The World of LDAP

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Databases are great for storing data that needs to be cross-referenced and easily searched. But the problem with databases is that they require a lot of overhead, in terms of both hardware to run them and software to access them.

The other problem with databases is that everyone who develops one ends up using a slightly different schema, even if they're storing the same data. This makes it difficult to write general-purpose applications that don't need to have specific information about each installation's database layout provided to them.

One solution to this problem is to use a directory-oriented storage mechanism rather than a database. In a directory, the same fields are always used for the same types of data.

LDAP grew out of the old X.500 directory standard that was a part of the ISO oligarchy. Like most things ISO, X.500 was complicated, specialized to certain types of networking, and generally not what the masses were looking for.

LDAP is intended to provide an open , convenient way for organizations to manage directory-style information in a way that all of their applications can share. It's part of the overall push to let enterprises share data rather than create islands of data around each application. A directory literally can be used like a phone directory ”to store contact information about individuals ”but it also can store data such as salary details, information about nonhuman entities such as corporate divisions or servers, or even information about trading card collections.

In the scope of your sample application, you might want to store your customer information using an LDAP directory if you have a direct-mailing application that could take its input from an LDAP source. That way, you could do a direct-mail advertising campaign to your customer base without having to convert from a proprietary database format.

As with most of the technologies in this book, a thorough tutorial on LDAP would take an entire other book. The basics can be covered in a few pages, however.

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