| The Ultimate Business Machine Technology, business And, not least, about by: Bernard Teo
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Sun 24 Sep 2006 Perfection and SimplicityCategory : Commentary/perfection.txt If you had watched Stuart Cheshire's talk about Zero Configuration Networking with Bonjour on Google Video, you may have the caught the part where he talked about the importance of simplicity : "Any fool can make something complicated. And he followed that with a reference to a quote by Antoine de Saint-Exupéry: "In anything at all, perfection is finally attained not when there is no longer anything to add, but when there is no longer anything to take away". I've had that quote playing on my mind the last two months working on Luca. It just so happened that I discovered an excellent book called "Let My People Go Surfing - The Education of a Reluctant Businessman - by Yvon Chouinard, founder of Patagonia, and what did I find but that quote again from Saint-Exupéry leaping off the 25th page : "Have you ever thought, not only about the airplane but whatever man builds, that all of man's industrial efforts, all his computations and calculations, all the nights spent working over draughts and blue-prints, invariably culminate in the production of a thing whose sole and guiding principle is the ultimate principle of simplicity?". "It is as if there were a natural law which ordained that to achieve this end, to refine the curve of a piece of furniture, or a ship's keel, or the fuselage of an airplane, until gradually it partakes of the elementary purity of the curve of the human breast or shoulder, there must be experimentation of several generations of craftsmen. In anything at all, perfection is finally attained not when there is no longer anything to add, but when there is no longer anything to take away, when a body has been stripped down to its nakedness." - excerpt from Wind, Sand and Stars by Antoine de Saint-Exupéry. There you have it - art, science, sex, poetry, engineering, and simplicity. It all adds up to perfection. The JourneyCategory : Technology/journey.txt "It took me a long time to learn where he came from. The little prince, who asked me so many questions, never seemed to hear the ones I asked him. It was from words dropped by chance that, little by little, everything was revealed to me." It started with the question - do currencies always round to two significant digits, like US$9.99? The answer is no. There is at least one case, the Japanese Yen, e.g., ¥1,280 for a pack of Pampers, where they have no decimal places. So how do we make Luca work universally across all currencies without hard-coding all these things? The question started me on a journey of discovery where I learnt about NSDecimalNumbers, creating a custom NSNumberFormatter class in Cocoa together with its own Interface Builder palette, and also about storing blob values in SQL databases so I can stash these number formats that the user has created. And I'm now almost done. I have an interface in Luca that now allows a user to create custom number formats for any individual currency, and he can apply these formats wherever he's entering currency values in any voucher.
If he chooses the Japanese yen as the base currency for the accounting system in Luca, then all calculations where rounding has to be applied (e.g., in exchange rate or tax calculations) are done to zero decimal places. That's triggered in just one place in the code and there's no hard-coding. So, to answer my own question : it can be done. Along the way, I think, I can now really articulate why Cocoa and, especially, Objective-C are such good software development tools. It's all about design. You've got to take a Janus-like stance and look both inwards and outwards at the same time. You've got to look inwards into the code and be aware that the world you're modelling is as complicated as only life can be. And so, you've got to simplify, simplify, and simplify yet again wherever you can in the coding, to get everything neat, clean, crisp and small. Because if you don't don't, then you're going to get drowned in all the possible permutations when things come together in combination, when you meet a real user in the real world. It's from this perspective that we should value the simplicity of the Mac. And the wonderful pragmatism of the Objective-C language. And see how PC people like Paul Thurrott totally miss the point. And so I continue to simplify Luca. I'm pulling all Luca application settings into one single Preferences window, and I hope I can organise its presentation into a narrative to help the user understand what he has to do to set up an accounting system. If I can get this Prefs window done, then Luca will be reduced to just two menu items - an Accounts menu and a menu for Journal, and that would be about it. Sat 09 Sep 2006 SubversionCategory : Technology/subversion.txt I've made massive changes to, at least, the internals of Luca. I couldn't have done it without using Subversion, a version control system that I used to store my evolving Luca project files. There is a one-click install of Subversion for Mac OS X that you can get from Martin Ott's web site. I access my Subversion repository using this GUI front-end called svnX :
This combination of Subversion and svnX, together with FileMerge, below, which comes with Xcode, provides me with some sort of a Time Machine (no need to wait for Leopard). I'm able to compare across different versions of every file in my project, thus making it possible to do the kind of multiple changes that I was doing to a rather complicated project, in the last three weeks, in a very systematic way :
