Karl Brodowsky's IT-Blog – Seite 19 – IT Sky Consulting GmbH

Eatable Devices

Wearable devices have become normal and it is hard to buy clothes these days that do not actually belong to this category. If you don’t know, the NSA knows.

The new trend are eatable devices. It has been quite a challenge to create chips and batteries that can be chewed and swallowed without pain and without exploding while being eaten. But the newest chips are made of Bio-Silicon which is 100% eatable and riskless to eat. Batteries have been replaced by condensators, which proved to be the better choice.

Now this opens a huge range of applications. We can write apps that work on the cluster of eatables and support our diet, because they register exactly when, how and by whom they are eaten. Newer pricing models allow us to buy food and pay some part of the price only when we actually eat it. We can see when food is expired and discard it. Of course not in the regular garbage, but finally each household will now get a separate garbage can for electronic devices. Remember to put your clothes in there, even though you were not aware of the chips inside when you bought them. It will be better for the environment.

The labs of IBM and Coca Cola have jointly developed microchips that actually float in the drink and are so small that we usually do not see them. This will support the usual functions of eatable devices and will equip the drinker with so many chips inside the body that permanent tracking will become easy even without a cell phone.

Apple finally found their core business. Eatables. Apples. They almost taste like old style apples, are nicely designed and we buy them in the apple store instead of the supermarket. The first eaters waited half a week in front of the Apple stores to get the taste of the real Apple-apple as early as possible.

Oracle buys the NSA

Do we still need Experts when everything is in the Internet

We find a lot of information about pretty much everything on the internet. We do not have to remember things because we are always online and always able to find the information we are looking for. It is true. I do it, you do it, everybody does it. Wikipedia, Google, Forums and of course specific sites…

I just give an example, I once met a doctor, a physician. A patient had a problem that was unclear to him and he actually told the patient that he would google for the problem. In the end he came up with a very helpful solution for the guy, much better than what many of us would get in the same situation. I will not disclose any details.

Now why do we need an expert at all, if the expert did not know and found a more helpful answer than the other experts only by using a search engine that all of us can use?

Actually it is the conjunction of the expert and the online information that became so helpful. At least since the last presidential election in some country on the North American continent we have learned that media (and probably even the internet) may be unreliable and that truth is relative, if we at all accept the concept of truth.

Or to become more tangible, there are numerous sites that promise us easy solutions at least to questions that really many find important like diets, raising money easily (and legally), and a lot more, we all know it. It is quite easy to put a site online and put any information on there. It is a bit harder, but possible to get found. The author of the site can sell something that he would never buy himself or something that he believes, even though it is not true. I have met a person in Switzerland who seriously told me that eating would be unnecessary for humans and he or she just practiced it for the joy of eating. In case of medical advice it is quite obvious that this might be dangerous, but in almost any area we have more or less the same problem. A government agency that enforces that only the truth is written on web pages would be a nightmare. Just think of your favorite politician being in charge of such an agency…

But for the expert it is easy to recognize which information is serious and useful. And even easier to use the right keywords for searching.

And there is more. The expert knows the situation, consciously and subconsciously he combines experience and what he sees, hears, …. to solve the problem. And builds in the input from the search.

We should also think that searching is extremely efficient, but knowing 99% without searching is so much more efficient. Just think of languages. I speak a couple of them, and it is often useful to use online dictionaries or even translators. But needing them for every other word is inefficient and will actually sometimes lead to wrong understanding.

The information on the internet will become better. There will be new concepts implemented by sites for providing reliable content in certain areas. We already see Wikipedia, which is not 100% reliable, but probably about as good as a printed encyclopedia in this aspect.

Anyway, the experts will not become useless, but we will need them in the future as well.

Forrest roads

In forests we usually find unpaved roads like this:

Now we should observe how they are constructed. Usually the need to somehow allow access to areas in the forest. It does not have to be the shortest connection, it does not have to be as flat as possible, it is not required to build for high speed and it is not at all required to build for high capacity.

Often it is necessary that trucks and heavy machinery can use the road. So it needs to be constructed in a way that it withstands occasional usage by heavy vehicles, for example to extract wood from the forest or in bad cases to fight a forest fire. And the network usually provides a reasonable way for a truck with a trailer to get out again by driving forward only.

