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The new dashboard from the CloudStack 3.0 beta.

Over the last year I have been working on the CloudStack Open Source Cloud Computing project. This month we are getting ready to launch CloudStack 3.0 which really raises the bar for cloud computing platforms.  So what is CloudStack ? short It is an infrastructure-as-a-service(IaaS) platform that orchestrates virtualized servers into an elastic compute environment. The project was originally developed by Cloud.com and is now sponsored by Citrix since they acquired Cloud.com in July of 2011.

CloudStack provides multiple methods for interacting with the CloudStack compute platform. Users can request resources through a rich menu-driven web interface. Operations personnel can use an enhanced version of the web interface or interact with CloudStack’s RESTful API or command line interface (CLI). The new 3.0 UI takes things up a notch making it very intuitive for users to administer their own cloud computing so administrators can delegate infrastructure provisioning and focus on more high value tasks than spinning up servers.

Another thing that I think sets CloudStack apart is it’s networking-as-a-service capabilities. CloudStack administrator can create any number of custom network offerings in addition to the default network offerings provided by CloudStack.  These offerings can be attached to the virtualized machines deployed by Cloudstack. Cloudstack allows user to choose the type of network architecture that best fits their needs.  Out-of-the-box support includes the Basic Network, or flat network mode or advanced networking VLAN support and integration of network elements including external firewalls and load balancers. Administrators can offer different classes of service on a single multi-tenant physical network with a combination of networking offerings that include DHCP, Source Network Address Translation (NAT), Gateway, Load Balancing, Firewall, VPN, Port Forwarding.

You can get the details on the beta of CloudStack 3.0 from the CloudStack open source project and the GA version should be available in the upcoming weeks.

What’s New in CloudStack 3.0

For those of you who are familiar with CloudStack here’s a list of features that will be included in CloudStack 3.0.

• Organize Users and Resources by Projects – users can group themselves into projects so they can collaborate and share virtual resources. CloudStack tracks usage per project as well as per user, so the usage can be billed to either a user account or a project.
• Support for Citrix Netscaler – Citrix NetScaler(MPX, VPX, SDX) is now supported as an external network element for load balancing in zones that use advanced networking (also called advanced zones). Set up an external load balancer when you want to provide load balancing through means other than CloudStack’s provided virtual router.
• Sticky Session Policies for External Load Balancers – Sticky sessions are used in Web-based applications to ensure continued availability of information across the multiple requests in a user’s session. For example, if a shopper is filling a cart, you need to remember what has been purchased so far. The concept of“stickiness” is also referred to as persistence, or maintaining state.
• LDAP User Authentication – you can use an external LDAP server such as Microsoft Active Directory or ApacheDS for end-user authentication. Just map CloudStack accounts to the corresponding LDAP accounts using a query filter.
• VM  Storage Migration - CloudStack administrator can move a virtual machine’s root disk volume or any additional data disk from one storage pool to another in the same zone.
• OpenStack Swift for Secondary Storage - In previous versions of CloudStack, NFS storage is supported for secondary storage. In CloudStack 3.0, OpenStack Object Storage (Swift, http://swift.openstack.org) is also supported for secondary storage.
• Password and Key Encryption – CloudStack stores several sensitive passwords and secret keys that are used to provide security. Starting in CloudStack 3.0, these values are always automatically encrypted. (Database Secret Key, Database Password
• Security Group Egress Rules - In addition to ingress rules that control incoming network traffic to VMs in a given security group, starting in CloudStack 3.0 you can also define egress rules to control outgoing network traffic.

Technorati Tags: cloud computing, cloudstack, Iaas, Infrastructure-as-a-Service, Networking-as-a-Service, Open Source

common_schema, revision 218 is released, with major new features, top one being server side scripting. Here are the highlights:

• QueryScript: server side scripting is now supported by common_schema, which acts as an interpreter for QueryScript code.
• Throttling for queries is now made available via the throttle() function.
• Enhancements to processlist-related views, including the new slave_hosts view.
• Inline documentation/help is available via the help() routine.
• more...

QueryScript

common_schema makes for a QueryScript implementation for MySQL. You can run server side scripts, interpreted by common_schema, which allow for easy syntax and greater power than was otherwise previously available on the MySQL server. For example:

foreach($table, $schema, $engine: table like '%')
  if ($engine = 'ndbcluster')
    ALTER ONLINE TABLE :$schema.:$table REORGANIZE PARTITION;

QueryScript includes flow control, conditional branching, variables & variable expansion, script throttling and more.