I'm highlighting this because I'm always puzzled why enterprises don't use Macs more. If they're worried about being locked in, a case can be easily made that they're even worse off, as far as being locked in is concerned, using Microsoft as their development platform. The tools I've mentioned, Subversion and svnX, are both free, open source projects. They're fast and work remarkably well. And they allow multiple programmers, spread out geographically, to work togther and synchronise their work with fine-grained precision. The databases I've been using, MySQL and SQLite, are also free and open source. In fact, in the last four years, I've totally turned over the things I know how to do. Prior to that, my main development platform was 4D (4th Dimension) and Oracle, and I used to pay $10,000 at least every two years for the privilege of using them. It slowly dawned on me, after OS X was released, that the economics of software development, at least on the Mac, was changing. I don't have to do those enterprise-scale systems I was doing anymore, to keep me in my fix, since I do enjoy building systems. But I was building systems for Windows users (although I stubbornly clung on to our PowerBooks) and that wasn't what turned me on each day. I wondered, then, if I could be doing the things I am doing now - selling the software I build over the Internet to Mac users, doing things on a smaller scale with, say, no more than three people, and spending more time with my kid. If this is any inspiration to others, I mean to say that if you can visualise something you want to achieve, you can often make it come true. But coming back to the topic, the tools we have at our disposal today are stupendous, absolutely first class. And most of them are free. Why is the enterprise not picking up on this opportunity? Systems are the life-blood any enterprise, whether you are a passion-driven company like Patagonia or a staid old company like (fill in the blanks). You need to be able to get at the data and shape your systems to meet your company's needs and its beliefs. Tools are the key. The best tools you can find. The simplest, easiest, strongest tools. Because building a company is hard. Why complicate things by using clumsy, overly elaborate, unfathomable systems like Windows? I like to think that the thing I'm doing now is subversive - to the current entrenched corporate wisdom. I'm using the best possible software development tool I can find, to build systems at the cheapest possible price, on a platform that nobody else had believed had a relevance to business, except for the Mac users, and to help make these Mac users successful in business. If I could ever be successful at it, that would be like proving a point. Fri 08 Sep 2006 Business, Computing, and the MacCategory : Technology/numberTest.txt I realised I hadn't written anything in three weeks. But I'm only now re-surfacing, having spent all that time inside the bowels of Luca, pulling out all references to doubles and floating point numbers, and replacing them with Cocoa's NSDecimalNumber class. Is it worth it? Consider the following code snippet : - (void)test:(id)sender So, we've got two numbers. One expressing 0.0001 as an NSDecimalNumber and the other as a floating point number. We loop around and add them up 10000 times. These are the results we get : [Luca 1397] total, as NSDecimalNumber = 1 With the NSDecimalNumber, we get the result we expected, 1. The floating point number, on the other hand, came very close to 1 but then, not quite. That's the problem we face working with floating point numbers. They really do float away from what they are meant to be. Let's see what havoc this causes in an accounting application. Let's say we're adding a long list of debits and credits. The two columns often won't balance, if we don't apply a mathematical function to round the figures. But then, when do you do the rounding? After the addition, or on each line item? And to how many decimal places? Two, if you're working with US dollars, none if we're working with the Japanese yen. The code easily becomes very complicated - unecessarily so because if the computer knew how to do its math, we wouldn't have to round at all. So that's what NSDecimalNumber does - it lets you work with greater precision so you get the result you want without having to go through all these contortions. That doesn't mean you eliminate rounding completely. You still have to apply a rounding function when you multiply, say, a monetary figure by an exchange rate, and you have to decide how many places you want to round it to (probably to the number of decimal places used by the currency you base your accounting system on). And you still have to work out how to handle dividing 1 dollar between 3 people, like who gets to keep the last cent. But at least we've cleared up, say 80% of the clutter in our code. So, imprecise calculation is one problem we faced in business computing that we can solve with that new data structure, called the NSDecimalNumber in Objective-C, and BigDecimal in Java. Then there's the problem of storage. Does the database system handle exact-number mathematics? Luckily, MySQL does, with its Decimal data type (since MySQL 5.0.3). So shuttling the data between Luca and MySQL is sweet - things go in and out the way you want. Not so with SQLite3. You get all this muck (in red, below) because SQLite still works only with floats and doubles and it can't represent a number like 513.58 exactly :
The problem comes when you read the data back. (Again, just when do you round the data, and to how many decimal places?) I'll have to attack this problem next. But let's move on. I keep mentioning that we need to figure out how many decimal places to round, say, an exchange rate calculation to, because it depends on the context. In the picture below, I show a Luca payment voucher where three currencies are involved. The original invoice was billed in Singapore dollars, and is being paid with Malaysian dollars. The base currency (the local currency used by our fictitious example company) is in US dollars and that's what we use to book the bank charges and the currency exchange gain under.