Apart from this there is one very important requirement. The construction must be cheap. It should usually be so cheap that it can easily be paid by a relatively small fraction of the money that is obtained by selling the wood from the forest. There can be a significant secondary use for recreational purposes or even as route through the forest, typically for MTBs and pedestrians, which might justify using money from other sources than the revenue from the forest. Interestingly forests in Switzerland have much denser road networks than forests in Norway or Sweden.

What we never see is forest roads that are somehow prepared for the case that it might be decided in the future to expand them to eight lanes or to transform them into high speed highways. It would be good to use a route that allows this, to already pass hills with cuts or tunnels and to build bridges already much wider than currently necessary. Real highways usually run on a dam or at least they include a thick sequence of layers that often add up to a few meters under the upper asphalt layer. There are „best practices“ about building highways, even relatively narrow highways like this one:

Highway E45 in the Taiga in northern Sweden 2014

They are mostly ignored, apart from very universal principals that apply to any kind of construction.

One kilometer of forest road costs a very tiny fraction of one kilometer of such a highway with two lanes.

We should learn from this for our IT solutions. We should think how big our IT solution might actually become. How many customers do we need to serve? What kind of sophisticated functionality needs to be added? Very often we see the mistake that IT solution are built too small. They do not scale, cannot easily be expanded or simply not serve the load or the availability requirements.

Companies like Google. Facebook, Twitter, Netflix or VK serve millions of users 7×24. There is even an implicit promise that there will be no down times and people start relying on this.

We expect banking software to be accurate to the cent. Not sometimes, but always.

Running a device in a chemical plant or steering a rocket requires absolutely reliable software. Errors can be very expensive and cost human lives.

On the other hand there is plenty of software that is useful. Of course it needs to work properly. But the requirements are much lower. A typical app for a mobile phone does not need to be able to run on millions of servers simultaneously. Downtimes during software updates are no problem. Usually a small development team is sufficient to build them. And when it comes to money, the real business logic for this is usually on the server. And we just should not control a chemical plant by a mobile phone app. But mobile phone apps usually have to come at neglectable prices to the users. They either have to pay themselves by the business that they indirectly promote or by a very small amount of money per user, usually combined with a very small number of users.

It is important to really understand the requirements well and build the right size of application. Building too small is very bad, but building too big can be as bad for the project and the organization. And even if the company is lucky and discovers that the software is so attractive that a bigger solution is necessary, then maybe this is a good moment to rewrite it and consider the first version as proof of concept.

Whenever a new highway is built on a route that is previously only covered by a forest road, the highway will usually be built from scratch, ignoring the routing of the old forest road. If the forest road becomes obsolete by that, then the money for the original construction of the forest road is neglectable. Trying to transform a forest road into a highway did happen in many small steps over centuries to create part of our current road network, but it is usually not a recommended approach.

ä ö … in HTML

In the old days of the web, more than 20 years ago, we found a possibility to write German Umlaut letters and a lot of other letters and symbols using pure ASCII. These are called „entities„, btw.

Many people, including myself, started writing web pages using these transcriptions, in the assumption that they were required. Actually in the early days of the web there were some rumors that some browsers actually did not understand the character encodings that contained these letters properly, which was kind of plausible, because the late 80s and the 90s were the transition period where people discovered that computers are useful outside of the United States and at least for non-IT-guys it was or it should have been a natural requirement that computers understand their language or at least can process, store and transmit texts using the proper characters of the language. In case of German language this was not so terrible, because there were transcriptions for the special characters (ä->ae, ö->oe, ü->ue, ß->ss) that were somewhat ugly, but widely understandable to native German speakers. Other languages like Russian, Greek, Arabic or East-Asian languages were in more trouble, because they consist of „special characters“ only.

Anyway, this „ä“-transcription for web pages, which is actually superior to the „ae“, because the reader of the web page will read the correct „ä“, was part of the HTML-standard to support writing characters not on the keyboard. This was a useful feature in those days, but today we can find web pages that help use with the transliteration or just look up the word with the special characters in the web in order to write it correctly. Then we can as well copy it into our HTML-code, including all the special characters.

There could be some argument about UTF-8 vs. UTF-16 vs. ISO-8859-x as possible encodings of the web page. But in the area of the web this was never really an issue, because the web pages have headers that should be present and inform the browser about the encoding. Now I recommend to use UTF-8 as the default, because that includes all the potential characters that we might want to use sporadically. And then the Umlaut kann just directly be part of the HTML content. I converted all my web pages to use Umlaut-letters properly, where needed, without using entities in the mid 90s.

