COM/COM+ Advantages: · Fastest DataSnap Protocol on Windows platform · Can be used with other MS« and 3rd party COM applications · Can be use as Transaction Server (MTS/COM+) objects Disadvantages: · Location Dependant · DCOM has proven to be unstable · Relies on Windows NT Domain · Can be difficult to set up · Cannot port to other environments, MS« only technology When to use: · Same machine application server and client application · A department sized implementation of +- 30 connected clients · When there is a need to integrate into other MS« or COM based applications · Closed NT domains (i.e. No WAN or internet access required) · Pure speed is at a premium · Reliability is not at a premium COM/COM+ 优点: Windows平台上最快的DataSnap协议 可以和微软或第三方的COM应用程序一起使用 可以像MTS/COM+的事务服务对象一样使用 缺点: 位置依赖 DCOM被证明是不稳定的 依赖Windows NT域 安装困难 不能用于其它的环境下,只是微软的技术 什么时候用呢: 客户端和服务器使用相同的机器 大约30个客户端同时执行 需要整合到其它基于微软或者基于COM的应用中去 封闭的NT域(没有广域网或互联网的存取需要) 速度非常宝贵(速度要求非常高) 可靠性要求不是很高CORBA (VisiBroker) Advantages: · Location Independent · Automatic Fail-Over · Automatic Load-Balancing, Scales easily · Easy to set up · Easily ported to other systems, CORBA is a standard · Proven technology - reliable, robust · Highly scalable Disadvantages: · Relies on TCP/IP Subnet · Costly (?) (Outweighed by advantages!) · Cannot "talk" to MS® software When to use: · Large implementations · Reliability is at a premium · Scalability (potential for growth) is required · When implementation requires connectivity to: o Non-Windows legacy systems o state-of-the-art systems (EJB's and JSP's) o heterogeneous external parties (clients and suppliers) CORBA (VisiBroker) 优点: 位置无关 自动失败恢复 自动负载平衡,易扩展 易安装 易分发到其它系统,CORBA是一个标准 被证明是可靠的技术 高扩展性 缺点: 依靠TCP/IP子网 昂贵?(优点超过代价) 不能和微软的软件交互 什么时候用呢: 大型应用 对可靠性要求高 必须有一定扩展性 当应用需要和以下进行交互时: 非Windows系列系统 state-of-the-art systems (EJB's and JSP's) 异构的外部部分(客户或者提供者)TCP/IP (Sockets) Advantages: · Uses COM, can be used as add-on to existing COM implementations · Easy to connect to over remote connections or the internet · Easy to configure · Can be secured (with interceptor) Disadvantages: · Dependant on COM · Single-point-of-entry, busy socket will bottleneck! · Slow, single socket must marshal all incoming calls. · Does not work on DCOM (no remote COM objects) · Location dependant When to use: · Remote or dial-up access is required · Tiny implementations were COM is to difficult to configure TCP/IP (Sockets) 优点: 用COM,可以被当作插件添加到已有的COM应用中 方便的连接到远程连接或互联网中 配置容易 可以是安全的 缺点: 依靠COM 单点接入,繁忙的端口将是瓶颈 速度慢,单一的端口必须要分配给所有的进来的调用 不在DCOM上运行(没有远程的COM对象) 位置依赖 什么时候用呢: 需要远程或拨号存取数据 小型的很难配置COM的应用HTTP (Web) Advantages: · Uses COM, can be used as add-on to existing COM implementations · Very easy to connect to over the internet · Easy to configure · Very secure (with IE to IIS SSL) Disadvantages: · Dependant on COM · Single-point-of-entry, busy web-server will bottleneck! · Slow, web-server must marshal all incoming calls. · Does not work on DCOM (no remote COM objects) · Web-site dependant When to use: · Pure Internet connection is required · Tiny implementations that use the Internet as backbone. HTTP (Web) 优点: 用COM,可以被当作插件添加到已有的COM应用中 方便的连接到远程连接或互联网中 配置容易 非常安全(用IE连接到IIS SSL) 缺点: 依靠COM 单点接入,繁忙的WEB服务器将是瓶颈 速度慢,WEB服务器必须要分配给所有的进来的调用 不在DCOM上运行(没有远程的COM对象) 依靠网站 什么时候用呢: 纯互联网接入 小型的用互联网作为骨干的应用译自http://bdn.borland.com/article/0,1410,27860,00.html
Advantages:
· Fastest DataSnap Protocol on Windows platform
