How can I execute a custom action in wix just before service installation?

Question

This my Product.wxs:

In the custom action, I want to make changes in the httpd.conf file before Apache 2.4 service is installed, actually the Apache 2.4 Service takes Configuration parameters from httpd.conf, so its mandatory for the code that the changes should be made before installation of service, If any idea help me on this ?

<?xml version="1.0" encoding="UTF-8"?>
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi" xmlns:util='http://schemas.microsoft.com/wix/UtilExtension'>

  <Product Id="*" Name="MyExampleProject" Language="1033" Version="1.0.0.0" Manufacturer="Mq" UpgradeCode="08bd3c48-deef-4370-ab94-f8b4d49406e3">
        <Package InstallerVersion="200" Compressed="yes" InstallScope="perMachine" InstallPrivileges="elevated"/>

        <MajorUpgrade DowngradeErrorMessage="A newer version of [ProductName] is already installed." />
        <MediaTemplate />           
<!--System Configuration Condition - Installation install only above Windows XP-->

    <Condition Message="This application is only supported on Windows XP, or higher.">
      <![CDATA[Installed OR (VersionNT >= 501)]]>
    </Condition>

    <Directory Id='TARGETDIR' Name='SourceDir'>
      <Directory Id='ProgramFilesFolder' Name='PFiles'>
          <Directory Id='INSTALLDIR' Name='AgentFramework'>
            <Directory Id='INSTALLBIN' Name='bin'/>
                <Directory Id='INSTALLCONF' Name='conf'/>
            <Directory Id='INSTALLMODULES' Name='modules'/>
            </Directory>
        </Directory>
      </Directory>
    <Feature
     Id = "ProductFeature1"
     Title  = "AgentFramework"
     Level  = "1"
     Absent="allow">

      <ComponentRef Id='libapr_dll'/>
      <ComponentRef Id='libapriconv_dll'/>
      <ComponentRef Id='libaprutil_dll'/>
      <ComponentRef Id='libhttpd_dll'/>
      <ComponentRef Id='Pcre_dll'/>
      <ComponentRef Id='Configurationfile'/>
      <ComponentRef Id='Authzmodule'/>
      <ComponentRef Id='Dirmodule'/>
      <ComponentRef Id='ServiceComponent'/>
    </Feature>    

    <DirectoryRef Id='INSTALLCONF'>
      <Component Id='Configurationfile' Guid='2E0D2957-10EB-463A-A4FC-62B9062FE8A3'>
        <File Id='Configurationfile' Name='httpd.conf' DiskId='1' Source='$(sys.CURRENTDIR)\httpd.conf' KeyPath='yes'>
        </File>
      </Component>
    </DirectoryRef>
    <DirectoryRef Id='INSTALLMODULES'>
      <Component Id='Authzmodule' Guid='62AA97B6-7821-4CB4-9F89-B2A8FF0CC6BD'>
        <File Id='Authzmodule' Name='mod_authz_core.so' DiskId='1' Source='$(sys.CURRENTDIR)\mod_authz_core.so' KeyPath='yes'>
        </File>
      </Component>
      <Component Id='Dirmodule' Guid='9966BB3B-8296-43B9-A6DC-712561303329'>
        <File Id='Dirmodule' Name='mod_dir.so' DiskId='1' Source='$(sys.CURRENTDIR)\mod_dir.so' KeyPath='yes'>
        </File>
      </Component>
    </DirectoryRef>
    <DirectoryRef Id='INSTALLBIN'>
      <Component Id='libapr_dll' Guid='FB82D093-0B32-465B-8D8B-08B3127EB414'>
        <File Id='libapr_dll' Name='libapr-1.dll' DiskId='1' Source='$(sys.CURRENTDIR)\libapr-1.dll' KeyPath='yes'>
        </File>
      </Component>
      <Component Id='libapriconv_dll' Guid='667D6D5B-6FE4-4A6B-827F-C496239628E2'>
        <File Id='libapriconv_dll' Name='libapriconv-1.dll' DiskId='1' Source='$(sys.CURRENTDIR)\libapriconv-1.dll' KeyPath='yes'>
        </File>
      </Component>
      <Component Id='libaprutil_dll' Guid='72C688D2-8E25-49D9-9E76-F6BDBC33D394'>
        <File Id='libaprutil_dll' Name='libaprutil-1.dll' DiskId='1' Source='$(sys.CURRENTDIR)\libaprutil-1.dll' KeyPath='yes'>
        </File>
      </Component>
      <Component Id='libhttpd_dll' Guid='8946D5B1-0EA2-443E-8C20-CD8D877ACF75'>
        <File Id='libhttpd_dll' Name='libhttpd.dll' DiskId='1' Source='$(sys.CURRENTDIR)\libhttpd.dll' KeyPath='yes'>
        </File>
      </Component>
      <Component Id='Pcre_dll' Guid='0466BB2A-137C-4A95-A510-43E7A274F834'>
        <File Id='Pcre_dll' Name='pcre.dll' DiskId='1' Source='$(sys.CURRENTDIR)\pcre.dll' KeyPath='yes'>
        </File>
      </Component>
      <Component Id ="ServiceComponent" Guid="8A1BF3F0-8A84-456E-816A-5907B40B2DDB" >
        <File Id='Applicationfile' Name='httpd.exe' DiskId='1' Source='$(sys.CURRENTDIR)\httpd.exe' KeyPath='yes'>
        </File>
        <ServiceInstall Id="ServiceComponent" Type="ownProcess" Name="Apache2.4"
                        DisplayName="Apache2.4" Description="Service" 
                        Arguments="-k runservice" Start="auto"  Account="LocalSystem" ErrorControl="normal" 
                        Vital="yes" > 
          <util:PermissionEx  User="Everyone" ServicePauseContinue="yes" ServiceQueryStatus="yes"
                              ServiceStart="yes" ServiceStop="yes" ServiceUserDefinedControl="yes" /> </ServiceInstall>


