Tango 2000 HOWTO
 Shayne Lebrun
 July 2000

 This document describes the installation, configuration, and basic
 troubleshooting of Pervasive Software's Tango Application Server on
 Sun Solaris and various flavours of Linux.
 ______________________________________________________________________

 Table of Contents



 1. Introduction

    1.1 Contributors and Contacts
    1.2 Acknowledgements
    1.3 Revision History
    1.4 New Versions
    1.5 Copyrights and Trademarks
    1.6 Feedback

 2. The Basics

    2.1 Tango Application Sever
    2.2 TAS, Web Server and Web Client
    2.3 TAS Life Cycle

 3. System Configuration / Requirements

    3.1 Solaris
       3.1.1 System Requirements
       3.1.2 System Configuration
    3.2 Linux

 4. Tango Installation and Configuration

    4.1 Installation - Tango 3.x
       4.1.1 Solaris
          4.1.1.1 Installing the Files
          4.1.1.2 Setting up the Tango user account
       4.1.2 Linux
    4.2 Tango 2000
       4.2.1 Solaris
       4.2.2 Linux
    4.3 Tango 2000 Service Pack 1
       4.3.1 Solaris
       4.3.2 Linux
    4.4 tXserver.ini - TAS Settings
       4.4.1 Cache
       4.4.2 CacheIncludeFiles
          4.4.2.1 CacheSize
       4.4.3 ConfigPasswd
       4.4.4 DataSourceLife
       4.4.5 DebugMode
       4.4.6 DSConfigFile
       4.4.7 ItemBufferSize
       4.4.8 License
       4.4.9 ListenerPort
       4.4.10 LoggingLevel
       4.4.11 MaxActions
       4.4.12 MaxHeapSize
       4.4.13 QueryTimeOut
       4.4.14 RequestQueueLimit
       4.4.15 ThreadPoolSize
       4.4.16 ValidHosts

 5. TAS and Web Servers

    5.1 Netscape Server Configuration
       5.1.1 Tango 3.x
       5.1.2 Tango 2000
       5.1.3 Tango 2000 Service Pack 1
    5.2 Apache Server Configuration
       5.2.1 Tango 2000
       5.2.2 Tango 2000 Service Pack 1
    5.3 tXclient.ini - CGI/Plugin configuration
    5.4 Load Splitting/Load Balancing
       5.4.1 Tango Load Splitting
       5.4.2 Load Balancing - Hardware Load Balancers

 6. TAS and Oracle

    6.1 Oracle Support

 7. TAS and ODBC

    7.1 Solaris
    7.2 Linux
    7.3 The odbc.ini Configuration File
    7.4 Solaris, ODBC and Oracle

 8. Handy TAF Files

    8.1 CGI_OR_PLUGIN.taf


 ______________________________________________________________________

 1.  Introduction


 This is the Tango for Linux and Solaris HOWTO, designed to be a quick
 reference to the installation and configuration of various versions of
 Tango on supported UNIX and UNIX-like platforms. This guide is valid
 for Solaris 2.6 and 7 on the SPARC architecture, and for Red Hat 5.2
 and 6, S.U.S.E 6.2+ and Caldera OpenLinux 2.2+, all running on Intel.

 1.1.  Contributors and Contacts


 This HOWTO was created by Shayne Lebrun <mailto:[email protected]> and
 is currently maintained by the same. Pervasive Software technical
 support can be reached at 1-800-287-4383 or [email protected]
 <mailto:[email protected]>

 1.2.  Acknowledgements


 Many thanks to the fine HOWTO HOWTO by Mark F. Komarinski. You should
 be able to find it at the LDP homepage at http://www.linuxdoc.org
 <http://www.linuxdoc.org>

 The Tango Documentation Team makes a damn fine set of manuals; don't
 let your MTCV book out of sight!

 1.3.  Revision History


 This is the first attempt at laying this all down.

 1.4.  New Versions


 The latest version is always available at
 http://www.members.home.net/slebrun/howto/TangoHOWTO.html

 1.5.  Copyrights and Trademarks


 (c) 2000 Shayne Lebrun

 This manual may be reproduced in whole or in part, without fee,
 subject to the following restrictions:

 �  The copyright notice above and this permission notice, and the
    trademark notice below, must be preserved complete on all complete
    or partial copies

 �  Any translation or derived work must be approved by the author in
    writing before distribution

 �  If you distribute this work in part, instructions for obtaining the
    complete version of this manual must be included, and a means for
    obtaining a complete version provided

 �  Small portions may be reproduced as illustrations for reviews or
    quotes in other works without this permission notice if proper
    citation is given

 Exceptions to these rules may be granted for academic purposes: Write
 to the author and ask. These restrictions are here to protect us as
 authors, not to restrict you as learners and educators.