In this case, all three currencies are denoted to two decimal places. But if we get paid in Yen, we'd like, as Mac users, to see no decimal places at all when we're entering the Yen value. And when we print out that voucher we'd like to see the Yen symbol being printed, too. Fortunately, Cocoa has a user-interface class called the NSNumberFormatter class, that I have built a custom sub-class for, and that I can use inside Interface Builder, as if it were one of the supplied palette objects :
And the great thing about being able to use your own custom number formatter class is that it opens up a lot of possibilities. Suddenly, you're able to format numbers the way the French or the Swedes or the Indians want, and since you can get hold of your formatter object in your code during run-time, you can do a lot of currency formatting on the fly, or let the users customise it themselves.
If the user decides to format the Yen to no decimal places, you will be able to tell from the "Max fraction digits" parameter, above, and that's what you use to control the rounding behaviour. Plus you can set the rounding behaviour to say, the traditional way (which has a bias towards rounding up), or "bankers' rounding" where numbers are rounded down as often, statistically, as they are rounded up. And you can gather all these customisations in one logical place, so it's possible to avoid hard-coding anything in your application, and thereby making it all truly multi-currency. Cocoa is a wonderful development environment. Sometimes, like when I managed to get this working in Interface Builder, I was so excited and I wonder why don't more people see it? This is so great. Like, with the Spell Out Style, above, you can do cheque printing. And, though I haven't done it yet, you should be able to print it with fillers like asterisks between the currency symbol and the money value. Now, if all these are not doing things to support a business, then I wonder what is. And if the Mac is not a business machine, then what is? It took me three hours, from knowing nothing about Interface Builder palettes, to actually creating my own number formatter and getting it working in my own nib files. And I actually did this while parked near some people noisily playing mahjong in some relatives' house. I say this because I'm constantly amazed at how productive this development environment is. And yet how little people know about it in the mainstream. I was attending this talk by the CEO of Sybase, John Chen, yesterday (it was a very interesting talk - he shared his experience doing business in China - lots of interesting people pass through Singapore - I ought to be attending more of these). Anyway, I was talking to someone who found out that I'm working on the Mac, and he says, oh that's only a niche market, right? for the arty-farty types, right? Right. Fri 18 Aug 2006 BigDecimalsCategory : Technology/BigDecimals.txt This is very good tutorial, showing how BigDecimals are used in Java code : "Make cents with BigDecimal - Write Java programs to calculate and format currency". We can map all these calls to Objective-C in an equivalent way. Also, read this : "The Seven Habits of Highly Dysfunctional Design - In your face ! BigDecimal, BigInteger and BigMistake". Of Real Numbers, Floats, and DecimalsCategory : Technology/decimals.txt My last post about problems handling floating point numbers for financial calculations brought me a couple of responses. I make an assumption in Luca that all currencies work with two decimal places, and I round them wherever I can and store them to two decimal places. This way my accounts (should) always balance since, for every voucher, I make sure that the debits and credits are rounded to two decimal places and compared to be equal before I allow them to be saved. But what if I'm working with a currency that doesn't use two decimal places - they use three, or four, or five, or ... none? Guy Harris says - "Yes, the Japanese yen has no decimal places at all." That's just the motivation I need to go and dig further because the assumption I used wouldn't work if I want Luca to be used just about anywhere possible. Luca allows the base currency (the currency you use to base your accounting on and produce the financial statements) to be different from the billling currency and the settlement currency. So what if we get paid in Yen? Rounding the yen to two decimal places would make no sense at all. So what to do? I got one other mail from Quintin May that pointed me towards a whole new world of possibilities : "I read your post regarding floating point and rounding in Luca. It has been my experience when working with financial data to NEVER use floating point numbers. In Java, the BigDecimal type is preferred for this type of data representation. I'm not fluent in Objective-C, so I don't know if it has an equivalent data type. This article goes into excruciating detail on floating point arithmetic: http://docs.sun.com/source/806-3568/ncg_goldberg.html. Try a Google search for "objective-c" "bigdecimal". And that's