Internet Express Overview

Introduction

Cabinets (known as CAB files) are used to package groups of files into a single, compressed archive for distribution.  Files in the cabinets must be extracted using a program such as EXTRACT.EXE, that comes with Win95.

Once extracted, these files must be installed using a setup program such as ACME setup.  After the files have been installed, they must be manually deleted by the user.

There are three problems with this procedure:

  1. There is a dependence on an external extractor such as EXTRACT.EXE.
  2. A setup program must be manually executed in order to install the files.
  3. The files must be manually deleted from the system.

For these reasons a new process, referred to as IExpress, has been created.  This process remedies the above problems by providing the following solutions:

  1. Extraction is built into the cabinet.  In fact, the cabinet is an executable that, when run, extracts the files automatically.
  2. A setup program is executed automatically after extraction takes place.  The setup program can be an EXE file within the cabinet, an INF file within the Cabinet (in which case a GenInstall is executed on it) or some other command specified by the package maintainer.
  3. The extracted files are automatically removed from the user's system after installation has finished.

These attributes make IExpress an ideal solution for providing programs over the Internet.

Package Creation

There are three components that a package maintainer should be familiar with:

Makecab.exe
A Microsoft compression program that creates Cabinet files.
IExpress.exe
A Wizard that gathers information about the self-extracting archive, then packages it all together.
Wextract.exe
The extractor that handles the process of extracting, installing and cleaning up the Cabinet files on the user's system.

The steps to building a self-extracting/self-installing cabinet are:

  1. Install IExpress from the Web Site.
  2. Create an INF file is needed for the installation.
  3. Run IExpress.exe and create your package.

The wizard explains things at each step so the basics will not be covered here; however, there are some finer details which require some attention.


Command Line Arguments

You can specify the name of a IExpress Directive File to load on the command line.

Eg. IExpress c:\packages\myfile.cdf

This inserts the filename into the edit box on the first page.  It does not open the file, or create the package.  If you want to create the package right away without going through the wizard, then specify the "/n" (NOW) argument:

Eg. IExpress c:\packages\myfile.cdf /n

This tells IExpress to build the package right away and return to the command prompt when done.  If an error occurs during package creation, then a message box will pop up and wait for you to press the OK button.  If the package was created successfully, IExpress will return 0.  If an error occurred, IExpress will return 1.


Other command line options:

/Q Tells IExpress not to present any prompts on errors.  Useful for automated build processes.

Tip:  You should use START /W IEXPRESS <app.cdf> /N /Q when doing automated builds of packages.


Installation File Page

When you are choosing an installation command, you must make sure it does not run in the background (ie. return to the command line before it has finished processing the files).  This is because WExtract will delete all the files that were extracted as soon as the installation program returns, even though the program might still be running.

If you use the Windows 95 "Start" command in your custom install command, then be sure to specify the "/w" parameter so it knows to wait for the process to finish before returning.  Eg. "Start /w winword readme.doc"

If using InstallShield you should use SETUP.EXE -SMS when using it inside a IExpress package.

If you choose to install with an INF file, then it must follow the same basic outline as the SAMPLE.INF found in the WExtract tools dir; specifically, it should have a heading "[DefaultInstall]" which lists the steps required to perform an installation.


Show Window Page

You should almost always use the "Default" show window attribute. The only time you should use the "Hidden" attribute is to hide a DOS command that starts Windows programs.  This can occur if you use the "Start" command or run a DOS batch file that calls Windows programs.