Read more on common_schema's QueryScript implementation.

Query throttling

Throttling for MySQL queries was suggested by means of elaborate query manipulation. It is now reduced into a single throttle function: one can now just invoke throttle(3) on one's query, so as to make the query execute for a longer time, while taking short sleep breaks during operation, easing up the query's demand for resources.

Read more on query throttling.

Process views

The processlist_grantees view provides with more details on the running processes. slave_hosts is a new view, listing hostnames of connected slaves.

Read more on process views.

help()

The common_schema documentation is now composed of well over 100 pages, including synopsis, detailed internals discussion, notes and examples. I can't exaggerate in saying that the documentation took the vast majority of time for this code to release.

The documentation is now made available inline, from within you mysql client, via the help() routine. Want to know more about redundant (duplicate) keys and how to find them? Just type:

call help('redundant');

and see what comes out!

The entire documentation, which is available online as well as a downloadable bundle, is embedded into common_schema itself. It's rather cool.

Tests

common_schema is tested. The number of tests in common_schema is rapidly growing, and new tests are introduced for new features as well as for older ones. There is not yet full coverage for all views, but I'm working hard at it. common_schema is a robust piece of code!

Get it!

Download common_schema on the common_schema project page.

Read the documentation online, or download it as well (or call for help())

common_schema is released under the BSD license.

Introducing QueryScript: a programming language aimed for SQL scripting, seamlessly combining scripting power such as flow control & variables with standard SQL statements or RDBMS-specific commands.

QueryScript is available fro MySQL via common_schema, which adds MySQL-specific usage.

What does QueryScript look like? Here are a few code samples:

Turn a bulk DELETE operation into smaller tasks. Throttle in between.

while (DELETE FROM archive.events WHERE ts < CURDATE() LIMIT 1000)
{
  throttle 2;
}

Convert all InnoDB tables in the 'sakila' database to compressed format:

foreach ($table, $schema, $engine: table in sakila)
{
  if ($engine = 'InnoDB')
    ALTER TABLE :$schema.:$table ENGINE=InnoDB ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=8;
}

Shard your data across multiple schemata:

foreach($shard: {USA, GBR, JAP, FRA})
{
  CREATE DATABASE db_:$shard;
  CREATE TABLE db_:$shard.city LIKE world.City;
  INSERT INTO db_:$shard.city SELECT * FROM world.City WHERE CountryCode = $shard;
}

This tight integration between script and SQL, with the power of iteration, conditional statements, variables, variable expansion, throttling etc., makes QueryScript a power tool, with capabilities superseding those of stored routines, and allowing for simplified, dynamic code.

QueryScript code is interpreted. It's just a text, so it can be read from a @user_defined_variable, a table column, text file, what have you. For example:

mysql> set @script := "while (TIME(SYSDATE()) < '17:00:00') SELECT * FROM world.City WHERE id = 1 + FLOOR((RAND()*4079));";
mysql> call run(@script);

For more details, consult the QueryScript site.

If you're a MySQL user/DBA, better read the common_schema QueryScript documentation, to better understand the specific common_schema implementation and enhanced features.

common_schema, including the QueryScript interpreter, can be downloaded from the common_schema project page.

In my day job at SkySQL I work with Drupal as our content management system.  One thing we often need to do is provide a way for people to sign up for events and the like.  One such event is the upcoming SkySQL and MariaDB: Solutions Day for the MySQL® Database and unlike other events we needed to take into account the dietary requirements of those wishing to attend.

For events registration we use the Signup module and use a theme template function to provide a set of standard fields.  The code looks something like this:

function ourtheme_signup_user_form($node) {
  $form = array();
  // If this function is providing any extra fields at all, the following
  // line is required for form form to work -- DO NOT EDIT OR REMOVE.
  $form['signup_form_data']['#tree'] = TRUE;

  $form['signup_form_data']['FirstName'] = array(
    '#type' => 'textfield',
    '#title' => t('First Name'),
    '#size' => 40, '#maxlength' => 64,
    '#required' => TRUE,
  );
  $form['signup_form_data']['LastName'] = array(
    '#type' => 'textfield',
    '#title' => t('Last Name'),
    '#size' => 40, '#maxlength' => 64,
    '#required' => TRUE,
  );

And so on, building up the elements and then returning the form.  This is great because it allows us to have a standard set of fields for all signup pages, making life a lot simpler when creating content that requires registration.  But the Solutions Day event required an extra field.  I could have done this a number of ways, including putting logic in the template file to check for that particular node and only display the field then, or perhaps some other hack specific to this node.  I, however, don't like specifics and tend to look for a generic solution, as the exception invariably becomes the rule.