what I did. Objective-C seems to have an equivalent class - the NSDecimalNumber. It has methods for adding, subtracting, multiplying, dividing, and comparing two objects of the same NSDecimalNumber type, plus conversion to formatted strings for display, with the correct separators and currency symbol, depending on locale. This looks like just what I need. Better still, new to MySQL 5.0, there's an equivalent exact-number data type called Decimal. So if all these pan out, a good strategy to take is : don't round, store all financial values as Decimal data types in MySQL, and load them into NSDecimalNumber data objects in Objective-C. Display them in windows and views as strings formatted according the appropriate locale, set according to whether the displayed value is in the billing, settlement or base currency. Do not add them like you would double or floating point numbers. Use the supplied methods, for addition, multiplication, and especially for comparison. So, this looks like a very neat idea. But will it all work out? And what about SQLite? It doesn't have an equivalent data type. There's only one way to find out - Just Do It ! I've often asked myself why I bother writing a weblog or why people would bother coming over to read it. Well, this is one benefit. I get responses. When I'm stuck, they point me to new, fortuitously more productive directions. And I hope you, dear reader, learn something useful also when I do. Wed 16 Aug 2006 Do the math ... or when is 156.14 != 156.14 ?Category : Technology/maths.txt This is a Cash Disbursement voucher in Luca :
I have a rule that says you can't save a voucher unless the debits and credits balance. So, here we have $156.14 being paid out of a checking account, recorded against an equal $156.14 in expenses. Yet the Save button refuses to be enabled. What is going on here? Looking a bit closer at the objects : NSLog(@"vouAmount = %f", [vouAmount doubleValue]); we get : Luca[1046] vouAmount = 156.140000 It's as we would expect but it remains puzzling, so we zoom even closer : NSLog(@"vouAmount = %1.24f", [vouAmount doubleValue]); we get : Luca[1046] vouAmount = 156.140000000000014779288904 The vouAmount is taken straight off the object. The total column has a rounding function applied to it, but still it's just one line item, for simplicity's sake. So both items are off the expected figure of 156.14. They never balance. This happens only at certain values, not all the time. It happens because "real numbers" in digital computations are only a very close approximation to the mathematical concept of real numbers. The difference is infinitesimally small (my favourite expression in engineering school), but it's there all the same. It's what throws us off. This reminds me of that paradox of Zeno, of a foot race between Achilles and a tortoise. The tortoise is given a headstart, but picture Brad Pitt as Achilles, huffing and puffing, always covering half the distance to the tortoise, always gaining, but never quite reaching, because the half-distance keeps getting smaller, and smaller, and smaller, but never disappears. It's become infinitesimally small. The solution is to round both numbers before comparing them, even the one entered exactly as 156.14.. But we have to take care to do the rounding at lots of places, not just when the value is entered. For example, you do rounding when one value is multiplied by another. But what happens when you divide a dollar by three. You lose that last infinitesimally small fraction of a cent because computers work with discrete values, not a continuum. So, that's why building such systems, mundane though they seem, is hard. It's a craft. It's precision work. But it's not the kind that will win Apple Design Awards at WWDC. I'm fixing this in a Luca 2.2.2 release. But I have the rounding done all over the place. The art is to find a way to control this in just one spot in the application. What happens when I find a user whose currency system works with other than two decimal points? Is there such a thing? Mon 14 Aug 2006 6000 CustomersCategory : Commentary/6000Customers.txt I think we've crossed 6000 paid customers. I just read that the guys at Parallels sold 100,000 copies of their virtualisation software at $80 per copy. So 6000 pales into insignificance when compared with that. But I know it'll mean something to me if I do get to cross the 10,000 mark. Building a business one customer at a time. Is this too slow? Slow is when you're waiting for time to pass in Eternity. "To see a world in a grain of sand, I'm reading this book "Art and Physics - Parallel Visions in Space, Time & Light" by Leonard Shlain. If you've ever done physics in school and know enough to tell a Monet from a Manet, this may make interesting reading (in spite of the pretty bad reviews it's gotten at Amazon, but one man's meat is another man's poison and so on ...) DNS Enabler in GermanCategory : Technology/DNSEnablerDeutsch.txt Matthias Schmidt at Admilon contributed this German localisation of DNS Enabler 2.1, including the new Bonjour panel.
