Business Application Framework


A Java™ Framework for accessing relational database





Communicating with databases is a base functionality in enterprise systems, but it represents a non-trivial issue when is treated in development phases. In common cases a relational database is used, and access is given to Java™ applications through the JDBC connector API. However, this technology just offers a set of “query-level” functions that not solve the so called “impedance problem”, i.e. the inherent incompatibility between objects and relational databases, product of different approaches used in both models to treat identities, identifiers and associations between entities.

As consequence of this lack of transparency in moving from the object-oriented model to the relational schema (and vice versa), developers usually adopt its own -and then- non-standard mapping operations. Furthermore, because of the access to database isn’t generally the main functionality of the system under development (it is not what the final user will appreciate), adopted solutions rely on lightweight designs, that don’t cover all the aspects that a reliable and scalable application should address.

The Persist framework is our Java™ instrument proposed for accessing relational databases under Object-Oriented perspective. It is composed by a set of classes built on the JDBC connection API, that offers high-level representation of a database schema. Persist allows developers to omit writing SQL statements, in favor of using an object oriented representation of the request. In this way, programmers can access relational tables as they were object collections, records as specific instances, and fields as their attributes.

Persist is organized in two levels:

  • The meta-level, associated to the Data Definition Language (DDL) of a database, where resides the representation of the relational schema, that is, tables, relations, attributes and specific database-vendor data types. Thanks to this information, Persist can be used to automatically produce the database schema in a DBMS
  • The statement-level, associated to the Data Manipulation Language (DML) of a database, allows the creation and execution of queries exploiting an object-oriented perspective. These queries can be executed in a transaction-oriented context, with commit and rollback support


The Object model of the framework

DbRecord DbField DbIdRecord DbCounter DbStatement SchemaStatement DbReferenceRecord DbRelazrecord DbReferenceField DbConnection WhereStatement InsertStatement CallStatement DbRecordSelection SelectStatement UpdateStatement DeleteStatement

The dictionary of Classes



It contains information about the connection and the type of database. It holds the dictionary that maps standard SQL data types and specific database vendor types. It encapsulates low-level operations for opening and closing connections, and implements transaction management basic methods.

  • Aggregated by DbStatement


This is the base class used to build different types of database queries under an objectified approach. It allows the construction of simple queries (e.g. simple selects) or complex ones (e.g. nested selections with join between tables). The DbStatement class encapsulates both an instance of DbConnection and an instance of JDBC statement. This class also declares the transaction management methods –internally mapped to DbConnection’s transactional methods- that are inherited by the statement objects.

  • Generalization of WhereStatement
  • Generalization of CallStatement
  • Generalization of InsertStatement
  • Generalization of SchemaStatement
  • Aggregates DbConnection


It implements operations for creating and destroying tables and indexes in the database.

  • Specialization of DbStatement


It implements the operation “insert” in the database.

  • Specialization of DbStatement


It allows the invocation of DBMS “stored procedures”.

  • Specialization of DbStatement


This is an abstract class used to enable filtering conditions (associated to the “where” clause in a SQL statement) in classes that perform accesses to the database (SelectStatement, UpdateStatement and DeleteStatement).

  • Generalization of SelectStatement
  • Generalization of DeleteStatement
  • Generalization of UpdateStatement
  • Specialization of DbStatement


It implements the operation for deleting one or more records from the database. The filtering mechanism of the records to delete is inherited from WhereStatement. Operations of commit/rollback are also available (inherited from DbStatement).

  • Specialization of WhereStatement


It implements the operation for selecting fields or entire records from the database. The filtering mechanism of the records to select is inherited from WhereStatement. Operations of commit/rollback are also available (inherited from DbStatement).

  • Specialization of WhereStatement


It implements the operation for updating fields or entire records in the database. The filtering mechanism of the records to update is inherited from WhereStatement. Operations of commit/rollback are also available (inherited from DbStatement).

  • Specialization of WhereStatement


It represents the SQL statement for selection of entire records or just subsets of fields. It inherits from WhereStatement.

  • Specialization of WhereStatement


DbField is one the most important classes because it pertains to the meta-level of the framework. Each instance of DbField describes a single table field value and its type (name, type, length).

  • Aggregated by DbRecord
  • Generalization of DbReferenceField


Correspond to the Object Oriented representation of a database record. A DbRecord is composed of a collection of DbFields that represent a database table structure. Operations for selecting, inserting, deleting, creating tables, dropping tables are implemented in this class.

  • Generalization of DbIdRecord
  • Generalization of DbReferenceRecord
  • Generalization of DbCounter
  • Aggregates DbField


It is an extension of DbRecord used to represent records with an internal numerical identifier. It adds to the inherited methods operations for updating data, and for managing internal identifiers (including the search operation).

  • Generalization of DbRelazRecord
  • Specialization of DbRecord


It represents a service table used for automatic generation of internal identifiers for all the tables inheriting from DbIdRecord.

  • Specialization of DbRecord


It corresponds to the Object Oriented representation of “foreign keys” that maps references to records pertaining to other tables.

  • Specialization of DbField


It is a class used to support two-way references between classes.

  • Specialization of DbRecord


It represents all relational tables with an internal numerical identifier key.

  • Specialization of DbIdRecord

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This page last updated on Nov 10, 2002.
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