Grokbase Groups Struts dev June 2008
FAQ

[Struts-dev] environment awareness (project stage in JSF)

Frank W. Zammetti
Jun 29, 2008 at 1:19 pm
"In order to complete the test one the databases of one
application was dumped to disk and moved to another available database
server, and that individual applications configuration was updated to
point at the new server (the other apps on the app server remained
pointing at the original cluster). If the techies at DR just had a "dev,
test, or prod" switch how could they have done that?"

I don't see how this says the environment switch doesn't work... This type of config is at the app server level and can be changed independently for any given app regardless of what env it's in... We do this sort of thing all the time too because of multiple versions in flight and under QA review, but we still maintain a single EAR being deployed to all environments for any given version.

-----Original Message-----
From: Al Sutton <al.sutton@alsutton.com>
Sent: Sunday, June 29, 2008 3:37 AM
To: Struts Developers List <dev@struts.apache.org>
Subject: [OT] Re: environment awareness (project stage in JSF)

Brian,

It's always good to get a discussion going :).

The application isn't changed between boundries, it's the configuration
that changes, and the configuration is controlled at each stage by the
person responsible for that environment and not by the developer.

Let me give you a concrete example; During a DR test for a major bank
the DR database cluster was found not to be able to handle the load of a
full DR scenario. In order to complete the test one the databases of one
application was dumped to disk and moved to another available database
server, and that individual applications configuration was updated to
point at the new server (the other apps on the app server remained
pointing at the original cluster). If the techies at DR just had a "dev,
test, or prod" switch how could they have done that?

Yes configuration is a feature of the environment, but it should be up
to the environment manager to manage the configuration, and not up to
the developer to dictate what is correct.

Al.


Brian Pontarelli wrote:
Wow. This got way off topic, but I'm compelled to answer. ;)

Your assumption about QA being the only problem is incorrect. It is
environment based. The application should not be changed in anyway
when it is migrated across boundaries. It should be able to determine
where it is and how it should behave. If you look at the differences
between environments, you'll see that this is true for many things.

Your example of LDAP appears to support my case. You are providing an
environment based configuration source. In addition, your LDAP is
configured per environment via an IP constraint. Lastly, you've just
moved the configuration from files to LDAP. It is still different for
different environments. This could have been as easily done using
JNDI. What you are talking about IS environment awareness.

In terms of payment processing, to be specific, we hit the gateway
using a different message that indicates it is a test. How do you
propose to determine if we should use a test message? The only way is
via configuration and that configuration must be different between
environments. However, you could as easily mock things out. But you
still have to contact a different URL. This is all based on environment.

Again, I think you are simplifying this and by saying that people are
lazy. Trust me when I say that writing environment aware configuration
is not a reduction of work or management. Furthermore, you assume only
two environments it seems. We had 5 different environments and they
all had different configuration.

-bp

On Jun 28, 2008, at 10:06 AM, Al Sutton wrote:

Brian,

From what I can see your only real problem is QA on config files and
given that how can you you can guarentee that all of your servers
will never have their config drifted between zones because a certain
problem occurr in dev but does in production.

I've previously worked on a project that used LDAP directories for
everything (data storage and configuration). The app servers were
only given the LDAP FQDN to bind to and pulled all of their config
data from there. The LDAP servers had IP access control rules which
prevented any machine outside of the domain attaching to them, this
meant a server on the dev network couldn't get the production
configuration and vice versa. You could use an HTTP URL and web
server as an alternative, but the principal is the same, protect the
data which can cause things to go wrong (i.e. the config file), and
don't try to code to prevent every screw-up a support techie will
make (they can be pretty inventive when it comes to how to screw
things up).

I can also see concerns over where do you draw the line between
environments. With your example of credit card processing where would
you say dev and production separate, do you write the code to return
dummy auths and/or declines in dev mode, or do you call out to the
payment gateway? One means that anyone with a spare machine can test
something, the other means you need them to have the correct config
and equipment to talk to the payment gateway?, what happens if
someone wants to switch between the two in order to test the gateway
interface, do you create another environment label?

All in all it does seem like a lazy solution to me, whats needed is
better QA, not a solution which makes people sloppy because they
think that the code will catch their mistakes.

Al.




Brian Pontarelli wrote:
I think this is an over-simplification of a complex problem. Here
are a few examples from orbitz.com:

- Thread pool sizes. We couldn't replicate production (1500+
servers) in staging, so instead, we created as many VMs as we could
handle on the limited number of machines we had (~100) to get an
accurate simulation. This required smaller thread pools to not kill
the OS

- Different back end host connections to the GDSs. You can't book a
real flight in staging or development.

- Different server names. We had around 7 tiers that spanned
multiple servers. Each request to Orbitz hits anywhere from 10-20
different machines. Although we used Jini to discover the services,
we still had to configure the Jini lookup servers differently
between environments

- A classic example that everyone uses is database configuration and
SMTP servers. These are could be in a JNDI entry or the application
might create connections directly, depends. If the application
creates this stuff it will need different configuration per
environment.

