Agile Software Company From Scratch

Road to Ruin: Mortgage fraud scandal brewing

erace — Thu, 14 May 2009 20:27:37 +0000

I am really eager to see what will happen out of this:

It’s so gr8 to have values

erace — Thu, 23 Apr 2009 19:48:29 +0000

Gr8 movie! I love their office.

EndTheFed.us

erace — Mon, 23 Feb 2009 20:12:48 +0000

I have found a gr8 explanation of how FED in the US is operating.

CouchDB – document database

erace — Sat, 21 Feb 2009 18:21:04 +0000

In the first video I watched over the weekend, Damien Katz, the creator of CouchDB, gives some advices as about when one should use the document database, which CouchDB is. He suggests to look at the real world task that is being computerized. If one would use a number of pieces of paper that are passed around to different people than is a every good indication that document based database will suit the solution well. In addition, if the piece of information is to be taken offline to be edited and later on replicated to the server to reflect the most recent version of the document, CouchDB is something to consider. Katz said that with CouchDB he is trying to bring the Lotus Notes model of document centered database to the open source world. He touches a bit upon Google’s BigTable: he believes that it’s only benefit is scalability and that CouchDB is trying to address different problems. CouchDB allows to create a view of the data whereas BigTable if just “this big key value table store.”

By the way, I also learned that Exchange was suppose to be an MS version of IBM Lotus Notes document database but it did not work out quite that well.

In the 2nd video, the presentation given by Katz at RubyFringe, I did not expect to find the great presentation about doing what you like and enjoying life (reaally something I did not expect). The stuff was good but not much practical info about CouchDB.

While browsing through planet@CouchDB I have found an excellent post about how CouchDB can make all ORM/GORM stuff obsolete. Since CounchDB does not enforce particular schema, my understanding is that all the document that are stored can be quite different i.e. contain different set of attributes. That really makes sense but I am still not sure if this is good – for sure it makes things easier in the beginning. The question that bothers me is how that affects the system once its running. What if we store a number of documents with one set of attributes and then update the view/editor to include some more. Data will be inconsistent and may lead to unpredicted results. It requires some additional checking for the presence/notnull/whatever parameters when working on the view part. If we were to use traditional/relational/schema model It would be required to alter the schema before new version could be up and running. It would be an explicit step to make sure that all the old data is suitable for new view.

Resources
Measuring performance

Apache Proxy for GWT and Alfresco

erace — Tue, 03 Feb 2009 15:30:45 +0000

Starting with GWT 1.5.3 it is not possible to read data from other servers than local. It makes development a bit tedious since if one was to do a test run of an app it would have to be first compiled (which takes sooo long) and then transferred to the server that all the XMLHttpRequest would be going to. Obviously we need some kind of proxy that will help us to fool the browser. Apache mod proxy fits great. Not to have repeat the same installation and configuration procedure on our all development machines I have created a VMWare vm that contains all the necessary things. Below are the steps that I followed.

Configure NAT interface for VMWare 192.168.100.1/255.255.255.0 (on host machine)
Install Ubuntu server 8.10
Configure /etc/network/interfaces
# The loopback network interface auto lo iface lo inet loopback # The primary network interface auto eth0 iface eth0 inet static address 192.168.100.3 netmask 255.255.255.0 gateway 192.168.100.2
sudo apt-get install apache2
Enable http proxy module
a2enmod proxy_http
Enable virtual hosts
a2enmod vhost_alias
Allow connections to proxy from all hosts (for convenience) in /etc/apache2/mods-enabled/proxy.conf
AddDefaultCharset off Order deny,allow Deny from all #Allow from .example.com Allow from all

Enable proxy mapping by adding /etc/apache2/sites-enabled/010-proxy:


    ServerAdmin spam@poland.pl
    ServerName gwtproxy.poland.pl
    ServerAlias gwtproxy
    ErrorLog /var/log/apache2/gwtproxy.poland.pl-error_log
    CustomLog /var/log/apache2/gwtproxy.poland.pl-access_log common
    ProxyPass /pl.poland.cube.Cube http://192.168.100.1:8888/pl.poland.cube.Cube
    ProxyPassReverse /pl.poland.cube.Cube http://192.168.100.1:8888/pl.poland.cube.Cube
    ProxyPass /alfresco http://repo.cube.poland.pl:1030/alfresco
    ProxyPassReverse /alfresco http://repo.cube.poland.pl:1030/alfresco
    DocumentRoot /var/www

Add to /etc/hosts (on host machine):
192.168.100.3 gwtproxy gwtproxy.mxts.pl
Edit run configuration in Intellij Idea

When run the hosted browser should run app via proxy and it should be possible to read data from http://gwtproxy/alfresco/* which is actually on completely different server.

