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1139 lines
59 KiB
Plaintext
/*_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
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* *
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* FEATURE-LIST *
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* *
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* Function:..A description of the basic of TWEB, *
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* the Tuebinger Web-X.500 gateway *
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* *
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* *
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* Authors:...Dr. Kurt Spanier & Bernhard Winkler, *
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* Zentrum fuer Datenverarbeitung, Bereich Entwicklung *
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* neuer Dienste, Universitaet Tuebingen, GERMANY *
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* *
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* ZZZZZ DDD V V *
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* Creation date: Z D D V V *
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* September 14 1995 Z D D V V *
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* Last modification: Z D D V V *
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* January 15 1999 ZZZZ DDD V *
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* *
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_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/*/
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0 TABLE OF CONTENTS
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1 Introduction
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2 General overview
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2.1 A case of Public Relations
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2.2 Configuration files and TWEB start-up
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2.3 The running gateway
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2.4 check4access: who is allowed to see (what) data
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2.5 Preparing the data
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2.6 Searching for data
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2.7 Data based behaviour: the dynamic gateway
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2.8 Restricting the service
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2.8.1 Restricting the number of entries
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2.8.2 Suppression of certain entries by RDN
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2.8.3 Defining DIT areas for search-only operations
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2.8.4 Controlling the hackers
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3 Configuration of TWEB features in detail
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3.1 Technical configuration options
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3.2 Political configuration options
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3.3 Load balancing configuration options
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3.4 Display configuration options
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4 Support and discussion list
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1 INTRODUCTION
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TWEB is based on the Web500gw implementation by Frank Richter,
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Technische Universitaet Chemnitz-Zwickau, which is based on the
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go500gw implementation by Tim Howes, University of Michigan.
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TWEB was compiled and tested on LINUX with cc, HPUX 9.05 with the
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HP-ANSI C compiler, as well as SunOS 4.1.2 with the SUN C compiler.
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TWEB was also compiled with gcc on all platforms. On SUN Solaris
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2.6.x TWEB was also compiled with gcc 2.7.2.
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The UMICH LDAP client library version 3.0 or 3.3
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( URL:ftp://terminator.rs.itd.umich.edu/ldap/ldap-3.3.tar.Z )
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must be installed on the machine (library path and include file
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path is configured in Makefile). With QUIPU ICR-2.x the ISODE-
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provided LDAP libraries should be used. As such, TWEB only supports
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LDAP version 2 with the University of Michigan type C API. TWEB is
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also adapted for the OpenLDAP LDAP library, release version 1.1.2
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(http://www.openldap.org).
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An upgrade to LDAP version 3 and a C API standadized by the IETF
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is planned for a not so far away future, most probably in step
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with the OpenLDAP package.
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TWEB, as provided here is a fully functional core gateway, which
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is extended at the author's site by some local features. These
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extensions are included into the same code base, so that some
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"#ifdef TUE_TEL" or "#ifdef AMBIX" pre-processor statements can
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be found throughout the code.
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2 GENERAL OVERVIEW
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2.1 A case of Public Relations
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TWEB is a gateway between the HTML-based World-Wide-Web (WWW
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for short) and the X.500-based wordlwide directory, nowadays
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mainly accessed through LDAP, the Leightweight Directory Access
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Protocoll. As such, TWEB is a mediator between these worlds,
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providing run-time access to a lively database and preparing
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results in a usable format.
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Why not access the directory directly via my browser-built-in
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LDAP functionality, you may ask. One answer is, that TWEB with
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it's build-in security features may provide access to more
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internal data for permitted users, while denying these data for
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outside users. This might be very handy from the database
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administration point of view, easing the task of checking
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for consistencies between seperate inside and outside databases.
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Secondly, TWEB provides for a flexible display of results,
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not just showing the pure data. Corporate identity, even when
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using a staff's directory, can be implemented by an organization.
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Furtheron, important messages and hints can be added on the fly,
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that are relevant to the directory user. This is also possible
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via HTTP links, provided either through the directory data (e.g.,
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links to personal home pages) or embeded into HTML text loaded
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during result page preparation. Thus, the integration of WWW and
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the directory can be two-ways, not just one-way.
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Thirdly, TWEB can, with some extensions not yet provided in
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the current distribution, easily be configured to access the
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directory more than once, in order to return results for a
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single request. For example, this can be used to build a page
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with the phoenbook entries of a whole department, institute, or
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faculty, spanning many hierarchies is the underlying directory
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database, as implemented at the University of Tuebingen.
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When running TWEB with some of the configuration options, one
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might easily find more points that are in favor of a gateway
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solution, rather than purely accessing the data of a single
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directory entry at a time.
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BUT AFTER THIS SHORT EXCURSION INTO THE WORLD OF PR, LET'S
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HAVE A LOOK AT WHAT TWEB PROVIDES AND WHAT FEATURES CAN
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BE USED.
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2.2 Configuration files and TWEB start-up
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Allmost anything what TWEB provides is determined by a set of
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configuration files during start-up, or at run-time. There is
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the main ressource file (tweb.rc) that provides for basic,
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language-independant features, like host and port of the connected
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directory server. Language-specific configuration parameters
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are located in the config files (tweb.conf.x), with x (0-9)
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standing for any of a set of supported languages. Language
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strings, that are used to build an HTML result page are taken
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from the language files (tweb.lang.x), again with x indicating
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the language in question. Those files are located in the
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TWEB_conFiles subdirectory; the TWEB binary, probably via a
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symbolic link, should also reside within that directory.
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Header and footer files, and certain message files are loaded
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during run-time, so that the content can be updated on-the-fly,
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without restarting the gateway. Those files can be found in the
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LDAP_etc subdirectory, but can also be located elsewhere, after
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setting the ETCDIR parameter in the tweb.rc file.
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Certain configuration parameters can be overridden by command
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line parameters during start-up. Type 'tweb -h' to get a short
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description of each command line parameter, or have a look at
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the description below. The important parameters are '-l' for
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selection of the LOCAL user of the syslog facility, and '-L'
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for selection of languages.
