Merge commit 'origin/master' into HEAD

[urisagit/Stem.git] / FAQ / faq.text

S: About M<Stem>


Q: What is M<Stem>?

A: M<Stem> is a general purpose networking toolkit and a suite of ready
to use network applications. Its goal is to transform common network
programming to configuration and make uncommon network programming much
simpler. Some M<Stem> users will use its suite of applications and
modules and just configure them to perform their needed network
tasks. Others will create new M<Stem> modules to perform their specific
tasks and integrate them with M<Stem>'s standard modules using
configurations.  In both cases, M<Stem> will speed up network
application development, simplify maintenance, and lower lifetime costs.


Q: Where can I get M<Stem>?
A: M<Stem> can now be downloaded by the general public. Go to the 
<A HREF="download.html">download</A> page to get the latest version.


Q: What Can I Do With M<Stem>?
A: M<Stem> is a general purpose networking toolkit. As such, it can
be the backbone or framework of almost any networked (distributed)
application you can imagine. M<Stem> is designed with standard modules 
that are aimed at specific application niches. Some M<Stem> users
want a simple solution to common problems while others need a way to 
accelerate network application development. Via this modular design, 
M<Stem> can satisfy the differing needs of both groups. 


Q: What Are the Top M<Stem> Applications?
A: The most commonly requested applications of 
M<Stem> are log management, file distribution, 
monitoring and remote command execution. For more on 
M<Stem> applications, see the <A href="products.html">niches</A> page.

QUOTE<
        Stem Monitoring. \
        Overloaded Server Appears. \
        Remediation. \
        -- U.G. \
     >

Q: Why Should I Use M<Stem>?
A: You should use M<Stem> if:
<UL>
        <LI><P>You are tired of reinventing the wheel for each
        network application you build. M<Stem> provides you with all
        the common services that a network application needs and
        makes them very simple to use.</P></LI>

        <LI><P>You don't want to be forced to rely on a commercial
        monolithic network tool that everyone hates to use. M<Stem> is
        low cost and Open Source. You can easily write new modules
        to customize M<Stem> to your needs.</P></LI>

        <LI><P>You want to dramatically reduce the development
        and maintenance costs of developing your new
        network applications. M<Stem> tranforms common network
        programming to configuration. Even if you create new M<Stem>
        modules, it is very simple to connect them together with
        M<Stem> configurations. This lowers your development time and
        costs in many ways.</P></LI>

        <LI><P>You just want to use a well-designed network system that
        will make your profession much more enjoyable. M<Stem> is
        architected to be easy to use at both the configuration and
        coding levels. Our goal is for all M<Stem> users to enjoy
        working with it and reduce the frustrations and stress of
        network management.</P></LI>
</UL>

<P>These are just a few of the many reasons why 
M<Stem> should be in place on your network.  
If you have questions on how M<Stem> will benefit 
your individual needs, <A HREF="mailto:faq@stemsystems.com">please contact us</A>.


Q: Who Is Using M<Stem>?
A: A start up firm hired M<Stem Systems> to implement a specialized
web crawler.  M<Stem> will be used as
the communications backbone for this multiprocessor system and
it will interconnect and manage all of its components. Some of
those components include subprocesses doing the page fetches,
site objects, html page parsers, custom filters, crawl management
and a database.

QUOTE<
        Divers search limpid pools. \
        Precious Perl is summer's find, \
        But Stem is loved more. \
        -- D.G. \
>

Q: How can I be notified about M<Stem> updates?
A: M<Stem Systems> has a email list dedicated to M<Stem> updates.  To
subscribe, send an empty email to: news-subscribe@stemsystems.com.  This
is a low volume list used for sending important news regarding M<Stem>
(ie - new releases).

S: M<Stem> Design

Q: Do I Need To Get Rid Of [Commercial Application] To Use M<Stem>?
A: No, M<Stem> can run in parallel with all of 
your existing applications. As long as M<Stem> 
can have access to its own TCP ports (which can be configured to
any available ones), it has no need to conflict with any of your current
systems.

QUOTE<
        superglue the net \
        tie the machines together \
        stem keeps it all sane \
        -- U.G. \
>


Q: What is a M<Stem> Hub?
A: A M<Stem> Hub is a single Perl process running 
M<Stem>. It can function as a complete standalone 
application or be connected to other M<Stem> Hubs in a
networked application. M<Stem> Hubs contain the 
M<Stem> core system and M<Stem>
Cells that have been created by configuration files. 

<P>For more on this, read the 
<A href="technotes/arch_notes.html">architecture notes</A> document or find it 
in the Design directory of the tarball.