 1.6.  Feedback


 Suggestions, flames, corrections, requests for a dinner date, etc etc,
 should be sent to [email protected] with a subject of 'HOWTO'
 <mailto:[email protected]?subject=HOWTO> and they'll be looked at.
 Remember, it's you who knows what needs to be in that document that
 currently isn't. And it won't get there if you don't tell me about it.

 2.  The Basics


 2.1.  Tango Application Sever


 Tango Application Server, aka TAS, runs as a daemon process. Tango 3.x
 is 'tangod' and Tango 2000 is 'tango4d'. Tango 2000 also runs a
 seperate Server Watcher process. Tango is a 'green threaded'
 application; it spawns a series of threads, but manages the threads
 itself. This means that a single TAS will not take advantage of
 multiple processors. However, Tango 3.6 and Tango 2000 include load
 splitting capabilities which allow you to run multiple TAS daemons on
 one box.

 2.2.  TAS, Web Server and Web Client


 The Tango Application Server is never contacted directly by the web
 browser; nor does it ever send information directly to the web
 browser. The browser only ever makes requests of the web server, which
 then forwards the request to the TAS through either a CGI or a web-
 server specific plugin. There are several advantages to this scheme.
 First, nothing on the browser side needs to be updated; no plugins,
 Active-X objects, client side Java, or anything are required. Second,
 the CGI/Plugin allows the Tango Server to be on a machine other than
 the web server, or indeed on several machines other than the
 webserver.

 2.3.  TAS Life Cycle


    Born
       Tango Server is instanced, and loads it's configuration files
       and what not. No user requests are accepted.

    Startup
       Tango Server first looks for a StartupURL. If one is specified,
       a request is generated. A successful return will allow Tango to
       move to the next stage. If the request cannot be sent, or if
       there is no URL specified, Tango Server moves on to the
       'Running' stage.

    StartupURL-Response
       Tango Server stays in this stage until a response is received
       from the StartupURL, or until the request times out.

    Running
       This is the normal operating state for Tango Server; user
       requests are accepted, Tango Cron jobs are run, and so on.

    Shutdown
       When a shutdown request is received, or generated by Tango
       itself on a fatal exception, a ShutdownURL is looked for, and
       run if it exists.  Otherwise, it moves on to the Waiting for
       Running Threads stage.

    ShutdownURL-Response
       Tango stays in this stage until either a response is received
       from the URL requested, or it times out.

    Waiting
       Tango Server waits for threads already running to finish, but no
       longer than the specified waiting period.

    Dead
       Tango Server kills all still running threads, cleans up, and
       exits.

 3.  System Configuration / Requirements


 3.1.  Solaris


 3.1.1.  System Requirements


 Tango for Solaris requires Solaris 2.6 or Solaris 7, SPARC
 architecture, approximately 30 megabytes of disk space, and
 approximately 2 megabytes of memory per user, given what Pervasive
 considers to be 'average' memory use.

 Tango 2000 requires Solaris system patches. 105591 for Solaris 2.6.
 106300 and 106327 on Solaris 7. Note that 105591 revision 08 causes
 Tango to core dump, as does 106327 revision 07. Not all the crashes
 are Tango's fault. :-) Solaris patches are available at
 http://access1.sun.com <http://access1.sun.com>

 3.1.2.  System Configuration


 There are a series of changes which can be made to your /etc/system
 file to increase various resources. These changes will often increase
 Tango performance, as well as preventing resource related crashes. The
 changes will require a reboot. Be very careful when making such
 changes.

 These are generic values which are nevertheless better than defaults.



 *** New Settings
 set shmsys:shminfo_shmmax=4294967295
 set shmsys:shminfo_shmmin=1
 set
  shmsys:shminfo_shmmni=100
 set shmsys:shminfo_shmseg=10
 set semsys:seminfo_semmni=100
 set
  semsys:seminfo_semmsl=100
 set semsys:seminfo_semmns=200
 set semsys:seminfo_semopm=100
 set
  semsys:seminfo_semvmx=32767
 *** New Settings End



 Take a look at your Solaris documentation, or http://docs.sun.com
 <http://docs.sun.com> for further information.