For this exercise I wanted to be able to have a way of specifying for a particular node any extra fields that are available for this form.  So I now have in the template.php file the following code:

// If there is a special field required for this, check and display
  if (!empty($node->field_signup_extra) && !empty($node->field_signup_extra[0]['value'])) {
    $extras = explode("\n", $node->field_signup_extra[0]['value']);
    foreach ($extras as $field_def) {
        $field_def = trim($field_def);
        if (empty($field_def)) {
            continue;
        }
        $elems = explode('|', $field_def);
        $field_name = array_unshift($elems);

        $form['signup_form_data'][$field_name] = array();
        foreach ($elems as $field_element) {
          list($key, $val) = explode('=',$field_element);
          if ($key == 'options') {
              $val = explode(',', $val);
          }
          $form['signup_form_data'][$field_name]['#' . $key] = $val;
        }
    }
  }

Now all I need to do is create a field that is non-displayable but contains information to build extra fields.  For example the content that describes the Dietary Requirements field is:

dietary_requirements|title=Dietary Requirements|size=40|type=textfield

The production version does a little more analysis of the input to ensure there are no possible attack vectors, but I've left that out for clarity sake.

Now, if I have an event (or other content type) that needs extra signup fields, I ensure that the content type has the new Signup Extras field and fill it on the new content with a simple field definition that Signup can use.

Dear Kettle fans,

Today I’m really excited to be able to announce a few really important changes to the Pentaho Data Integration landscape. To me, the changes that are being announced today compare favorably to reaching Kettle version 1.0 some 9 years ago, or reaching version 2.0 with plugin support or even open sourcing Kettle itself…

First of all…

Pentaho is again open sourcing an important piece of software.  Today we’re bringing all big data related software to you as open source software.  This includes all currently available capabilities to access HDFS, MongoDB, Cassandra, HBase, the specific VFS drivers we created as well as the ability to execute work inside of Hadoop (MapReduce), Amazon EMR, Pig and so on.

This is important to you because it means that you can now use Kettle to integrate a multitude of technologies, ranging from files over relational databases to big data and NoSQL.  You can do this in other words without writing any code.  Take a look at how easy it is to program for Hadoop MapReduce:

In other words, this part of the big news of today allows you to use the best tool for the job, whatever that tool is. You can now combine the large set of steps and job entries with all the available data sources and use that to integrate everything. Especially for Hadoop the time it takes to implement a MapReduce job is really small taking the sting out of costly and long training and testing cycles.

But that’s not all…

Pentaho Data Integration as well as the new big data plugins are now available under the Apache License 2.0. This means that it’s now very easy to integrate Kettle or the plugins in 3rd party software. In fact, for Hadoop, all major distributions are already supported including: Amazon Elastic MapReduce, Apache Hadoop, Cloudera’s Distribution including Apache Hadoop (CDH), Cloudera Enterprise, EMC Greenplum HD, HortonWorks Data Platform powered by Apache Hadoop, and MapR’s M3 Free and M5 Edition.
The change of Kettle from LGPL to Apache License 2.0 was broadly supported by our community and acts as an open invitation for other projects (and companies) to integrate Kettle. I hope that more NoSQL, Big Data and Big Search communities will reach out to us to work together to even broaden our portfolio. The way I see it, the Kettle community just got a whole lot bigger!

Where are the goodies?

The main landing page for the Big Data community is placed on our wiki to emphasize our intention to closely work with the various communities to make Pentaho Big Data a success. You can find all information over there, including a set of videos, PDI 4.3.0 preview download (including Big Data plugins), Hadoop installation instructions, PRD configuration information and much more.

Thanks for your time reading this and thanks for using Pentaho software!

