Unit 12: Introduction to Multitier Application Development - PowerPoint PPT Presentation

1 / 10
About This Presentation
Title:

Unit 12: Introduction to Multitier Application Development

Description:

Avoid DCOM setup issues: security/ access, packaging and interface (MIDAS.dll) ... Use Remote Data Module for middle-tier. Use DCOM Connection for thin-client ... – PowerPoint PPT presentation

Number of Views:96
Avg rating:3.0/5.0
Slides: 11
Provided by: conest
Category:

less

Transcript and Presenter's Notes

Title: Unit 12: Introduction to Multitier Application Development


1
Unit 12 Introduction to Multi-tier Application
Development
  • Review Model-View Separation
  • Client-Server Architecture
  • BCB Multi-tier Distributed Application Services
    (MIDAS)
  • BCB Remote Data Module
  • TDataSetProvider
  • TClientDataSet

2
BCB Model-View Separation
  • Business Logic
  • Data Module (i.e., Model)
  • Presentation logic
  • Form (i.e., View)
  • Using Data Module
  • Pro Code is maintainable
  • Con Fat client
  • business logic distributed to all clients
  • If business logic changes, need to re-deploy to
    all clients

3
Client-Server Architecture
  • Fat Client Form and Data Module
  • Server Centralized Database

Fat Client
DataModule.cpp
SQL Server
TADO Connection
TDataSource
TADOTable
4
Multi-tier Architecture
  • BCB Multi-tier Distributed Application Services
    (MIDAS)
  • Application resides in three (or more) machines
  • Thin Client Form and Client Data Module
  • Middle-tier Remote Data Module
  • Business logic stored in the Remote Data Module
  • BCB DataSetProvider encapsulates the COM
    interface and exports the DataSet to clients
  • Also known as Application Server
  • Server Centralized Database
  • SQL Server, Oracle, Sybase, DB2, MySQL

5
MIDAS Remote Data Module
Thin Client
DataModule.cpp
TClient DataSet
DCOM Connection
TDataSource
TDataSet Provider
RemoteDataModule.cpp
TADO Connection
SQL Server
TADOTable
Middle-tier
6
Remote Data Module
  • RDM uses COM IAppServer interface
  • Client needs MIDAS.dll to connect to the
    TDataSetProvider
  • TDataSetProvider
  • Exports the DataSet and makes it available for
    clients.
  • Must set Export property to true

7
DCOM Connection
  • Pros
  • BCB supports DCOM using TDCOMConnection component
  • Simplifies connection from client to middle-tier
  • Cons
  • DCOM is a Microsoft platform only solution
  • Requires NT/W2K
  • Requires MS Domain Name Server (DNS)
  • Requires admin rights to DCOM config and security

8
TClientDataSet
  • Similar to the regular TDataSet such as TADOTable
    and TADOQuery
  • Key Properties
  • Remote Server
  • Use the DCOMConnection in DM
  • Provider Name
  • Use the DataSetProvider name in Remote DM
  • Key Method
  • ApplyUpdates(0) to propagate changes to RDM
  • Argument of zero (0) means to stop updates if an
    error or exception is encountered.

9
RDM Exercise
Extra Use COM interface for additional business
logic
10
Assignment 6
  • Objective Convert a Data Module to Remote Data
    Module
  • Now available due next week
  • Testing limited to one machine only
  • Avoid DCOM setup issues security/ access,
    packaging and interface (MIDAS.dll), DNS and RPC
    server availability, etc.
  • Use MS Access (PayData2002.mdb)
  • Use Remote Data Module for middle-tier
  • Use DCOM Connection for thin-client
Write a Comment
User Comments (0)
About PowerShow.com