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Source: ONLamp.com Maybe you know how to drive a car. Maybe you can fix the carburetor. You
probably don’t assume that you know how to design the car. However,
programmers who can write huge SQL statements and understand the output of an
EXPLAIN statement often assume that they can design a
database. Admittedly, unless we’re comparing Oracle 9i with the 1967
Volkswagen Beetle, databases usually aren’t more complex than cars, but a
properly designed database can be very hard to come by yet it’s the key to a
solid application.
Recently, a friend asked for help with a programming problem and I agreed
to take a look. After hearing a bit of explanation of the problem domain, and
taking a poke and what he had, I realized that while his code was indeed
buggy, the underlying bug stemmed from bad database design in an older version
of MySQL (some version 4, but I don’t recall the exact one). Many, many
developer hours are wasted on bad database design, but they often don’t seem
to realize this. We accept that bugs are something we need to deal with but don’t always realize our opportunities for minimizing those bugs. We curse at cleaning up garbage data in our database without
realizing that if you have a properly designed database, it can be very
difficult to insert garbage data.
Note: I’ve heavily changed the description of the problem domain to avoid
causing my friend problems, but database design is identical. In fact, I’ve so heavily changed the problem description that I’m practically lying about my role in it. I’m an American. Sue me.
My friend’s problem stemmed from some code which was trying to insert an undefined value into an
ENUM field named task.priority and he wasn’t sure why his
code was generating a warning. A warning in and of itself isn’t a bug, but it can hint at bugs. Boy were there bugs! (The warning was generated by code converting an undefined value to a NULL, but I won’t go into that). I did some digging in the database to
understand what was up. Here was my first query:
mysql select * from task where priority not in ('1','2','3');
+-----------+--------------+--------------+----------+
| job_queue | task | name | priority |
+-----------+--------------+--------------+----------+
| 0 | glj_three | Sum Accounts | |
| 0 | glj_demand | Reconcile | |
+-----------+--------------+--------------+----------+
So my second query was SHOW CREATE TABLE task.
CREATE TABLE task (
job_queue int(10) unsigned NOT NULL default '0',
task varchar(15) NOT NULL default '',
name varchar(50) NOT NULL default '',
priority enum('1','2','3') default NULL,
PRIMARY KEY (task),
KEY id (job_queue)
);
Note that many versions
of MySQL allow an empty string in this ENUM field :(
Before covering the numerous issues involved, let’s discuss what this is
for. We have ‘job queues’ which get executed and each job comprises a
series of tasks with a human readable name and a priority for the task in the
queue. What’s really crucial here is the business rules. As much as is
possible, business rules must be in the database layer, not in the
code layer. If you do this, another application using the database is much
less likely to get the business rules wrong. Here are the rules for this
problem.
Each job must have one primary task (priority 1).
Each job must have one secondary task (priority 2).
A job many have zero to many tertiary tasks (priority 3).
No task may be in more than one queue.
As a job is canceled, all tasks are released and do not have to be
reassigned.
Primary tasks must run first for each job.
Secondary tasks must run second for each job.
Tertiary tasks must run after secondary but in any order.
There is no job with an id of 0 (zero), so this was used to represent
‘free’ tasks (why they didn’t use NULL is beyond me, but even then
there’s a better way of doing this). As it turns out, special casing of the
job id can lead to bugs, but we’ll ignore that for this blog entry.
Since we had priority tasks failing, I decided to see if we had priorities
without jobs since this wouldn’t make much sense.
mysql select name, priority from task where job_queue = 0 limit 5;
+------------------+----------+
| Name | priority |
+------------------+----------+
| Cleanup Accts | 2 |
| Check Free Space | 1 |
| Allocate Funds | 2 |
| Process Invoices | 1 |
| Check Bonus | 2 |
+------------------+----------+
This was apparently from code which attempted to release tasks from jobs
with the SQL similar to the following:
UPDATE tasks SET job_queue = 0 WHERE job_queue = ?
Before we go on, a side note is in order. The above code is better written as this:
UPDATE tasks
SET job_queue = 0,
priority = NULL
WHERE job_queue = ?