Matt

Dear Kettle fans,

Today I’m really excited to be able to announce a few really important changes to the Pentaho Data Integration landscape. To me, the changes that are being announced today compare favorably to reaching Kettle version 1.0 some 9 years ago, or reaching version 2.0 with plugin support or even open sourcing Kettle itself…

First of all…

Pentaho is again open sourcing an important piece of software.  Today we’re bringing all big data related software to you as open source software.  This includes all currently available capabilities to access HDFS, MongoDB, Cassandra, HBase, the specific VFS drivers we created as well as the ability to execute work inside of Hadoop (MapReduce), Amazon EMR, Pig and so on.

This is important to you because it means that you can now use Kettle to integrate a multitude of technologies, ranging from files over relational databases to big data and NoSQL.  You can do this in other words without writing any code.  Take a look at how easy it is to program for Hadoop MapReduce:

In other words, this part of the big news of today allows you to use the best tool for the job, whatever that tool is. You can now combine the large set of steps and job entries with all the available data sources and use that to integrate everything. Especially for Hadoop the time it takes to implement a MapReduce job is really small taking the sting out of costly and long training and testing cycles.

But that’s not all…

Pentaho Data Integration as well as the new big data plugins are now available under the Apache License 2.0. This means that it’s now very easy to integrate Kettle or the plugins in 3rd party software. In fact, for Hadoop, all major distributions are already supported including: Amazon Elastic MapReduce, Apache Hadoop, Cloudera’s Distribution including Apache Hadoop (CDH), Cloudera Enterprise, EMC Greenplum HD, HortonWorks Data Platform powered by Apache Hadoop, and MapR’s M3 Free and M5 Edition.
The change of Kettle from LGPL to Apache License 2.0 was broadly supported by our community and acts as an open invitation for other projects (and companies) to integrate Kettle. I hope that more NoSQL, Big Data and Big Search communities will reach out to us to work together to even broaden our portfolio. The way I see it, the Kettle community just got a whole lot bigger!

Where are the goodies?

The main landing page for the Big Data community is placed on our wiki to emphasize our intention to closely work with the various communities to make Pentaho Big Data a success. You can find all information over there, including a set of videos, PDI 4.3.0 preview download (including Big Data plugins), Hadoop installation instructions, PRD configuration information and much more.

Thanks for your time reading this and thanks for using Pentaho software!

Matt

Dear Kettle fans,

Today I’m really excited to be able to announce a few really important changes to the Pentaho Data Integration landscape. To me, the changes that are being announced today compare favorably to reaching Kettle version 1.0 some 9 years ago, or reaching version 2.0 with plugin support or even open sourcing Kettle itself…

First of all…

Pentaho is again open sourcing an important piece of software.  Today we’re bringing all big data related software to you as open source software.  This includes all currently available capabilities to access HDFS, MongoDB, Cassandra, HBase, the specific VFS drivers we created as well as the ability to execute work inside of Hadoop (MapReduce), Amazon EMR, Pig and so on.

This is important to you because it means that you can now use Kettle to integrate a multitude of technologies, ranging from files over relational databases to big data and NoSQL.  You can do this in other words without writing any code.  Take a look at how easy it is to program for Hadoop MapReduce:

In other words, this part of the big news of today allows you to use the best tool for the job, whatever that tool is. You can now combine the large set of steps and job entries with all the available data sources and use that to integrate everything. Especially for Hadoop the time it takes to implement a MapReduce job is really small taking the sting out of costly and long training and testing cycles.

But that’s not all…

Pentaho Data Integration as well as the new big data plugins are now available under the Apache License 2.0. This means that it’s now very easy to integrate Kettle or the plugins in 3rd party software. In fact, for Hadoop, all major distributions are already supported including: Amazon Elastic MapReduce, Apache Hadoop, Cloudera’s Distribution including Apache Hadoop (CDH), Cloudera Enterprise, EMC Greenplum HD, HortonWorks Data Platform powered by Apache Hadoop, and MapR’s M3 Free and M5 Edition.
The change of Kettle from LGPL to Apache License 2.0 was broadly supported by our community and acts as an open invitation for other projects (and companies) to integrate Kettle. I hope that more NoSQL, Big Data and Big Search communities will reach out to us to work together to even broaden our portfolio. The way I see it, the Kettle community just got a whole lot bigger!

Where are the goodies?

