The technology world has just lost another giant, though one without the towering public persona of Steve Jobs.

If you’re not actually a programmer, you’ve probably never heard of Dennis Ritchie. But the vast majority of software you use was built using a tool that he originally designed, and the rest by tools that very liberally sample from his.

The “native language” that the central processor in a computer understands is an ornery beast. For one thing, back in the 1970s every two-bit computer company (if you’ll pardon the techy pun) had its own native language; these days, there still remain two very common ones, and dozens of less common examples out there. More importantly, it’s almost incomprehensible, even to most programmers. Take this little snippet, part of the preliminaries to a very simple program that just prints the message “hello, world” to the screen:

_start:
        mov    eax, 4
        mov    ebx, 1
        mov    ecx, str
        mov    edx, str_len
        int    80h

Writing long and complicated bits of software with such unhelpful notation is extremely slow and error-prone.

“High-level” languages, that allowed the logic of software to be expressed in more compact and readable notation, had existed since the 1950s; Grace Hopper was responsible for one of the first. Over time, more and more of the scientific and business software run on the large computers of the era was written in FORTRAN, COBOL, and other high-level langages. However, the “operating systems”, the software plumbing that joined those applications to the hardware, was invariably written in the machine language of specific systems.

In the late 1960s, Ritchie, working with Ken Thompson at Bell Laboratories, hacked together their own little operating system for an obsolete computer nobody was making use of. It was small, but it worked, and was one of the first practical systems to support “timesharing” – the ability for multiple users to run multiple programs simultaneously and interactively. Fairly early on, they had another brainwave; they would rewrite as much of the system – which became known as Unix – as possible in a high-level programming language, to speed development. But first, they needed a suitable high-level language. The resulting language, an evolution of earlier languages entitled BCPL and B, was called “C”.

Both C and Unix were raging successes, partly because of their inherent strengths. The use of C allowed Unix to be “ported” to many different computer systems, a process that continues today as its spiritual successor Linux, written in C, runs on everything from IBM mainframes (and the amphormous “Googleplex” of Google’s servers which, reportedly, draw 240 megawatts of power), to virtually every smartphone on the planet (the iPhone’s operating system is not Linux, but it is also a derivation of Unix and substantial parts are written in C). They also had the good fortune, as with the Internet and World Wide Web which owes so much to both, that they gradually escaped the crush of intellectual property law to become part of the intellectual commons of the field.

Almost as important was the elegance and economy that Ritchie, along with Brian Kernighan, brought to teaching the language. Their textbook The C Programming Language remains the best programming language textbook ever written, in my view, and the one that I still strongly recommend to my students.

Much of the Windows operating system, and Mac OS X, are implemented in C. Those parts that aren’t, are implemented in computer languages directly derived from it – C++ and Objective-C. Most of the software that runs on those systems is also written in C or its successor languages. And perhaps the most pervasive “new” high-level language of the last 20 years – Java – retains so much of C’s “look and feel” that it often takes a second glance to tell which language a piece of code is written in.

Neither C nor Unix were by any means perfect. While some of its design faults have been eliminated in its successors others remain, and will likely continue to bamboozle neophyte (and, all too often, experienced) programmers, for generations to come. But there was so much he and his colleagues got right. Fate did play its part, but there are very good reasons that generations of software developers not yet born will express themselves in notations largely based on Ritchie’s.

RIP, dmr.

via Dennis Ritchie: The Shoulders Steve Jobs Stood On | Wired Enterprise | Wired.com.

I was off the client site so I couldn’t rely on a fast connection to their development databases. I just wrote a dummy function that was called the same as the real function with the same input and output parameters and instead of the complex function body it just wrapped a simple mock table of test data. Problem solved, Oracle XE to the rescue. But first you have get Oracle XE running on your Mac, this is what the rest of this article is about, because you can’t just download an Oracle XE edition for the Macintosh.

Virtualisation is great – use a Linux VM

However modern Virtualisation is your saviour. Put simply, you can use a virtualisation tool like Parallels, or my choice, VMWare Fusion, to run a virtualised version of Linux that contains the Oracle XE instance.

Because VMs can waste a bit of your local resources, luckily there is a specialised version of Ubuntu designed for running as a virtualised machine of this type. Its called JeOS (pron. Juice, apparently). It doesn’t have an X-window environment, just the shell, so it’s pretty lightweight and can run, with Oracle XE, in less than 512MB of memory. Perfect for getting a copy of Oracle XE onto your Macbook Pro.

It will however, eat up a couple of gigabytes of disk space, up to the maximum limit you choose for your disk size in the VMWare configuration. However it will only use the current amount of disk needed, as VMWare will expand the size of the image as needed (I’ll just assume that Parallels does something similar).

Setting it up – basic instructions

This page here – has a great set of instructions for getting JeOS installed and configured with Oracle XE on it. Follow the instructions there exactly – but only to the point where you install and configure Oracle XE – don’t go further than that.

Make sure you configure plenty of swap space as outlined in the instructions.

