Microsoft Excel 2002提供了一種新特性來實時查看和更新數據代替原有的動態數據交換Dynamic Data Exchange(DDE),這一新途徑一直沿用到后來的Excel 2003、2007、2010和2013版本。這個特性的強大之處是處理不斷變化的數據比如股票報價、匯率、庫存水平、報價、天氣預報、體育成績等等。Add-in Express支持RTD技術，并提供與COM插件和Smart Tags智能標記相同的RAD的方式。對于Excel GUI的高級定制,Add-in Express還提供了一些高級任務窗格Advanced Task Panes并支持EExcel Automation以及XLL外接程序用于開發自定義用戶定義函數(UDF)。下面是這一特性的具體介紹：

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: .