The Mars Mission Continues

In this Q&A with James Gosling,Father of Java find out more about the role of Java in the Mission to Mars

Q:What exactly is Java's role in the Mars Rover mission?

A: The places where NASA scientists have used Java for this mission is all on the ground side right now. They have created this collaborative command and control system called Maestro, which does this combination of data visualization, collaboration, command and control. It lets them look at images and create 3-D reconstructions of terrain. It allows various experimenters to look at the scenes and topography, browse the image databases and take part in all the participation they need to do. And to do it in a remote, distributed and collaborative kind of way - so they could actually have scientists at institutions all over the world who are not only looking at the data, but also collaboratively deciding on the way the mission should proceed. One of the nice things that the JPL guys have done is that they've made a "cleaned up for civilians" version of this application available that's called Maestro.

Q:How is the Java assisting in controlling the Rover from earth?

A: There's a Java API called Java Advanced Imaging, that's used for the images captured by the panoramic camera - the one that producing images with excruciating detail. Those panoramas are being created by combining images from two different cameras onboard the Rover, so with the two lenses they get two images - just like you've got two eyes - so you can do a stereoscopic mapping where your brain is able to figure out how far away things are. Because they've got these stereoscopic images, they can go through a process that's called stereo-image correlation, so they can calculate for each pixel in the image how far away that picture element really is.

With this information, the JPL scientists can calculate how far away each rock is, each picture element, for all of the millions of pixels in one of these large images. So you can get the depth of the image at every point. That's what a stereo camera gives you. When you've got the depth information, you can then actually build a 3-D model, the actual model of the terrain. And then you can actually map the image back onto the 3-D model. So then what you've got is a colored, three-dimensional model of the world around you.

Q:Are they actually commanding the Mars Rover with Java?

A: For the command and control system, big parts of it are this rather large Java application. There are a lot of parts involved in this. The Rover itself has a computer onboard. There's no Java in that computer now. But on the ground-side, there are a number of parts of the whole command and control chain that goes out to the Rover that's done in Java. It's not like every last piece of every subsystem is based on the Java code. Great big pieces of it are. In particular, all the data visualization, user interface front-end stuff and I believe a whole lot of the database stuff is.

Q:How does the public version of the Maestro application work?

A: If you go to the Maestro website you will find that they've got two sets of downloads. One is the Maestro application itself, and the other is a first teaser set of data from Mars. There are different versions for different platforms. There's one for Solaris, a version for Linux, there's a version for Windows and more. The fact that they've got all those versions just shows you how portable Java is, how cross-platform it is. It's exactly the same program in all of those, they are just packaged differently.

So when you download the first set of data. There's a script that walks you through looking at some of the data. Using the 3-D model they have there, and using your mouse, you can actually manipulate the 3-D model and you can get a view as if you're standing off to the side of the landing looking back at it. You can actually wander around the landing site. You can see the rocks. You can see one of the places where one of the air bags didn't deflate completely. All of this 3-D, walk-through visualization is using standard Java APIs like Java 3-D API, Java Advanced Imaging API, Java networking APIs and the user interface APIs.

Using the Maestro version they are distributing, not only do you see a 3-D model of the terrain, you see a 3-D model of the Rover. You can actually drive the Rover on this simulated terrain. It has this "video game" aspect to it. Except that you're actually driving it on a terrain model that's real. It's real Mars data that's constructing this terrain. It's not like playing Dune, where you're going through this maze that's completely fictitious.

Q:How has it been to work with the JPL scientists on this project?

A: I've spent a good amount of time down there with JPL, not only interacting with some of them, but I'm also on one of their advisory boards. In terms of talent density, IQ points per square meter, it's just an amazing place. Plus, they are doing things that most people would think of as science fiction. Most people read science fiction stories about driving dune buggies on Mars. These guys actually build them. They actually know how to fly between the planets. I've spoken to some of the guys that do interplanetary navigation, and that is really spooky stuff. You actually have to pay attention to relativity, the fact that time is not a constant - the faster you go, the slower things are. They function in a world where relativity actually matters. They are way outside of Newtonian mechanics.