 Also, add the following line to the login script of the Tango user
 after installation:

 ulimit -n 1024



 3.2.  Linux


 Tango for Linux requires the appropriate flavour for the version you
 downloaded or purchased. Pervasive will NOT support running a version
 of Tango for Linux on a different Linux flavour; Tango for Red Hat
 Linux might not run on Caldera 2.2, let alone on Debian.

 Tango for Linux currently only supports the x86 architecture.

 If you're using Red Hat 5.2, you'll need to upgrade your kernel. The
 Tango for Linux documentation has the details.

 4.  Tango Installation and Configuration


 4.1.  Installation - Tango 3.x


 4.1.1.  Solaris


 4.1.1.1.  Installing the Files


 The current version of Tango 3.x for Solaris is Tango 3.62. There is
 not expected to be any further updates to the 3.x codebase. The
 installation path is designed for incremental upgrades, so is a bit
 tricky.

 First, you'll need the Tango 3.6 version.  This is a compressed
 tarball, and will untar itself into /var/opt/EDI/. You'll need to be
 superuser to install this.



 ______________________________________________________________________
 $su -
 Password: ********
 # uncompress tango36sol.tar.Z
 # tar -xvf tango36sol.tar
 ______________________________________________________________________



 Next, you'll need to grab the Tango 3.62 patch file.  This too is a
 compressed tarball. This one will uncompress to whatever directory
 it's in, so make a temp directory somewhere and use that.

 ______________________________________________________________________
 $su -
 Password: ********
 # mkdir Tango362
 # cp ./tangoSol362.tar.Z ./Tango362/
 # cd Tango362
 # uncompress tangoSol362.tar.Z
 # tar -xvf tangoSol362.tar
 ______________________________________________________________________



 What you'll wind up with are three binary files, a Readme.txt, and an
 'odbc' directory. Move the TangoNS_ep3.so to /var/opt/EDI/lib and the
 t3.cgi and tangod files to /var/opt/EDI/bin. Finally, remove your
 /var/opt/EDI/odbc directory and replace it with this one.

 ______________________________________________________________________
 # mv./TangoNS_ep3.so /var/opt/EDI/lib/TangoNS_ep3.so
 #mv ./t3.cgi /var/opt/EDI/bin/t3.cgi
 #mv ./tangod /var/opt/EDI/bin/tangod
 # rm -rf /var/opt/EDI/odbc
 #mv ./odbc /var/opt/EDI/
 ______________________________________________________________________



 4.1.1.2.  Setting up the Tango user account


 Next, you'll need to use your favourite method to create a user
 account to run Tango. You can use the graphical 'admintool' program,
 or command line programs such as 'adduser' or 'useradd' depending on
 your installation.

 Generally, you'll want to call the account 'tango' and also perhaps
 make a group called 'pvsw'. The user should be given ownership of
 everything in the /var/opt/EDI directory tree. If deploying in a
 production environment, especially on something outside of a firewall
 or the like, set the account to have no password, no login
 capabilities.

 4.1.2.  Linux


 There is no version of Tango 3.x for Linux. Had you going, though.

 4.2.  Tango 2000



 4.2.1.  Solaris


 Tango 2000 is shipped in the form of a Solaris Package Archive. You'll
 need to login as root, and using either the 'admintool' graphical
 utility, or run the pkgadd command. If you have a CD-ROM copy,mount
 the CD. The automounter will generally mount it in /cdrom. Copy the
 /cdrom/tango_as-2000/tango2000/T2000Install.tar file to a temporary
 directory. If you downloaded Tango 2000, it will be a compressed tar
 file, and you'll need to uncompress it first. If it's already
 uncompressed, skip the first step below.

 ______________________________________________________________________
 # uncompress T2000Install.tar.Z
 # tar -xvf T2000Install.tar
 # cd T2000Install
 # pkgadd -d. PVSWtango
 ______________________________________________________________________



 and follow the prompts.

      Warning: the shipping Tango 2000 installer sometimes rejects
      valid CD-keys as being invalid. If this occurs, leave the
      CD-Key blank, and manually add your key later (see section
      x.x).


 4.2.2.  Linux


 Tango 2000 for Linux is distributed as an RPM. On a distribution CD,
 you'll find the file in the tango2000 directory. Copy the appropriate
 file to a temp directory; Tango2000-server-4-Linux_i386.rpm if you're
 using Red Hat 6, Caldera 2.2 or S.U.S.E 6.2 or later.
 Tango2000-server-4-RedHat52_i386.rpm if you're using Red Hat 5.2.
 Either way, you'll need to be root.

