Professional Excel Development [Electronic resources] : The Definitive Guide to Developing Applications Using Microsoft® Excel and VBA® نسخه متنی

Conclusion

By representing our data as XML, we are able to define its structure, content, data types and other rules and validate any data file against those rules before we attempt to process it. This can greatly increase the robustness of our data processing code, while also reducing its complexity and thereby making it much easier to maintain.

XML adds names, data types and hierarchies to our data, enabling us to think of our data in terms of individual elements and the data they contain, in the same way that class modules allow us to think of our application in terms of objects and their properties and methods. Indeed, Visual Studio.NET displays XML data in IntelliSense lists and so on, in almost the same way as it does the content of object libraries.

Excel 2003's XML-handling features can perform most of the processing we would otherwise have to code, including checking for completeness and consistency and removing unwanted data such as header and footer records (by simply not mapping that data to worksheet cells).

Web services are programs running on Web servers that expose the functions they contain for use over the Internet. They can be used to provide access to proprietary financial models, company data and so forth without having to expose the code for the model, the database connection information or any other details that should be kept secret. By using the Office Web Services Toolkit, we can use the features provided by Web services from within our VBA code and from within our worksheets (via VBA user-defined functions).

We can combine Excel 2003's use of XML with the ability to connect to Web services to create an entirely new breed of Excel applicationthat of the rich client of a distributed, Web-based application, such as this final iteration of our Professional Excel Timesheet Reporting and Analysis System.

Unfortunately, we cannot use Web services directly from our worksheets (we need some VBA to glue them together), nor can we expose the financial models in our worksheets as Web services for others to use (because Excel is not designed as a server product). Excel 2003 is so close to achieving both those, it wouldn't surprise us to see a Web Services button on the Tools > Add-ins dialog and a File > Save as Web Service menu in a future version.