First off, NULL values in a database can be very dangerous as they can easily lead to logic problems which produce incorrect query results. Second, if you find yourself with several fields in table which are coupled together and must always be updated together, perhaps they’re not really dependent on your primary key and should be in another table? It doesn’t guarantee a bug, but it’s a code smell which should be investigated. In our case, it’s a smell which leads to a better solution later.
Back to the issue at hand, we have a potential problem. If the code naively pulls tasks based on
priority and the code which removes jobs (sets job_queue to zero)
forgets to clear out priority, that could be a bug and different sections of
the code are tightly coupled. In fact, it could be easy to get confused
priorities merely by having this field:
SELECT job, task, name
FROM task
ORDER BY job, priority
As it turns out, priorities might have an empty string, but they could also
be NULL (arg!) so that should be written as:
SELECT job, task, name
FROM task
WHERE job != 0
AND priority != ''
AND priority IS NOT NULL
ORDER BY job, priority
Why do we have these weird special cases showing up? They’re hardly
intuitive. Instead, considering the aforementioned code smell, it would be better to have a job_queue_task table (typing
this SQL from memory, so it may have mistakes):
CREATE TABLE job_queue_task (
job_queue int(10) NOT NULL,
task varchar(15) NOT NULL UNIQUE,
priority enum('1','2','3') NOT NULL,
PRIMARY KEY (job_queue, task),
INDEX jq_idx (job_queue),
FOREIGN KEY (job_queue) REFERENCES job_queue(id),
INDEX task_idx (task),
FOREIGN KEY (task) REFERENCES task(id)
);
And your task table now looks like this (may as well make it
plural):
CREATE TABLE tasks (
task varchar(15) NOT NULL PRIMARY KEY,
name varchar(50) NOT NULL,
);
What this does is allow you to insert a record in the
job_queue_task table for each task for a job and to delete that record
when not needed (or delete an entire job_queue id from that table and not
worry about individual fields). Inserting or deleting entire records usually leads to fewer bugs than trying to always remember which fields to update and which to leave alone, particularly as tables grow in size. Selecting tasks now becomes this:
CREATE VIEW job_tasks AS SELECT
job_queue AS queue,
tasks.task AS task,
tasks.name AS name
FROM job_queue_task, tasks
WHERE job_queue_task.task = tasks.task
ORDER BY job_queue, priority
Then for all apps to figure out which jobs tasks are available, they can skip the tricky logic with:
SELECT queue, task, name FROM job_queue
Want to remove a job queue? Remember that we had this SQL:
UPDATE tasks
SET job_queue = 0,
priority = NULL
WHERE job_queue = ?
Now it’s as simple as this:
DELETE FROM job_queue_tasks WHERE job_queue = ?
The special cases have gone away and wrapping the CREATE TABLE statement in a view (not
possible in my friend’s version of MySQL) that apps have read access to can abstract
most of the problems away.
That leaves the question of the single primary and secondary priorities and
zero to many tertiary priorities. Depending on your database, you can write
the rule in a trigger or have the trigger call a stored procedure which,
before inserts or updates, validates that you’re not inserting a duplicate
primary or secondary priority (note that you can do interesting things by associating triggers with views, but MySQL doesn’t support this).
There’s a lot more which could be done with this, but this is just a basic
example of how to better represent business rules in a database. When
properly enforced, other applications can then use this database and are much
less likely to corrupt the data in there. This saves developer time as they
write fewer bugs and it lets your DBAs sleep at night.
Source: ONLamp.com I rarely see my colleagues, both in my work and in my hobbies. I spend most of my time collaborating with them, and one primary communication medium is email.
My personal mail server runs Postfix. Besides one small problem with a spam filtering message loop (mail forwarding to an account which rejects spam messages and includes the spam in the response is at least as evil as challenge-response), I’ve never had a lick of trouble.
Throw in server-side filtering with procmail or Email::Filter, as well as extended addresses, and I’m thrilled.