      Note that to use Red Hat 5.2, you'll need to manually
      upgrade your kernel to version 2.2 or higher.



 ______________________________________________________________________
 #rpm -Uvh Tango2000-server-4-Linux_i386.rpm
 ______________________________________________________________________



 4.3.  Tango 2000 Service Pack 1


 4.3.1.  Solaris


 Tango 2000 SP1 for Solaris is a Solaris Package Archive, designed to
 replace/update the existing installation. It is, however, a full
 install, so if you don't have Tango installed already, you'll get a
 working install. Otherwise, the procedure to install is the same as
 Tango 2000, only the archive is T2000InstallSP1.tar.Z

 You'll probably want to back up your t4client.ini and t4server.ini
 files, as well as your web server configuration files.


 4.3.2.  Linux


 Tango 2000 SP1 for Linux is an RPM designed to replace/update the
 existing installation. It is, however, a full install, so if you don't
 have Tango installed already, you'll get a working install. Otherwise,
 the procedure to install is the same as Tango 2000, only the RPM is
 Tango2000-server-4.05.i386.rpm, or
 Tango2000-server-4.05.RedHat52.i386.rpm if you're using Red Hat 5.2.

 4.4.  tXserver.ini - TAS Settings


 Tango uses a file called 't3server.ini' or 't4server.ini' to control
 many of it's behaviors and functions. For Tango 3.x, this file is
 /var/opt/EDI/t3server.ini and for Tango 2000, it's
 $TANGO_HOME/configuration/t4server.ini. You can find a complete
 description of all entries in your Metatags and Configuration
 Variables book, but the most important/commonly used ones are listed
 here.

 4.4.1.  Cache


 Possible entries: TRUE, FALSE

 This controls weather or not Tango caches TAF files. Caching will
 reduce disk access, speeding up TAF execution.

 4.4.2.  CacheIncludeFiles


 Possible entries: TRUE, FALSE

 This controls weather or not Tango caches included files. Caching will
 prevent repeated disk access, speeding up TAF execution.

 4.4.2.1.  CacheSize


 Possible entries: Numeric, measured in bytes

 This measures the size of the cache for TAFs and included files. If
 cache grows to near this size, older documents will be flushed.

 4.4.3.  ConfigPasswd


 Possible entries: text

 This is the password of the config.taf online configuration
 application.

 4.4.4.  DataSourceLife


 Possible entries: numeric, measured in minutes.

 This controls how long an unused datasource connection will live. A
 setting of 0 will cause a datasource connection to be closed as soon
 as it's query is finished.

 4.4.5.  DebugMode



 Possible entries: ForceOn, ForceOff, appFileSetting

 This controls how the TAS handles placing debug information on the
 bottom of each page created; always, never, or per file settings.

 4.4.6.  DSConfigFile


 Possible entries: path to file

 This points to the Data Source configuration file, which gives you
 some finer control over how Tango uses data sources. See the Data
 Sources section for more details.

 4.4.7.  ItemBufferSize


 Possible entires: numeric, measured in bytes

 This is the maximum size of any given field that can be returned in a
 database action. It's main function is to prevent Tango from becoming
 bogged down while downloading an unusually large piece of data from a
 database.

 4.4.8.  License


 Possible entries: alphanumeric CD-Key

 This is the Tango license. The CD-Key contains the licensing
 information which tells Tango how to configure itself in terms of
 licenses and behavior.

 4.4.9.  ListenerPort


 Possible entries: TCP/IP Port number

 This tells Tango what port to monitor for incoming connections from
 the Tango CGI or Plugins. Ports cannot be shared between server
 software, so multiple servers running on one machine will need their
 own ports.

 4.4.10.  LoggingLevel


 Possible entries: NoLogging, LogLevel1, LogLevel2, LogLevel3,
 LogLevel4

 This controls how much logging Tango does. The log, "Tango.log", is
 written to the location specified in the LOGDIR config variable.
 LogLevel 3 is the best to use if you're trying to debug a Tango
 problem, but will slow Tango down, and will eat disk space.

 4.4.11.  MaxActions


 Possible entires: numeric, 0 for no limit

 This controls how many actions Tango will allow in a TAF file. This
 guards against things like infinite loops and overly large programs;
 most often used in development environments.