JPL is a place to go to have your mind blown - partly, because they are really charged up about what they do. This is a crowd of people who are living a dream. What they are doing is so out there, so wonderful. They are doing something that is very heroic, noble, exploratory and exciting. They are the only part of the U.S. government that I can really get excited about. NASA has this incredible public outreach program, because they know that they are loved and it's a tremendous public service. They do lots of stuff with schools. The fact that they put this stripped-down version of Maestro out there is a wonderful piece of public outreach.

Q:What is it about Java that makes it so attractive to this type of application?

A: The answer is there's a bunch of things, not just one thing. One of the aspects of Java that was really important to them is that it runs on a lot of platforms. If you look at JPL, they've got Solaris boxes, Linux boxes, Windows boxes, Apple boxes - it works on all of them. If you look at the standard available API libraries available for Sun, there's a huge toolkit of things that you bring to bear. There are things like the 3-D modeling APIs, the Advanced Imaging APIs, and all the user interface APIs and networking APIs. The JPL guys used all of them. They were able to leverage all of these standard tools.

Plus, there's been a lot of experience with Java where folks have measured things like developer productivity. For example, if you compare how long it takes someone to develop a piece of software in Java versus C or C++, essentially all of the measurements show it to be about twice as effective. So if it takes some team of engineers ten months to do something in C++, it will take them five months to do it in Java. For an outfit like JPL that does everything on a shoestring budget, that also means you can trim it down five months - or still do it in ten months, but trim it down to half as many people.

There are also a number of aspects to Java that are all about building more reliable applications. It is a lot easier to build things that are more reliable - that break less often - so you don't have to worry about blowing your machine to bits. There's also a lot in Java that's all about security. So when you've got something like their large databases - whose integrity is something they need to be careful about - security is important. So, it's a whole bunch of things that all swirl together. Whenever you talk to Java developers, you get a different answer to the "why did you do it Java" question. Although, there tends to be a standard set of themes.

Q:Is this the first time that Java has been used for this type of application - being beamed out into space?

A: Actually, I don't think so. I've talked to people that have been doing various things with satellite ground station control and people that control systems for giant telescopes. People are doing stuff like this all over the place. The JPL project is what people tend to talk about because it's too damn cool for words.

Java Technology and the Mission to Mars

By Dr. James Gosling
CTO, Developer Programs
Sun Microsystems

Monday Jan 5, 4:00 PM PT

This weekend I saw what has to be the coolest Java(TM) app ever. We talk about "Java everywhere," which usually means Java(TM) technology in vehicle navigation, imaging, control consoles and things like that. This time "everywhere" means all of that and then some, because Java technology is playing a big role in NASA's latest, highly successful, Rover Mission to Mars.

On Saturday night I watched as a control room full of immensely tense geeks explode with joy as they successfully landed the six-wheeled Mars Rover "Spirit" on the planet's surface. From there, scientists at NASA's Jet Propulsion Laboratories in Pasadena will get to use their powerful, Java technology-based, ground side control system to maneuver Spirit on the Martian terrain in what has to be the most amazing network "video game" in history.

Java 3D and Java Advanced Imaging technology are also key to the software JPL is using to render and interpret realtime images captured by the Rover. NASA has even made a stripped down version of the software that you can download so you can view a simulated 3D landscape and drive the Rover around in it.

There are all kinds of reasons JPL is using Java technology for control and imaging systems for the Rovers. NASA engineers had access to hundreds of specialized APIs and network protocols that they needed to bring this off. They got great productivity and reliability. The data they're collecting through this program is part of a distributed, collaborative network of scientists and engineers, and the ability of Java technology to run on any platform enables a secure, reliable global dialogue within NASA's scientific community.

Now that Java has helped us get to Mars, who knows what "Java Everywhere" will mean in the future?

Sean O'Keefe, administrator of the National Aeronautics and Space Administration, celebrates after the staff in the Mars Mission Control Room receives a signal that the Mars Rover has landed safely on Mars.


Mars mission controllers, Stan Thompson, foreground, and Bill Currie, prepare for the long evening ahead in the Mars Mission Control Room.