Then I discovered how to add just a couple of lines of configuration to make temporary, expirable addresses stunningly easy to create and manage and expirable, lightweight mailing lists, both of which require MTA administration beyond one initial configuration.
I never have to think about Postfix. It silently hums along, delivering buckets of mail. Thank you to all of its developers and contributors!
Source: ONLamp.com I ran into a beehive of standardization activity at
LinuxWorld Expo
this year. The outcomes of these efforts aren’t the traditional
standardization documents, numbingly complex yet short on critical
detail, that companies have to rush to implement. Instead, the
outcomes are working code, the open source way to achieve
interoperability.
This blog will talk about two organizations I met with and their
members–the Linux Mobile Foundation and the Open Solutions
Alliance–plus other interesting people I met at LinuxWorld Expo.
General LinuxWorld comments
I should make it clear that this weblog focuses on issues that are of
interest to me personally, and hopefully to readers of the O’Reilly
Network, which might not be the issues dominating the minds of the
LinuxWorld organizers and vendors.
The show itself, while offering a range of topics in tutorials and
sessions, focused on large data center issues such as storage and
virtualization. It was held in conjunction with another large-scale
trade show,
Next Generation Data Center,
and the joint theme could be summarized by a central statement made
by the first keynoter: “Data centers are cool and exciting.” As one
might expect, the bottom-line message in this keynote (by Werner
Vogels, VP and CTO of Amazon.com) is that after you’ve considered all
the complexities of running a data center (overprovisioning, disaster
and downtime prevention, load balancing, etc.) you’d do better to rent
space from Amazon. And it’s true that S3 has gotten fine reviews. I
mentioned it in a
blog
several months ago, comparing the model to CleverSafe (which was also
at LinuxWorld). But on to the show.
Mobile Movement
I’m starting with the Linux Mobile Foundation because I figure it’s
truly significant for major vendors such as Motorola, NEC, DoCoMo,
Samsung, Vodafone, and McAfee to throw their fate in common on a
jointly developed reference platform. A consortium of handset
manufacturers and service providers, they’re also looking for chip
manufacturers (which could integrate the platform at the chip level)
and application developers to join.
Linux Devices indicates that the platform is
not open source,
but I’ll be curious to see how dear the vendors treat the restrictions
if they discover benefits from sharing.
The LiMO representatives I met with stressed that development of open
source applications by a free software community was important to the
success of the platform, and thus of the products that LiMo members
were putting their money into. This suggests to me that pressure from
programmers to loosen the terms of the license can have a strong
effect. Motorola has released one SDK, and Japanese manufacturers NEC
and Panasonic have released another.
The reference platform is created from working software components
used by various members in actual products, so it starts out at a high
quality level, although the foundation will take a year to integrate
and test it, and those deploying it obviously have to add their own
testing.
The LiMO platform is currently aimed at mid-range phones and high-end
Smartphones. Phase 2 is hoped to encompass consumer devices; in
effect, someone will get used to using a single device both to control
consumer equipment in the home and to access voice and Internet
content on the road.
The range of components is pretty comprehensive. For instance,
protocols include cellular voice access, WiFi, Bluetooth, and GPS.
When moving in and out of a WiFi region, the phones should be able to
switch seamlessly between Wifi and cellular.
The user interface is left up to each service provider, but there is a
common user interface framework based on GTK+. LiMo representatives
said that GTK+ was appealing not only because it was open source but
because of its “rich technology.”
I also talked to representatives from Motorola, who pointed out the
continued growth of Linux-based mobile devices. They shipped 9 million
0f them since their first offering in China in 2003. Their Linux-based
MOTOMING handset became the best-selling SmartPhone in China,
capturing 1% share of the entire handset market in that country alone.
At the show, Motorola announced their next generation mobile Linux
platform, MOTOMAGX, which is designed to support three development
environments: Java (the most popular), native Linux, and WebUI (based
on Web Core). They are offering potential developers a series of
MOTODEV summits
in the U.S., England, and China on the new platform.
Current phones utilizing Motorola’s MOTOMAGX platform
(such as MOTORAZR2 V8 and MOTOROKR Z6) contain some proprietary
software, but Motorola intends to move to the open architecture
defined by LiMo for future MOTOMAGX releases.