Q: What is a M<Stem> Cell?
A: A M<Stem> Cell is a Perl object that has 3 major characteristics:

<OL>
   <LI><P>First, it is registered as a Cell in this Hub with a cell name and 
        an optional target name</P></LI>
   <LI><P>It has a set of methods designated to handle messages directed at 
        the Cell</P></LI>
   <LI><P>It sends messages to other cells.</P></LI>
</OL>


S: M<Stem> Features


Q: What is a M<Stem> Message?
A: M<Stem> Messages carry commands and data between 
M<Stem> Cells. They are addressed with a 
Hub/Cell/Target triplet. 

<P>Messages can be any one of a wide range of types including command, 
data, log, stderr etc. They can carry any form of data to a maximum 
(to be designated later) size. 

<P>See
<A HREF="technotes/message_notes.html">message notes</A> document for more.

QUOTE<
        Nets catch more than fish. \
        Data's trapped beneath the waves. \
        Stem frees; packets breathe. \
        -- D.G. \
>


Q: How Hard Is M<Stem> To Install/Configure?
A: M<Stem> is very easy to install. It only requires 
Perl 5.005_03 and one code module Event.pm that you can get from 
<A HREF="http://search.cpan.org">CPAN</A>. The rest of
M<Stem> is comprised of pure Perl modules.

<p>M<Stem> has a step by step installation
script that guides you through the installation process and any
required modules that are necessary for the normal functioning of M<Stem>.
It is easy to use and allows you to customize the installation to
your liking or take the default install.

<P>Much more on this can be found in the 
<A href="technotes/config_notes.html">config notes</A> 
document or in the Design directory of the tarball.


Q: Can M<Stem> Do Guaranteed Messaging?
A: M<Stem>'s core design does not directly support 
guaranteed message delivery. It was designed this way, as the 
technical market that M<Stem> targets
doesn't have a strong requirement for this feature as the
commercial/e-business markets have. 

<P>Future releases of M<Stem> will support guaranteed delivery via a 
separate module that is now under development.



Q: Does M<Stem> Use XML?
A: M<Stem>'s messages are designed to not be specific 
to any format or encoding. They can carry data structure in any format the 
designer wants, including XML.  In fact, the message itself can also be in 
any format as long as it is properly identified and a module to decode that 
format is installed. 

<p>M<Stem> is currently in the process of including
<a href="http://www.yaml.org" name="YAML">YAML</a> as its primary format for
messages, configuration files, and logs, but as demand arises other message formats
including XML will be supported.

<P>One longer-term goal is that message formats from many other
systems will be supported by gateways modules, which will translate
between M<Stem> and external messages.

Q: What Kind Of Security Does M<Stem> Use?
A: M<Stem> doesn't do direct authentication and secure
transmissions. Currently it relies upon industry standard utilities such as ssh and
stunnel to provide the secure socket connections between 
M<Stem> hubs (processes).  Security is a great concern to
everyone and M<Stem> development is looking into the possibilities
of supporting various mechanisms and levels of security (i.e. - ssh, ssl, etc)
through configurable modules.

QUOTE<
        Information rain \
        Can drown the sleepy server, \
        But for Stem's shelter. \
        -- D.G. \
>


Q: Can M<Stem> Do Central Configuration Management?
A: The log management project under development has this requirement. The
lists of log files on each system that need to be monitored are
maintained on the central system. Configuration files are autogenerated
from those lists and distributed to all the M<Stem> hubs in this network
application. The same mechanism can be used to distribute configuration
files for other applications and M<Stem> can also notify them to reload the
new files.

Q: Can M<Stem> Handle My Content Distribution?
A: Distributing content is similar to distributing configuration files and
will use the same mechanisms. What content is distributed to where can
all be easily controlled by M<Stem> configurations without any additional
programming.


S: Developing with M<Stem>


Q: Can I Extend M<Stem> Myself To Suit Our Needs?
A: M<Stem> is designed to be modified and extended very
easily. You can copy existing modules or use design ideas from them to
created new Cells for your own needs.

<P>The high level Cell API hides the complexities of
network communication and message transfer, leaving you free to focus on
the specific design and coding of your custom Cells.


QUOTE<
        Just one message lost \
        could stop your business blooming. \
        Fear not: grasp the stem! \
        -- D.G. \
>

Q: Is There a M<Stem> Tutorial?
A: M<Stem> Development has created a <a href="cookbook.html" name="cookbook">cookbook</a> of examples that demonstrates the
design of M<Stem> cells from the simplest form up
to various levels of complexity.


Q: Should I Modify M<Stem> On My Own Or Use M<Stem>'s Development Team?
A: If your requirements are simple, and you have skilled staff to do the
work, there's no reason not to develop and maintain your own M<Stem>-based
systems. If your applications are complex applications, your staff new
to M<Stem>, or your time-frame short, you will probably find it more
cost-effective to let M<Stem Systems>' expert team develop your system for
you.