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When starting, TWEB first of all determines which languages should
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be supported. A sub-process is created for each language by the
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fork() system call, and the starting process is terminated. (In case
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of only one language, TWEB will not fork, but instead use the first
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process for the gateway service.) Each sub-process is responsible for
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one of the languages, and presents hyperlinks to the other languages'
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HTTP addresses on HTML pages, so that the user can switch from one
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language to the other. When language hints are provided within the
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directory data (see below) even attribute values may be presented
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language-specific. (This is not to be mixed up with the LDAPv3
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standard, which provides for language specification via attribute
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options.)
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The starting TWEB initializes itself by reading the tweb.rc, the
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tweb.conf.x, and the tweb.lang.x files, and stores the configuration
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in a global data structure that can be used by all parts of the
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program. Command line options are considered last, and can override
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previously defined parameters. In the tweb.rc and tweb.conf.x files
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parameters are generally additive, meaning that configuration can be
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spread across those files (e.g., GW-SWITCH can be set to language-
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independant gateways in tweb.rc and extended by language-specific
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gateways in the tweb.conf.x files.)
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Also, message, header and footer files are checked for presence, and
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a warning is printed to standard output, if they are missing. After
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some more sanity checks of the configuration, TWEB connects to the
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port it was configured for and starts listening for HTTP requests.
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(In the tweb.rc config file only a base port is given; the gateway
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process serving for language 0 will listen at this port; the gateway
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for language 1 at port+1, for language 2 at port+2, and so on, upto
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the language with number 9.)
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2.3 The running gateway
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When a request is started by an external HTTP client, TWEB checks
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for access rights of that client (see below), and decides, whether
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the request can be handled by the process itself (mainly simple
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requests, like, e.g., sending the help file), or whether another
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sub-process should be started. In both cases the TWEB master process
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returns to listening for requests, so that new request can be
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handled while old ones are still in progress.
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A request is encoded into the URL, the Universial Ressource Locater,
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the HTTP client sends to the gateway process. Such an URL is build
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of different parts, as follows:
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http://host:port/request
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First of all, 'http://' defines the HTTP protocoll itself. As
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TWEB is the mediator between WWW and the directory, it is an HTTP
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server towards the browser, accepting normal HTTP request, but is an
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LDAP client towards the directory server, sending LDAP requests.
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Host and port are the same as in the tweb.rc configuration file,
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and tell the browser, where to direct the request.
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The request for TWEB is given in the last part of the URL, in a more
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or less complicated format. The most simple request is the EMPTY
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request ( http://host:port/ ), which will cause TWEB to return a
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listing of directory entries just below it's BASEDN. (Besides beeing
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the "home" for TWEB when sending an URL without further specification,
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the BASEDN can also be configured as beeing the root entry of an DIT
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area, and TWEB will only serve requests within, but not outside that
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area; STRICT-BASEDN.)
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All other requests are given by a starting letter (beware: that
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letter is CASE-SENSITIVE) and possibly a further specification.
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That letter directs TWEB to one of several actions, like returning
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a directory listing, reading a specified entry, or sending a
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formular for modification of an entry. If a directory look-up
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is necessary, TWEB will perform that via LDAP, prepare the results
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as an HTML page, and return it to the requesting client. After
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that the process will die, unless it was the master process, that
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returns to listening for further requests. Thus, TWEB's action is
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as state-less as the HTTP protocoll itself, but some information
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for subsequent client requests can be embedded into the result,
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like for example a gateway-switch (see below) or an entries' old
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data in a modification formular.
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Like in HTTP, the TWEB request URL should contain no space characters,
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and certain special chars should be HTML escaped. TWEB will allways
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prepare such URLs in its own results, e.g., when returning a list of
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entries, with each one beeing a clickable hyperlink for the next data
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retrieval. Thus, during interaction with TWEB, the user has not to
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consider such special characters, for they are converted automatically.
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Only the very first link to TWEB, be it embedded into a web page, or
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entered directly into the browser's 'goto URL' field, or whatever it is
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called, should be checked for those characters.
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2.4 check4access: who is allowed to see (what) data
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A requesting client not only gives the URL to TWEB, but also it's
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IP or Internet address. This is an address needed by computers to
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find each other in the world-wide network. Normally, computers
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have also so-called Internet Names, that are more human-readable.
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To match IP addresses and internet names, the Domain Name Service
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(DNS) is run on the Internet. When TWEB receives an IP adress,
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it will try to look up the corresponding internet name of the
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requesting client and use that information to decide on access
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rights of the client. If a host's name cannot be found in the
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DNS, this is also used as a bit of information. The configuration
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parameters GRANT, REFUSE, ALLOW-STRING, and DENY-STRING can be
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set to specify access rights based on internet names in a very
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flexible way. Furtheron, the HTTP information of proxy access
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is considered, if the parameters NO-PROXY and ALLOW-PROXY are set.
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When TWEB has decided on access rights, it will continue depending
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on these rights. When service is totally refused to a requesting
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host, or a complete IP domain, a corresponding message is send to
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the client and the TWEB process terminates. Otherwise, TWEB selects
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one of two configured WEBDNs (the directory names of corresponding
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entries in the local directory) and WEBPWs (corresponding passwords)
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and sends the LDAP requests with these DNs to the directory server.
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The server should of course be configured in a way, that the one DN
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has access to internal data, whereas the other has not. Thus, data
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retrieval can be controlled by the server, not only by TWEB itself.
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2.5 Preparing the data
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Almost any result page is build by combining different areas, as
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appropriate for the result returned. A header and footer is located
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at the top and the bottom of the HTML page, respectively. (In fact,
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the footer is followed by a tiny TWEB version info, so the footer
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is only the second-last element.) Below the header some internal
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message can follow (ALLOW-MESSAGE), which will not be shown to an
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outside requestor, and in front of the footer there can be a Legal
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Message for the outsider (LEGAL; actually, if the ON-TOP parameter
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is specified for the LEGAL option, this Legal Message will also be
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printed at the beginning of the result page). Below the header/
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internal message, an area for navigation, reading the current base
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position and a search box may follow, that can be used for entering
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further requests. Below that, the results of the current request
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are shown.
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If there are more than one result entries to the current request (e.g.,
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due to a listing of entries below the current DIT position, or multiple
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matches for a search request), a hyperlink for each entry is displayed,
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to give the user the possibility to follow the link and obtain the
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results for the next request. The HREF within the hyperlink is a
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complete URL, with host:port, and the directory entries' distinguished
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name (DN) for the next request to TWEB.