The LiMo announcement has no immediate effect on at least three vendors
in the mobile Linux space.
I talked to a representative from
Trolltech
who cited the features of Qtopia (their proprietary toolkit for
mobile phones, based on Qt). Most recently, Qtopia integration with
the WebKit browser engine allows any application to draw on the same
advanced features as the Konqeror and Safari browsers. Flash
animation will also be integrated into Qt over the next three to six
months. Increased modularization in Qtopia 4.3 allows platform
developers to choose the features they want (the JVM, messaging, etc.)
and swap in components from other vendors.
Representatives at the booths of both
ACCESS
and
Unicon Systems
(who are both promoting developer kits)
also said they were confident in the value of their platforms and were
not planning to change them in response to LiMo.
Open Solutions Alliance and Application Vendors
Open source projects, ironically, are often harder to integrate than
proprietary ones. Dominic Sartorio of
SpikeSource
believes this is because many large proprietary companies, such as
Microsoft and Oracle, have whole suites of applications under their
ownership, and their managers can dictate how they interoperate.
Meanwhile, typical open source application communities focus on
solving the needs served by their projects, while not fully
considering interoperability issues.
Sartorio is president of the Open Solutions Alliance, formed six
months ago from seven application vendors in the open source
space. Their goal is to make all their products easy to integrate, an
effort that can have a wider effect on free software development as
well. They have provided a reference implementation combining their
products, and hope to provide a good example to other open source
projects.
OSA uses the members’ projects internally whenever possible. Thus,
they manage the company using Team Elements from
Centric CRM.
Single sign-on is implemented through SpikeSource’s product. This
provides one critical form of integration–sharing the user account
among all components–and is achieved through a language-independent
interface. Many new languages were added to this single sign-on
interface through a hackathon at the O’Reilly Open Source
convention. Another critical form of integration is sharing data,
accomplished through a product created by another OSA
member–Talend–using standard
JDBC and web services.
Centric itself has 11,000 registered members, who help with major
efforts such as ports to new databases, as well as routine bugs,
translations, etc. As with many vendors of open source products,
Centric tends to hire anyone who they find contributes a lot of good
software.
Another cofounder of OSA is Openbravo, a comprehensive ERP
platform. This was the #2 download on SourceForge when I met with
Josep Mitja, its COO and a board member of OSA, at LinuxWorld.
Enjoying 250,000 downloads by an estimated 50,000 people, Openbravo is
already looking beyond direct support (which is its income source) and
has built a set of service integrators to serve its customers.
Training has therefore become a major company activity.
Openbravo offers web-based interface and runs over Tomcat with either
an Oracle or a PostgreSQL database. It is thus a cross-platform
solution. But 30% of questions on the forum from people who download
Openbravo for free concern installation. For corporate customers
paying for support, therefore, Openbravo uses
rPath’s appliance-building tools
to provide a turn-key product. The rPath building system creates a
software image that can be loaded onto bare metal, into virtual
machine such as VMware, and so on.
Integrating a company’s data into the Openbravo system, along with
writing functions in Java to process activities for which defaults
don’t exist, takes an estimated 400 hours. They aim for the SME
market.
Building a user community is critical to the company’s success. All
source code is open; there is no difference between the commercial and
free versions. Participation on the wiki is strong. Mitja says,
“Everything we do has to support either dissemination or
monetization. Dissemination is the first requirement for success in
open source: if it doesn’t get out to the users, it can’t thrive. So
if an activity supports dissemination, we don’t force it to support
money-making as well.”
I stopped by the booth of SugarCRM, one of the earliest open source
companies in the CRM space, and also one of the first to prove that
open source could thrive at the application layer. Chris Harrick,
Director of Product Marketing, says that the company overcame
observers’ initial bias that open source was only for infrastructure,
and their skepticism about its ability to produce successful
commercial applications.
Like the other application companies, he considers building a community
around the software a crucial goal. “Our developers live on the forums,” he
says. The user base has responded with bug fixes, extensions, and
contributions to SugarCRM’s developer web site, SugarForge.org.
