How to Use OWC to draw charts in ASP. NET (1)

How to Use OWC to draw charts in ASP. NET (1)
I. Overview
2. Set the chart Engine
Iii. OWC license issues
Iv. Operation Mechanism of OWC
5. Install OWC 10 on the Web Server
Vi. OWC programming mode
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I. Overview
When developing applications, interactive charts are often required. For example, you may be developing an application that manages sales and product data and stores the data on the SQL Server database. The application allows users to add data and update existing data, in addition to these features, applications are also required to intuitively describe data in the form of a pie chart, column chart, or XY scatter chart.
In Windows desktop applications, such requirements are never a problem. There are too many graphics libraries and drawing components available. However, for Web applications, the problem becomes much more complicated. You can use the following methods to draw charts in a Web application:
■ Client:
Using various ActiveX components, Web browsers are likely to achieve the "rich" Features of Windows client programs. The disadvantage is that the client settings are complicated and client software must be released. The license fee is usually calculated per client. In addition, non-MS Windows/IE clients are generally difficult to run.
■ Server:
Use the server code running on the Web server to dynamically generate charts and send them to the client as GIF or JPG images. The advantage of this method is that the client only needs a standard browser. The disadvantage compared with the client technology is that the graphic interaction capability is poor (no scaling or scrolling is allowed unless a new request is submitted to the server ). Many map websites (such as Mapquest.com) use this technology extensively. Note: map images are not stored on the Web server, but are dynamically generated from the map database when a user sends a request.
This article mainly discusses how to use the server-side chart rendering technology in ASP. NET Web pages provide graphical functions. Specifically, this article analyzes how to use the data stored in the ms SQL database to generate a scatter chart.
2. Set the chart Engine
To draw a chart in an ASP. NET application, you must have an appropriate chart engine. ASP. NET has a built-in Graphics Tool library, that is, System. the GDI + of the Drawing namespace can be used to create simple pie charts, column charts, and line charts. However, it is a low-level API and cannot be used as an engine for Drawing charts, in particular, it is not suitable for drawing complex charts.