<P>Otherwise, M<Stem Systems> can assist you in the design, development and
configuration of your application. How much assistance can be provided
depends on the customer subscription deal and any other contracts. If
you do not have a subscription, our support will be limited to bug fixes
and email and you will have to maintain your modified code on your own.

Q: Which Operating Systems Support M<Stem>?
A: M<Stem> runs runs without any modification under any Unix flavor (Solaris,
Linix, FreeBSD, etc.)  Support for WinX is in the planning stage and is
expected to be released in the near future.

Q: What Is M<Stem>'s License?
A: M<Stem> will be released under the <a
href="http://www.gnu.org/copyleft/gpl.html" name="GPL">GNU General
Public License</a> starting with version 0.06.  Our intent is for
M<Stem> to be free for non-commercial use.  Commercial licenses can be
purchased through M<Stem Systems>.  Please contact <a
href="mailto:info@stemsystems.com">Stem Systems</a> for more
information regarding commercial license.


S: M<Stem Systems>


Q: What Is M<Stem Systems>?
A: M<Stem Systems> is the company which is developing and maintaining M<Stem>. It
owns the copyright to the M<Stem> codebase and is releasing it to its
customers and the open source community. M<Stem Systems> also sells support
subscriptions to the M<Stem> user community.

QUOTE<
        Black chips nurture life. \
        Data shoots out, seeking Spring. \
        Stem makes all fertile. \
        -- D.G. \
>

Q: What Is The Business Model Of M<Stem Systems>?
A: M<Stem Systems> has three business models,
<ol>
        <li>Development Projects</li>
        <li>Support Subscriptions</li>
        <li>3rd Party products and VAR's</li>
</ol>

Q: How Much Does M<Stem> Cost?
A: 0.06 will be under the
<a href="http://www.gnu.org/copyleft/gpl.html" name="GPL">GNU General
Public License</a>.  M<Stem> can be used freely for non-commercial
use.  For commercial and acedemic licenses please contact us at <a
href="mailto:sales@stemsystems.com">Stem Systems</a> for more
information.


Q: Who Are Your Technical Advisors?
A: Our technical advisors are listed <A HREF="company.html">here</A>.

S: Miscellaneous


Q: How Can I Learn M<Stem>?
A: The best way right now is to start with the technical notes and get a
basic understanding of M<Stem>, its architecture and
its nomenclature. Then run the various demo scripts and read their 
configuration files. Developers will go next to the Cell documentation that 
describes each Cell's function, their attributes and how to configure it. 
Once some insight into each Cell is attained the next step would be to go
through M<Stem>'s <a href="cookbook.html" name="cookbook">cookbook</a>
of examples put together by the developers of M<Stem>.  This will
show you how to extend M<Stem> with your own Cells.

<P>We are discussing the
creation of classes with a training firm when the demand arises.

Q: What Is The Future Of M<Stem>?
A: M<Stem> will constantly be growing its Cell library and adding support for
new features. Whenever any repeated networked operations can be
identified, M<Stem> will create a M<Stem> Cell to 
perform it. Then M<Stem>'s
users can easily integrate that new Cell without programming or needing
to re-invent that wheel.

Q: Who Created M<Stem>?
A: M<Stem> was created by Uri Guttman, and is the 
culmination of his long career in systems architecture and development. He has combined a
quarter century of experience designing and implementing event-driven
systems with his love of Perl to produce a powerful, yet easy-to-use
framework for network applications. 

<P>For more on M<Stem>'s creator, see the 
<A HREF="http://stemsystems.com/company.html">M<Stem> Team biographies</A>.

Q: How (and why) Was M<Stem> Conceived?
A: M<Stem> was created when its designer was contracted 
to a network application development group who were constantly 
putting out fires and creating a massive ad hoc system. It was clear that they needed a
framework to give structure to their network application design. 
M<Stem> was the result.

QUOTE<
        Coders or firemen? \
        System in conflagration. \
        From ashes rose Stem. \
        -- U.G. \
>


Q: What Does M<Stem> Stand For?
A: M<Stem> is not an acronym or an abbreviation, rather it is named from the
real word 'stem' which has several dictionary meanings that map well to M<Stem>.

<DL><DT><B>v. tr.</B></DT>
<DD><OL><LI>To stop or hold back by or as if by damming; as in "stem the tide"</OL></DD></DL>

<DL><DT><B>n.</B></DT>
<DD><OL><LI>A slender stalk supporting or connecting another plant part, such as a leaf or flower.
        <LI>A connecting or supporting part.
</OL></DD></DL>

<DL><DT><B>n.</B></DT>
<DD><OL><LI>A line of ancestry : STOCK; especially : a fundamental line from
which others have arisen. as in "stem cell" in biology.</OL></DD></DL>


QUOTE<
        To keep your network \
        flowering when the heat's on, \
        it needs a strong stem. \
        -- D.C. \
>