Sources
Solution on google groups

Changing Grails datasource to use PostgreSQL

erace — Sun, 18 Jan 2009 12:53:53 +0000

My database name is erace (not to have to type the actual name of the database each time I invoke psql).

Get JDBC Driver for PostgreSQL
Drop the jar in $project_home/lib

Change $project_home/conf/DataSource.groovy to this:

dataSource {
	pooled = true
	driverClassName = "org.postgresql.Driver"
	username = "erace"
	password = "passw0rd"
}
hibernate {
    cache.use_second_level_cache=true
    cache.use_query_cache=true
    cache.provider_class='com.opensymphony.oscache.hibernate.OSCacheProvider'
}

environments {
	development {
		dataSource {
			dbCreate = "update" // one of 'create', 'create-drop','update'
			url = "jdbc:postgresql:erace"
		}
	}
	test {
		dataSource {
			dbCreate = "update"
			url = "jdbc:postgresql:erace"
		}
	}
	production {
		dataSource {
			dbCreate = "update"
			url = "jdbc:postgresql:erace"
		}
	}
}

Docs:
Grails Ref Guide on DataSource

Getting on the REST bandwagon

erace — Sat, 17 Jan 2009 18:58:48 +0000

It looks like terms such as cloud computing, SAAS, web services, REST, loose coupling and similar are popping here and there more and more often. Unlike in case of SOA big shmuzz buzz (see my favorite site on SOA) the above mentioned terms do have some meaning and can take some shape or form. Today the time to explore REST has come.

Intro
The definition of REST can be found in the number of places. Below I highlight only the things that I consider worth to emphasize.

REST (Representational State Transfer) is:

Architectural style
Architecture of the web as it is today.

Further REST:

Enforces widely acceptable and understandable patters dealing with representation and access to the resources on the Internet
Action performed and the resource must carry a representation of it’s state plus metadata
The data carried with the request or response may be in different depending on the implementation for example XML (in case of AtomPub) or JSON etc,.
If I understand correctly metadata should carry info about further possiblities of actions on the resource (metadata with JSON?)

Defining REST
The name of the resource that is and item to be manipulated is a noun for example http://unisalveo.org/food (if to return single entity) or http://unisalveo.org/foods (if to return collection). We can “stack” a number of nouns on top of each other for a example http://unisalveo.org/foods/newest or http://unisalveo.org/foods/drinks.

The operation that is to be performed on the item is a verb. There is a number of “out of the box” operations that can be performed on the given resource (noun) with HTTP protocol namely:

POST – place new item as a resource
GET – get the recource
PUT – replace the existing item with a new one
DELETE – remove a given resource.

Those operations roughly correspond to CRUD database operations operations or COPY, PASTE OVER, PASTE AFTER, and CUT. It looks like it is encouraged to use only those verbs in order to perform the operation on the resources. I thought that it makes sense to build URI’s such as http://unisalveo.org/food/search but it looks like it is discouraged. It is better to add parameters (constraints) to GET request in order to limit the data returned by the server (are HTTP methods really enough for all the possible operations?!).

In addition, constructing the mixes of nouns and verbs in a single word in the URI, for example http://unisalveo.org/searchForFood, is also considered a bad practice.

Other findings

According to REST principles outlined by Fielding it should be possible to traverse the resources from one point without prior knowledge about the API specifics of this resource.
It looks like Google returns JSON without new lines from its web services. Nice thing to do to preserve bandwidth.
Fielding distinguishes between RPC based on URI and REST. For the moment it’s a bit blurry to me and I have a feeling that might completely change my view on the subject . InfoQ has some discussion on the subject. Another good resource seem to be here.
There is a question about how to represent a particular type of service i.e. how to group nouns. Maybe just putting service in URI http://charts.unisalveo.org/piechart? Is there a need to PUT or DELETE? Maybe this given service should be used as cache that is updated (PUT) when applicable data changes. That sounds tricky but can limit the amount of dynamically (i.e. per request) degenerated content.
Versioning of the particular REST web service is also important. It is potentially very easy to break the functionality of the system if data and matadata returned by the service changes without maintaining the previous version. In loosely copuled architecture is must be very hard to test all the dependencies especially in the case in which we do not control all the resources.
It might be desirable to return different content types from different resources. Does the break some standards, protocols or patterns?
It might be worth to explore having multiple URI schemes. Since I would like to use UUID for identification of most of the resources it might be difficult for human to read and find particular resource.
There must be a way to describe which methods (verbs) are supported on different resources.