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Results can be grouped to different lists and sorted within each
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group, according to the settings of the SORT configuration parameter,
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and the entries' objectclasses. The objectclasses given in the SORT
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configuration parameter are scanned for in each result entry,
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sequentially, and an entry is placed into the appropriate group, as
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soon as an objectclass is found. (Entries having none of the SORT
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objectclasses will only be shown, if the SHOW-DEFOC configuration
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parameter as well as a DEFAULT DISPLAY-TYPE is given.) After scanning
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for groups, each group of entries is sorted according to the contents
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of the sort attribute listed within the group's SORT clause, or by the
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attribute "sn" (surname), if no explicite sort attribute is given, or
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according to the entries' relative distinguished name, if there is no
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sn attribute within the entries. The sorted groups are displayed in
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the order, that is given numerically in the SORT clauses. Thus, the
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order while scanning for objectclasses (i.e., preparing the groups)
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is distinct from the order during display. Each group is prepanded
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by the label given in the SORT clause, with a label consisting only
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of space characters meaning no label. (Labels containing space
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characters must be surrounded by double quote characters, i.e., '"'.)
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If there is only one result to a request, TWEB will perform a read
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request for the X.500 entry and display the attributes of the entry.
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Since access rights are also checked at the server (see above), the
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attribute list for a permitted user can differ from the list of an
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external user. In each case, the attributes are sorted according to
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the DISPLAY-OBJECT given in the SORT configuration parameter, after
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classification of the entry to one of the SORT groups in much the
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same way, as described above. The DISPLAY-OBJECT selects the attributes
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to be displayed and determines the order of, as well as labels for
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the attributes. (If the DISPLAY-OBJECT parameter is not given to the
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SORT configuration option, DISPLAY-OBJECT DEFAULT will be used; if
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that, however, is not given by the configuration files, the entry
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will NOT be displayed!) The method for displaying is also given. Thus,
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attributes can be displayed as simple strings, prepared as HTTP URLs,
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or as mailto hyperlinks. A complete list of display methods is given
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below with the description of the FIRST-PAGE configuration parameter.
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Within the DISPLAY-OBJECT definition, FIRST-PAGE describes attributes
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to be shown on a first HTML page, and SECOND-PAGE lists attributes
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for a second HTML page, if given. To obtain the second page, a hyper-
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link that directs TWEB to read the same entry again with additional
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attributes, is placed at the end of the first page's attribute list.
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2.6 Searching for data
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As described above, one element of a result page may be a search box
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that can be used to enter appropriate search strings. The input is
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taken by TWEB and used according to the definitions of the
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ldapfilter.conf file (a basic version is located in the LDAP_etc
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sub directory.) In that file, rather complicated search algorithms
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can be defined, but the most simple ones will be to look for cn or
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sn attributes. By default, the search scope is restricted to one
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level below the current DIT position, unless the base entry (the
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current position) containes objectclasses 'organization' or
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'organizationalUnit'. In this case, the search will cover the whole
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DIT area rooted at the current position. (Subtree search.) This
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scope also determines which search rules are taken from the
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ldapfilter.conf file. (Look for "web500gw onelevel" and "web500gw
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subtree".)
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One word for a warning: since TWEB is currently based on LDAPv2 and
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servers that are NOT aware of special characters, like german umlaute,
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such characters should NOT be entered to the search box. Depending
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on the server's implementation and configuration, these characters
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might crash the server, since they are not one of the expected ASCII
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characters. TWEB, on the other hand, can hardly figure out the
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character entered because of differrent code tables in use with
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the browsers and the platforms housing TWEB itself. If someone has
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a simple sollution to the latter problem, the authers would welcome
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a hint, so they could implement a safe character conversion method.
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2.7 Data based behaviour: the dynamic gateway
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In the 'preparing data' section, the construction of hyperlinks for
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further requests was described for situations, when more than one
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entry matches the previous request. For these hyperlinks, the under-
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lying URL will normally contain the TWEB's own host and port address,
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so that requests will be directed towards the same gateway. This,
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however, can be modified by a feature called "gateway-switching",
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directing further requests to other gateways.
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Gateway-switching exists in two flavors: static (via the GW-SWITCH
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configuration option) and dynamic (selected by the configuration
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option DYNAMIC-GW) due to data contents. In both cases, a new host
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and corresponding port address is inserted into the URL of a hyperlink.
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Static gateway-switching is performed, if a DN given in the configu-
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ration file, or an entry below that DN, is referred to in the hyperlink.
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In that case, the beginning of the URL is taken from the configuration
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file and the DN of the referred-to X.500 entry is appended. Like other
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configuration options, GW-SWITCH in the tweb.rc file will refer to one
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such external gateway for all TWEB languages, whereas GW-SWITCH in the
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tweb.conf.x files will be language-specific.
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When the configuration option DYNAMIC-GW is given, TWEB will scan each
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entry to be referred to, for the presence of a so-called gateway-
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switch-URL. For the time beeing, this is encoded in the attribute
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"labeledURI", with the value having a special syntax. Normal syntax
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is an URL of the from "http://host/ label". With the gateway-switching
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option, this format is extended to "http://host:port/ label (gw)",
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for a language-independant switch, and "http://host:port/ label (gw-xx)",
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for a languager-specific switch. The "xx" has to be replaced by the
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international 2-letter language tag, as defined in ISO 639, "Code for
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the representation of names of languages" (see also RFC-1766). Thus,
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"gw-de" means "german language", "gw-en" means "english", "gw-fr"
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means "frensh". When displaying the contents of a labeledURI attribute,
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TWEB will suppress values that follow the above syntax. For performance
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reasons, searching of entries, as well as listing entries below the
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current position (i.e., browsing through the directory), will allways
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include look-up of the labeledURI and other attributes.
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If both static and dynamic gateway-switching are active, the dynamic
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switch will be considerred first; if no gateway-switch URL, first testing
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for a language-specific one, than testing for an independant one, is
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found within an entry, static switching is tested, again the specific
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case prior to the un-specific.