Setting it up on standard Ubuntu/Debian

If you are running a full Ubuntu or other Debian based instance, the instructions are somewhat simpler. Install it as per normal in your VM. But make sure your swap space is twice the memory you have assigned to the VM! Oracle XE demands things to be like that.

Add

deb http://oss.oracle.com/debian unstable main non-free

to /etc/apt/sources.list and then:

$ wget http://oss.oracle.com/el4/RPM-GPG-KEY-oracle  -O- | sudo apt-key add -
$ sudo apt-get update
$ sudo apt-get install oracle-xe

These instructions were cribbed from here.

After installing and configuring Oracle XE

After you run the XE configuration (‘$’ represents the Unix shell prompt and should not be typed);

$ sudo /etc/init.d/oracle-xe configure

If you’re running on JeOS don’t yet make the machine “headless”! Or you might find there are issues with the “Apex” application. The problem is that the Apex application, which is a useful web-based administration program for Oracle XE (especially for developers who don’t want to be forced to use sqlplus for all their database administration), will only allow connections from localhost – and you don’t have X-window, or a browser, to access it (I don’t know if lynx will work with Apex and I wasn’t going to try).

Get SSH installed

First get SSH installed in JeOS so you can get to the command prompt remotely:

$ sudo apt-get install ssh

Find out the VM’s IP address

Now, if you type ifconfig (/sbin/ifconfig if that’s not found on your path) you will be able to determine the IP address of your VM running on your Macintosh. At this point you can connect to the VM using ssh from a Macintosh terminal window:

$ ssh username@ip_address

Actually, at this point you can go ahead and make the machine headless, if you want. I would recommend not to do that until you’re sure of everything you’ve configured.

Configure environment to run sqlplus

After you’ve logged back into the running Linux VM using ssh from the Mac Terminal, the next thing is you’ve got to get sqlplus access working to the XE instance you installed. Funnily enough, although the .deb file that is installed off the Oracle site creates an oracle user, it doesn’t in any way set that user up so you can use the command line tools. SO you can’t just su – oracle and get a functional environment.

Anyway, you will need to do two things to your environment; add the ORACLE_HOME environment variable and set up your PATH so it can find sqlplus.

$ export ORACLE_HOME=/usr/lib/oracle/xe/app/oracle/product/10.2.0/server
$ export PATH=${PATH}:${ORACLE_HOME}/bin

You should add these two lines to your .profile or .bash_profile file – probably best for the ‘oracle’ user that the installation will have created. But you can actually set this up for any regular user that you configure in this VM. You can also just type them at the command line to get them in your current environment, if you have to.

Configure Apex to accept non-localhost connections

The web-based administration software for XE, called “APEX”, only binds to localhost. This is a big hassle if your VM copy of Linux (like JeOS) doesn’t have a GUI, because you don’t have a browser (lynx/links excluded, I did not try those!).  However, you can make Apex bind to the “external” IP address for your VM, but you’ll need to use sqlplus.

To run sqlplus, do the following:

$ sqlplus system@XE
  Enter password:

Enter the password you specified at the ‘oracle-xe configure’ step above.

At the SQL prompt, enter the following command:

SQL> EXEC DBMS_XDB.SETLISTENERLOCALACCESS(FALSE);

Now you’ll have to stop and start Oracle to make the configuration active:

$ sudo /etc/init.d/oracle-xe restart

After which, if you type

$ netstat -tna

You should find a line

tcp        0      0 0.0.0.0:8080            0.0.0.0:*               LISTEN

This indicates a process is listening to the port 8080 on all IP addresses for connections coming from any other IP address. Assuming you specified port 8080 at the ‘oracle-xe configure’ step. Sometimes I use 8888 especially if I have a Tomcat instance in the same VM, as Tomcat will also like to run on 8080 and I’d prefer it if it did.

Test and use Apex

Test this connection in your browser, in my case, the address was 10.1.2.17, but you will have to substitute your own VM’s IP address – http://10.1.2.17:8080/apex. I like to make an /etc/hosts entry that points to this address as ‘oracleXE’. That way I can use a symbolic name in my jdbc connection strings and actually switch which instance of XE I am using depending which VM I’ve fired up without editing the jdbc configuration of the application under development – I just change the /etc/hosts entry instead.

Anyway once you connect to apex you can login using the user name and password you set up during your XE install and configuration process (same as you used for sqlplus). The users will be sys and system, you can use them to create new users to contain your databases for development.

The same IP address as above will be used to connect to your Oracle database from the programs you are developing. The default port should be 1521 and the SID should be XE.

Enjoy!