Some links
Roy Fielding Dissertation
REST Triangle: nouns, verbs and content type spaces
REST Methods (verbs)
RESTful searching
Google RESTful search API
RESTful Design
URL Construction
XML.com Resources on REST
Intro into the AtomPub by Google
Intro into REST by Google

I guess thats enough for today .

Collecting requirements

erace — Sun, 29 Jun 2008 21:00:34 +0000

When reading about exodus of staff from Google to Microsoft I have found very valuable information about how to make a great connection between software team and the client.

‘Questions every Candidate should ask a potential new employer’

erace — Sun, 29 Jun 2008 17:46:49 +0000

It was my plan to create a software organization for some time now. I have been collecting interesting writings on the subject. About a year ago I have found a set of questions that every candidate should ask their potential employer. I knew it would be fun to answer them myself from the employer perspective . Here they come along with answers.

Explain the company’s development process at a high level.
Phase 1 – collect underpants, phase 2 – ?, phase 3 – profit
How are releases scheduled/planned, do you utilize iterations
We try to have releases every Thursday but so far that proved to be a bit problematic due to short deadline, lack of automated builds, lack of unified skills, too loose coupling of components. As for the 2nd part – sure we try to use iterations.
Do you have dedicated environments (development, qa, stage, production)
Not really. We have a server dedicated for testing but it is not very formally defined.
Do you follow any formal methodology (agile (what flavor), waterfall, etc)
I am trying to implement Scrum. Currently we were only able to implement morning Scrum meetings and they proved to be vary valuable.
What is the company’s philosophy on team member involvement in the SDLC process
SDLC-what?
Do you have a continuous build environment setup
Nope.
Do you follow some form of TDD
We try to. Actually I have assigned the task of “getting through” the testing of components in Seam to 3 people on the team but none of them was able to complete task. It might be my fault since I tried to push quicker implementation of the components that we needed rather than exploration of tests under Seam.
How do you track/follow bugs/issues
We have successfully implemented and used Jira. Not all team members had enough knowledge to us it but I believe that we are slowly getting there. I would like to push Mylyn.
Do you perform code reviews
Not yet. Last Friday we have delivered so so ready first version of our product. This week we should be able to install it at the customer’s site and after that we will do formal code review.
What type of development tools do you have
Apart from Jira we use SVN and Red Hat Developer Studio. I am really thinking about using Mingle but that costs quite a bit of money and I really should have time to investigate it a bit longer. Last week we have started to play with VMWare as we have to test everything on different database and directory server than in development environment.
What type of hardware for the developers to you have
Dell Precision M4300 Core 2 Duo T7500 (2.2GHz,4MB) with Base Discrete FX360M Graphics with 4GB of RAM.
Is QA involved from the onset of development
Yyyy not really?
Do you have a knowledge center for the team such as a team portal, wiki, etc
Nope. We have setup document repository based on Alfresco but I did not have time to show it to the team.
Do you have up to date specs on the application
I am not sure if we need it. We are working more in R&D kind of way. There is some initial, high level overview but that is about it.
What form of stake holder involvement is there in the development cycle
They pay .
Do you have documented coding standards, are they followed
One of the team members has actually created such a document but I need to look at it further and possibly make some adjustments.

Uff… that was rather painful reality check. Lets make things harder — in the comments to the original questions I have found some more suggestions about how to make a better code. Lets try to go through those as well.

Do you use source control?
Yes.
Can you make a build in one step?
Kind of. If exporting an EAR file from IDE counts as one step then yes.
Do you make daily builds?
No.
Do you have a bug database?
Yes.
Do you fix bugs before writing new code?
Nope. We do not have very rigorous testing so we do not know what kind of bugs are there.
Do you have an up-to-date schedule?
No.
Do you have a spec?
No.
Do programmers have quiet working conditions?
Yes – it could be better. Our next office is not going to be on the 2nd floor on the city’s main street. The building is nice but it is kind of distracting when one opens a window.
Do you use the best tools money can buy?
Not yet.
Do you have testers?
Kinda – rather not.
Do new candidates write code during their interview?
No.
Do you do hallway usability testing?
No.

4 out of 12 – ouch again. It looks like there are still quite a few things that should be improved . I guess I better prepare some plan with the things that should be done. See next posts.

Ron Paul ReEVOLution Anthem (Unofficial)

erace — Sat, 14 Jun 2008 13:40:00 +0000

If this is way way that the message will be spread I am pretty sure it will be heard.

Check out this one as well.

Interview with Aimee Allen on The Alex Jones Show.

I am wondering how IPv6 will influence the ways in which I will be able to find about the things that are true and important.