Some entities are still useful:

„<“ for „<“, because „<“ is used as part of the HTML-syntax
„&“ for „&“ for the same reason
„>“ for „>“ for consistency with „<„
„ “ for no-break-space, to emphasize it, since most editors make it hard to tell the difference between regular space and no-break-space.

Observer Effect

Scientists have to deal with the observer effect, which means that observing something actually changes it. Typically we think of quantum physics, where this effect is very strong and surprising and closely related to the Heisenberg Uncertainty Principle, but it is actually something that in a more abstract sense is present in a multitude of situtations. Just think of human interaction. If we want to find out about people, we can ask them. But this conversation actually changes the people, sometimes in a way that we can neglect or tolerate.

But we also have this in the case of IT. If we think of a software and we want to observe if the software behaves well, we need ways to observe the software. Very often we use logging, sometimes monitoring tools, and sometimes debugging or even profiling. We think that they do not hurt us, apart from using resources, but we have to be quite careful. The example of logging is quite good, because it is quite common and usually something that we do a lot, without wasting too much thoughts about it.

Now logging slows our application down that is known already. Now we tend to use a slightly less noisy log level, because terabytes of log are still a pain, even today. But usually the messages are calculated and then discarded by the logging framework. With functional language features there are quite elegant ways to deal with this, by just passing a function that calculates the message on demand instead of passing the message. It has always been possible, but too clumsy to actually do it, unless the logging framework can rely on macro facilities, even such simple ones as the C-preprocessor. The deferred evaluation has its dangers as well. If an object that is passed as an ingrediant for a potential message already changes, while the message is created, we might get funny effects. Maybe only in the log, but maybe it could crash the application or stop the main program flow from doing its work. We need to be careful, unless the object is immutable.

In case of Hibernate or JPA or similar frameworks this can be specially interesting, even with eager message calculation. Accessing attributes of the object can actually lead to database operations. They can fail. They can create load, maybe deadlocks. They can have lost their transaction. A lot of things can happen in places far away from where we assumed to do the DB-work. This actually changes the objects. Do we want such operations to occur during logging? Maybe differently depending on the log level? Immutability is our friend, especially in conjunction with JPA, but that is a long story. We may at least be lucky that we actually have some tables that we only read. We can make the objects „pseudo-immutable“, but still JPA-magic must mutate them at least during the read operation. It is tempting to let tools generate the toString-methods of objects, but it is very dangerous here. We should avoid including any potentially lazily loaded attributes in the toString-output, because otherwise they will be loaded during the logging or even worse differently depending on how we log.

The next thing is the NullPointerException during logging. It is quite common in Java, for example. And we do not want to burden our program logic with NullPointerExceptions from the logging, especially not with those that occur only sporadically. So it is a good idea to be careful and to test well. Only the combination is possibly good enough.

Modern times create more demand for some kind of real multi threading, not in the JEE-sense with a couple of EJBs that can run in parallel, but with massively parallel operations. Even though we have a multitude of logging frameworks and unifying logging frameworks and even more of them, there is a common weakness that they tend to share. Writing into one single target is achieved by some kind of synchronizing, which can slow our application down and change the timing behavior in ways that we did not desire. Asynchronous logging could be good, but in a way this only shifts the problem a bit.

Functional Programming: Article in another Blog

I wrote a Guest Blog Article about Functional Programming on Adesso’s Blog in German.

Testing and Micro Components

It is an interesting trend to create micro components, microservices and use building blocks that are very easy to understand. As always, a new approach will not eliminate all problems. The problem that we are solving has an inherent complexity that we cannot beat. But usually we create a lot of complexity that would not be necessary to solve the problem and this can be avoided. Any approach that really helps us here is welcome. If and how micro components and micro services can help us, is another issue, I will just assume that they are in use.

Think of constructing a building. Now this is a very complex task, but we simplified it by building Lego pieces instead. They are simple, easy to understand, well tested and we just have to compose them to get the building. The building does not become trivial buy that, but maybe it becomes easier to create it.