 4.4.12.  MaxHeapSize


 Possible entries: numeric, measured in bytes

 This controls how much memory the Tango Daemon process will allow
 itself to consume. Memory is consumed by variables, datasource
 connections, and cache.  If Tango exceeds this number, it will shut
 itself down with a 'process size exceeded' message and attempt to
 restart itself normally. This number should be changed to provide 20%
 more than what you record Tango as generally using during peak use.

 4.4.13.  QueryTimeOut


 Possible entries: numeric, measured in seconds

 This controls how long Tango will wait for a response from a database
 call before timing out. Note that not all databases and drivers
 support this functionality.

 4.4.14.  RequestQueueLimit


 Possible entries: numeric

 This controls how many requests from a CGI Tango will allow to
 'queue'.  A very busy site can sometimes have so many CGIs stacked,
 waiting for Tango to service them, that some will get lost and
 orphaned. This helps prevent that situation.

 4.4.15.  ThreadPoolSize


 Possible entries: numeric

 This controls how many simultaneous threads Tango will run with. On
 Solaris, it is generally better to have several Tango servers running
 a few threads apiece than to have one Tango server running the same
 number of threads.

 4.4.16.  ValidHosts


 Possible entries: TCP/IP addresses, colon delimited.

 This is a list of what IP addresses Tango will allow incoming requests
 from. On a machine where the web server and Tango server are both
 running, this should be set to 127.0.0.1, the localhost.

 5.  TAS and Web Servers


 The Tango Application Server runs as it's own process, where it
 services requests from a web server. This allows for some
 functionality such as load splitting and direction, as well as freedom
 of choice in web server and platform.  The TAS need not be on the same
 machine as the web server, nor is it limited to being even on one
 machine.

 The preferred way of having a web server talk to Tango is through a
 plugin.  The plugin is written in the web server's API, or Application
 Programming Interface, to take advantage of specific features of that
 web server, as well as the advantage of having the code execute as
 part of the web server, instead of as a separate CGI process. On
 Solaris, Tango has a plugin for Netscape Server and for Apache in
 later versions of Tango 2000. Tango for Linux has a plugin for Apache.

 5.1.  Netscape Server Configuration


 5.1.1.  Tango 3.x


 Locate your Netscape configuration files in
 /whatever/netscape/suitespot/https-MYSERVER/config generally. To the
 mime.types file, add this line:

 type=magnus-internal/taf exts=taf



 Add these two lines to the top of the obj.conf file (no line breaks;
 each line which starts with 'init' is a full line. Thus, there are two
 lines total)

 Init fn=load-modules shlib=/var/opt/EDI/lib/TangoNS_ep3.so funcs="Tango_main,Tango_main_init"



 Init fn=Tango_main_init stanza="TangoNS_ep3.so"



 Add this line to the obj.conf file inside of the <Object name=default>
 area, with the other services.

 Service fn="Tango_main" method="(GET|HEAD|POST)" type="magnus-internal/taf"



 You'll then need to use your Netscape Administration Server to restart
 the server, telling it to load the configuration files when it informs
 you that they've been hand-edited. Then, try hitting a TAF file. If it
 works, great!  If not, go through your configuration file again. Most
 of the time, a misconfiguration is the reason for it not working. One
 space or quotation mark out of place will destroy the entire setup.

 5.1.2.  Tango 2000


 Locate your Netscape configuration files in
 /whatever/netscape/suitespot/https-MYSERVER/config, generally. To the
 mime.types file, add this line:

 type=magnus-internal/taf exts=taf,tcf



 Then, add these two lines to the beginning of the obj.conf file. Note
 that there are no line breaks in each line.

 Init fn=load-modules shlib=/opt/PVSWtango/lib/libtango4ns.so funcs="Tango_main,Tango_main_init"



 Init fn=Tango_main_init stanza="libtango4ap.so" tangoconfigpath=/opt/PVSWtango/configuration



 Add this line to the obj.conf file inside of the <Object name=default>
 area, with the other services.
 Service fn="Tango_main" method="(GET|HEAD|POST)" type="magnus-internal/taf"



 You'll then need to use your Netscape Administration Server to restart
 the server, telling it to load the configuration files when it informs
 you that they've been hand-edited. Then, try hitting a TAF file. If it
 works, great!  If not, go through your configuration file again. Most
 of the time, a misconfiguration is the reason for it not working. One
 space or quotation mark out of place will destroy the entire setup.

