ( database engine) settings that are relevant ... :    The element The element specifies the database file and page size settings: The initial attribute specifies the initial size of every new database file. The resize attribute specifies

database file Checks a given ObjectDB database file, verifies that it is healthy and valid ... of a corrupted ObjectDB database file Repairs a corrupted ObjectDB database file by creating a new fresh database file and then copying all the recoverable data in the corrupted database file

support of the JPA and JDO APIs. Fundamental features of relational databases (e.g. primary keys ... Databases are also supported by ObjectDB. The combination of Object Database features with Relational Database features brings you the best of both worlds. Capabilities & Scalability ObjectDB

In JPA a database connection is represented by the EntityManager interface. Therefore, in order to manipulate an ObjectDB database we need an EntityManager instance. Operations that modify database ... of EntityManagerFactory that represents the relevant database and then we can use that factory instance

can apply recorded database operations on a matching database backup (if available). This ability is useful for two different purposes: It enables recovery from a database failure by replaying ... & Recording Files When recording is enabled , ObjectDB maintains for every database file a recording

  Boost your application database performance. Database performance is critical as ... solution. Using a relational database management system (RDBMS) to store and retrieve Java objects requires slow conversions between graphs of Java objects and flat database table rows. Object Relational

. However, you should consider the following points when doing your own objective comparison of object databases : ObjectDB is unique in supporting the standard APIs. It is the only object database with built in ... of the Java Data Objects (JDO) API than competing object databases . By using a standard API such as JPA

ObjectDB Server is a tool that manages ObjectDB databases in a separate dedicated process, making these databases accessible to client applications in other processes including ones on other remote ... are: The ability to access and use databases from different processes simultaneously. The ability to access

Given an EntityManager , em , that represents a JPA connection to the object database , we can use it to store, retrieve, update and delete database objects. Storing New Entity Objects The following code fragment stores 1,000 Point  objects in the database : em. getTransaction (). begin

To access relational databases using the Java Persistence API (JPA) you will need an Object Relational Mapping (ORM) tool, such as Hibernate, TopLink, EclipseLink, Open JPA or DataNucleus ... standalone Object Database Management System (ODBMS) and not an ORM tool, so it is not intended and cannot be used to access other database management systems.

ObjectDB is a unique NoSQL database . It doesn't have the known disadvantages and limitations ... , but they are easier to use in object oriented languages such as Java. In addition, unlike most other NoSQL databases ... ). Therefore, ObjectDB can be used in applications that cannot use conventional non ACID NoSQL databases because of a requirement for a very high level of consistency.

entity class. This is done automatically in memory each time the entity object is loaded. The database object is only updated to the new schema when that entity object is stored to the database

All about ObjectDB Database in Java/JPA database - explanations, examples, references, links and related information.

Describes the ObjectDB object database tools - the Explorer, the Server, the Enhancer, the Doctor and the Replayer.

The Java Persistence API (JPA) provides various ways to retrieve objects from the database ... of the database . The persistence context serves as a cache of retrieved entity objects. If a requested ... with data that is retrieved from the database (or from the L2 cache - if enabled). The new entity object

), which can represent physical objects in the database . Managing an ObjectDB Object Database using JPA ... database objects. Entity Object Life Cycle The life cycle of entity objects consists of four states ... the database . An entity object becomes Managed when it is persisted to the database

Every entity object that is stored in the database has a primary key. Once assigned, the primary key cannot be modified. It represents the entity object as long as it exists in the database . As an object database , ObjectDB supports implicit object IDs, so an explicitly defined primary key is not

New entity objects can be stored in the database either explicitly by invoking the persist method ... an instance of the Employee entity class in the database : Employee employee = new Employee("Samuel ... its state to Managed. The new entity object is stored in the database when the transaction

The term persistable types refers to data types that can be used for storing data in the database ... can be stored in the database directly. Other persistable types can be embedded in entity classes as fields ... multiple persistent fields  would cause data duplication in the database . Entity Classes An entity

in ObjectDB (and in JPA) is always at the database object level, i.e. each database object is locked separately. Optimistic locking is applied on transaction commit. Any database object ... is being performed on an old version of a database object, for which another update has already been committed

that do not participate in persistence and their values are never stored in the database (similar ... ) entity fields with no real content to be stored in the database . Persistent Fields Every non-static non ... the @Transient annotation). Storing an entity object in the database does not store methods or code

the database . A query identification variable is similar to a variable of a Java enhanced for loop in ... are query identification variables that iterate over all the database objects of a specific entity ... over all the Country objects in the database : SELECT c FROM Country AS c The AS keyword is optional

As explained in chapter 2 , entity objects can be deleted from the database by ...  by a cascading operation. Applying changes to the database by calling the commit method. JPQL ... , which are used to retrieve data from the database , DELETE queries do not retrieve data from

To be able to store Point objects in the database using JPA we need to define an entity class ... that is marked (annotated) as having the ability to represent objects in the database . Conceptually ... class, and accordingly, provides the ability to store Point objects in the database and retrieve

