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Microsoft Excel 2002提供了一种新特性来实时查看和更新数据代替原有的动态数据交换Dynamic Data Exchange(DDE),这一新途径一直沿用到后来的Excel 2003、2007、2010和2013版本。这个特性的强大之处是处理不断变化的数据比如股票报价、汇率、库存水平、报价、天气预报、体育成绩等等。Add-in Express支持RTD技术，并提供与COM插件和Smart Tags智能标记相同的RAD的方式。对于Excel GUI的高级定制,Add-in Express还提供了一些高级任务窗格Advanced Task Panes并支持EExcel Automation以及XLL外接程序用于开发自定义用户定义函数(UDF)。下面是这一特性的具体介绍：

1. Create a new Excel RTD Server project

To create a new real-time data server project with Add-in Express, close all opened solutions, choose File | New | Project, select the "Other Projects | Extensibility Projects" item, click the Add-in Express RTD Server icon, and click the OK button.

This will start the wizard that asks you to select a programming language, either C# or VB.NET, and then generates the project.

2. RTD Server module

The project contains an RTD Server module, which is the core part of every Excel RTD Server developed with Add-in Express. The file name for the module is RTDServerModule.vb or RTDServerModule.cs for VB.NET and C# projects respectively. You place RTD Server Topic components onto the module's designer in order to create the information interface of your RTD Server. To add topics to your real-time date server, the module provides a special command available either in the Properties window or in the context menu of the module's designer. Also, you handle RTD Server properties and events in the module.

3. Excel RTD Server topics

An RTD Server topic component allows you to specify a part of the information flow provided by the Excel real-time data server. You identify the topic using its properties and handle its RefreshData event.

Private Function TopicLastPrice_RefreshData(sender As System.Object) As System.Object _

Handles TopicLastPrice.RefreshData

Dim actualTopic As AddinExpress.RTD.ADXRTDTopic = _

CType(sender, AddinExpress.RTD.ADXRTDTopic)

Dim symbol As String = actualTopic.String02

Try

If IsValidSymbol(symbol) Then

Return GetLastPrice(symbol)

Else

Return "Unknown symbol"

End If

Catch ex As Exception

Return "error"

End Try

End Function

4. Deploying the real-time data server

You deploy and update your Excel RTD server in a variety of ways described in the Developer Tutorial: Step 7. Deploying the RTD server. Your real-time data server can be per-user or per-machine, i.e. for all users on the PC.

You may also be interested in:

• A series of articles by an independent software vendor who shared his experience of developing a real-life RTD server using Add-in Express: .
• How to create an integrated Excel extension: .