 5.1.3.  Tango 2000 Service Pack 1


 Installation is the same as for Tango 2000, but with this extra line
 added to the services in the <Object name=default> area of the
 obj.conf file:

 Service fn="Tango_main" method="(GET|HEAD|POST)" type="magnus-internal/tml"



 Also, the mime.types file should have this line used instead of the
 one for Tango 2000:

 ______________________________________________________________________
 type=magnus-internal/taf exts=taf,tcf,tml
 ______________________________________________________________________



 5.2.  Apache Server Configuration


 Tango 2000 for Linux, and Tango 2000 Service Pack 1 for Solaris both
 support the Apache webserver through an Apache plugin. Apache will
 require mod_so support for all of these. The documentation states that
 you must custom build your Apache; this is misleading. You must build
 your Apache only if the pre-built version you're using doesn't have
 mod_so support. There are two places to check for this:

 First, try running your Apache server with a '-l' argument. If mod_so
 is listed, you're fine.

 ______________________________________________________________________
 # httpd -l
 Compiled-in modules:
 http-core.c
 mod_so.c
 ______________________________________________________________________



 Second, try looking in your httpd.conf file for an 'AddModule
 mod_so.o' line. If you don't have mod_so support (also known as DSO
 support) in some way, you'll need to compile a version that does.

 5.2.1.  Tango 2000


 At the end of your httpd.conf file, add these lines:

 LoadModule t4_module /usr/local/tango/lib/libtango4ap.so
 TangoModule t4_module
  /usr/local/tango/configuration/t4client.ini

 Modify the paths to the .so and .ini files as appropriate on your
 setup.

 Your t4client.ini will then need a stanza for t4_module. See the
 t4client.ini section for examples.

 5.2.2.  Tango 2000 Service Pack 1


 At the end of your httpd.conf file, add these lines:

 LoadModule t4_apache /usr/local/tango/lib/libtango4ap.so
 TangoModule t4_apache
  /usr/local/tango/configuration/t4client.ini



 Modify the paths to the files as appropriate; Solaris defaults to
 /opt/PVSWtango/ for the Tango home.

 Your t4client.ini will then need a stanza for t4_apache. See the
 t4client.ini section for examples.

 5.3.  tXclient.ini - CGI/Plugin configuration


 Tango uses a client configuration file to tell the CGI or Plugins
 where to send Tango requests. The file consists of two sections; a
 declaration section and an information section. Here is an example for
 a file controlling a CGI:

 [Tango Client Definitions]
 t4.cgi=Put A Description Here



 [t4.cgi]
 TANGO_SERVER=127.0.0.1,18100



 And an example of a file with both a CGI and an Apache plugin:

 [Tango Client Definitions]
 t4.cgi=My Tango CGI
 t4_apache=My Apache
  Plugin



 [t4.cgi]
 TANGO_SERVER=127.0.0.1,18100



 [t4_apache]
 TANGO_SERVER=127.0.0.1,18100



 Further entries can be made as appropriate. Use this list to find what

    CGI
       Use the name of the CGI. For example, you could have two CGIs,
       t4.cgi and t4private.cgi, each pointing to a different Tango
       server.
    Netscape Plugin (Tango 2000)
       Use 'libtango4ns.so' as the name. You shouldn't try to load
       multiple plugins.

    Netscape Plugin (Tango 3.x)
       Use 'TangoNS_ep3.so'

    Apache Plugin
       Use 't4_module' for Tango 2000 and 't4_apache' for Tango 2000
       Service Pack 1. You shouldn't try to load multiple modules.

 Tango 3 versions earlier than 3.6 use a slightly different format.
 TANGO_SERVER is broken into two lines; TANGO_HOST and TANGO_PORT.
 Here's an example:

 [Tango Client Definitions]
 t3.cgi



 [t3.cgi]
 TANGO_HOST=127.0.0.1
 TANGO_PORT=18000



 5.4.  Load Splitting/Load Balancing


 All versions of Tango starting with 3.6 have allowed Load Splitting.
 You can define a series of Tango servers that a plugin can use, and it
 will distribute new requests between the servers. Users who make
 subsequent requests are directed back to the server they were at
 previously via the UserReference search argument or cookie. Users
 cannot move between servers without losing their variables and what
 not. Also, what Tango currently does is not load balancing; that is
 expected for a future release of Tango.

 Tango does not need to be running on the same machine as the web
 server in any event. You need only run configure Tango's VALIDHOST
 configuration variable to include the IP address of the web server
 machine. Then, in the web server machine's t4client.ini file, put in
 the IP address and port number as usual.