In the end we want to sell a building. The fact that it is constructed of ISO and TÜV and CE and whatever certified lego blocks is not really relevant for the users of the building. They actually want a building, not lego blocks. Maybe they do not even care how it has been made, as long as it is good. They should not care, but usually they do at least a bit. We do not live in an ideal world and I would care too.

Now the building has to fit into the city. It has a function to play. It is itself a lego block for building the city. But for the moment we are actually only doing one building, not a whole city. So we need to provide tests that it works with its environment and provides the functionality that we expect. There is an API and an API-contract. We need to test this API in the way it will be used in production. That is on Linux, if the productive servers run Linux, not on MS-Windows. But Linux is anyway better for developement than MS-Windows, unless we are working on MS-specific technologies, where the servers will run MS-Windows anyway. We have to test with the database product that is used in production, for example PostgreSQL or Oracle. Tests with In-Memory-DBs or products like sqlite are interesting and maybe helpful for finding bugs by having tests that run presumably faster or with less overhead, but there are ways to provide the real DB to each developer and the overhead is not much, once this has been prepared. And a local Oracle instance is not much slower than an in-memory-DB, but allows us to inspect and change data with SQL, which can be very useful. And if we use application servers or middleware, it is mandatory to test with the same middleware as in production, no matter how much compatibility between the implementations of different vendors has been promised. All of these issues are in theory not existent, but I have seen them in practice and that is what counts. Yes, I love theory. 🙂

The other thing is that the fact that the lego pieces have been tested does not guarantee that the whole building will work. The composition creates something special, that is more than the sum of its pieces. That is what we want to achieve. So we need to test it.

So it is good to have automated tests that run against the service using the API that is used in production, possibly REST or SOAP, for example. And to run the test against an instance of the application that runs on the same kind of server against the same kind of database and on the same kind of middleware as in production. At least continuous integration should work like that. The smaller our components are, the more important it becomes to test them in conjunction. Problems will occur there, even though the components by themselves seem to work perfectly.

Now there is demand for running more local tests, unit tests, as they are commonly called, to actually test lego blocks or small groups of lego blocks. It is good to locate problems, because the end-to-end-tests just provide the information that there is a bug, but it is hard to locate. And without thorough testing of the sub components it is possible that we overlook edge cases on the overall tests that will anyway hit us in production, because only the more local tests can explore the boundaries that are visible to them, but obfuscated when accessed indirectly. Also we do not want to be happy with two bugs that cancel each other, because they will not always work together in our favor. So in the end of the day it is important to have automated tests at all levels. And to make them an important issue.

I have seen many projects, where Unit-Tests eroded. They were once done, but did not work any more and were impossible or hard to fix, of course lacking the time to do so. Or the software was hiding access points that were needed for testing. Just two examples for this, for our Java friends: methods can be package private and test classes in the same package to allow testing. And application servers need to actually allow certain remote access, usually via REST or SOAP these days. And we need remote debugging access. This is all easy to achieve, but can be made hard by company policies, even on development workstations and continuous integration servers.

Comments

I like comments that really address the content that I have written, no matter if they agree or disagree with me.

But I am getting a lot of spam these days and comments that advertise pharmaceutical products, credits, dating sites or other non-related issues are spam, when applied to this site, unless we discuss the IT of their web shops, and I delete them. Generally I will delete comments that do not contain content referring to the article, but only consist of links. I like languages and I speak German, English, Swedish, Norwegian, Spanish, Russian and French, but I will usually delete comments in languages other than the article, if their text is not obviously an interesting reference to the article. Even comments like „great blog“ with no content, however nice they are, do not create any value for the readers and will not be released.

Clojure-Art

It is an interesting idea to generate colorful images using or music. In both areas Clojure seems to be quite attractive. Not having explored the music side, I did find the idea of creating images fun and inspiring. It also shows us something about the functions we are working with, if we learn to read the images right, but that will come or not, depending on the circumstances. It is useful not to be too scared of some mathematics when reading this.

Now the challenge is to create an image on a two dimensional array of points, for example 1000×1000 pixel, with x- and y-coordinates ranging from 0 to 999. Each pixel needs to be colored. While it is very interesting to explore different color models, we can for simplicity assume that we need 3 numbers each ranging from 0 to 255 for the red, green and blue channels. This is how most displays work, more or less. Now the goal is to create something that looks good. And of course is reasonable to program, otherwise we could just color one million points individually using for example GIMP, but a million is a lot.