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Web 2.0 :: The Next Generation

Beginer's All-purpose Symbolic Instruction Code

In computer programming, BASIC an acronym for Beginner's All-purpose Symbolic Instruction Code refers to a family of high-level programming languages. It was originally designed in 1963, by John George Kemeny and Thomas Eugene Kurtz at Dartmouth College, to provide access for non-science students to computers. At the time, nearly all computer use required writing custom software, which was something only scientists and mathematicians tended to do. The language became widespread on home microcomputers in the 1980s, and remains popular to this day.

Prior to the mid-1960s, computers were extremely expensive tools used only for special-purpose tasks. A simple batch processing arrangement ran only a single "job" at a time, one after another. During the 1960s, however, faster and more affordable computers became available. With this extra processing power, computers would sometimes sit idle, without jobs to run.

Programming languages in the batch programming era tended to be designed, like the machines on which they ran, for specific purposes (such as scientific formula calculations or business data processing or eventually for text editing). Since even the newer less expensive machines were still major investments, there was strong tendency to consider efficiency to be the most important feature of a language. In general, these specialized languages were difficult to use and had widely disparate syntax.

As prices decreased, the possibility of sharing computer access began to move from research labs to commercial use. Newer computer systems supported time-sharing, a system which allows multiple users or processes to use the CPU and memory. In such a system the operating system alternates between running processes, giving each one running time on the CPU before switching to another. The machines had become fast enough that most users could feel they had the machine all to themselves. In theory, timesharing reduced the cost of computing tremendously, as a single machine could be shared among (up to) hundreds of users.

The original BASIC language was designed in 1963 by John Kemeny and Thomas Kurtz and implemented by a team of Dartmouth students under their direction. BASIC was designed to allow students to write programs for the Dartmouth Time-Sharing System. It intended to address the complexity issues of older languages with a new language design specifically for the new class of users time-sharing systems allowed — that is, a less technical user who did not have the mathematical background of the more traditional users and was not interested in acquiring it. Being able to use a computer to support teaching and research was quite attractive enough. In the following years, as other dialects of BASIC appeared, Kemeny and Kurtz' original BASIC dialect became known as Dartmouth BASIC.

The eight design principles of BASIC were:

1. Be easy for beginners to use.
2. Be a general-purpose programming language.
3. Allow advanced features to be added for experts (while keeping the language simple for beginners).
4. Be interactive.
5. Provide clear and friendly error messages.
6. Respond quickly for small programs.
7. Not require an understanding of computer hardware.
8. Shield the user from the operating system.

The language was based partly on FORTRAN II and partly on ALGOL 60, with additions to make it suitable for timesharing. It had been preceded by other teaching-language experiments at Dartmouth such as the DARSIMCO (1956) and DOPE (1962 implementations of SAP and DART (1963) which was a simplified FORTRAN II). Initially, BASIC concentrated on supporting straightforward mathematical work, with matrix arithmetic support from its initial implementation as a batch language and full string functionality being added by 1965. BASIC was first implemented on the GE-265 mainframe which supported multiple terminals. Contrary to popular belief, it was a compiled language at the time of its introduction. It was also quite efficient, beating FORTRAN II and ALGOL 60 implementations on the 265 at several fairly computationally intensive programming problems such as maximization Simpson's Rule.

The designers of the language decided to make the compiler available without charge so that the language would become widespread. They also made it available to high schools in the Dartmouth area and put a considerable amount of effort into promoting the language. As a result, knowledge of BASIC became relatively widespread (for a computer language) and BASIC was implemented by a number of manufacturers, becoming fairly popular on newer minicomputers like the DEC PDP series and the Data General Nova. The BASIC language was also central to the HP Time-Shared BASIC system in the late 1960s and early 1970s. In these instances the language tended to be implemented as an interpreter, instead of (or in addition to) a compiler.

Several years after its release, highly-respected computer professionals, notably Edsger W. Dijkstra, expressed their opinions that the use of GOTO statements, which existed in many languages including BASIC, promoted poor programming practices.[2] Some have also derided BASIC as too slow (most interpreted versions are slower than equivalent compiled versions) or too simple (many versions, especially for small computers left out important features and capabilities).