An ObjectDB database can be backed up by simply copying or archiving the database file while the database is offline (i.e. when it is not open in an ObjectDB server and not in use by any application), since an ObjectDB database is stored as an ordinary file in the file system.  ObjectDB

to the database . The element                ... a private directory for every user. The required permissions attribute specifies which database file ... : access - permission to open a database for read. modify - permission to modify the content

when connecting to the database (as explained in the JPA Overview section in chapter 3). The max attribute ... of ObjectDB databases that the server manages. The $objectdb prefix, if specified (as demonstrated ... to the document root directory of a web server. Every database file in the data directory and in

;within an active transaction. Applying changes to the database by calling the commit method. JPQL UPDATE queries ... to retrieve data from the database , UPDATE queries do not retrieve data from the database , but when executed, update the content of specified entity objects in the database . Updating entity objects in

The ObjectDB Object Database ObjectDB is a powerful Object-Oriented Database Management ... all the standard database management services (storage and retrieval, transactions, lock management, query processing, etc.) but in a way that makes development easier and applications faster. ObjectDB Database Key

is that SQL works with relational database tables, records and fields, whereas JPQL works with Java ... rather than just field values from database tables, as with SQL. That makes JPQL more object oriented friendly ... Query The following query retrieves all the Country objects in the database : SELECT c FROM Country

Modifying existing entity objects that are stored in the database is based on transparent ... Once an entity object is retrieved from the database (no matter which way) it can simply be modified in memory ... (); The entity object is physically updated in the database when the transaction is committed

ObjectDB is highly scalable and can manage efficiently databases in a wide range of sizes, from ... supports: Database file size up to 128 TB (= 131,072 GB = 134,217,728 MB). Up to 2,147,483,648 entity classes per database file. Up to 2,147,483,648 indexes per database file

The Java Persistence API (JPA) is a standard API for accessing databases  from within Java applications. The main advantage of JPA over JDBC (the older Java API for interacting with databases ... database programming. A JPA implementation (sometimes referred to as a JPA provider) is needed in

Existing entity objects can be deleted from the database either explicitly by invoking the remove ... an object from the database it has to first be retrieved (no matter which way) and then in an active ... object is physically deleted from the database when the transaction is committed. Embedded objects

). @PostPersist - after storing a new entity in the database (during commit or flush ). @PostLoad - after an entity has been retrieved from the database . @PreUpdate - when an entity is identified as modified by the EntityManager . @PostUpdate - after updating an entity in the database (during commit or flush

Persistence objects represent data in the database . 6.1  Making Objects Persistent In JDO applications, every object in memory is either a persistent object, i.e. represents some database content, or a transient object, i.e. not related to any database . Storing Objects Explicitly

ObjectDB Explorer is a visual tool for managing ObjectDB databases . You can use the Explorer to browse databases , execute JDOQL queries, create new databases and edit the content of existing databases .   9.1  Running the Explorer The Explorer is a pure Java GUI application

;The PersistenceManagerFactory interface represents a factory of database connections. Its main role is to provide PersistenceManager instances. The PersistenceManager interface represents a database connection. Every operation on a database requires a PersistenceManager instance. The Transaction interface represents

;Hello World The HelloWorld sample program manages a list of strings in the database . Each time the program is run another string is stored in the database and all the strings in the database are printed ... of the second run is expected to be: Hello World 0 Hello World 1 After two runs, the database contains

ObjectDB for Java/JDO is a powerful Object Database Management System (ODBMS) written entirely in Java. It can efficiently handle a wide range of database sizes, from a few KBs to hundreds of GBs ... of them. ObjectDB is an Object Database Developing object oriented applications with ObjectDB

, IOException { // Obtain a database connection: EntityManagerFactory emf = (EntityManagerFactory ... , response); } finally { // Close the database connection: if (em.getTransaction().isActive()) em ... is retrieved from the application scope attribute, and then an EntityManager (representing a database

, HttpServletResponse response) throws ServletException, IOException { // Obtain a database connection ... .getRequestDispatcher("/guest.jsp") .forward(request, response); } finally { // Close the database connection ... , and then an EntityManager (representing a database connection) is constructed. If a new guest has registered

An ObjectDB server can manage one or more databases . Databases that are managed by a server ... these databases from remote machines by TCP/IP. More details about client server mode vs. embedded database mode are discussed in Section 1.2 . Because the JDO API and the format of the database file

Persistent Classes are user defined classes whose instances can be stored in a database using JDO. Instances of these classes that represent objects in the database are called persistent objects or persistent instances . Objects that do not represent anything in the database (including instances

Welcome to the ObjectDB for Java/JDO Developer's Guide. Here you can learn how to develop database applications using ObjectDB and JDO (Java Data Objects), the revolutionary database programming ... basic database programming using ObjectDB. Subsequent chapters contain detailed instructions

database , ObjectDB always uses datastore identity with its own object-id class). 4.3   ... the database . The main difference is that, on transaction rollback, it returns automatically ... object is retrieved from the database its fields are not ready yet. Only when the program accesses

databases is more important than general portability to both object and relational databases . JPA is designated to be used mainly with relational databases . ObjectDB is the only object database ... databases and it is probably the most popular Java API for object databases today.