Manipulating Data in your non-database Data Store

In Chapter 12, our first ADO chapter, we said that one of the main strengths of OLE-DB is its ability to retrieve information from any data store – not only from databases. However, for the examples so far in these chapters we've used a database as our data store. We haven't deliberately sidestepped the issue of using other types of data store, it's just that in order to extract data from other types of data store, it's helpful to first understand the principles of data retrieval from a database. It's also because the principle of data retrieval from other forms of data storage is much more complex than with databases.

The technology that is added in ADO 2.5 to enable you to make use of other forms of data store is still in its relative infancy and quite difficult to get working across servers on a network. However, it forms the cornerstone of a new Microsoft technology, namely Distributed Author Versioning or DAV for short. In fact, IIS 5.0 is referred to as a WebDAV server. WebDAV is actually a specification that uses extensions to the HTTP 1.1 protocol and, thus, can be used on any platform. WebDAV is of great interest because it enables someone browsing on the client to move files on the server, or change the contents of files on the server using these objects. It allows distributed authoring of documents on the Web. It can also equally apply to e-mails on a remote mail server or to any other form of data store for which there is an OLE-DB provider. As the technology is still evolving and not supported by many web servers, we won't be spending that much time on it. However, as an important part of future development, it merits some coverage.

The two new objects that enable WebDAV, and come with ADO 2.5 are:

• The Record object: this can be used to represent a record in a recordset, or it can represent a file or even a folder in a file system
• The Stream object: this can be used to represent the most basic denomination of data – that is, either binary data or just plain text

As we've said, ADO 2.5 is the version of ADO released with Windows 2000. If you're using another operating system then you'll be able to acquire ADO 2.5 as part of the MDAC 2.5 download from the Microsoft web site. Watch out for more up-to-date editions of ADO in the future!

Detailed discussion of these two objects is really beyond the scope of this book. However, the following pages serve to introduce their purpose and usage.

If you'd like to know more about the ADO Record and Stream objects, the titles Professional ASP 3.0 (Wrox, ISBN 1-861002-61-0) and Professional ADO 2.5 (Wrox, ISBN 1-861002-75-0) provide progressively more detailed explanations. (Neither of these books is still available new from Wrox but you might find them from a store that sells used books.)