Notwithstanding the language's use on several minicomputers, it was the introduction of the MITS Altair 8800 microcomputer in 1975 that provided BASIC a path to universality. Most programming languages required more memory (and/or disk space) than were available on the small computers most users could afford. With the slow memory access that tapes provided and the lack of suitable text editors, a language like BASIC which could satisfy these constraints was attractive. BASIC also had the advantage that it was fairly well known to the young designers who took an interest in microcomputers. Kemeny and Kurtz's earlier proselytizing paid off in this respect. One of the first to appear for the 8080 machines like the Altair was Tiny BASIC, a simple BASIC implementation originally written by Dr. Li-Chen Wang, and then ported onto the Altair by Dennis Allison at the request of Bob Albrecht (who later founded Dr. Dobb's Journal). The Tiny BASIC design and the full source code were published in 1976 in DDJ.

In 1975, MITS released Altair BASIC, developed by Bill Gates and Paul Allen as Micro-Soft. The first Altair version was co-written by Gates, Allen and Monte Davidoff. Versions of Microsoft BASIC soon started appearing on other platforms under license, and millions of copies and variants were soon in use; it became one of the standard languages on the Apple II (based on the quite different 6502 MPU). By 1979, Microsoft was talking with several microcomputer vendors, including IBM, about licensing a BASIC interpreter for their computers. A version was included in the IBM PC ROM chips and PCs without floppy disks automatically booted into BASIC just like many other small computers.

Newer companies attempted to follow the successes of MITS, IMSAI, North Star and Apple, thus creating a home computer industry; meanwhile, BASIC became a standard feature of all but a very few home computers. Most came with a BASIC interpreter in ROM, thus avoiding the unavailable, or too expensive, disk problem. Soon there were many millions of machines running BASIC variants around the world, likely a far greater number than all the users of all other languages put together.

There are more dialects of BASIC than there are of any other programming language. Most of the home computers of the 1980s had a ROM-resident BASIC interpreter.

The BBC published BBC BASIC, developed for them by Acorn Computers Ltd, incorporating many extra structuring keywords, as well as comprehensive and versatile direct access to the operating system. It also featured a fully integrated assembler. BBC BASIC was a very well-regarded dialect, and made the transition from the original BBC Micro computer to more than 30 other platforms.

During this growth time for BASIC, many magazines were published such as Creative Magazine that included complete source codes for games, utilities, and other programs. Given BASIC's straightforward nature, it was considered a simple matter to type in the code from the magazine and execute the program. Different magazines were published featuring programs for specific computers, though some BASIC programs were universal and could be input into any BASIC-using machine.

Many newer BASIC versions were created during this period. Microsoft sold several versions of BASIC for MS-DOS/PC-DOS including BASICA, GW-BASIC (a BASICA-compatible version that did not need IBM's ROM) and QuickBASIC. Turbo Pascal-publisher Borland published Turbo BASIC 1.0 in 1985 (successor versions are still being marketed by the original author under the name PowerBASIC).

These languages introduced many extensions to the original home computer BASIC, such as improved string manipulation and graphics support, access to the file system and additional data types. More important were the facilities for structured programming, including additional control structures and proper subroutines supporting local variables.

However, by the latter half of the 1980s newer computers were far more capable with more resources. At the same time, computers had progressed from a hobbyist interest to tools used primarily for applications written by others, and programming became less important for most users. BASIC started to recede in importance, though numerous versions remained available. Compiled BASIC or CBASIC is still used in many IBM 4690 OS point of sale systems.

BASIC's fortunes reversed once again with the introduction of Visual Basic by Microsoft. It is somewhat difficult to consider this language to be BASIC, because of the major shift in its orientation towards an object-oriented and event-driven perspective. While this could be considered an evolution of the language, few of the distinctive features of early Dartmouth BASIC, such as line numbers and the INPUT keyword, remain.

