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  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:slebrun@home.com> and
  is currently maintained by the same. Pervasive Software technical
  support can be reached at 1-800-287-4383 or techsupport@pervasive.com
  <mailto:techsupport@pervasive.com>

  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 slebrun@home.com with a subject of 'HOWTO'
  <mailto:slebrun@home.com?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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