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1、Delphi 三层架构开发基本概念介绍（Introduction to the basic concept of Delphi three-tier architecture）The Delphi three-tier architecture development concept is introducedThree levels of customer/serverOne: advantages: flexibility and extensibility.The reason for applying the three-tier development technique (dist
2、ributed)(bibliography: Delphi 5.x distributed multilayer application system)1. Solve the problem of maintenance cost of client/server structure and improve the problem of client/server structure extension.The client/server structure supports a limited number of users (below 200 people). The structur
3、e limits the development of Internet/Intranet and e-commerce. Three-tier development application Database Pooling, Object Pooling, Resource Pooling, thread mode provides high scalability.2. Solve the problem of reuse of application logic.For example, when the enterprise wants to add a Web browsing s
4、ervice to its original client/server structure, it needs to configure the Web server, rewrite all the application logic, and update the MIS system. In the three-tier structure, you can solve the above problems by using COM/DCOM, the Common Object Request Broker Architecture Object, or Enterprise Jav
5、a beans, which encapsulate the Enterprises logical program code (called Enterprise objects). Significantly reduces the cost of development and maintenance.Iii. Integrate the needs of different system structures and timely apply new technologies.Second: Microsofts three-tier service model1. Structure
6、: the component object model of the distributed Internet applications (distributed Internet applications) is used as a tool to realize the system and application services.User serviceL business servicesL data service(1) user service: Windows DNA defines four customers that can be used to implement t
7、he user service layer:N standard browsing customers: rely on simple, page-based HTML to manage data representation and interact with users. The compatibility is good and the function is not rich.The advantages of the special browser (ex: Dynamic HTML, scripts and ActiveX controls) to maximize the ri
8、chness and functionality of the user interface are applicable to the Intranet.N dependent Internet customer: you can integrate the Internet access and access to the operating system on the client machine.N enhanced Internet customers: Microsoft Office 97 and Microsoft Visual Studio.(2) business serv
9、ices: by integrating a server-based Microsoft product with a custom COM component operating environment.N Web services (Microfsoft Internet Information Server and Active Server Pages).Transaction server and component services (Microsoft Transaction server and COM).N message service (Microsoft messag
10、e queue server).General data access (Microsoft data access)The interoperability of the mainframe environment (Microsoft SNA server). Details are listed in the following topics.(3) data services:N Microsoft SQL server 7 database.N Microsoft Exchange server 5.5 version of the directory and information
11、 library.Topics:Business servicesOne: Web services (Microsoft Internet Information Server and Active Server Pages).Web service object model:1, the server object: provides access to methods and properties on the server. Example: q (universal data access) (Microsoft data access components) setobjmyobj
12、ect = server createobject ( businessserver. Myruleobject )2: Session object: information necessary to store a specific user Session.Application object: to share interest with all users of an Application.4: Request object: slightly.5: Response object: slightly.Ii: Transaction and component services (
13、Microsoft Transaction server and COM)The Microsoft transaction server (MTS) is a component-based transaction processing system for complex transaction processing. MTS support SQL Server and anyA database of XA protocols based on the X/open algorithm (see comments).The services provided by MTS includ
14、e:Support for distributed transactions.N is used to control instantiation and to use the service of object security.Automatic management of n processes and threads.Management of the n object instance.N database connection management (connection pool).The corresponding artifacts can be declared in th
15、e application to complete the above services.2: the MTS, like SQL server transactions, requires atomic execution, or overall success, to fail. Transaction Server and Microsoft Distributed Transaction Coordinator (MSDTC) interact to confirm that the Transaction satisfies ACID (Atomicity, Consistency,
16、 separateness Isolatation, and Durability).3: differences between MTS and SQL server transactions. MTS can be encapsulated with visual basic, visual c + +, etcAnd attribute access. Example: q (universal data access) (Microsoft data access components) setobjmyobject = server createobject ( businessse