 5.4.1.  Tango Load Splitting


 To add multiple Tango servers, add an entry to the t4server.ini file
 with the new name of the server, and add a new stanza for it,
 generally by copying an existing stanza. Then, change all directory
 names to be unique, such as LOGDIR. Make sure that it's running on a
 unique port. Tango defaults to port 18100. Here is an abbreviated
 example of a t4server.ini file with two Tango Application Server
 instances:

 [Tango Definitions]
 TAS_1=MyFirstServer
 TAS_2=MySecondServer



 [TAS_1]
 ...
 LISTENERPORT=18100
 ...
 LOGDIR=/usr/local/tango/log.TAS_1

 ...



 [TAS_2]
 ...
 LISTENERPORT=18101
 ...
 LOGDIR=/usr/local/tango/log.TAS_2
 ...



 All other configuration variables would be filled in as appropriate.

 To run Tango with a specific configuration definition, use the -c
 switch.

 ______________________________________________________________________
 $ ./tango4d -c TAS_1
 $ ./tango4d -c TAS_2
 ______________________________________________________________________



 The -c switch can be used in conjunction with the -k switch to kill
 servers as well.

 Note that you'll need the appropriate licenses, either one Corporate
 or Professional license, or as many Standard licenses as you want
 Tango servers.

 In the t4client.ini file, simply add the IP address and port of each
 server to the TANGO_SERVER line of the appropriate CGI or Plugin,
 colon delimited.  Here is an example t4client.ini file, using the CGI,
 pointing to three separate Tango servers running on the same machine,
 on ports 18100, 18101 and 18102.

 [Tango Client Definitions]
 t4.cgi=My CGI



 [t4.cgi]
 TANGO_SERVER=127.0.0.1,18100:127.0.0.1,18101:127.0.0,1,18102



 5.4.2.  Load Balancing - Hardware Load Balancers


 You can use a hardware load balancing device with Tango so long as
 your webserver farm is behind the load splitting device, and each
 webserver is using an exact copy of the same t4client.ini file. The
 t4client.ini file should be configured to use every Tango machine you
 want available. The UserReference based Tango redirection should
 function normally.



 6.  TAS and Oracle


 6.1.  Oracle Support


 Tango 3.x for Solaris does not have native Oracle support. Tango 2000
 for Solaris supports Oracle 8 and 8i, and generally works with Oracle
 7.3.4 and above. Tango 2000 Service Pack 1 was not tested with Oracle
 7.x however, and there have been reports of problems. The Oracle 8
 client can connect quite happily to the Oracle 7 server, however, so
 that is an option.

 To use Oracle with Tango, first you require the Oracle Client to be
 correctly installed on the machine. Generally, a good way to check for
 this is to:

 �  check to see if there is an 'oracle' account on the machine

 �  try to run the Oracle program 'sqlplus'

 If you can successfully run sqlplus, you should be fine. If not, well,
 go install Oracle.

 Next, you need to make sure that the client has the appropriate
 entries for the datasource in question to your TNS service; generally
 a tnsnames.ora file. You accomplish this with your Oracle software;
 there are programs such as net8config and what not that do it for you.
 The thing to remember here is that the name of the datasource needs to
 be the same as the name of the datasource you're using in Tango.

 Finally, to allow Tango to use the Oracle software, you need to add
 this path to the LD_LIBRARY_PATH environment variable of the tango
 user account.

 ______________________________________________________________________
 $ORACLE_HOME/lib
 ______________________________________________________________________



 You'll also need to define what $ORACLE_HOME is; this, of course, is
 the root directory of Oracle, and will be some forboding path such as,
 for example, /u01/software/products/8.1.5/oracle or something similar.

 If you're using Oracle 7.x or 8.0.x you'll probably need to create a
 new client library. Instructions for this are in
 $TANGO_HOME/odbc/src/oracle in the readme.ora file. You can check to
 see if you require this patch by attempting to load the Oracle ODBC
 driver (see section 6). If it fails with an 'unresolved symbol' error,
 then you need the patch.

 As the readme file says, this newly created library must appear in
 your LD_LIBRARY_PATH before the reference to $ORACLE_HOME/lib does. If
 there are no other programs running, it's generally easiest to replace
 the old library with the new.

 Some shells seem to have trouble with the LD_LIBRARY_PATH ordering;
 I've seen ksh fail to correctly load the new library, and switching to
 sh or bash solve it.

 7.  TAS and ODBC



 7.1.  Solaris


 Tango for Solaris includes the Merant ODBC driver pack, which Tango
 can use to connect to a wide array of databases, such as Informix,
 Sybase, Oracle, and now Microsoft SQL Server.