1. Local development: localhost, localhost, localhost, joes-dev-box
2. Development / Integration: tomcatdev-svr1, orcldb0, mq-dev, joes-dev-box
3. Testing / UAT: uat-redhat3, uat-rhas7, messageQ-uat1, security-ldap12-DEV
4. Production: appserver-weblogic-PROD0, orclRAQ-1, mq0, fw0-sec-ldap-bldg6

This of course, necessitates a number of custom configurations for every environment, and depending on your technology, your deployment strategy, and your configuration management , it can quickly and rapidly get either unmanageable, or worse, configuration can be lost, or at least not backed up or documented adequately to enable reconsititution in case of catastrophic failure. What we as developers, often yearn for is a simple scheme like the following:

1. app-server, database, message-queue, ldap-server

Of course, we sometimes try to map those sorts of schema into the chaotic environment listed above. Then we have custom host-file entries to manage the IP address resolution for us. of course, is this /etc/host file in any sort of configuration management scheme? Usually not. The trick is course, to use the schema as above but /etc/resolv.conf file to force resolution to a default sub-domain, which in the four cases above, are;

1. developer
2. integration
3. uat
4. prod

Then using either network-based split-segment DNS resolution, or simply a private dns server only visible to resources inside the firewall, to resolve to the relevant sub-domain and thence to the correct IP. But then, there’s the inertia from the infrastructure management, who want to identify machines according to the operating system and the major software brand that’s installed into them, rather than the functional description. Quite apart from the fact that those two schemes can live side by side anyway in a split-segment DNS.

I’m sorry that I don’t have a full solution, I just wish it was easier.

Tip – I found where it was installed with this simple series of *nix commands that should work on most Unix variants such as Linux, for anything on your ${PATH}, using the ‘which’ command:

CrazyMcphee:systems smcphee$ which mvn
/usr/bin/mvn
CrazyMcphee:systems smcphee$ ls -lrta /usr/bin/mvn
lrwxr-xr-x  1 root  wheel  24  9 Mar 22:50 /usr/bin/mvn -> \
  /usr/share/maven/bin/mvn

Following the information on this page as a template, here’s the procedure I used to upgrade to the latest version at time of writing, Maven 2.1.0:

CrazyMcphee:~ smcphee$ sudo su -
Password:
CrazyMcphee:~ root# cd /usr/share/
CrazyMcphee:share root# mv maven maven-2.0.6
CrazyMcphee:share root# cp -R \
/Users/smcphee/Development/systems/apache-maven-2.1.0/ \
maven-2.1.0
CrazyMcphee:share root# ln -s maven-2.1.0/ maven
CrazyMcphee:share root# exit
logout
CrazyMcphee:~ smcphee$ mvn -version
Apache Maven 2.1.0 (r755702; 2009-03-19 05:10:27+1000)
Java version: 1.5.0_16
Java home: /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home
Default locale: en_AU, platform encoding: MacRoman
OS name: "mac os x" version: "10.5.6" arch: "i386" Family: "unix"

You’ll note I used a symlink for the ‘maven’ directory to the ‘maven-2.1.0′ directory (the command ‘ln -s maven-2.1.0/ maven’ …). This is to allow me to quickly switch back to version 2.0.6 if I find any incompatibilities in my old POM files with the new version of Maven, by simply changing which directory the symlink points to.

I think that maybe this is because they are a ‘UNIX’ company with an excellent ‘UNIX’ pedigree and a generally ‘UNIX’ mentality through and through. Unlike Oracle, which is pretty agnostic about operating systems, and IBM, which only caught the UNIX fervor in the last decade (although it’s always had a UNIX implementation, i.e. AIX, it’s not like the whole company has been orientated around this operating system, unlike Sun and SunOS/Solaris). But what does UNIX have to do with agility?

I am of the firm view that MS Windows is just not a development platform. The reason is that I think it just doesn’t have the right command-line interface. There’s no find, diff, ps, awk, sed, and the other multitude of small tools that make a developer’s life much easier. It almost embodies the big-tool-does-it-all thinking that I think is terribly inelegant – and unagile.

Now I have been using UNIX since 1989. In those days it was a Amdahl UNIX as well as a version of SunOS. Some point after that – early 1990s I guess – I had a version of Linux installed on a personal computer of mine. In those days you had to boot off floppy with a super-basic kernel and a 25×80 terminal, recompile the kernel to suit the exact hardware setup of your computer. Just to get a serial port and modem functioning to run PPP over. It was pretty dire, hands-on, stuff – but I was young and had time to do it. This doesn’t sound very simple does it?

But there is a simplicity to UNIX, it’s the entire UNIX philosophy. And it is this:

Write programs that do one thing and do it well. Write programs to work together. Write programs to handle text streams, because that is a universal interface. (wikipedia)

And from the same Wikipedia page as above, here’s an extension of the UNIX philosophy by Mike Gancarz, the “9 Paramount Precepts”:

1. Small is beautiful.
2. Make each program do one thing well.
3. Build a prototype as soon as possible.
4. Choose portability over efficiency.
5. Store data in flat text files.
6. Use software leverage to your advantage.
7. Use shell scripts to increase leverage and portability.
8. Avoid captive user interfaces.
9. Make every program a filter.

I reckon that points 1, 2, 3 and 6 are definitely Agile in nature (point 8, I think, goes to the point I was trying to make about IDE-to-Server integration in the ADF post).

None of this is exactly the Agile Manifesto, of course. However Agile is a similar philosophy that values simplicity in order to manage complexity. And this simplicity takes some considerable effort to achieve, as it does in Unix. But its benefits in the end are enormous.