17.1 Configuration Planning

Configuring a Web server to run the ClearCase Web interface includes both ClearCase administration and Web administration tasks. In many cases, especially when setting up the interface for Internet access, the two types of tasks are not handled by the same person. As an aid to planning the configuration, this chapter includes lines for recording information that may need to be shared between the ClearCase administrator and the Web administrator. We recommend that you record information on the lines provided and share it as appropriate.

Web Administration Considerations

This section discusses decisions that a Web administrator must make before beginning configuration. It assumes that the Web administrator has experience setting up corporate Web servers and is familiar with such things as security issues.

• Running the ClearCase Web interface requires that ClearCase LT be installed on a system running a Web server. Supported Web servers are Apache, Microsoft Internet Information Server (IIS), and iPlanet. The server needs enough free disk space to load ClearCase LT plus approximately 0.5 to 1.0 MB for each user who will use the Web interface through the server. Start by noting the name of the ClearCase LT server.

Server Name: ____________________

Server Type (UNIX or Windows) ____________________

The Server Name can be either a system name (for example, within an intranet) or a domain name (for an Internet server).

Approximate disk space required ____________________

• In a number of places, the installation requires a pathname beginning with the base URL for the interface. The base URL (referred to as ccbase-url in the instructions) can be any arbitrary string, for example, ccaseweb or ccweb. Select a base URL name.

ClearCase Base URL: ____________________

The full URL for the Web interface:

http://server-name/ccbase-url/bin/ccweb (UNIX computers) http://server-name/ccbase-url/bin/ccweb.exe (Windows computers)

• If the Web server on the system to be configured is an iPlanet server, the configuration requires the name of the iPlanet administration server. The URL for the iPlanet administration server is identified during installation of the iPlanet server.

iPlanet Administration Server ____________________

• If there are security concerns, you may want to provide a secure port through which to access ClearCase. The ClearCase Web interface can run through either a secure port using the Secure Socket Layer (SSL) or through a standard HTTP port. If the server is on a secure port, the URL begins with https rather than http.

ClearCase Considerations

This section discusses issues for consideration by the site's ClearCase administrator.

• In addition to the ClearCase base URL, configuration requires the location of the ClearCase installation directory. This is typically C:\Program Files\Rational\ClearCase on Windows computers and /usr/atria on UNIX computers. This location is denoted by ccase-home-dir in the configuration instructions.

ClearCase installation directory: ____________________

• The Web interface creates snapshot view directories for client users on the server.

Although the snapshot view directories on the ClearCase LT server are typically empty (no files loaded), they are used for temporary storage of files that are checked out or that are to be created as elements. Therefore, they must be on a disk volume that has enough space for the number of users to be supported. Depending on how many files a typical user will have checked out at once, or how many new elements are to be created at once, allow for at least 0.5 MB to 1 MB of disk space for each user.

By default, the Web interface creates those directories under what is known as the "host data" area for ClearCase. On UNIX systems, this is typically /var/adm/atria. On Windows systems, it is the var subdirectory under the ClearCase installation directory. A ccweb subdirectory is created in the host-data directory at ClearCase installation time, and all snapshot view directories are stored under that ccweb directory. (If ClearCase is installed in a pathname that contains spaces, such as C:\Program Files, the ccweb directory is created in the root of the drive on which ClearCase is installed.)

However, if the default directory is not appropriate, you can select a different area by modifying the ccweb.conf file in ccase-home-dir/config/ccweb. Add the line

-view_storage pathname

to ccweb.conf, where pathname is the directory in which you want snapshot view directories used by the Web interface to be created. This pathname must be local to the Web server host.

NOTE: Even though the Web interface may create a separate ccweb directory for view storage, it continues to keep administrative information in a ccweb subdirectory under the ClearCase installation directory (for example, C:\Program Files\Rational\ClearCase\var\ccweb).

• You may want to limit the size of files that can be uploaded to the Web server, to reduce the likelihood of denial of service attacks. If an extremely large file is uploaded and the Web server disk is filled, operation of the server computer may be disrupted, (depending on which disk it is).

To limit the size of uploaded files, modify the following line in the ccweb.conf file:

-upload_limit size

where size is the approximate desired size limit in bytes. An attempt to upload a file that is too large results in an error message in the Client Upload output window.

• We recommend that you specify the primary group for all users who access ClearCase using this Web server by modifying the following line in the ccweb.conf file:

-primary_group group-name

where group-name is the name of the ClearCase users group. See Setting the ClearCase Primary Group for more information on this topic.

• You can configure the session timeout interval, which controls how long a user login remains valid. The default value is 14400 seconds (four hours). You can change this default by modifying the line

-session_timeout seconds

in the ccweb.conf file, where seconds is an integer number of seconds between 600 (10 minutes) and 2147483647 (about 68 days). Values lower than 600 will be interpreted as 600.

• You can designate a directory where the ClearCase Web interface will store temporary files by adding a line of the form

-tmpdir directory-name

to the ccweb.conf file, where directory-name is a directory on the Web server host. If this line is not present in the ccweb.conf file, the ClearCase Web interface uses the value of the TMP or TEMP environment variables, if they exist. The ClearCase Web interface must be able to create and delete files in this directory regardless of the files' ownership or permissions.

• If users from multiple domains will access ClearCase using this Web server, you must enable domain mapping as described in Using Proxy Groups and Domain Mapping in Windows NT Domains. If you enable domain mapping, you must also specify the primary group of each user of the ClearCase Web interface by setting the primary_group in ccweb.conf.

NOTE: When the Web server runs on a Windows computer, ClearCase Web interface users must be given permission to Log On Locally to the Web server host. Windows NT Server and Windows 2000 Server do not grant this permission by default. (Microsoft Internet Information Server can be configured in a way that does not require users to have this permission. See Microsoft Internet Information Server (IIS) for more information on this topic.)

Browser Considerations

Because Windows 2000 and Windows XP require special privileges to download components through Internet Explorer, users accessing the ClearCase Web interface on one of these platforms must be members of the Power Users or local Administrators groups to download the Web interface applets. After the applets have been downloaded (the first time the Web interface is used), these privileges are no longer required, although new releases of ClearCase and ClearCase patches may change the applets, which will require them to be downloaded again.