· Can be used with other MS« and 3rd party COM applications
· Can be use as Transaction Server (MTS/COM+) objects
Disadvantages:
· Location Dependant
· DCOM has proven to be unstable
· Relies on Windows NT Domain
· Can be difficult to set up
· Cannot port to other environments, MS« only technology
When to use:
· Same machine application server and client application
· A department sized implementation of +- 30 connected clients
· When there is a need to integrate into other MS« or COM based applications
· Closed NT domains (i.e. No WAN or internet access required)
· Pure speed is at a premium
· Reliability is not at a premium
COM/COM+
优点:
Windows平台上最快的DataSnap协议
可以和微软或第三方的COM应用程序一起使用
可以像MTS/COM+的事务服务对象一样使用
缺点:
位置依赖
DCOM被证明是不稳定的
依赖Windows NT域
安装困难
不能用于其它的环境下,只是微软的技术
什么时候用呢:
客户端和服务器使用相同的机器
大约30个客户端同时执行
需要整合到其它基于微软或者基于COM的应用中去
封闭的NT域(没有广域网或互联网的存取需要)
速度非常宝贵(速度要求非常高)
可靠性要求不是很高CORBA (VisiBroker)
Advantages:
· Location Independent
· Automatic Fail-Over
· Automatic Load-Balancing, Scales easily
· Easy to set up
· Easily ported to other systems, CORBA is a standard
· Proven technology - reliable, robust
· Highly scalable
Disadvantages:
· Relies on TCP/IP Subnet
· Costly (?) (Outweighed by advantages!)
· Cannot "talk" to MS® software
When to use:
· Large implementations
· Reliability is at a premium
· Scalability (potential for growth) is required
· When implementation requires connectivity to:
o Non-Windows legacy systems
o state-of-the-art systems (EJB's and JSP's)
o heterogeneous external parties (clients and suppliers) CORBA (VisiBroker)
优点:
位置无关
自动失败恢复
自动负载平衡,易扩展
易安装
易分发到其它系统,CORBA是一个标准
被证明是可靠的技术
高扩展性
缺点:
依靠TCP/IP子网
昂贵?(优点超过代价)
不能和微软的软件交互
什么时候用呢:
大型应用
对可靠性要求高
必须有一定扩展性
当应用需要和以下进行交互时:
非Windows系列系统
state-of-the-art systems (EJB's and JSP's)
异构的外部部分(客户或者提供者)TCP/IP (Sockets)
Advantages:
· Uses COM, can be used as add-on to existing COM implementations
· Easy to connect to over remote connections or the internet
· Easy to configure
· Can be secured (with interceptor)
Disadvantages:
· Dependant on COM
· Single-point-of-entry, busy socket will bottleneck!
· Slow, single socket must marshal all incoming calls.
· Does not work on DCOM (no remote COM objects)
· Location dependant
When to use:
· Remote or dial-up access is required
· Tiny implementations were COM is to difficult to configure
TCP/IP (Sockets)
优点:
用COM,可以被当作插件添加到已有的COM应用中
方便的连接到远程连接或互联网中
配置容易
可以是安全的
缺点:
依靠COM
单点接入,繁忙的端口将是瓶颈
速度慢,单一的端口必须要分配给所有的进来的调用
不在DCOM上运行(没有远程的COM对象)
位置依赖
什么时候用呢:
需要远程或拨号存取数据
小型的很难配置COM的应用HTTP (Web)
Advantages:
· Uses COM, can be used as add-on to existing COM implementations
· Very easy to connect to over the internet
· Easy to configure
· Very secure (with IE to IIS SSL)
Disadvantages:
· Dependant on COM
· Single-point-of-entry, busy web-server will bottleneck!
· Slow, web-server must marshal all incoming calls.
· Does not work on DCOM (no remote COM objects)
· Web-site dependant
When to use:
· Pure Internet connection is required
· Tiny implementations that use the Internet as backbone. HTTP (Web)
优点:
用COM,可以被当作插件添加到已有的COM应用中
方便的连接到远程连接或互联网中
配置容易
非常安全(用IE连接到IIS SSL)
缺点:
依靠COM
单点接入,繁忙的WEB服务器将是瓶颈
速度慢,WEB服务器必须要分配给所有的进来的调用
不在DCOM上运行(没有远程的COM对象)
依靠网站
什么时候用呢:
纯互联网接入
小型的用互联网作为骨干的应用译自http://bdn.borland.com/article/0,1410,27860,00.html
知道题目答案的不一定就能都写好这方面的程序。
能写好这方面程序的不一定能回答这个问题。
比如某个人很了解COM/COM+,但不了解CORBA,但你能说他不了解三层,他不是高手吗?