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The most prominent usage of the gateway-switching feature is to direct
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requests for other organizations' data within a country (or for sub-
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|
organizations within one organization) to specific gateways, thus
|
|
giving the option to implement a Corporate Identity for each organi-
|
|
zation via organization-specific header and footer files. Beside that,
|
|
of course, specific access policies can be implemented by each orga-
|
|
nization, and network traffic is reduced by accessing an organization's
|
|
data directly with a HTTP browser, not via an intermittant gateway
|
|
and X.500 server of another organization. This latter point may also
|
|
mean a much reduced response time, when unnecessary data transfers are
|
|
ommited.
|
|
|
|
|
|
2.8 Restricting the service
|
|
|
|
A number of configuration options can be used to restrict the display
|
|
of certain information, or to deny service totally for certain users.
|
|
These options are described in the following sub-chapters.
|
|
|
|
2.8.1 Restricting the number of entries
|
|
|
|
Normally, an X.500 server will have an option "sizelimit" set to
|
|
some small or medium value, e.g., 100 or 500. This sizelimit will
|
|
prevent the number of entries returned for any one request, to
|
|
exceed that number. This is mainly set by the server's administrator
|
|
to reduce system and network load.
|
|
|
|
When displaying all entries returned from the server, TWEB might
|
|
produce a very large HTML file. That file may take some time for
|
|
transfer, and may be very un-handy, because of the long list of
|
|
entries.
|
|
|
|
To prevent the possibiloty of such large files, the TWEB administrator
|
|
can reduce the number of entries displayed even further, by use of
|
|
the MAXCOUNT configuration option. This will reduce the number of
|
|
ALL entries returned from the server.
|
|
|
|
If this restriction should only apply to person's entries, the
|
|
configuration option MAX-PERSON can be used. This option will
|
|
apply to each sub list of person's entries seperately. Thus, the
|
|
total number of persons may exceed the MAX-PERSON limit, if more
|
|
sub lists containing person's entries are given.
|
|
|
|
Each restriction of the number of entries to be displayed, will
|
|
lead to a random list of entries, cutting the results as soon as
|
|
the maximum count is reached. However, rhis is also true for the
|
|
sizelimit option at the server itself.
|
|
|
|
2.8.2 Suppression of certain entries by RDN
|
|
|
|
The server's access control rules will normally define, which entries
|
|
can be obtained by the TWEB gateway. In some situations, the TWEB
|
|
administrator might want to suppress even more entries, e.g., DSA
|
|
entries or other mere technical ones. (This can also mean, that
|
|
complete DIT areas could be hided from the user.)
|
|
|
|
To invoke that, the configuration option NO-SHOW-RDN can be defined
|
|
to reflect a space-seperated collection of RDNs, or parts of RDNs,
|
|
which will not be shown to the user. This, of course, is a very
|
|
crude method, but normally will give the results, the TWEB admin
|
|
may be interested in.
|
|
|
|
2.8.3 Defining DIT areas for search-only operations
|
|
|
|
As described allready in the "Restricting the number of entries"
|
|
section, large lists of entries may be cumbersome to read, if at
|
|
all they are returned completely by the server. To exclude the
|
|
possibility of such partial, or ultra-long lists, TWEB can be
|
|
configured to display the search box only at certain DIT positions.
|
|
This is done via the SEARCH-ONLY configuration option, which defines
|
|
the DIT area(s) for this restriction, as well as certain message
|
|
files, which should explain the local restriction to the user, and
|
|
tell him, how to find the information, he is looking for. The
|
|
SEARCH-ONLY configuration option will only take effect, when
|
|
browsing the directory, but not prevent a normal subtree search.
|
|
|
|
This configuration option, of course, can also be used to implement
|
|
certain access policies. The option will be active for both the
|
|
internal and the external user.
|
|
|
|
2.8.4 Controlling the hackers
|
|
|
|
From time to time, users will direct tools to the world-wide-web,
|
|
that will screen through all, what is supplied in the system. This
|
|
tools are known as robots, or crawles, and normally the collect data
|
|
to build indices for faster information retrieval.
|
|
|
|
Sometimes, however, these tools can be very ugly, especially, when
|
|
they try to collect data as fast as possible. This might cause
|
|
severe performance decrease, preventing other users to get data
|
|
at all. In order to have some mechanisms against this type of
|
|
data harvest, TWEB can be configured with the COMREFUSE option
|
|
activated, which will control the number of accesses to the gate-
|
|
way by a certain number of IP ranges within a selected time-slice.
|
|
|
|
Those IP ranges are constructed by reducing the requesting host's
|
|
32-bit Internet address to a 13-bit number, thus giving 8192
|
|
different IP ranges. Each IP range is controlled seperately during
|
|
a pre-set time-slice, and each IP range can be excluded from
|
|
further service (returning an appropriate error message), when
|
|
a pre-set number of accesses is reached within that time-slice.
|
|
All hosts of that IP range are suspended from TWEB's service for
|
|
a number of time-slices, and resumed for service afterwards.
|
|
|
|
|
|
3 Configuration of TWEB features in detail
|
|
|
|
Runtime configuration is provided by the files tweb.rc (general
|
|
configuration) and tweb.conf.x (language-specific configuration).
|
|
For each supported language there must be a tweb.conf.x and
|
|
tweb.lang.x file, with 0 <= x <= 9.
|
|
|
|
Remark: most of the features are best configured in the files as given
|
|
below, but there may be situations, where transfer, or even
|
|
splitting to other configuration files could be used, e.g.,
|
|
static gateway-switching may be configured in tweb.rc listing
|
|
organizations which support only one gateway, whereas organi-
|
|
zations supporting different language-specific gateways may be
|
|
configured in the appropriate tweb.conf.x files; the resulting
|
|
gw-switch list will contain all organizations, regardless of the
|
|
originating files.
|
|
|
|
In order to keep off WWW robots from blocking the gateway put
|
|
a file with name robots.txt into the directory, together with
|
|
the tweb binary, containing the following:
|
|
|
|
# go away
|
|
User-agent: *
|
|
Disallow: /
|
|
|
|
This is the same behaviour as if there were a www-server with a
|
|
corresponding public directory containing the file robots.txt.
