Session Class Reference
[GDB]

Session class. More...

Inheritance diagram for Session:

Inheritance graph
Collaboration diagram for Session:

Collaboration graph

List of all members.

Public Member Functions

virtual ~Session ()
 Destructor.
GraphGetGraph ()
 Gets the Graph instance.
ObjectsNewObjects ()
 Creates a new Objects instance.
void Begin ()
 Begins a transaction.
void Commit ()
 Commits a transaction.

Friends

class Database
class Graph
class Objects
class ObjectsIterator
class Values
class ValuesIterator
class TextStream


Detailed Description

Session class.

A Session is a stateful period of activity of a user with the Database.

All the manipulation of a Database must be enclosed into a Session. A Session can be initiated from a Database instance and allows for getting a Graph instance which represents the persistent graph (the graph database).

Also, temporary data is associated to the Session, thus when a Session is closed, all the temporary data associated to the Session is removed too. Objects or Values instances or even session attributes are an example of temporary data.

Moreover, a Session is exclusive for a thread, thus if it is shared among threads results may be fatal or unexpected.

Transactions

A Session allows for enclosing a set of graph operations into a transaction. A transaction defines a granurality level for concurrent execution of Sessions. The explicit use of transactions may improve the performance of concurrent execution of Sessions.

All operations within a transaction are considered an execution unit. By default, if no transactions are defined by the user, all operations behave as autocommit, that is a transaction is created just before each method and closed when the method finishes.

For the moment, transactions have a partial support of the ACID properties.

Transaction type

There are two types of transactions: Read or Shared, and Write or Exclusive. DEX's concurrency model is based in a N-readers 1-writer model, thus read transactions can be executed concurrently whereas write transactions are executed exclusively.

The type of a transaction is defined for the operations it contains. Initially, a transaction starts as a read transaction and just when a method which updates the persistent graph database is found it automatically becomes a write transaction. Obviously, to become a write transaction this must wait until all other read transactions have finished.

Author:
Sparsity Technologies http://www.sparsity-technologies.com

Member Function Documentation

Graph* Session::GetGraph (  ) 

Gets the Graph instance.

Returns:
The Graph instance.

Objects* Session::NewObjects (  ) 

Creates a new Objects instance.

Returns:
The new Objects instance.


The documentation for this class was generated from the following file:

Generated on Mon Oct 15 14:40:43 2012 for Dex by  doxygen 1.5.6