Linux Professional Institute: A Global Force
I spent a good deal of time with staff and board members of the Linux
Professional Institute (some of whom helped write O’Reilly’s
LPI Linux Certification in a Nutshell)
and heard some interesting assessments of Linux’s spread as well as
certification.
The certification market was oversold in the mid-90s and experienced a
dip, but is now rebounding. Globalization accentuates the importance
of certification. For instance, lots of Chinese companies would like
to prove that they offer competent IT staff, and need to show this
through a global standard. Many endorsements of LPI show that’s
recognized as just such a global standard. This Toronto-based,
vendor-independent, non-profit organization has put tremendous effort
into developing international affiliates and translating its exams
into many languages.
A Latin American affiliate reported progress there. By now, even
Microsoft supports LPI in order to promote interoperability, because
the exams test for interoperability in areas such as Samba and
LDAP. But the affiliate manager said that what he called the “war
against Microsoft” has held up adoption of Linux and open source in
Latin America. Companies intrinsically know that their adoption of
open source will have to be gradual and that it will have to co-exist
with Microsoft products, so they worry about the free software
community’s ability to enable that co-existence. A lack of
applications has also held up adoption, and–the area LPI can help
with–the lack of qualified professionals.
Closer to home, U.S. veterans can now use their educational benefits
to pay for taking the LPI.
Over 46,000 people are certified on various LPI levels. This has not
been achieved by handing out certifications willy-nilly, because over
150,000 exams have been taken. LPI has developed a special Ubuntu
exam, and have been asked by some other distributions to do the same
for them.
Notes from an interview with Ian Murdock
I was lucky to get an interview with Murdock, where I could talk about
both his opinions on Linux distributions and his current work for Sun
Microsystems. Ian describes himself as “always loving Sun.” As a
student in the early 90s, he “wanted a Sun workstation, like everybody
did.” A Sun staffer said they hired Ian because Sun had contributed a
lot to free software but were inadequately recognized for that, and
needed to build relations with the community.
The biggest community effort now, with the most potential payoff, is
Project Indiana, which makes it easier to obtain a binary of
OpenSolaris. When Solaris was opened, its source was put up publicly,
but Sun still built binaries internally for its customers. It was hard
for anybody outside Sun except technically sophisticated developers to
build binaries. Thus, Sun is reorganizing the architecture of Solaris
to make builds easier and working with Solaris community members to
smooth out the binary build process. Getting OpenSolaris will then be
as easy as loading the popular Linux distributions that offer
binaries.
Comparing the distribution of Linux and Solaris, Ian pointed out that
Linux vendors used to differentiate themselves partly on the basis of
the kernel (making it hard for ISVs to support the different
distributions) but that they’re much more similar now at the kernel
level. The variety of distributions is great for choice, but the lack
of compatibility that remains in file locations and other matters
still complicates application development and system administration.
Sun, through Project Indiana, hopes to achieve the same flexibility
without having the fragmentation. The differentiation between
distributions will presumably lie in the higher-level packages
offered, not the kernel.
In particular, offering an ABI for device drivers makes it easy for
outsiders to build Solaris drivers. The device companies don’t have to
offer the source, and the ABI is stable so that drivers should
continue to work through many future kernel upgrades. The Linux
community has politicized the issue of binary drivers and strongly
discourages them. Ian thinks the issue will ultimately be decided by
the marketplace. If open source is fundamentally an advantage,
companies that offer the source to their drivers will do better and
will win out.
The availability of device drivers for Solaris has improved a lot
since OpenSolaris was released, although it hasn’t caught up to the
number of devices supported by Linux.
So according to Murdock, “Solaris is not trying to be Linux.” It is
trying to build community and offer diversity in Sun’s own way. Sun’s
advantage in the marketplace is its presence at all levels up the
stack from the SPARC chip to middleware and applications.