|
|
|
|
|
|
The following sections will list TWEB's configuration options.
|
|
(See also the example configuration files.)
|
|
|
|
|
|
3.1 Technical configuration options
|
|
|
|
This section lists options, which define the technical parameters of
|
|
TWEB's operation. Most of them are located in the tweb.rc configuration
|
|
file, but some could also go into the tweb.conf.x files.
|
|
|
|
LDAPD -- The host running the LDAP daemon
|
|
( usually located in tweb.rc )
|
|
|
|
example: LDAPD x500.zdv.uni-tuebingen.de
|
|
|
|
LDAPPORT -- The port the LDAP daemon is listening on
|
|
( usually located in tweb.rc )
|
|
|
|
example: LDAPPORT 389
|
|
|
|
WEBPORT -- The base port the gateway is attached to
|
|
(the language-specific offset x is added
|
|
to this number for every running GW)
|
|
( usually located in tweb.rc )
|
|
|
|
example: WEBPORT 7000
|
|
|
|
TIMEOUT -- Timeout in seconds for any one LDAP
|
|
operation
|
|
( usually located in tweb.rc )
|
|
|
|
example: TIMEOUT 240
|
|
|
|
ETCDIR -- The directory containing support files
|
|
(help files, header/footer files ...)
|
|
( usually located in tweb.rc )
|
|
|
|
example: ETCDIR ./LDAP_etc/
|
|
|
|
FILTERFILE -- The LDAP filterfile
|
|
( usually located in tweb.rc )
|
|
|
|
example: FILTERFILE ldapfilter.conf
|
|
|
|
BASEDN -- The default starting point of DIB access, when
|
|
no other directory position is given
|
|
At this position, optional header and footer
|
|
information (HTML code in file) can be displayed
|
|
( usually located in tweb.conf.x )
|
|
|
|
example: BASEDN "o=Universitaet Tuebingen, c=DE"
|
|
tweb-base.head.0 tweb-base.foot.0
|
|
|
|
HELPFILE -- Name and path of the help-file
|
|
( usually located in tweb.conf.x )
|
|
|
|
example: HELPFILE tweb.help.0
|
|
|
|
FRIENDLYFILE -- Name and path of the friendly-file
|
|
( usually located in tweb.conf.x )
|
|
|
|
example: FRIENDLYFILE ldapfriendly.0
|
|
|
|
HEADER/FOOTER -- General header/footer information displayed on
|
|
every HTML-page, except when other headers/footers
|
|
apply
|
|
( usually located in tweb.conf.x )
|
|
|
|
example: HEADER tweb.header.0
|
|
FOOTER tweb.footer.0
|
|
|
|
ALLOW-MSG -- Option to specify a special file located in the
|
|
ETCDIRectory containing a message to be displayed
|
|
in case of an allowed access to TWEB
|
|
(see next section)
|
|
( usually located in tweb.conf )
|
|
|
|
example: ALLOW-MSG allow.msg.0
|
|
|
|
|
|
3.2 Political configuration options
|
|
|
|
This section lists options to implement a certain access policy with the
|
|
TWEB web-X.500 gateway, or to alter the behaviour of the gateway when
|
|
displaying data from certain DIT areas.
|
|
|
|
WEBDN -- The DN of a technical webgw X.500 entry,
|
|
which is used for a permitted (internal) user
|
|
(for logging AND access control)
|
|
( usually located in tweb.rc )
|
|
|
|
example: WEBDN "cn=TWEB-quickie-intern,
|
|
ou=SERVICES, o=Universitaet
|
|
Tuebingen, c=DE"
|
|
|
|
WEBPW -- The Password in the WEBDN entry
|
|
( usually located in tweb.rc )
|
|
|
|
example: WEBPW password4quickie-intern
|
|
|
|
WEBDN2* -- The DN of a technical webgw X.500 entry,
|
|
which is used for a not-permitted (external) user
|
|
(for logging AND access control)
|
|
( usually located in tweb.rc )
|
|
|
|
example: WEBDN2 cn=TWEB-quickie-extern,
|
|
ou=SERVICES, o=Universitaet
|
|
Tuebingen, c=DE"
|
|
|
|
WEBPW2* -- The Password in the WEBDN2 entry
|
|
( usually located in tweb.rc )
|
|
|
|
example: WEBPW2 password4quickie-extern
|
|
|
|
* setting WEBDN2 as well as WEBPW2 to real values is useful,
|
|
if the X.500 service in the background is also used by other
|
|
directory user agents; in this case, a clean distinction,
|
|
even on the ACL level, can be made between TWEB and those
|
|
other DUAs.
|
|
To fully exploit the feature of two different WEBDNs the
|
|
DSA must support an ACL policy, which can reduce access
|
|
rights for a specified DN, while at the same time defining
|
|
broader access rights for a group of other DN, which may
|
|
also include the specific DN; such a behaviour is NOT
|
|
implemented in Isode's QUIPU 2.x DSA; a patch introducing
|
|
such a policy was developped at the University of Tuebingen
|
|
for QUIPU 2.2v4, and can be optained seperately.
|
|
Slapd stand-alone LDAP servers implement a different ACL
|
|
mechanism and can be configured more easily by use of the
|
|
first matching access-rule in the slapd.conf configuration file
|
|
|
|
GRANT** -- A string describing IP domains allowed to access
|
|
the gateway
|
|
( usually located in tweb.rc )
|
|
|
|
example: GRANT (www9|mog|x500server|meal)
|
|
\.zdv\.uni-tuebingen\.de$|
|
|
(abcde01|xyz)\.modem\.org\.de$
|
|
|
|
REFUSE** -- A string describing IP domains refused to access
|
|
the gateway
|
|
( usually located in tweb.rc )
|
|
|
|
example: REFUSE hackhost\.(org1\.)?uni-xyz\.de$
|
|
|
|
ALLOW-STRING** -- A string describing IP domains allowed to
|
|
access the DIB authorized by WEBDN (see above)
|
|
example: "\.de$|\.us$|\.edu$"
|
|
==> host of domains de, us and edu will
|
|
have authorized access to the DSA, others NOT
|
|
( usually located in tweb.rc )
|
|
|
|
example: ALLOW-STRING uni-tuebingen\.de$
|
|
|
|
DENY-STRING** -- The opposite of ALLOW-STRING. Here, access for
|
|
subsets of the ALLOW-STRING may be reduced.