17、rver. Myruleobject )2: Session object: information necessary to store a specific user Session.Application object: used to enable all users of an Application to share interest.4: Request object: slightly.5: Response object: slightly.Ii: Transaction and component services (Microsoft Transaction server
18、 and COM)1: the Microsoft transaction server (MTS) is a component-based transaction processing system for complex transaction processing. MTS support SQL Server and anyA database of XA protocols based on the X/open algorithm (see comments).The services provided by MTS include:Support for distributed
19、 transactions.The n is used to control instantiation and to use the service of object security.Automatic management of n processes and threads.Management of the n object instance.N database connection management (connection pool).The corresponding artifacts can be declared in the application to comp
20、lete the above services.2: the MTS, like SQL server transactions, requires atomic execution, or overall success, to fail. Transaction Server and Microsoft Distributed Transaction Coordinator (MSDTC) interact to confirm that the Transaction satisfies ACID (Atomicity, Consistency, separateness Isolata
21、tion, and Durability).3: differences between MTS and SQL server transactions. MTS can be implemented with visual basic, visual c + + and other encapsulated MTS components, Recordset pairsThe addnew method of the image adds a new line. SQL server transactions can only be written by transact-sql code,
22、 such as (ADO).4: Windows distributed Internet application architecture: develop the customer/service pattern with the web and with the strategy.Using HTML, DHTML, Active server pages provides users with the first layer (expression layer), MTS and MTS artifacts, such as IIS (Internet information ser
23、ver), IIS/ASP components and ASP scripts to occupy the middle tier (business logic layer), SQL server as the data service layer.5: MTS USES Distributed Transaction Coordinator (DTC) service engine. DTC USES two-stage delivery standard.Information about DTC can be obtained by using the MMC: winnt sys
24、tem32 services. MSC,Find the DTC service in the list on the right and look at its properties.6: maximize system performance using MTS. (notes)N avoids passing or returning objects.The parameters are passed as far as possible through the value (BY VAL). (By Val keyword to minimize the journey between
25、 the network)Avoid creating database cursors. Use fewer RecordSet objects.By making object package container threading (Apartment threads), MTS can execute concurrent customer requests in multiple objects.7:Note: XA is a two-phase commit protocol defined by the X/Open organization, allowing multiple
26、 database service transactions to be coordinated and treated as a transaction. (Unix databases, including oracle, informix, and db2 support)Three: message service (Microsoft message queue server).1: Microsoft Message Queue (MSMQ) provides asynchronous communication capabilities for applications. MSM
27、Q is considered to be a bridge connecting the business and data services layers in distributed applications.2: MSMQ is automatically integrated with MTS. Applications can encapsulate MSMQ messages in MTS transactions.The MSMQ is different from the Microsoft exchange server. Exchange provides the mes
28、saging of the user to the user (person-to-person). The MSMQ provides the application to the application to the application (application-to-application) messaging.4: universal data access (Microsoft data access artifacts)Data access artifacts span the boundaries between the business service layer and
29、 the data service layer. ADO,OLE DB (embedded database) and ODBC together form Microsoft data access artifacts (MDAC).5. Interoperability of mainframe environment (Microsoft SNA server)Microsofts COM & DCOM (profile)A: COM is a protocol that defines how an object server interacts with an object clie
30、nt. The object server is the module that implements the COM class. Object consumer is a module that USES COM objects.DCOM extends the COM protocol so that the object server can be located on a different computer from the customer. Calls to the object server through RPC. (CORBA is also distributed ob
31、ject protocol)COM manages the objects Security through the SSPI (Security Support Provider Interface).Two: the features that the application server should have:The ability to start, monitor, and abort the n remote layer.N extensible capability.Lang = en-us MTS component implementation, Recordset pai
32、rThe addnew method of the image adds a new line. SQL server transactions can only be written by transact-sql code, such as (ADO).4: Windows distributed Internet application architecture: develop the customer/service pattern with the web and with the strategy.Using HTML, DHTML, Active server pages pr
