Application, heal thyself

The Windows Installer in Windows 2000 doesn’t guarantee users an escape from “DLL Hell,” but early users say the operating system’s installation technology is a big slice of heaven.

DLL Hell is the most infamous and costly manifestation of the precarious ease with which newly installed Windows applications can overwrite the essential files of other Windows applications on a PC or server.

A Dynamic Link Library (DLL) performs a function, such as data access, that many applications often need. Windows Installer can’t prevent new applications overwriting vital DLLs, but by storing the names of all the files associated with an application in a database, it can quickly determine what is missing and restore it.

The database architecture is a quantum leap over the old model of installations used in earlier versions of Windows, which relied on ad hoc scripts written by the developer, said Bob Friedman, CIO at communications and financial services provider 800-777-Club Inc. in El Monte, Calif. “There was no back-end record of that file once the product was installed,” he said. Now there is.

Clean Uninstalls

The better record-keeping of the database will also make clean uninstalls possible where they were difficult before, added analyst Brian Kalita at Aberdeen Group Inc. in Boston.

Users say the so-called “self-healing” quality will save them tremendous quantities of time and money. The release last month of installation development tools from InstallShield Software Corp. in Schaumburg, Illinois, and Wise Solutions Inc. in Canton, Mi., has allowed users to begin testing Windows Installer even before the release of Windows 2000. The tools allow users to configure the underlying database and write scripts to guide the installation. They also alert developers about which files to include in the installation package.

A modest 30-member help desk at the Church of Jesus Christ of Latter-day Saints in Salt Lake City, Utah, supports genealogy applications at 3,000 churches worldwide and in the homes of more than 400,000 members, said Don Stringham, a senior programmer/analyst.

In the past, the church has fielded help desk calls and sent out disks with patches to fix applications that had been broken by DLL conflicts with other software such as Microsoft Office, Stringham said. Because Windows Installer can fix problems automatically, the calls and disks may no longer be necessary. Windows Installer is new in Windows 2000 but can run on older versions of Windows.

The Franklin Life Insurance Co. in Springfield, Ill., expects similar savings in supporting its 2,000 field associates, but Microsoft Corp. has to hold up its end of a bargain it is making with users, said systems analyst Bill Rogers.

One Less Headache

Independently of Windows Installer, Microsoft has told users that it will simplify the distribution of key DLL files by including new ones with operating system upgrades. By distributing them with the operating system, Microsoft will relieve developers of the need to distribute them with applications. “It would make my day a lot easier if they go that way,” Rogers said.

Microsoft is also directing users and independent software vendors to move away from the once favored development model in which DLLs reside in the operating system directory and are shared by many applications. Now, to prevent conflicts, Microsoft recommends that they be installed in the application’s directory.

The management headache of keeping track of DLLs in each directory may be mitigated by Windows Installer’s use of a database architecture to track them, Rogers said.