[Overview] [Demos] [Components] [Function libs] [Changes] [Soon]

Overview VG Midas Library is extension of VG VCL Library.
Library includes a number of components for Midas multi-tier application
development. It is compatible with Delphi 3 and 4 client/server editions.
VG Midas component set together with BDE Server application
server provides a complex solution in development client/server
application using Midas technology.
Library reqires VG VCL
Library to be installed.
There are some classes in the library inherited from classes released
in the RX library. These
components are optional. To use them you should have RX library 2.50 or
higher to be installed.
There is April, 1999 release of VG Midas
Library.
Demos \Demos\DB\MastApp standart demo project
have been ported into real multi-tier during 40 minutes! You can download
it's compiled version with full source here.
Components
[Mulitier]
- TProviderList component manages
list of run-time created providers. Component working with conjunction
with TvgRemoteDataModule makes list of providers available for client
applications trough IvgRemoteDataModule interface without reqiring to
publish each provider as property while designing server module.
- TProviderFactory hooks data
packets exchange between remote server and client datasets. It allows to
centralize both on client and server implementation of user-defined
operations on data packets which realize data crypting and/or
compression.
- TvgClientDataSet component is
TClientDataSet descendent. It implements support for parameters and
macroses (see TRxQuery) both for Delphi 3 and Delphi 4 and is compatible
with TvgProvider and TRxQuery on server side. Component also implements
enhanced sorting functionality that allows you to sort both in ascending
and descending orders.
- TClientDataSetHook is
TDataSetHook descendent that hooks TClientDataSet events to make them
defined only one time within application (see TBDEDataSetHook).
- TSinglePointServer is remote
server component descended from TvgRemoteServer (see below) that
implements single-point connection. In conjunction with
TvgRemoteDataModule it implements internal OLE automation server and
allows to create multi-tier applications in single-point mode.
- TvgCustomRemoteServer and it
descendents TvgRemoteServer, TvgCORBARemoteServer provide an additional
way of abstraction in using remote server components.
TvgCustomRemoteServer "hooks" real remote server component and hides
(Delphi 4) it's implementation (COM or CORBA) under number of virtual
method and properties. TvgCustomRemoteServer provides support for BDE Server interface. It
supports TProviderFactory (see above) and allows to automatically loggon
onto remote servers.
- TvgSocketConnection is
advanced remote server components that implements thread-safe socket
remote server. It allows you to make calls to the COM server from
different threads without care about critical sections. Also it fixes a
number of bugs of original TMidasConnection and TSocketConnection
components. Also it supports datablock interception for Delphi 4 like
Delphi 4 TSocketConnection does.
- TvgSocketDispatcher is
enhanced TSocketDispatcher that provides events for custom interception
of datablocks. TvgSocketDispatcher supports timeouts for inactive
connections.
- TDatabaseProvider is
server-side portion of IDatabase interface that incapsulates TDatabase
functionality. It supports remote transaction control, alias
connectivity and autocreation of providers by client request.
BDE Server client components
BDE Server client components in conjuntion with BDE Server
application implements the newest Midas-based BDE replacement.
Components allows you to work with same properties, methods, error codes
and even property editors as their BDE prototypes has but doesn't reqire
BDE to be installed.
Client components client components support aliases, databases,
transactions, tables, queries, stored procedures, update SQL statements,
cached updates and BDE error codes.
With BDE Server and VG Midas you can easy create new or port old
applications within distributed architecture that will be powered with
both BDE functionality and Midas flexibility.
- TvgClientDatabase
incapsulates client-side functionality of TDatabase component.
TvgClientDatabase allows to use TvgClientTable, TvgClientQuery and
TvgClientStoredProc at client side. Component controls remote database
connection, transaction control and manages the list of connected
TvgClientBDEDataSets.
- TvgClientTable implements
client-side TTable analog that allows to open remote tables.
- TvgClientQuery implements
client-side TQuery analog. It allows to open or execute SQL statement in
the same way as TQuery does. Component supports SQL, Params and Macros
properties (see TRxQuery).
- TvgClientStoredProc is
client-side TStoredProc analog that allows to open or execute remote
stored procedures.
- TvgClientUpdateSQL is
TUpdateSQL analog. This is a helper object that is used by
TvgClientBDEDataSet to implement client-side cached updates mechanism
and apply updates into remote server. It has the same properties as
TUpdateSQL. TvgClientUpdateSQL also supports macroses in update
statements.
- TvgClientBatchMove is
full-functional TBatchMove analog. TvgClientBatchMove extends
functionality of their prototype and supports any TDataSet descendent as
it's source dataset.
- TvgClientSQLScript
component allows execution of multiple SQL statements in one query.
Component supports parameters and macroses.
- TvgClientUpdateScript is
another update object. It executes multiple SQL statements for update
purposes. Component supports parameters and macroses.
Function libraries
- vgCDSUtl.pas - client dataset
utility routines
- vgSock.pas - WinSock utility
routines
Changes
Changes list
Soon
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