|
|
( usually located in tweb.rc )
|
|
|
|
example: DENY-STRING not\.secure\.host
|
|
\.uni-tuebingen\.de$
|
|
|
|
** GRANT/REFUSE are considered first to decide, whether the
|
|
requesting host will be served at all; only hosts granted
|
|
the service will be checked against ALLOW-STRING/DENY-STRING
|
|
to classify as internal or external user (hence, giving
|
|
WEBDN or WEBDN2 as the DN during X.500 look-up);
|
|
both, GRANT and ALLOW-STRING are used as positive-lists,
|
|
whereas REFUSE and DENY-STRING are used as negative-lists;
|
|
if the positive-lists are defined, and the requesting host's
|
|
IP domain is NOT covered by the list's description, the
|
|
host is considered as not-permitted; only when the host
|
|
is accepted by the positive-list, the negative-list will
|
|
be considered to decide on a more specific exclusion of
|
|
the host's IP domain;
|
|
if the positive-lists are not defined, each host will be
|
|
accepted, as if contained within the list; if the negative-
|
|
lists are not defined, each host will be accepted, as if
|
|
NOT contained within the list;
|
|
hosts NOT found in the Domain Name Service (DNS) will be
|
|
granted access, but will NEVER have authorized access
|
|
via WEBDN
|
|
|
|
TWEBHOST -- Supplies a constant hostname in the returned URL
|
|
of HTTP links independant from the local one
|
|
( usually located in tweb.rc )
|
|
|
|
example: TWEBHOST x500.zdv.uni-tuebingen.de
|
|
|
|
NO-PROXY -- Access restrictions for WWW-PROXY-Servers
|
|
( usually located in tweb.rc )
|
|
|
|
example: NO-PROXY
|
|
|
|
ALLOW-PROXY -- if NO-PROXY is configured
|
|
access from a given set of proxy-hosts
|
|
('host1:host2') is allowed
|
|
( usually located in tweb.rc )
|
|
|
|
example: ALLOW-PROXY www1.zdv.uni-tuebingen.de:
|
|
www2.zdv.uni-tuebingen.de
|
|
|
|
COMREFUSE -- If configured, implements an interrupt-driven
|
|
time-slicing of the gateway. During these
|
|
slices only a maximum number of accesses
|
|
from a given group of IP-addresses is permitted;
|
|
additional accesses will lead to immediate
|
|
suspension of the IP connection to the WWW
|
|
client; this suspension will last for a con-
|
|
figured number of time-slices, and service
|
|
for the IP domain in question will resume
|
|
afterwards. Additionally, access statistics will
|
|
be dumped to a file at given intervals;
|
|
the duration of a time-slice will be computed
|
|
randomly between a minimum and maximum;
|
|
all times are given in seconds
|
|
( usually located in tweb.rc )
|
|
|
|
example: COMREFUSE 100 200 40 12 43200
|
|
./stats/hack-stats
|
|
|
|
i.e.: minimum timeslice -> 100 secs
|
|
maximum timeslice -> 200 secs
|
|
number of accesses to tolerate in slice -> 40
|
|
how long will be blocked -> 12 slices
|
|
period to write a stat-file -> 43200 secs
|
|
name of stat-file -> ./stats/hack-stats
|
|
(i.e., file relative to TWEB binary)
|
|
|
|
STRICT-BASEDN -- Access to entries not below basedn is relayed
|
|
to another gateway ( -> GW-SWITCH must be set)
|
|
( usually located in tweb.rc )
|
|
|
|
example: STRICT-BASEDN
|
|
|
|
MAXCOUNT -- The maximum number of displayed entries
|
|
( usually located in tweb.rc )
|
|
|
|
example: MAXCOUNT 200
|
|
|
|
MAX-PERSON -- Maximum number of persons displayed in any of
|
|
the configured sub-lists ( -> SORT option),
|
|
if access is not allowed;
|
|
if STRICT is given, this number of persons is
|
|
shown at maximum, even in case of an
|
|
allowed access;
|
|
if NO-BROWSE is given, only non-person entries
|
|
will be displayed while browsing, whereas persons
|
|
have to be searched for
|
|
( usually located in tweb.rc )
|
|
|
|
example: MAX-PERSON 5 STRICT NO-BROWSE
|
|
|
|
NO-SHOW-RDN -- Matching rules for RDNs that will NOT be displayed
|
|
(e.g., technical entries in the DIT or internal
|
|
OUs not to be displayed by the GW)
|
|
words surrounded by spaces will be matched as
|
|
substrings; allignment to the start or end of
|
|
the tested RDN can be enforced by surrounding
|
|
the words with "|", on either side
|
|
( usually located in tweb.rc )
|
|
|
|
example: NO-SHOW-RDN "|cn=Dummy notToBeShownRDN"
|
|
|
|
SEARCH-ONLY -- Defines the root of a DIT area, where browsing
|
|
is restricted to non-person entries; person
|
|
entries can only be found by explicite searching
|
|
(with appropriate header and footer information)
|
|
( usually located in tweb.conf )
|
|
|
|
example: SEARCH-ONLY "ou=students, o=my-university,
|
|
c=my" search-only.head.0
|
|
search-only.foot.0
|
|
|
|
LEGAL -- Flag for displaying of a comment concerning
|
|
Peoples Rights
|
|
(the text is configured in the tweb.lang.x files,
|
|
string numbered 65 of the gateway)
|
|
(Comment: certainly, it would be better to have
|
|
that text in an external file)
|
|
Sub-option ON-TOP directs TWEB to display the
|
|
message immediately below the HEADER information,
|
|
not above the FOOTER message
|
|
( usually located in tweb.rc )
|
|
|
|
example: LEGAL ON-TOP
|
|
|
|
CACHE-EXPIRE-DEFAULT -- The default value for the expire time
|
|
in seconds. After this time the page is no
|
|
longer cached by a browser or WWW cache.
|
|
( usually located in tweb.rc )
|
|
|
|
example: CACHE-EXPIRE-DEFAULT 900
|
|
|
|
CACHING-TERMS -- A more detailed description of caching directives.
