[Datalayer-devel] Changes in DataServices and DataLayer

[DataLayer D. L. <dat...@li...>]

DataServices
 
DataSourceManager:
 
- data_sources modified to use a generic dictionary with string keys and
DataSource values.
- LoadDataSources static function to read configuration file and instanciate
each DataSource and add it to data_sources.
- New Static constructor calling LoadDataSources()
 
DataSource:
 
-         New constructor to create a DataSource passing each connection
parameter using separate variables.
-         New instance fields to store each connection parameter separately
(username, password, host, port and database)
-         New abstract BuildConnectionString() to build a connection string
based on connection parameters stored in DataSource instance fields
(username, password, host, port and database)
-         New abstract DeconstructConnectionString() to extract connection
parameters from connection_string instance field and save them on separate
instance fields (username, password, host, port and database)
-         Call BuildConnectionString and DeconstructConnectionString on
respective constructors.
-         Connection instance and property removed. No connection instance
is mantained by DataSource.
-         GetType function removed to enforce DataSource abstraction and
avoid DataSource modification on future provider additions.
-         TODO: Remove ConnectionStringBuilder()static function. This
functionality is implemented by BuildConnectionString()
-         BeginTransaction() uses new connections for new transactions.
-         CreateCommand functions removed. There is no need of Command
object. That functionality is delegated to Query object on DataLayer to keep
DataSources a low-level layer. Only IDbCommands are used by this layer.
-         FillSchema() function now receives a DbDataAdapter instead of a
Command containing that DbDataAdapter. Locks implemented to avoid concurrent
DataTable modification on mult-threaded environments. A new FillSchema()
overload to accept a select IDbCommand from which a DbDataAdapter will be
created.
-         Fill() overloaded and changed with similar behavior to
FillSchema().
-         Update() similar changes to Fill and FillSchema with additional
overload to accept an array of DataRow's
-         New ComparisonOperators and LogicalOperators enumerations.
-         New ParseComparisonOperator and ParseLogicalOperator virtual
functions to parse those enum values to sql equivalent operators.
-         New ParseRowFilterValue function to parse a parameter value into a
valid string to be used as filter on a DataView
-         CreateCommandBuilder function removed. Command building process is
delegated to each provider DataSource implementation. 
-         Open and Close functions removed. No connection is maintained on
DataSource
-         New ConstructParameter() and DeconstructParameter() to let each
DataSource implementation create the string parameter to be used with an
IDbCommand. (Different characters are used to parse parameters. SQL: '@',
MySQL: '?', PGSql: ':')
-         New LiteralDate() and LiteralString() abstract functions to let
each DataSource provider specify literals for strings and dates.
-         New ColumnInfo struct to store metadata information related to a
field.
-         New abstract function GetTableColumns to retrieve metadata
information related to a table.
-         New abstract function ParseType to map equivalent specific
provider data types with standardized DbType enumeration.
-         Each DataSource implementation was updated with new changes.
-         Added one resources file for each DataSource to store commands to
retrieve metadata information and keep clean code.
 
DataLayer
 
-         New DataBaseManager class to create DataBase's based on
DataSource's maintained by DataSourceManager from DataServices layer. Each
DataBase is stored on a dictionary with the same string key of the
DataSource and a DataBase value.
-         New Table and Query Objects wich uses DataSource's services.
-         New IQueryComponent  
-         New TableJoin, TableJoinCollection, WhereStatement and
WhereStatementCollection classes used by Query class. All classes implement
IQueryComponent interface.
 
DataBase:
-         New Constructor to receive a DataSource to be used by DataBase.
-         New data_source field and DataSource property to store and expose
the DataBase's DataSource.
-         All static functions are now instance functions.
-         New table_pool generic dictionary to keep a collection of Table
objects mapped to DataTables stored on instantiated DataSet.
-         DataSet is now maintained as an instance field. Property also
changed to instance scope.
-         New DataSource instance field to bind DataBase with related
DataSource. All DataBase's operations are done trough this field.
-         Fill now accepts only a Query object which is used to execute and
fill DataTable stored on DataBase.
-         Update now only accepts a table name to be updated and uses Table
and Query services.
-         New GetTable function to retrieve a Table stored on table_pool if
it has been created previously or creates a new one, stores it on the pool
and returns it.
 
TableAttribute
-         New DataSource property to specify the key name of table's
DataSource.
-         New constructor to specify table name and DataSource's key.
-         New data_source field to store table's DataSource key. If it's not
specified, Table is mapped to first configured DataSource.