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The C# column
Deploying .NET applications - I
 Though
distributing libraries in the form of DLLs was a major step forward,
it suffered from the now infamous DLL hell. COM could avoid this
but it had no versioning mechanism. Moreover, a COM component had
footprints at so many places that if one of them got modified/corrupted,
the application used to break down. .NET has come up with more sophisticated
approaches for deployment and versioning.
Deployment issues
Deployment is a process by which you distribute a finished application or component
to be installed on other computers. In Visual Studio .NET, deployment is based
on Microsoft Windows Installer technology. Microsoft Windows Installer is a
service shipped with Windows ME, Windows 2000, and Windows XP. It is used for
installation and configuration of applications to be installed.
Every .NET application is deployed in the form of one or more assemblies. Assemblies
may be deployed as regular standalone files (DLL or EXE files), or they may
be deployed using CAB, MSI, or MSM files. The simplest way of deploying a private
assembly is to use an XCOPY, i.e. copying the assembly in the desired folder.
On the other hand we can deploy shared assemblies by installing them in the
Global Assembly Cache of the target machine by using the Gacutil.exe.
To help programmers develop setup and deployment solutions, Visual Studio .NET
provides several templates and wizards. We can create a setup or deployment
project by selecting ‘Setup and Deployment Projects’ in the ‘New
Project’ dialog box shown in the following figure.
Let us first discuss the types of projects shown in the dialog box and see the
usage of each. Later we have illustrated how to deploy different types of applications
using these projects.
* Setup Project
 A setup project
builds a Windows Installer file or an MSI file with the .msi extension. This
file is used to install the specified files and resources on the target machine
automatically. The .msi file contains the application, any dependent files,
information about the application such as registry entries, and instructions
for installation. When the .msi file is distributed and run on another computer,
you can be assured that everything necessary for installation is included; if
for any reason the installation fails (for example, the target computer does
not have the required operating system version), the installation will be rolled
back and the computer returned to its pre-installation state.
* CAB Project
A CAB project creates a cabinet file with the .cab extension. It is much like
a Zip file, compressing a number of specified files into an easy to use and
easy to deploy package. The resulting cabinet (.cab) file can then be deployed
or downloaded. The files present in the .cab file can be extracted by double-clicking
the .cab file.
* Merge Module Project
A Merge Module project produces a merge module file having a .msm extension.
A Merge Module is a single package that contains all files, resources, registry
entries, and setup logic necessary to install a component.
Merge Modules are used to install components that are shared by multiple applications.
The basic distinction between a Merge Module (.msm) and a Windows Installer
(.msi) is based on the user using these components. Whatever we wish to deploy
directly to the end-user of the application (executable files, documents, HTML
pages) should be packaged in a Windows Installer, whereas, whatever we wish
to deploy to the developer (DLLs, controls, resources) should be packaged in
a Merge Module. The developer can then repack it in a Windows Installer for
distribution to the end-user. It is possible to put multiple components into
a single Merge Module but it’s best to create a Merge Module for each component
in order to handle versioning problems. Once you have distributed a Merge Module
it should never be modified; instead you should create a new Merge Module for
each successive version of your component.
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Web Setup Project
Web Setup Project helps us to deploy Web-based applications. In addition to
this, any Windows application or its installer can be deployed to a Web server
so that users can later download and run them from a website. In order to deploy
Web-based applications we will have to build a Web Setup Project, copy it to
the Web server and run the installer to install it on the server.
* Setup Wizard
The Setup Wizard is used to help us start creating any of the above-discussed
projects in a fast and simple manner. We just have to follow some simple steps
the wizard leads us through and the wizard does the initial job for us. Next
we may extend the project further as per our requirements. Now let us understand
the projects discussed above in detail.
Setup Projects
We know that a Setup Project creates a .msi file, which actually installs the
application on the target computer. To demonstrate this we plan to deploy a
simple Windows application using the Setup Project. Here we have assumed that
the Windows application stands created and the .EXE named windowsapp1.exe is
ready. To deploy this Windows application we need to select ‘New | Project’
and select ‘Setup and Deployment project’ from the available options.
Next we must select ‘Setup Project’ as the project template and specify
the name (say winsetup) and the location of the setup project and click OK.
Then we are taken to the File System Editor. The File System Editor is shown
in the following figure.
The File System Editor has three folders—the Application Folder, the User’s
Desktop folder and the User’s Programs Menu folder. These folders actually
represent the folders on the target machine. For example, whatever you put in
User’s Desktop will be deployed on the desktop of the target machine. From
the three folders in the file system editor, files from Application Folder would
be deployed in the Program Files folder; typically it is ‘C:\Program Files\Company
Name\Application Name’ of the target machine. User’s Desktop folder
contains files and folders that would appear on the desktop of the target machine
on a per-user basis. Typically the path is ‘C:\Documents and Settings \username\Desktop’.
User’s Programs Menu folder contains user’s program groups that would
usually get deployed in ‘C:\Documents and Settings \username\Start Menu\Programs’.
Now we need to add the Windows application EXE file into this project. For this
we must right-click on the Application Folder. A menu opens up. We must select
Add | File and on doing so an ‘Add Files’ dialog pops up. Now we need
to browse for ‘windowsapp1.exe’ file so that it gets added to the
Application Folder. We can add the EXE to User’s Desktop and User’s
Programs Menu as well but while doing so we must keep in mind that these two
folders are on per-user basis. This means that only the user who installs the
application would be able to access the file on his desktop and not the other
users.
This completes the basic steps needed to build an installer. We can now build
this project and an installer called ‘winsetup.msi’ gets created in
the debug folder. Now all we need to do is to distribute this installer, and
on running the installer on the target machine the application would get installed
there.
On running the installer we get a series of screens depicting different stages
of installation. Note that if our application needs more files than just the
‘windowsapp1.exe’ then we can copy them to any of the above-mentioned
folders.
There is much more to a Setup Project than what we discussed
above. We saw the simplest form and there are several more features that we
need to explore. All the deployment capabilities discussed below are not mandatory
and we can customise our installation process according to the needs of our
application.
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Adding Shortcuts
We can add shortcuts to our application in any of the 3 folders.
For this we need to right-click on the application file (‘windowsapp1.exe’)
that we added to the project and select ‘Create shortcut to windowsapp1.exe’.
On doing so a shortcut for our application would get created. Now we must drag
this shortcut in the User’s Desktop Folder. If we wish to add a shortcut
in User’s Programs Menu also, we need to create another shortcut in the
same manner discussed above and drag it in the folder. On building and installing
the application, the shortcuts get added in the specified folders of the target
machine.
* Adding Registry Entries
We can make a provision that some registry entries would be added for a particular
application during installation of the application. We can then access these
entries later through our application’s code at run-time. To add the registry
entries we must right-click on winsetup in the Solution Explorer and select
View | Registry. On doing so we will be presented with the Registry Editor shown
in the following figure.
To be continued…
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Yashavant Kanetkar, one of
the first Express Computer columnists, is an established software
expert, speaker and author with several best-sellers to his
credit, including titles like “Let Us C” and the “Fundas” series.
Contact him at kanetkar@dcubesoft.com |
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