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This article introduces the sample analysis of .NET Framework and DLL Hell problems, the content is very detailed, interested friends can refer to, hope to be helpful to you.

.net Framework and DLL Hell issues: version issues

From the customer's point of view, the most common version problem is what we call the DLL Hell problem. Simply put, DLL Hell refers to a series of problems that arise when multiple applications try to share a common component, such as a dynamic link library (DLL) or a component object model (COM) class. Typically, an application is about to install a new version of a shared component that is not backward compatible with the existing version on the machine. Although the newly installed application is working properly, applications that originally relied on the previous version of shared components may no longer work. In some cases, the cause of the problem is more difficult to predict. For example, when users browse some Web sites, they will download a Microsoft ActiveX at the same time? Control. If you download the control, it will replace any original version of the control on the machine. If an application on the machine happens to use the control, it is likely to stop working as well.

In many cases, it takes a long time for the user to find that the application has stopped working. As a result, it is often difficult to remember when machine changes affected the application. Users may recall that something was installed a week ago, but the installation has nothing to do with the state you are seeing so far. To make matters worse, there are few diagnostic tools to help users (or their technical support staff) determine what's wrong.

The reason for these problems is that the version information of different components of the application is not recorded or enhanced by the system. Moreover, changes made by the system to an application affect all applications on the machine-it is not easy to build applications that are completely isolated from the changes.

One reason it is difficult to build an isolated application is that the current runtime environment only allows the installation of individual versions of components or applications. This limitation means that component writers must write their code in a backward-compatible manner, otherwise they risk terminating existing applications when they install new components. In fact, if possible, it is very difficult to write code that is always backward compatible. In .NET, the concept of side by side is at the heart of the version problem. "Side by side" is the ability to run different versions of the same component on the same machine at the same time. With components that support juxtaposition, programmers do not have to strive to maintain strict backward compatibility because different applications are free to use different versions of a shared component.

.net Framework and DLL Hell issues: release and installation

Installing the application is now a multi-step process. In general, installing an application includes copying many software components to disk and performing a series of registration entries in the system that describe those components.

The separation of keys in the registry and files on disk makes it difficult to copy applications and uninstall them. Also, many of the entries required to fully describe a COM class in the registry are loosely related. These entries often include entries for federated classes, interfaces, type libraries, and DCOM app ID, and do not involve any entries placed in registry document extensions or component categories. Keep these items synchronized manually from time to time.

* this registration footprint is required to activate any COM class. This greatly complicates the process of publishing distributed applications because appropriate registration entries must be made to each client's machine.

Another common problem today is that it is unrealistic to update a running application. This is the problem with the Web application *, *, *

These problems are mainly caused by the separation of the component description from the component itself. In other words, the application is not self-describing and independent.

This is the end of the sample analysis on the .NET Framework and DLL Hell. I hope the above content can be of some help and learn more knowledge. If you think the article is good, you can share it for more people to see.

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