 The .odbc.ini file (see below) should be located in the home directory
 of the Tango user account. It can be stored elsewhere, for
 centralization or what not, and located using an environment variable
 called ODBCINI.

 7.2.  Linux


 Tango 2000 for Linux includes the iODBC driver manager, and a
 Pervasive.SQL driver is included with Pervasive.SQL for Linux. It will
 also work with Postgres SQL and MySQL drivers. Other drivers are
 available at http://www.unixodbc.com <http://www.unixodbc.com> and
 http://www.iodbc.org <http://www.iodbc.org>

 The .odbc.ini file (see below) should be located in
 /usr/local/tango/etc/odbc.ini which can be symlinked to
 /usr/local/psql/etc/odbc.ini if both are installed.

 7.3.  The odbc.ini Configuration File


 The drivers are controlled by an ini file called .odbc.ini (note the
 leading period; it's a hidden file on Solaris.)

 The file contains a list of Data Source Names followed by a definition
 section. It is a standard INI file format. So long as the DSN name
 used by a TAF is listed in this file, and the database schema is the
 same as the one on the development machine, the database access will
 work transparently.

 Here is an example of a .odbc.ini file containing a single DSN called
 MyOracleDatabase, which is pointing to an Oracle database with a TNS
 name of 'LocalOracleDatabase'.

 [ODBC Data Sources]
 MyOracleDatabase=



 [MyOracleDatabase]
 Driver=/opt/PVSWtango/odbc/lib/VQor815.so
 ServerName=LocalOracleDatabase



 All entries will have, at minimum, a Driver line; this points to a .so
 shared object which is the actual ODBC driver. There will be other
 lines dependant on the driver itself; server configuration, special
 flags, that sort of thing.  Refer to the readmes and to the
 odbchelp.pdf file (on Solaris) or to specific driver documentation for
 those settings, as well as any environment settings required.

 Note that ODBC drivers still often require database specific Client
 software; for example, the ODBC Oracle drivers require the same Oracle
 OCI client software that Tango requires for a native Oracle
 connection. Sybase client software must be installed for the Sybase
 ODBC driver to function, and so on. Again, see the odbchelp.pdf file,
 or driver documentation for specifics.

 Anybody who would like to write small crib notes on configuring
 specific databases to work with Tango for Solaris or Linux through
 ODBC, feel free and send them to me and they'll be included in this
 HOWTO, with full credit of course.

 7.4.  Solaris, ODBC and Oracle


 Certain versions of the Oracle client are missing key functionality
 that the Oracle ODBC drivers require, as well as the Tango native
 Oracle drivers.

 The easiest way to check for this condition is to use the 'ivtestlib'
 program to attempt to load the Oracle ODBC driver. Become the Tango
 user, and move to $TANGO_HOME/lib. Look for a driver with 'or7' for
 Oracle 7, or 'or8' for Oracle 8. Depending on your version of Tango,
 the full name might be 'IVor714.so' or 'VQor714.so'. The last number
 before the .so is the ODBC version.

 Once you have this file name, move one directory up, and then go into
 the as an argument.

 ______________________________________________________________________
 $ cd $TANGO_HOME/odbc/lib
 $ ls *or8*
 VQor814.so
 $ cd ../bin
 $ ./ivtestlib ../lib/VQor814.so
 Load of ../lib/VQor814.so successful, qehandle is 0xFF24120
 ______________________________________________________________________



 If the Oracle drivers need to be patched, you'll see a long message
 ending in the fact that there is an 'undefined symbol slpmprodstab'.
 This will prevent Tango Oracle Native connections from working as well
 as ODBC. In the $TANGO_HOME/odbc/src/oracle directory is a readme.ora
 file and two scripts, one for Oracle 7 and the other for Oracle 8. The
 readme file details the creation of a new 'libclntsh.so' file, which
 is the main Oracle client library. In a nutshell, make sure you have
 ORACLE_HOME defined, and run the appropriate script for your version
 of Oracle. This will create the .so file and place it, by default,
 into $TANGO_HOME/odbc/lib.  Then, make sure that that path appears in
 your LD_LIBRARY_PATH before any references to $ORACLE_HOME/lib does.
 You can also move the libclntsh.so file to your $ORACLE_HOME/lib
 directory, or create a link between $ORACLE_HOME/lib/libclntsh.so and
 the one you just created; the preexisting libclntsh.so is a link to
 another library anyway.

 8.  Handy TAF Files


 8.1.  CGI_OR_PLUGIN.taf

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