Host Default-Page Precedence

orcmid> centrale> web> IIS> C030400> 0.01 2003-12-14 -21:18 -0800 (pst)

Each IIS server is configured to resolve direct references to folders by searching for a default page within the folder.  With IIS, the search order is controlled separately for each subweb, and each can have its own default-page precedence rules.

The Compagno configuration  for development of Centrale sites is hosted on IIS 5.1 under Microsoft Windows XP Pro.  Each site-development subweb can be adjusted so that access on Compagno matches the host-service default-page behavior.  That leaves open the question of what an individual hosting service provides.

To test the hosting service, typically also an IIS server, I upload a set of potential default pages and see which one is served up.  Then I delete that one and see what comes to the top next.  That's the drill.  Eventually I will be left with a set of pages that are not recognized as defaults and cannot be used.  I will, however, have established what the server response for access to the index of a directory is.

1. Determining Precedence
2. Precedence Convention
3. Missing-Default Treatment
4. Open Questions

1. Determining Precedence

This section has the following potential default pages:

• default.asp     #3 

• default.aspx    (not recognized)

• default.htm     #1

• default.html    #2

• index.htm       #4

• index.html      #5

The actual precedence on the hosting site was determined by uploading a full set of self-identifying versions for each page.  A browser was directed to the URL of the directory to see which page is presented by default.  Each time the browser presented a given file, it was deleted on the server and the URL refreshed in the browser.  This was done until the server no longer provided a default page.  In the above list, #1 has precedence over all other default candidates, whether or not they are present.  Likewise, #5 will only be presented if no other default is available.

In the absence of a default page, the server presents the following message for this directory:

    Directory Listing Denied

    This Virtual Directory does not allow contents to be listed.
   

2. Precedence Convention

Based on the precedence already provided at the hosting site, the development-site precedence was altered to match.  This description is updated to reflect that precedence and to also be useful in detecting that hosting-site precedence has not changed.

In addition, the following conventions are used for all pages anchored on nfoCentrale:

• default.htm
will always be used if present.  None of the lower-precedence pages will be displayed as the default page even if they are there.  They can be explicitly accessed however.  For orcmid, this default page is reserved for when we want to intentionally block visibility of a default.asp.  This page has been used in the past as a standard default without consideration of having a default.asp page.  We will end that practice and make default.asp instead, whether or not there is any ASP processing required.

• default.html
  is the next lower level of precedence.  This file name is not used in ordinary sections.
     

• default.asp
  is next in order of usage.  Generally, this means that a default.htm page should not be employed if there is a chance that a default.asp page will also be introduced and be intended to have the highest precedence.  Since this is the only .asp default page, this is always reserved for that use, with default.htm introduced only when we want to block or obscure a default.asp page.
     

• index.htm
  is the next-lowest-precedence default page of all.  It is used only for default or explicit entry to the construction structure of a web section.

• index.html
  is the lowest-precedence default page.  Although there might be some value in using it, the convention here is to use only index.htm in ordinary sections
     

• Unrecognized Pages
  There are also pages that this server does not recognize as default pages.  In particular,

  • default.aspx is not recognized as a default page.

3. Missing-Default Treatment

The Centrale web sites do not allow access to directories that have no default page.  Instead, the server presents an error page.  

It is the practice with this site to never provide such an error message for normal Web requests.  Instead, there is always a default page in every reachable section.  That page might present an HTTP error condition, or it might make a default presentation.  A default-page announcement about the inaccessibility of content is usually provided using an index.htm page.

4. Open Questions

Although the use of this default scheme is sufficient for providing two or three levels of access to default pages, there are additional questions that remain to be resolved:

• Can the default-page precedence of the anchor site be controlled by virtue of its support for FrontPage extensions, or any other way?

• Can the error responses and the content of error-response message from the hosting server be controlled as part of the service?

• Can ISAPI filtering be instituted, and can executables and scripts be introduced for full ASP functionality?

• Can Web Service requests be intercepted and masked or accepted?

• What is the impact of SSL usage on the treatment of default pages and also the use of cloaking?

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0.01 2003-12-13 Create Centrale analysis of default rules applicable for nfoCentrale.net hosting (orcmid)

This page is derived from version 0.00 and used to identify the search order of the nfoCentrale.net host used to anchor Orcmid's Lair and other sites.

0.00 2003-04-20 Report initially-determined precedence for Software Engineering Group Project (orcmid)

The Group3 Project site for KIT eLearning module MSC-SE-030320-02 was implemented on the student.kitcampus.com server.   Determining the search order and matching it on my development configuration was important for the creation of a scaffolding structure where the scaffolding of a web presence site was never removed..

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created 2003-12-13-15:14 -0800 (pst) by orcmid $$Author: Orcmid $ $$Date: 05-02-11 16:47 $ $$Revision: 9 $