The main landing page for the Big Data community is placed on our wiki to emphasize our intention to closely work with the various communities to make Pentaho Big Data a success. You can find all information over there, including a set of videos, PDI 4.3.0 preview download (including Big Data plugins), Hadoop installation instructions, PRD configuration information and much more.

Thanks for your time reading this and thanks for using Pentaho software!

Matt

Topics for this podcast:

*Hadoop v1.0 and year ahead
*Oracle-Cloudera deal for more Hadoop
*Oracle’s ‘Sun spot’ with Solaris
*Open Source M&A outlook for 2012
*Our new MySQL/NoSQL/NewSQL survey

iTunes or direct download (28:49, 4.9MB)

Linux.conf.au this year kicks off next week in Ballarat, just down the road from me.  I'll be there and even have a speaking gig, not in the main conference but in the HA and Distributed Storage mini-conf before the main event.

I'll be talking about MySQL®, the companies that now exist to support it, and the third party products that are starting to proliferate in what appears to be a community effort to address perceived shortcomings in the Oracle offerings.  Many of these offerings are in the HA space, and there have been some pretty amazing developments recently.

So if you want to find some history of Oracle's effect on MySQL's development (and a hint, it started well before the Sun acquisition), or you want to find out what is out there to assist you in developing HA and Distributed database systems, come along.  I'll be wearing my SkySQL shirt so I should be easy to pick.

Documentation is an important part of any project. On the projects I maintain I put a lot of effort on documentation, and, frankly, the majority of time spent on my projects is on documentation.

The matter of keeping the documentation faithful is a topic of interest. I'd like to outline a few documentation bundling possibilities, and the present the coming new documentation method for common_schema. I'll talk about any bundling that is NOT man pages.

High level: web docs

This is the initial method of documentation I used for openark kit and mycheckpoint. It's still valid for mycheckpoint. Documentation is web-based. You need Internet access to read it. It's in HTML format.

Well, not exactly HTML format: I wrote it in WordPress. Yes, it's HTML, but there's a lot of noise around (theme, menus, etc.) which is not strictly part of the documentation.

While this is perhaps the easiest way to go, here's a few drawbacks:

• You're bound to some framework (WordPress in this case)
• Docs are split between MySQL database (my underlying WordPRess storage) & WordPress files (themes, style, header, footer etc.)
• Documentation is separate from your code - they're just not in the same place
• There is no version control over the documentation.

The result is a single source of documentation, which applies to whatever version is latest. It's impossible to maintain docs for multiple versions. You must manually synchronize your WordPress updates with code commits (or rather - code release!).

Mid level: version controlled HTML docs

I first saw this approach on Baron's Aspersa gets a user manual post. I loved it: the documentation is HTML, but stored as part of your project's code, in same version control.

This means one can browse the documentation (openark kit in this example) exactly as it appears in the baseline. Depending on your project hosting, one may be able to do so per version.

The approach has the great benefit of having the docs tightly coupled with the code in terms of development. Before committing code, one updates documentation for that code, then commits/releases both together.

You're also not bound to any development framework. You may edit with vim, emacs, gedit, bluefish, eclipse, ... any tool of your choice. It's all down to plain old text files.

Mid level #2: documentation bundling

One thing I started doing with common_schema is to release a doc bundle with the code. So one can download a compressed bundle of all HTML files. That way one is absolutely certain what's the right documentation for revision 178. There's no effort about it: the docs are already tightly coupled with code versions. Just compress and distribute.

Low level: documentation coupled with your code

Perl scripts can be written as Perl modules, in which case they are eligible for using the perldoc convention. You code your documentation within your script itself, as comment. Perldoc can extract the documentation and present in man-like format. Same happens with Python's pydoc. Baron's When documentation is code illustrates that approach. Maatkit (now Percona Toolkit) has been using it for years.

This method has the advantage of having the documentation ready right within your shell. You don't need a browser, nor firewall access. The docs are just there for you in the same environment where you're executing the code.

SQL Low level: CALL for help()

common_schema is a different type of project. It is merely a schema. There's no Perl nor Python. One imports the schema into one's MySQL server.

What's the low-level approach for this type of code?

For common_schema I use three levels of documentation: the mid-level, where one can browse through the versioned docs, the 2nd mid-level, where one can download bundled documentation, and then a low-level approach: documentation embedded within the code.

