global.asa file

Create application- or session-level obejcts or values.
ASA File Elements
Type Library Declarations

Allows the use of an object library's enumerated constants throughout the application. For example, by including the ADO typelib, you can use conn.OpenSchema(ADODB.adSchemaTables) instead of conn.OpenSchema(20).

<!-- METADATA TYPE="TypeLib"  { UUID="TypeLibID" | FILE="TypeLibFile" }  VERSION="major.minor" LCID="LocaleID" -->

Although the version and locale can be requested, there will be no error if the server cannot find the variant specified.

> Tip

You can add a descriptive name to the typelib declaration before the METADATA keyword, to make it more readable.

Some Common TypeLib Declarations
<!-- ADODB 2.5 METADATA TYPE="TypeLib" UUID="{00000205-0000-0010-8000-00AA006D2EA4}" -->
<!-- ADODB 2.6 METADATA TYPE="TypeLib" UUID="{00000206-0000-0010-8000-00AA006D2EA4}" -->
<!-- ADODB 2.7 METADATA TYPE="TypeLib" UUID="{EF53050B-882E-4776-B643-EDA472E8E3F2}" -->
<!-- ADODB 2.8 METADATA TYPE="TypeLib" UUID="{2A75196C-D9EB-4129-B803-931327F72D5C}" -->
<!-- ADOMD METADATA TYPE="TypeLib" UUID="{22813728-8BD3-11D0-B4EF-00A0C9138CA4}" -->
<!-- ADOX METADATA TYPE="TypeLib" UUID="{00000600-0000-0010-8000-00AA006D2EA4}" -->
<!-- CDONTS METADATA TYPE="TypeLib" UUID="{0E064ADD-9D99-11D0-ABE5-00AA0064D470}" -->
<!-- CDOSYS METADATA TYPE="TypeLib" UUID="{CD000000-8B95-11D1-82DB-00C04FB1625D}" -->
<!-- Scripting FSO METADATA TYPE="TypeLib" UUID="{420B2830-E718-11CF-893D-00A0C9054228}" -->
<!-- MSWC.IISLog METADATA TYPE="TypeLib" UUID="{B758F2F9-A3D6-11D1-8B9C-080009DCC2FA}" -->
<!-- MSXML2 METADATA TYPE="TypeLib" UUID="{F5078F18-C551-11D3-89B9-0000F81FE221}" -->
<!-- WinHttp5 METADATA TYPE="TypeLib" UUID="{C92A03CF-B92B-404F-9AC5-58664A592E4C}" -->
<!-- WinHttp5.1 METADATA TYPE="TypeLib" UUID="{662901FC-6951-4854-9EB2-D9A2570F2B2E}" -->
Object Declarations

Creates a COM object for the application or user session.that is available to the entire application. This allows you to set up a database connection, for example, and re-use it on each Active Server Page in the applicaiton, rather than re-connecting for each individual page.

<object runat="Server" scope="scope" id="varname"  { progid="ProgID" | classid="ClassID" } ></object>

The scope for an object must be either Application (a single object for the entire application) or Session (a copy of the object for each user session). The object will be available in the global namespace throughout the application, using the name varname, and in the StaticObjects collection of the Application or Session object (depending on the object's scope).

> Tip

Creating and initializing an object once per application or user is significantly faster than doing it repeatedly per page. For example, creating an ADODB.Connection for the application and connecting it to the database in the Application_onStart event, rather than on each page, saves the user the time of creating and connecting (and disconnecting, and releasing) the database connection on each page that uses the object. Multiple application objects: database connections, commands, XSLT templates, etc. taken together can make a site feel noticably faster.

(!) Warning

Creating a single object for multiple pages also creates a single point of failure. For example, if a global database connection is unexpectedly disconnected, all the pages that use the object will be unable to access the database, unless they can detect the problem and reconnect.

Also, be aware that COM objects used this way must be threadsafe (able to run for multiple pages at once).

Event Handler Script

Application and session event handlers are defined in one or more script sections, each of which can use a different language. An event handler is a subroutine with one of the following names:

Application_onStart

Called the first time a page of the application is processed.

Application_onEnd

Called when the web service is shut down.

Session_onStart

Called the first time a user accesses an application that has sessions enabled. Used to initalize user-specific settings.

Session_onEnd

Called when the user session expires.

OnTransactionAbort

Called when the transaction fails, in an application that has enabled transactions.

OnTransactionCommit

Called when the transaction completes, in an application that has enabled transactions.

Example 3.3.1 Sample global.asa
<!-- ADODB 2.5 METADATA TYPE="TypeLib" UUID="{00000205-0000-0010-8000-00AA006D2EA4}" -->
<object runat="Server" scope="Application" id="conn" progid="ADODB.Connection"></object>
<script language="VBScript" runat="Server">
Sub Application_onStart
  conn.Open "ConnectString"
  Application("MaxLogonTries")= 3
End Sub
</script>