Delphi三层架构开发基本概念介绍IntroductiontothebasicconceptofDelphithreetierarchitecture

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 enterprise's 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: microsoft's three-tier service model1.

6、 structure: 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 i

7、mplement the 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 maxim

8、ize the richness 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) bus

9、iness services: 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 (micros

10、oft message 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 i

11、nformation 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) s

12、etobjmyobject = 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 an

13、d component services (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

14、provided by mts include: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

15、 can be declared in the 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 (a

16、tomicity, consistency, 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 cre

17、ateobject (" businessserver. 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 serv

18、ices (microsoft transaction server 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 m

19、ts include:support for distributed 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 d

20、eclared in the 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,

21、 consistency, separateness isolatation, 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 onl

22、y 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 provides users with the first layer (expression layer), mts and mts artifacts, suc

23、h 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) service engine. dtc uses two-stage delivery standard.information about dtc can be ob

24、tained 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 parameters are passed as far as possible through the value (by val). (by val keywo

25、rd 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 in multiple objects.7:note: xa is a two-phase commit protocol defined by the x/op

26、en 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 queue server).1: microsoft message queue (msmq) provides asynchronous communication

27、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 msmq messages in mts transactions.the msmq is different from the microsoft exchange

28、 server. exchange provides the messaging 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 betw

29、een the business service layer and 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)microsoft's com & dcom (profile)a: com is a protocol that defines how an

30、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 different computer from the customer. calls to the object server

31、 through rpc. (corba is also distributed object protocol)com manages the object's 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 = e

32、n-us > mts component implementation, recordset pairthe 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 t

33、he strategy.using html, dhtml, active server pages provides 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: mt

34、s uses distributed transaction coordinator (dtc) service 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

35、. (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 the network)avoid creating database cursors. use fewer recordset objects.by making object package container threading (apartment thr

36、eads), 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 database service transactions to be coordinated and treated as a transaction. (unix databases, including oracle, informix, and db2 s

37、upport)three: message service (microsoft message queue 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

38、integrated with mts. applications can encapsulate msmq 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

39、-to-application).4: universal data access (microsoft 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 mainf

40、rame environment (microsoft sna server)microsoft's com & 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

41、 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 object protocol)com manages the object's security through the sspi (security support provider interface).two: the features that the app

42、lication server should have:the ability to start, monitor, and abort 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 machine's dcom service contr

43、ol manager (service control manager, scm) will start the com server automatically 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 registrati

44、on.extensible ability: scalable first and second grades. dcom provides two 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.r

45、elated technologies provided by delphi:u com/dcom/com + business object.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

46、ado, midas, internet express, activex and other pages in the component panel.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 des

47、ign, allows software objects to be reused in different operating system 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 l

48、inux/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

49、: the structure of corbaa corba object is a component that provides a specific service, which declares the services that can be provided by defining a set of output interfaces. in this output interface, the corba object defines the methods and access properties that the client can invoke. the client

50、 simply specifies corba for the provision of the servicesi-font-family: times new roman > message queue 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 i

51、n 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 messaging of the user to the user (person-to-person). the msmq provides the applicat

52、ion 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 the data service layer. ado, ole db (embedded database) and odbc make up the mic

53、rosoft data access artifacts (mdac).5. interoperability of mainframe environment (microsoft sna server)microsoft's com & 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

54、 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 object protocol)com manages the object's security through the sspi (sec

55、urity 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.n is easy to configure.n security failure capability.far layer of the function: if the user wants to create a com object on

56、the remote computer, the remote machine's dcom service control manager (service control manager, scm) will start the com server automatically 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 wi

57、ndows explorer to activate the registration or revoke registration.extensible ability: scalable first and second grades. dcom provides two 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.u corba enterprise object.u xml/htmlu cgi/sapi/nsapiu aspactive formu ado/ole dbu bde/idapi