Many BASIC dialects have also sprung up in the last few years, including Bywater BASIC and True BASIC (the direct successor to Dartmouth BASIC from a company controlled by Kurtz). Recently, the remaining community using Microsoft's pre-Visual Basic products have begun to switch wholesale to FreeBASIC, a GPLed compiler which has been in the process of moving BASIC onto a GCC backend. Many other BASIC variants and adaptations have been written by hobbyists, equipment developers, and others, as it is a relatively simple language to develop translators for. An example of an open source interpreter, written in C, is MiniBasic.

The ubiquity of BASIC interpreters on personal computers was such that textbooks once included simple TRY IT IN BASIC exercises that encouraged students to experiment with mathematical and computational concepts on classroom or home computers.

Sample Code

10 INPUT "What is your name: "; U$
20 PRINT "Hello "; U$
30 REM
40 INPUT "How many stars do you want: "; N
50 S$ = ""
60 FOR I = 1 TO N
70 S$ = S$ + "*"
80 NEXT I
90 PRINT S$
100 REM
110 INPUT "Do you want more stars? "; A$
120 IF LEN(A$) = 0 THEN GOTO 110
130 A$ = LEFT$(A$, 1)
140 IF (A$ = "Y") OR (A$ = "y") THEN GOTO 40
150 PRINT "Goodbye ";
160 FOR I = 1 TO 200
170 PRINT U$; " ";
180 NEXT I
190 PRINT

Ruby is…

A dynamic, open source programming language with a focus on simplicity and productivity. It has an elegant syntax that is natural to read and easy to write.

Top Ruby Features according to Michael Neumann

interpreted

advantage:

* immediately executable (no waiting period while compiling)

disadvantage:

* execution speed much slower than with compiler (e.g. Pascal, C++)

object-oriented

In Ruby everything is an object (as in Smalltalk). Ruby did not use multiple-inheritance, but the same is possible through mix-in.

portabel

Ruby is highly portable, so that one and the same Ruby program runs without changes under UNIX, Windows, DOS, Mac, BeOS and others. Of course that's only true unless using platform-specific modules, like for example some GUI's for UNIX or WinGKR (Win32 GUI Kit for Ruby).

advantage:

* less expenditure (only one program had to be managed)
* wider distribution of the program (because it runs on serveral platforms)

untyped

Variables in Ruby have no type, such as in Smalltalk, BASIC or Python. Variables behave as placeholders, but data is typed. In C++ or Pascal, variables are typed (e.g. int / Integer), but the data in the memory is not, that is you cannot recognize if it's a String or an Integer. In C++ or Pascal the types are checked at compile-time, whereas Ruby checks the type at runtime, so if the object understands the message (method-call) is first known after a method-call. You do not have to declare variables, because they are automatically created when you use them.

automatic memory-management (garbage collection)

You do not have to release allocated memory in Ruby (as you have to do in Pascal/C++ with dispose/free). No longer used memory, i.e. memory-frames where no variable points to, are automatically freed by the garbage collector.

advantage:

* no memory leaks
* fewer crashs or errors
* more easier, faster and more uncomplicated programming, because you do not have to look after the memory management.

disadvantage:

* less speed (about 10%). But Ruby is an interpreted language, where 10% are not so much.

easy and clear syntax

Ruby is based among others on the syntax of Eiffel (Ada)

* well legible
* ease to understand
* easy to learn
* fewer errors

Ruby often offers an additional C++ similar syntax

* hardly changes for those, who come from C++ (Perl) to Ruby
* less code ==> faster

advanced OO-concepts and features

* singleton methods
* mix-in instead of multiple-inheritance
* operator overloading
* method-overloading (such as C++)
* exception handling
* iterators and closures
* meta-class
* build-in pattern-matching (like Perl)

other features

* Ruby is free, also for commercial applications
* many existing libraries make programming easy
* Ruby is permanently developed, without loosing backward-compatibility
* There are interfaces to Python, Perl and Java. Thus existing programs can be reused.
* Many important data-structures are available (such as dynamic arrays (lists), strings, bignum, complex, ....)
* Easy to extend through C/C++ with dynamic (DLL's) or static binding.

Sun Developer Summit 2006 - A review

The most irritating Software Summit I have ever been to.