ObjectExtender User's Guide and Reference


Glossary

ACID
A mnemonic for the properties a transaction should have to satisfy the Object Management Group Transaction Service specifications. A transaction should be Atomic, its result should be Consistent, Isolated (independent of other transactions) and Durable (its effect should be permanent).

atomic
An atomic database transaction is one which is guaranteed to complete successfully or not at all. If an error prevents a partially-performed transaction from proceeding to completion, it must be "backed-out" to prevent the database from being left in an inconsistent state.

BO
Business object. This term denotes the objects in your problem domain that you wish to persist in a data store.

cardinality
Cardinality expresses the constraints on the number of instances that are related through a relationship.

code-generation
The function whereby code is generated automatically given certain specifications.

CB
Component Broker.

connect/disconnect
The attachment (or unattachment) of a target business object to/from a link.

consistency
In the context of ACID: a transaction is a correct transformation of the state. The actions taken as a group do not violate any of the integrity constraints associated with the state. This requires that the transaction be a correct program.

counter
Referring to the other side of a two-way business object relationship.

CRUD
Create/Read/Update/Delete, the four basic types of operations on database rows, records. ObjectExtender provides these operations on objects as well.

data model
The term, data model is used here, to make a distinction between it and an object model that you wish to persist. For example, the schema for a relational database represents the data model. Your object model is represented differently and will not need to be tightly coupled with the data model representation.

DDL
Data Definition Language. A language enabling the structure and instances of a database to be defined in a human- and machine-readable form.

DO
DO is an acronym for data object. Data objects contain the data for the business objects. The data is in the form in which it was retrieved from the data store.

durability
In the context of ACID: Once a transaction completes successfully (commits), its changes to the state survive failures.

framework
In object-oriented systems, a set of classes that embodies an abstract design for solutions to a number of related problems.

home collection
Home collections provide the logical home for business objects. They provide APIs for creating or locating instances.

hydration
The activity of populating the properties and relationships of a model object.

isolation
In the context of ACID: even though transactions execute concurrently, it appears to each transaction, T, that others executed either before T or after T, but not both.

link
The infrastructure that connects source and target business objects in a relationship.

metadata
Any information which describes according to prescribed specification a target data.

multiplicity
See cardinality.

nested transaction
A nested transaction is a tree of transactions, the sub-trees of which are either nested or flat transactions. Transactions at the leaf level are flat transactions. The transaction at the root of the tree is called the top-level transaction; the others are called subtransactions. A transaction's predecessor in the tree is called a parent; a subtransaction at the next lower level is also called a child . A subtransaction can either commit or roll back; its commit will not take effect though, unless the parent transaction commits. Therefore, any subtransaction can finally commit only if the top-level transaction commits. The rollback of a transaction anywhere in the tree causes all its subtransactions to roll back.

object model
Object model is to data model what a hierarchy of classes is to a schema of database tables. It is simply a distinction between the two representations of how the data is represented.

OO
Object-oriented. Can apply to analysis, design, and programming disciplines.

persistence
A property of a programming language where created objects and variables continue to exist and retain their values between runs of the program. This is in contrast to transient objects that cease existing when the application that created them is not running.

pre-fetch
The notion of defining a path to set of data that you want to preload from data store to object model to reduce the number of database trips improving performance.

relationship
As understood in the context of the ObjectExtender framework, a relationship is an instance variable in a business object which contains a reference to another persistent object.

transaction
A unit of interaction with a DBMS or similar system. It must be treated in a coherent and reliable way independent of other transactions.

UML
Universal Modeling Language.


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