Backups Behind Your Back
I stopped by Righteous Software (R1Soft) and talked to CEO David
Wartell, because I was intrigued by a uniquely flexible backup product
they offer. RiSoft can run incremental backups once every fifteen
minutes (or at another interval configured by the administrator)
without interfering substantially with system operation.
The key to the system is a device driver that sits below the Virtual
File System (VFS) and above the block device (SCSI, ATA, LVM, etc.).
The device driver keeps track of which blocks were written, and the
filesystem metadata. After the first backup, the driver marks which
blocks are dirty and backs up only the relevant data and metadata. The
driver therefore consists of two parts: one recording the data
written, and the other communicating with network software to perform
the remote backup.
This is more efficient than most backup solutions, which require a
userspace component and therefore have to go through the kernel on the
way up from the filesystem to userspace and down from userspace to the
network device. The operation is comparable to change tracking, but
ends up with a remote copy instead of one that shares the local
media. Data can be restored down to the granularity of a single file.
Snapshots are supported natively by NTFS’s Volume Shadow Copy feature,
and by LVM. For other filesystems supported by R1Soft–the popular
EXT2, EXT3, and ReiserFS–R1Soft adds shapshotting. Each snapshot
requires a very brief lock of the filesystem. Other than that, device
driver overhead is negligible. It requires about 3 Mb memory for each
100 Gb of hard drive.
The driver is binary-only, but can be rebuilt on the R1Soft web site
so that it can work with localized versions of the kernel. The
administrator doesn’t have to know the details of how the kernel was
built for his or her system, but just has to enter the pathname to the
kernel at the R1Soft web site, and then download the driver as a
loadable module. R1Soft will track open source developments and is
willing to consider open-sourcing the driver in the future.
R1Soft offers a similar product for MySQL backups. Instead of
filesystem metadata, database metadata is stored. Thus, data from
MySQL can be restored down to the granularity of a single table for
MyISAM and InnoDB storage engines. Wartell also says that R1Soft’s
backup system is the only way (other than LVM snapshots) to take a hot
backup of MyISAM without locking tables, and has several advantages
over Innobase’s commercial utility for taking hot backups of InnoDB.
What’s the Unbreakable in Unbreakable Linux?
I asked Monica Kumar, Senior Director for Linux and Open Source
Product Marketing at Oracle, what the company meant by that term. She
answered, “Unbreakable Linux is not a distribution,” a point that I
think is lost in many criticisms of Oracle’s marketing. Instead, she
writes, “Unbreakable Linux is all about seamless deployment of Linux
and enterprise-class supportability of Linux.” In short, it’s a
promise of support rather than a piece of software: “our commitment
and laser-sharp focus in helping end users deploy Linux for mission
critical applications.”
Oracle has made significant contributions to Linux, including
asynchronous I/O (AIO) and powerful distributed filesystems, their
newest announcement being called Btrfs. Asked to describe the demands
made by large files on databases and file systems, as well as the
contributions made by Oracle’s filesystems, Kumar listed:
Efficient snapshots
These will make it easier to perform live backups and other
administrative tasks.
Efficient incremental backups
Btrfs can quickly find the metadata and data that has changed since a
given revision, enabling very fast incremental backups.
Online filesystem check
An error in one part of the filesystem will not prevent the database
from coming online and doing its own internal datafile verification.
Metadata mirroring
Crucial filesystem data structures will be mirrored, and if one copy
of the metadata fails a checksum, Btrfs will be able to use the mirror
instead. This should reduce filesystem downtime in general.
Extent based storage
A number of Linux filesystems use extent based storage, because it
requires much less metadata and CPU time to address large files.
Device mapper integration
Btrfs will be able to work together with the device mapper layer to
optimize I/O on top of large storage arrays.
All of these features are aimed at general Linux usage, and will help
workloads outside of databases or large files. Kumar said that the
current Btrfs copy-on-write algorithms for file I/O will need tuning
before they are suitable for database usage.