Thanks, Matthias. Luca 2.2.1Category : Technology/Luca2dot2dot1.txt Over the weekend I've fixed some (rather embarrassing) user interface bugs with the last release of Luca, like buttons and text not sticking to their corners when windows get resized, or the default financial period not getting saved to preferences when the save-to-defaults button was pressed. Notifications also work better now, so when something happens in one window, e.g., when a voucher gets deleted, the totals showing on other windows will all get updated automatically. Also, I had some problems mapping date fields between SQLite and MySQL, especially handling NULL data types. These are handled better now. Things To Do 1. I need to improve the speed in which data is imported/exported between SQLite and MySQL. This is currently slow and still not robust enough to handle, e.g., three years worth of data without hanging. 2. I need to put in a button to let the user choose whether to drop a database before exporting the data. Currently it assumes you want to overwrite the destination database and tables in MySQL. Here is someone I know who's using Luca with MySQL now - Jan Steinman at VeggieVanGogh. 3. Need to handle the "last one cent" problem better, e.g., when a dollar is split three ways and you put them back again, you get 99 cents. Which account should get the last one cent so that the debits and credits always balance, no matter how often you go back and edit or rollback the data? This problem shows up when you're apportioning amounts to cost centres or when you're doing currency exchange gain/loss calculations. I don't think I've ever totally solved it while we were doing custom applications - once in a while, our user would find that she can't save the voucher because the accounts are out by one cent. In a custom application, we're on hand to guide the user to correct this manually. But not when it's going to be a "shrink-wrapped" application. So I've got to pin this down once and for all. 4. Tax handling on line items rather than on the consolidated total. 5. After all these I think I can move on to the invoicing module, a payroll module, or a time-billing module? Actually I have pieces of quite a lot of these in 4th Dimension code. I'm like a PC guy who just loves Macs. I do these PC things for PC-using companies but I want to use a Mac. I'm stuck between art and science, engineering and design, the PC and the Mac. Luca is a work-in-progress - for the Mac as The Ultimate Business Machine. Do keep the suggestions coming. Sat 12 Aug 2006 Luca 2.2 with MySQLCategory : Technology/Luca2dot2MySQL.txt I've released Luca 2.2 with support for storing the accounting data in a MySQL database. I've also written the import/export code to shuttle the data between SQLite and MySQL, and back. I realised then that I've got the basis of the code to do a "universal" SQL data converter, to shuttle data between any kind of SQL database. If I have time, I'll take a look at PostgreSQL or Oracle. (Now, look how richly endowed we all are on the Mac. Who would have thought?)
Luca is getting more stable now and working faster. There are probably a few more bugs lurking inside the system but I thought I'd better get this out as it's quite usable now, and I've made some improvements to the workflow and made several bug fixes. I hope that by the next release, I can be sure that Luca will be thoroughly reliable. I'm going to stress-test this release next. I've already seen where it's still breaking. But I've worked hard to get to this point and release it because I want this idea to take hold in people's minds - that you can really do a lot on the Mac. With this release, people who want to integrate an accounting system to the rest of the custom, say, PHP-based workflow that they've built can now do it. The database is open and you can flow your data onto it or get data out of it in ways that I cannot even anticipate now. And you can get at your accounting data even when you're half-way round the world. I've yet to put in the concurrency-handling code. But we've done this years ago while it was still a 4th Dimension-cum-Oracle-based system (though that would never have worked outside a local area network) and so I know we can do it. I'll get to the point one day when all these things - MailServe, WebMon, DNS Enabler, Luca, etc - will all come together and make sense as one seamless whole. I have an idea what that is but I can't yet explain, even to myself, what that means. I'm learning as I go. They say (actually it was Steve Jobs) that you shouldn't start a company just because you want to start a company. You start a company because nobody else believed in an idea and the only way you can get it out of your system (and keep from going crazy) is to go out and build it on your own. Wed 09 Aug 2006 DNS Enabler 2.1Category : Technology/DNSEnabler2dot1.txt I've released DNS Enabler 2.1.
It includes a Bonjour panel to allow DNS Enabler to be used as a configurator to enable wide-area discovery of Bonjour devices :
More information about the types of Bonjour services you can currently configure, and what you need to enter into the individual columns in the Bonjour panel, can be found at : http://www.dns-sd.org/ServiceTypes.html (DNS SRV (RFC 2782) Service Types). What DNS Enabler saves the user is the need to know the specific syntax to set up SRV and TXT records at the DNS server. All he needs to know is the Bonjour service type, e.g., _http._tcp for publicising web pages (that may be served even from local private networks - you can use the Port number field to publicise a different port other than 80 and port-map that incoming request to a specific local machine) and the domain that will serve that request. The service name is a label that will show up in the Bonjour menu in, say, Safari. And the TXT column contains the path to that specific web page. (The TXT column stores different things for different services. See the cited Bonjour reference). Stuart Cheshire may be showing this panel at work sometime in his Bonjour talk at WWDC on Thursday, 10th August, at 9.00 am (PST). PS : I've also added a button to populate the Forwarders field with the list of DNS servers that the user has set up in his Network Preferences. I've left the interface somewhat cluttered at the moment because I'm planning to add a couple more features in the next two weeks, and I'll clean up the interface then. Read more ... |
Mac@Work
Services running on this server, a Mac Mini running Mac OS X 10.9.2 Mavericks:
all set up using MailServe, WebMon, DNS Enabler, DNS Agent, VPN Enabler, Liya and our SQL installers, all on Mavericks. |
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