- Not charging credit cards in development, but charging them in
staging and production. And we also had specific merchant accounts
to test in staging that were full transactions, but they didn't
charge us the full amount. We also had many different bank accounts
setup to test all the different types of cards and transaction
boundaries.

And the list continues. I might agree that an MVC might not need to
know the environment, but an application will. The example you give
with logging has very little to do with environment concerns and
more to do with poor testing and programing. In addition, you should
have been able to turn it off.

I think a better example of bad environment configuration is using
it to configure everything and having complex and error prone
configuration files. I recall two cases that are quite humorous:

1. With Jini we could dynamically add machines and the system would
discover them and they would immediately start accepting work. Made
scaling simple. Someone had setup a box and mistakenly named the
environment to "pr0d" (yeah that's a zero in there). Took us hours
to figure that gem out and at 2am no less.

2. Someone was creating a new service to interact with a new GDS
feature that provided discounts on hotel rooms. They were testing it
out in development and being a developer, thought a 98% discount
would be some good test values. Rather than putting the value in the
config-development.properties file it ended up in the
config-default.properties file and made it all the way out to
production. The hotel called us up and mentioned that they had
quickly sold out over New Years at a whopping $6 a night. Luckily
they only had 5 rooms or something, but we ate the cost of selling a
5-star hotel at 98% off.

I think the principle is sound, just needs a lot of testing and
understanding. I definitely don't think it has anything to do with
lazy developers. In fact, some of the best developers I know use it
extremely well to control size, performance, scale, functionality,
and much more in different environments.

-bp

On Jun 28, 2008, at 4:56 AM, Al Sutton wrote:

I think the concept is an idea which will appeal to lazy developers.

Why on earth would you want to put conditionals into your code that
you know will only evaluate to a set value in the environment they
run in?

If anything it makes problems harder to track down because if
someone takes a copy of the app from a production machine to a dev
machine to further investigate a problem it will behave
differently, which is just a hiding to nowhere in multi-threaded
apps such as S2 webapps.

An example of one of the "joys" that can come from this type of
idea came from a project I worked on where a coder used log4j and
isDebug to conditionally build a log string and log some extra
data. This might be seen as a good idea, except the code within the
conditional block didn't properly check all the objects were not
null and under certain functionally valid conditions an NPE was
thrown, so when a problem arose in production at a customers site
they were asked to turn debug logging on and all that they sent
back was a log with an number of NPEs which didn't relate to the
original problem.

Ohhh the fun we had explaining that a new release had to go through
their change (long) control procedure just so we could find out
what the original problem was and until that we we're kind of
stuffed finding out what in their environment triggered the problem.

Yes in an ideal world it shouldn't have happened. Yes it probably
should have been picked up by some QA test somewhere. But don't we
all live in the real world?

Al.



Chris Pratt wrote:
We use something similar in our system. The system uses a bunch of
resource bundles that are separated into logical domains, and each
entry can be overridden by a local file on each machine. Plus each
entry can be scoped by environment (production, test, development),
machine, or application name (in case multiple applications are
sharing a library component). We have log4j and spring
configurers so
that it is tightly integrated into the tools we use. It's saved
us an
eternity of time tracking down bugs from one environment to the next
since we deploy the same WAR file that was accepted by the quality
assurance group into production and let the configuration take
care of
itself.

I've often thought of creating a Google Code project to open source
it, but wasn't sure if there would be enough interest.
(*Chris*)

On Fri, Jun 27, 2008 at 1:38 PM, Brian Pontarelli
wrote:
Yeah, I found that environment resolution was a key feature for
any large
application. At Orbitz we could deploy the same bundle to any
server and the
bundle would figure out where it was and configure itself for that
environment. Worked really well.

I have also provided this type of feature in JCatapult using an
API that can
be implemented however developers need. The default
implementation uses
JNDI, but it is simple to change it. The nice thing about that is
you can
assume at all times that the environment is available and make
assumptions
around that.

-bp

On Jun 27, 2008, at 1:53 PM, Frank W. Zammetti wrote:

We d something similar as well, but we decided to use a simple
env var in
all environments... So the exact same EAR can deploy to any
environment and
the code within simply looks for that var and acts accordingly.
Simple but
highly effective.

Frank

-----Original Message-----
From: Ian Roughley <ian@fdar.com>
Sent: Friday, June 27, 2008 2:59 PM
To: Struts Developers List <dev@struts.apache.org>
Subject: Re: environment awareness (project stage in JSF)

I've actually had to implement this type of feature in multiple
enterprise applications. However, I would say that it's not
knowing the
environment, but being able to change configuration elements per
environment that is important (for what I did, and in rails I

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