Now we can apply any function on x and y and play around with functions like exp, log, sqrt, sin, cos, tan, sec, csc, sinh, … and of course the basic operations +, -, * and /. It turns out that in most cases we do not get interesting images, but experience will show what is promising to explore. I tried to create pictures by keeping the three channels fairly independent, but this did not work so well. It seems that it is better to keep some connection. One approach that actually works quite well is to consider the pair $(x,y)$ as a complex number $z = x+iy$ and to apply just one complex function on it, again exp, log, sqrt, sin, …. are good building blocks. Now these complex functions have a tendency to grow to infinity somewhere. While real functions can avoid this issue by constraining themselves just to one strait line on the plane, complex functions almost have to go to infinity somewhere. By making the square small enough or by changing the scale we can avoid this, but it imposes quite severe constraints. The Riemann Sphere allows us to map any complex number to a point on the surface of a sphere. With some scaling we can already get to RGB-space and get coordinates that are using, but not exceeding the desired range. There are more ways to visualize complex numbers, but this is a possibility worth exploring.

Another way is to just use functions that calculate a real number and to apply a $\sin$ to it. With some shifting and scaling the values will be between 0 and 255 only and there are nor abrupt changes in color, unless the function we calculated is very steep or very chaotic. Using phase shifts by $\frac{2\pi}{3}$ and $\frac{4\pi}{3}$ the three color channels can be served and we get nice rainbow-waves like the following:

Another experiment was to just assume the HSV-model and to calculate the colors from assuming the function is the H-part. But this ended up looking like plastic and I did not like it too much.

An important issue to observe is that functions may end up in exceptions. I wrapped the functions, so that they do not stop the calculation of the image half way through, but instead provide default values in cases where an exceptions occured.

It can also be fun to explore bitwise-functions like bitxor or even functions like the p-adic exponential function, which yields totally different kind of images.

I have put some of the code from my experiments into Github and licensed it with the GPL, so you can use it as a starting point. Others have worked with this as well, for example Clojure Art on Tumblr, Clojure Art Collective on github, another „clojure art“ on github or creative computing with clojure on O’Reilly’s blog.

Enjoy it and learn some Clojure. I sometimes use this when teaching Clojure.

DB Persistence without UPDATE and DELETE

When exploring the usage of databases for persistence, the easiest case is a database that does only SELECT. We can cache as much as we like and it is more or less the functional immutable world brought to the database. For working on fixed data and analyzing data this can sometimes be useful.

Usually our data actually changes in some way. It has been discussed in this Blog already, that it would be possible to extend the idea of immutability to the database, which would be achieved by allowing only INSERT and SELECT. Since data can correlate, an INSERT in a table that is understood as a sub-entity via a one-to-many-relationship by the application actually is mutating the containing entity. So it is necessary to look at this in terms of the actual OR-mapping of all applications that are running on that DB schema.

Life can be simple, if we actually have self contained data as with MongoDB or by having a JSON-column in PostgreSQL, for example. Then inter-table-relations are eliminated, but of course it is not even following the first normal form. This can be OK or not, but at least there are good reasons why best practices have been introduced in the relational DB world and we should be careful about that. Another approach is to avoid the concept of sub entities and only work with IDs that are foreign keys. We can query them explicitly when needed.

An interesting approach is to have two ID-columns. One is an id, that is unique in the DB-table and increasing for newly created data. One is the entity-ID. This is shared between several records referring to different generations of the same object. New of them are generated each time we change something and persist the changes and in a simple approach we just consider the newest record with that entity-ID valid. It can of course be enhanced with validFrom and validTo. Then each access to the database also includes a timestamp, usually close to current time, but kept constant across a transaction. Only records for which validFrom <= timestamp < validTo are considered, and within these the newest. The validFrom and validTo can form disjoint intervals, but it is up to the application logic if that is needed or not. It is also possible to select the entry with the highest ID among the records with a given entityID and timestamp-validTo/From-condition. Deleting records can be simulated by this as well, by allowing a way to express a "deleted" record, which means that in case we find this deleted record by our rules, we pretend not having found anything at all. But still referential integrity is possible, because the pre-deletion-data are still there. This concept of having two IDs has been inspired by a talk on that I saw during Clojure Exchange 2017: Immutable back to front.