33、ovides users with the first layer (expression layer), MTS and MTS artifacts, such as IIS (Internet information server), IIS/ASP components and ASP scripts to occupy the middle tier (business logic layer), SQL server as the data service layer.5: MTS USES Distributed Transaction Coordinator (DTC) serv
34、ice engine. DTC USES two-stage delivery standard.Information about DTC can be obtained by using the MMC: winnt system32 services. MSC,Find the DTC service in the list on the right and look at its properties.6: maximize system performance using MTS. (notes)N avoids passing or returning objects.The pa
35、rameters are passed as far as possible through the value (BY VAL). (By Val keyword to minimize the journey between the network)Avoid creating database cursors. Use fewer RecordSet objects.By making object package container threading (Apartment threads), MTS can execute concurrent customer requests i
36、n multiple objects.7:Note: XA is a two-phase commit protocol defined by the X/Open organization, allowing multiple database service transactions to be coordinated and treated as a transaction. (Unix databases, including oracle, informix, and db2 support)Three: message service (Microsoft message queu
37、e server).1: Microsoft Message Queue (MSMQ) provides asynchronous communication capabilities for applications. MSMQ is considered to be a bridge connecting the business and data services layers in distributed applications.2: MSMQ is automatically integrated with MTS. Applications can encapsulate MSM
38、Q messages in MTS transactions.3: MSMQ is different from Microsoft exchange server.The exchange provides the messaging of the user to the user (person-to-person), while MSMQ provides the application to the messaging of the application (application-to-application).4: universal data access (Microsoft
39、data access artifacts)Data access artifacts span the boundaries between the business service layer and the data service layer. ADO, OLE DB (embedded database) and ODBC make up the Microsoft data access artifacts (MDAC).5. Interoperability of mainframe environment (Microsoft SNA server)Microsofts COM
40、 & DCOM (profile)A: COM is a protocol that defines how an object server interacts with an object client. The object server is the module that implements the COM class. Object consumer is a module that USES COM objects.DCOM extends the COM protocol so that the object server can be located on a differ
41、ent computer from the customer. Calls to the object server through RPC. (CORBA is also distributed object protocol)COM manages the objects Security through the SSPI (Security Support Provider Interface).Two: the features that the application server should have:The ability to start, monitor, and abor
42、t the n remote layer.N extensible capability.N is easy to configure.N security failure capability.Far layer of the function: if the user wants to create a COM object on the remote computer, the remote machines DCOM Service Control Manager (Service Control Manager, SCM) will start the COM server auto
43、matically and the COM object is available. Specific information can run the DCOMCNFG command in the start menu.Easy to configure: right-click a COM DLL or EXE in Windows explorer to activate the registration or revoke registration.Extensible ability: scalable first and second grades. DCOM provides t
44、wo load balancing. 1) static load balancing (the running machine that specifies the application server) can be specified in the properties of the application in DCOMCNFG. 2) : dynamic load balancing, allocated by the scheduler.Related technologies provided by Delphi:U COM/DCOM/COM + business object.
45、U CORBA enterprise object.U XML/HTMLU CGI/SAPI/NSAPIU ASPActive FormU ADO/OLE DBU BDE/IDAPI SQL LinksU MTS objectU MIDAS serverThe u CORBA server.The related components are in 1) File menu new Multitier and ActiveX pages.2) the ADO, Midas, Internet Express, ActiveX and other pages in the component p
46、anel.Introduction of Corba1: what is a common object request broker architecture?Corba is a distributed object standard structure defined by the object manangement group (OMG). Language neutrality, which USES object-oriented design, allows software objects to be reused in different operating system
47、platforms and applications.If you want to implement the functionality, corba is a better solution:The application system should integrate heterogeneous platform and operating system.The l application server must be executed on Linux/Unix machines.The l application system must perform key tasks, which have the capacity of safety and strong fault tolerance, which must be stable and efficient.L wants to develop Internet/Intranet solutions that use Web objects.The future of the application system wants to integrate with Java.2: the structure of corbaA cor