|
|
Format:
|
|
<expire-time> READ|MENU|L2ND RDN|OC <value>
|
|
...
|
|
|
|
To specify for a given access-type:
|
|
READ|MENU|L2ND (L2ND = second page) the expire-time
|
|
in seconds for given RDN|OC values
|
|
( usually located in tweb.rc )
|
|
|
|
BEWARE: THIS OPTION IS NOT USED AT THE AUTHOR'S
|
|
SITE, ROUTINELY. THUS, CORRECT BEHAVIOUR
|
|
CANNOT BE GARANTEED !
|
|
|
|
example: CACHING-TERMS 3600 READ RDN Fax
|
|
7200 MENU OC person
|
|
10800 menu RDN Mueller
|
|
|
|
MODIFY/MODATTR -- Selects for specified object-class (MODIFY) the
|
|
attributes permitted for modification, their
|
|
labels and the maximum number of values to be
|
|
handled by TWEB (MODATTR)
|
|
( usually located in tweb.conf )
|
|
|
|
BEWARE: THIS OPTION IS NOT USED AT THE AUTHOR'S
|
|
SITE, ROUTINELY. THUS, CORRECT BEHAVIOUR
|
|
CANNOT BE GARANTEED !
|
|
|
|
example: MODIFY person
|
|
MODATTR personalTitle title 1
|
|
telephoneNumber phone 2
|
|
...
|
|
|
|
NO-MODIFY -- Entries that contain one of the named
|
|
ObjectClasses will be displayed without
|
|
the possibility for modification.
|
|
( usually located in tweb.rc )
|
|
|
|
example: NO-MODIFY |toc_primas|
|
|
|
|
|
|
3.3 Load balancing configuration options
|
|
|
|
This section lists configuration options related to gateway-switching.
|
|
|
|
GW-SWITCH -- Defines DIT areas, which will direct TWEB to
|
|
introduce other gateway addresses for the
|
|
so-called gateway-switching
|
|
(STATIC gateway-switching; see section 2.7)
|
|
( usually located in tweb.conf )
|
|
|
|
REMARK: A set of slides explaining gateway-switching,
|
|
presented at the January-1999 DANTE meeting
|
|
in Utrecht, NL, can be found at the TWEB FTP
|
|
site at
|
|
ftp://ftp-x500.uni-tuebingen.de/tweb
|
|
|
|
example: GW-SWITCH "ROOT" HTTP://x500-relay.
|
|
uni-tuebingen.de:8901/M
|
|
"c=DE" HTTP://x500-relay.
|
|
uni-tuebingen.de:8911/
|
|
|
|
DYNAMIC-GW -- If given, tells TWEB to use dynamic gateway-
|
|
switching; if not given, only static switching
|
|
will be used, if configured;
|
|
a labeledURI attribute in an X.500 entry con-
|
|
taining (gw), (gw-de), or (gw-en) in its label
|
|
part is used to link this entry to another gateway
|
|
( usually located in tweb.rc )
|
|
|
|
example: DYNAMIC-GW
|
|
|
|
3.4 Display configuration options
|
|
|
|
This section lists options related to the displaying of results on an
|
|
HTML page. The options direct display of entries, attributes, as well
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as styles for displaying.
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|
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SORT -- Classification of a list of entries into sub-lists
|
|
according to their object classes; generating of
|
|
sub-lists will be according to the order the
|
|
OCs are given in the SORT option; displaying the
|
|
sub-lists will be according to the numbers given
|
|
as third parameter; sub-lists without an intro-
|
|
ducing label (second parameter) should have a
|
|
label of " "; the fourth parameter is the DISPLAY-
|
|
TYPE for a given object (see below) and the fifth
|
|
parameter is the attribute used for sorting;
|
|
parameters four and five are optional;
|
|
if not given reasonable defaults will be used;
|
|
if none of the entries objectclasses is given
|
|
in the SORT option, TWEB will randomly select
|
|
one of the entry's OCs as a new entry to the
|
|
SORT list, using DISPLAY-TYPE "default"; if that
|
|
type is not defined, the entry will NOT be
|
|
displayed at all
|
|
(see also section 2.5)
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|
( usually located in tweb.conf.x )
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|
|
|
example: SORT person Staff 4 person tat_sort
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|
organization Organizations 3 orgs
|
|
organizationalUnit "O Units" 2 ous
|
|
...
|
|
|
|
DISPLAY-OBJECT -- For specified DISPLAY-TYPES define the order,
|
|
labels and type of HTML-code produced for given
|
|
attributes (see FIRST-PAGE, SECOND-PAGE below);
|
|
a DISPLAY-TYPE "default" will match all types
|
|
NOT specifically listed; when the default type
|
|
is not giving, some X.500 entries might NOT be
|
|
displayed (see also SHOW-DEFOC below)
|
|
( usually located in tweb.conf.x )
|
|
|
|
example: DISPLAY-OBJECT person
|
|
FIRST-PAGE ....
|
|
|
|
FIRST-PAGE -- Attributes to be displayed for a specified
|
|
DISPLAY-TYPE
|
|
Format: <attribute> <label> <display-type>
|
|
Display-types:
|
|
MULTILINE -- attribute with multiple lines
|
|
DATE -- attribute as date
|
|
HREF -- attribute with syntax DN
|
|
as hyperlink (READ DN entry)
|
|
URI -- attribute with syntax URL
|
|
as hyperlink
|
|
MAILTO -- attribute as mailto (must be
|
|
supported by WWW client)
|
|
MOVETO -- like HREF, but the link will
|
|
be a LIST, instead of a READ
|
|
hyperlink
|
|
BMP -- phote as bitmap
|
|
JPEG -- photo as jpeg
|
|
JPEG2GIF -- convert jpeg to gif
|
|
BOOLEAN -- binary attribute
|
|
PGPKEY -- display PGPKey for cut&paste
|
|
DYNAMICDN -- uses DIT-CONFIG to show
|
|
attribute as hyperlink
|
|
INDEXURL -- show this hyperlink as defined
|
|
with INDEX-URL
|
|
DEFAULT -- anything else
|
|
|
|
example: DISPLAY-OBJECT person
|
|
FIRST-PAGE cn Name DEFAULT
|
|
personalTitle Title DEFAULT
|
|
...