MySQL's documentation is also built into the server: see the help_* tables within the mysql schema. The mysql command line client allows one to access help by supporting the help command, e.g.

mysql> help create table;

The client intercepts this command (this is not server side command) and searches through the mysql.help_* docs.

With common_schema, I don't have control over the client; it's all on server side. But the code being a schema, what with stored routines and tables, it's easy enough to set up documentation.

As of the next version of common_schema, and following MySQL's method, common_schema provides a help table:

DESC help;
+--------------+-------------+------+-----+---------+-------+
| Field        | Type        | Null | Key | Default | Extra |
+--------------+-------------+------+-----+---------+-------+
| topic        | varchar(32) | NO   | PRI | NULL    |       |
| help_message | text        | NO   |     | NULL    |       |
+--------------+-------------+------+-----+---------+-------+

And a help() procedure, so that you can call for help(). The procedure will look for the best matching document based on your search expression:

root@mysql-5.1.51> CALL help('match');
+-------------------------------------------------------------------------------+
| help                                                                          |
+-------------------------------------------------------------------------------+
|                                                                               |
| NAME                                                                          |
|                                                                               |
| match_grantee(): Match an existing account based on user+host.                |
|                                                                               |
| TYPE                                                                          |
|                                                                               |
| Function                                                                      |
|                                                                               |
| DESCRIPTION                                                                   |
|                                                                               |
| MySQL does not provide with identification of logged in accounts. It only     |
| provides with user + host:port combination within processlist. Alas, these do |
| not directly map to accounts, as MySQL lists the host:port from which the     |
| connection is made, but not the (possibly wildcard) user or host.             |
| This function matches a user+host combination against the known accounts,     |
| using the same matching method as the MySQL server, to detect the account     |
| which MySQL identifies as the one matching. It is similar in essence to       |
| CURRENT_USER(), only it works for all sessions, not just for the current      |
| session.                                                                      |
|                                                                               |
| SYNOPSIS                                                                      |
|                                                                               |
|                                                                               |
|                                                                               |
|        match_grantee(connection_user char(16) CHARSET utf8,                   |
|        connection_host char(70) CHARSET utf8)                                 |
|          RETURNS VARCHAR(100) CHARSET utf8                                    |
|                                                                               |
|                                                                               |
| Input:                                                                        |
|                                                                               |
| * connection_user: user login (e.g. as specified by PROCESSLIST)              |
| * connection_host: login host. May optionally specify port number (e.g.       |
|   webhost:12345), which is discarded by the function. This is to support      |
|   immediate input from as specified by PROCESSLIST.                           |
|                                                                               |
|                                                                               |
| EXAMPLES                                                                      |
|                                                                               |
| Find an account matching the given use+host combination:                      |
|                                                                               |
|                                                                               |
|        mysql> SELECT match_grantee('apps', '192.128.0.1:12345') AS            |
|        grantee;                                                               |
|        +------------+                                                         |
|        | grantee    |                                                         |
|        +------------+                                                         |
|        | 'apps'@'%' |                                                         |
|        +------------+                                                         |
|                                                                               |
|                                                                               |
|                                                                               |
| ENVIRONMENT                                                                   |
|                                                                               |
| MySQL 5.1 or newer                                                            |
|                                                                               |
| SEE ALSO                                                                      |
|                                                                               |
| processlist_grantees                                                          |
|                                                                               |
| AUTHOR                                                                        |
|                                                                               |
| Shlomi Noach                                                                  |
|                                                                               |
+-------------------------------------------------------------------------------+

I like HTML for documentation. I think it's a good format, provided you don't start doing funny things. Perhaps TROFF is more suitable; certainly more popular on Unix machines. But I already have everything in HTML. So, what do I do?

My decision was to keep documentation in HTML, and use the handy html2text tool to do the job. And it does it pretty well! The sample you see above is an automated translation of HTML to plain text.

I add a few touches of my own: SELECTing long texts is ugly, whether you do it via ";" or "\G". The help() routine breaks the text by '\n', returning a multi row result set. The above sample makes for some 60+ rows, nicely formatted, broken from the original single text appearing in the help table.

So now you have an internal help method for common_schema, right where the code is. You don't have to leave the command line client in order to get help.

Giuseppe offered me the idea for this, even while my own thinking about it was in early stages.

The next version of common_schema will be available in a few weeks. The code is pretty much ready. I just need to work on, ahem..., the documentation.