        <ServiceControl Id="ServiceComponent" Start="install" Stop="both"
                                Remove="uninstall" Name="Apache2.4" Wait="yes" />
      </Component>
    </DirectoryRef>
    <UIRef Id="CustomizeDlg" />

    <UI Id="MyWixUI_Mondo">
      <UIRef Id="WixUI_Mondo" />
      <UIRef Id="WixUI_ErrorProgressText" />

      <DialogRef Id="UserRegistrationDlg" />


      <Publish Dialog="LicenseAgreementDlg" Control="Next" Event="NewDialog" Value="UserRegistrationDlg" Order="3">LicenseAccepted = "1"</Publish>
      <Publish Dialog="SetupTypeDlg" Control="Back" Event="NewDialog" Value="UserRegistrationDlg">1</Publish>
    </UI>
    <Property Id="PIDTemplate"><![CDATA[1234<####-####-####-####>@@@@]]></Property>

    <CustomAction Id='CheckLogLevel' BinaryKey='CheckLogLevel' DllEntry='CustomAction1' />
    <Binary Id ='CheckLogLevel' SourceFile='$(sys.CURRENTDIR)\MqAgent_LogLevel.dll'/>
    <WixVariable Id="WixUIBannerBmp" Value="C:\Image\style39_banner.bmp" />
    <WixVariable Id="WixUIDialogBmp" Value="C:\Image\style39_dialog.bmp" />
    </Product>
</Wix>

Here's CustomizeDlg.wxs :

<?xml version="1.0" encoding="UTF-8"?>
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi">
  <Fragment>
    <UI Id ="CustomizeDlg">
      <ComboBox Property="SETUPLOGLEVEL">

        <ListItem Text="Debug" Value="1" />

        <ListItem Text="info" Value="2" />

        <ListItem Text="warn" Value="3" />

      </ComboBox>
      <Dialog Id="UserRegistrationDlg" Width="370" Height="270" Title="[ProductName] Setup" NoMinimize="yes">
        <Control Id="NameEdit" Type="ComboBox" X="52" Y="48" Width="156" Height="10" ComboList="yes"
          Property="SETUPLOGLEVEL" Sorted="no" RightToLeft="yes"/>
        <Control Id="CDKeyLabel" Type="Text" X="45" Y="147" Width="50" Height="10" TabSkip="no">
          <Text>CD &amp;Key:</Text>
        </Control>
        <Control Id="CDKeyEdit" Type="MaskedEdit" X="45" Y="159" Width="250" Height="16" Property="PIDKEY" Text="[PIDTemplate]" />
        <Control Id="Back" Type="PushButton" X="180" Y="243" Width="56" Height="17" Text="&amp;Back">
          <Publish Event="NewDialog" Value="LicenseAgreementDlg">1</Publish>
        </Control>
        <Control Id="Cancel" Type="PushButton" X="304" Y="243" Width="56" Height="17" Cancel="yes" Text="Cancel">
          <Publish Event="SpawnDialog" Value="CancelDlg">1</Publish>
        </Control>
        <Control Id="BannerBitmap" Type="Bitmap" X="0" Y="0" Width="370" Height="44" TabSkip="no" Text="WixUI_Bmp_Banner" />
        <Control Id="Description" Type="Text" X="25" Y="23" Width="280" Height="15" Transparent="yes" NoPrefix="yes">
          <Text>Please mention the log level</Text>
        </Control>
        <Control Id="BottomLine" Type="Line" X="0" Y="234" Width="370" Height="0" />
        <Control Id="Title" Type="Text" X="15" Y="6" Width="200" Height="15" Transparent="yes" NoPrefix="yes">
          <Text>{\WixUI_Font_Title}Select Log Level</Text>
        </Control>
        <Control Id="BannerLine" Type="Line" X="0" Y="44" Width="370" Height="0" />
      </Dialog>
    </UI>
  </Fragment>
</Wix>

Answer 1

What I've done before was put all my custom action's logic in an executable and then call the executable, which worked nicely. It turns out that WiX provides various Custom Action Projects within Visual Studio that remove the need to create a stand alone executable, see here for a nice example by James Schaffer.

As for controlling when the custom action is executed, you control this by adding an entry in the InstallExecuteSequence node of the *.wxs file, like this...

<InstallExecuteSequence>
  <Custom Action="CheckLogLevel"  Before="InstallServices" />
</InstallExecuteSequence>

... where CheckLogLevel is my custom action, and it's being directed to be run before the InstallServices action.

Answer 2

mattyB gets a big thumbs up.

To better understand this problem though I think it's important to view the MSI in Orca. Orca is a MS product which can view the lifecycle of MSI files. It also allows you to directly edit the MSI file.

Below is a screenshot of the "jobs" which will be run by the installer in sequence order. mattyB mentioned the "InstallServices" job, which I have highlighted in the screenshot below. We need to make sure all of our custom actions occur BEFORE this job runs. From here it's as simple as setting the "Before" attribute in the "Custom" tag to a value of "InstallServices."

Hopefully this helps to further demystify WiX.