|
|
|
|
SECOND-PAGE -- show additional attributes not displayed on
|
|
the first page
|
|
|
|
example: DISPLAY-OBJECT person
|
|
FIRST-PAGE ...
|
|
...
|
|
SECOND-PAGE sn Surname DEFAULT
|
|
info Information DEFAULT
|
|
|
|
SHOW-DEFOC -- Show Default Objectclass. If no objectclass
|
|
did match -> show entry with attributes as
|
|
defined in default-display
|
|
( usually located in tweb.rc )
|
|
|
|
example: SHOW-DEFOC
|
|
|
|
PULL-DOWN-MENUS -- Use BUTTONS and PULL-DOWN-MENUS instead of links
|
|
in order to support: help, language-switch,
|
|
move-upwards and read-entry functionalities
|
|
( usually located in tweb.rc )
|
|
|
|
example: PULL-DOWN-MENUS
|
|
|
|
LANGUAGE -- The labels of buttons for the switch to
|
|
the other started language-specific gateways
|
|
( usually located in tweb.rc )
|
|
|
|
example: LANGUAGE Deutsch
|
|
English
|
|
Français
|
|
|
|
STRIP-PIN -- Specify here the object-classes where numbers
|
|
( PINs, personal ident numbers, etc. ) following
|
|
an RDN will be stripped when displayed
|
|
( usually located in tweb.rc )
|
|
|
|
example: STRIP-PIN |toc_profs|person|toc_primas|
|
|
toc_cperson|toc_funcs|toc_pextra|
|
|
|
|
INDIRECT-ATTRS -- Format:
|
|
INDIRECT-ATTRS <ref-attribute>
|
|
IND_ATTRS <selection> REPLACE|APPEND <attribute>
|
|
<host> <port> <baseDN>
|
|
|
|
If there is an attribute with name <ref-attribute>
|
|
in a given entry, values of attribute <attribute>
|
|
in this entry will be REPLACEed|APPENDed by values
|
|
taken from the same attribute <attribute> of
|
|
an entry with DN:
|
|
"cn=<ref-attribute-value>,<baseDN>",
|
|
looked-up at an LDAP server <host>:<port>,
|
|
but only when some value in <ref-attribute>
|
|
matches <selection> at its beginning
|
|
( usually located in tweb.rc )
|
|
|
|
example: INDIRECT-ATTRS tat_refattr
|
|
IND_ATTRS POST- append postaladdress
|
|
x500.uni-tuebingen.de 10100
|
|
"ou=POST,ou=INTERNA,ou=NETZWERK,
|
|
o=Universitaet Tuebingen,c=DE"
|
|
|
|
DISP-SEA-RDN -- Make search-results to be displayed only by RDN
|
|
and not by DN relative to the search-base
|
|
( usually located in tweb.rc )
|
|
|
|
example: DISP-SEA-RDN
|
|
|
|
INDEX-URL -- Display labels of hyperlinks only with selected
|
|
RDN parts in the order configured by INDEX-URL;
|
|
this option applies to URL attributes within an
|
|
entry, which are directed towards other X.500
|
|
entries; an application of that might be an
|
|
index of entries
|
|
DISPLAY-TYPE must be set to INDEXURL.
|
|
( usually located in tweb.rc )
|
|
|
|
example: INDEX-URL 0,-2 "o=Universitaet Tuebingen, c=DE"
|
|
|
|
i.e.: labels of a hyperlink below the University
|
|
of Tuebingen are shown as follows:
|
|
|
|
1. lowest part of the DN (e.g., a person's name)
|
|
2. third-top-most part of the DN (e.g., faculty)
|
|
|
|
all other DN parts will be supressed
|
|
|
|
TABLES -- Format:
|
|
TABLES <ALLOW|ALL> <objectclass> <Button-label>
|
|
<mode-selection>:<attribute>,<col-width>
|
|
[&<attribute>,<col-width>]*
|
|
|
|
During browsing, the entries listed below a
|
|
base object (i.e., DIT position) can be displayed
|
|
together with some selected attributes in a
|
|
tabular format; the SORT configuration option
|
|
will be applied to the entries; attribute mail
|
|
will be displayed as mailto: and the RDN will
|
|
be displayed as a link to the respective entry;
|
|
in order to select the tabular format, TWEB will
|
|
display a button with a given label, that, if
|
|
pressed, will request the tabular format;
|
|
however, the button will only be displayed, if
|
|
the requesting user is allowed to get this
|
|
feature (i.e., ALLOW will select internal users
|
|
only, whereas ALL will select all users)
|
|
|
|
example: TABLES ALLOW oleaf Tabelle persontable:rdn,28
|
|
&telephonenumber,25&tat_dummyattr,2
|
|
&mail,45
|
|
|
|
i.e.: ALLOW -> only allowed users will see the table
|
|
oleaf -> table button is shown on presence of
|
|
the objectclass oleaf in the base entry
|
|
Tabelle -> the label for the table-request-
|
|
button
|
|
persontable -> the keyword for function-
|
|
selection of a persons' table
|
|
rdn,28 -> first the rdn-attribute is shown
|
|
in the table with width 28 percent
|
|
telephonenumber,25 -> telephonenumber,
|
|
width 25
|
|
tat_dummyattr,2 -> a separating column, width 2
|
|
mail,45 -> the e-mail-address with width 45
|
|
|
|
(all width values are given in percentage of
|
|
the width of the browsers window, and should
|
|
sum up to 100 %)
|
|
|
|
|
|
4 Support and discussion list
|
|
|
|
Bug reports and flames (but also critical comments) send to
|
|
|
|
tweb-support@mail500.uni-tuebingen.de.
|
|
|
|
For general discussion (e.g., about interesting new features,
|
|
which should be supported), there is a discussion list at
|
|
|
|
tweb-l@mail500.uni-tuebingen.de.
|
|
|
|
Send requests for subscription to
|
|
|
|
tweb-l-request@mail500.uni-tuebingen.de.
|
|
|
|
|
|
|
|
TWEB development team, Tuebingen, January, 15th, 1999
|
|
|
|
|