Finally, I asked whether Oracle’s acquisition strategy (SleepyCat,
Innobase, and an offer for MySQL) as well as the free-for-download
Oracle Database XE, showed they were leaning toward releasing the
database as free software and concentrating on revenue from
higher-level tools and applications. She rejected this suggestion,
pointing to
Gartner’s report
that Oracle on the Linux platform grew 72% in one year, much faster
than overall RDBMS market growth (14.2%) and faster even than general
RDBMS growth on Linux (67%). Out of 2.35 billion dollars spent on
RDBMS on Linux, Oracle gets 1.95 billion.
The virtualization space: an interview with VMware
Operating systems are interfaces between applications and hardware,
and therefore have two big jobs to do:
Scheduling and resource management for applications running on top
Managing the drivers, memory, and other physical aspects of the system
underneath
Jack Lo, Senior Director of R&D, suggested that virtualized systems, ultimately, will
be able to use stripped-down operating systems that focus on the first
job and leave most of the second to the hypervisor.
The Linux kernel, from version 2.6.20 on, now has a two-layer
virtualization scheme. VMware helped to develop this, along with Xen
developers, IBM, Red Hat, and others. The guest operating system rests
on a layer called Paravirt-ops, which provides a common interface and
in turn directs resource requests to specific hypervisors below. The
VMware hypervisor under Paravirt-ops is called VMI. No significant
performance hit has been detected due to this two-layer scheme.
The kernel developers are also taking more account of virtualization
in designing kernel features, particularly now that Linux includes its
own virtualization layer (KVM). For instance, they are allowing the
operating system to generate fewer timer interrupts, and to take the
time of the next timer interrupt into account when determining when to
wake up a system that is being put to sleep.
One of the interesting new VMware feature is record/replay, which
manages to take a trace of all important instructions and store it in
a fairly small space. This has proven useful for debugging
hard-to-track bugs (such as application bugs due to race conditions)
and many other interesting ideas are circulating about how to use it.
Brief Notes
The world of MVC web frameworks got a serious new contender:
Zend Framework, released
under a BSD license.
Although other frameworks for PHP have been developed, Zend
Technologies expects this one to consolidate community efforts and
give people confidence the framework will continue to grow and perform
well. Feedback from the early adopters, some of them very large
companies running-high traffic sites, indicates that Zend Framework
performs and scales very well, much better than expected for a 1.0
release.
Next month, the Eclipse Foundation will release PDT, an open-source
PHP interface to Eclipse. Zend believes so strongly in the superiority
of PDT that it is making it the underpinning of a new commercial,
Eclipse-based version of its own Zend Studio IDE.
Perhaps in a couple years, just as every word processing file contains
author metadata and every desktop application is associated with
properties, we’ll get used to seeing licensing information attached by
a computer system to each document. If so, this will probably come
about through the efforts of a number of talented young students who
presented tools they had developed at a
Creative Commons salon
I attended. Authors or uploaders can tag documents, graphical
interfaces can attach icons, and embedded links can take you directly
to a licensing site, just as
O’Reilly’s Safari book service
offers access to standard copyrighted material through the
Copyright Clearance Center’s Rightslink. However, no hint of
monetization came through at the salon. The enthusiastic
experimentation there seemed to bear out the article I wrote two years
ago,
The Commons Doesn’t Have a Business Plan.
Open source security tool vendor
Untangle
announced the results of
testing several open and proprietary anti virus products.
As just a sample of the results, Norton came out substantially better
than McAfee, and as for Watchguard–well, go look at the web page I
just cited. Untangle engineers told me they’ve run these tests
annually for three years, and get consistent results each
time. Untangle, of course, is built entirely on open source software.
Does leadership style determine the social interactions and
psychological atmosphere of a free software project? It would not be
far-fetched to say so, and many project founders have been praised or
blamed for drawing in contributors or driving them away. But one
member of a free software project suggested to me that everything down
to the interactions on technical mailing lists can be traced back to
the personalities of a few key leaders. Readers are left to search for
evidence to confirm or repudiate the hypothesis–but one can then go
on to ask whether the leaders who are inspired to start projects are
shaped by the environments in which they begin.
Black Duck
has announced support for the GPL version 3 license in its software
compliance offerings, while
Palamida
is
tracking project conversions to version 3.
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