\begin{chapterabstract}
The sheer number of connected devices around us is mind boggling and seems increases exponentially for many years.
- In 2022, there is an estimated number of 13.4 billion of devices connected that sense, act or otherwise interact with the world\footnote{\url{https://transformainsights.com/research/tam/market}, accessed on: \formatdate{2022}{10}{13}}.
- These devices, together with the networks that provide the communication, the servers realising the back end and the devices in our pockets are called the \gls{IOT}.
- \Gls{IOT} systems can be seen as layered systems, where each layer is powered by different types of computers; and programming languages and paradigms.
- Thes thesis shows a novel way of orchestrating these brobdingnagian systems using the \gls{TOP} paradigm.
+ In 2022, there is an estimated number of 13.4 billion of devices connected that sense, act or otherwise interact with people and the physical world surrounding us\footnote{\url{https://transformainsights.com/research/tam/market}, accessed on: \formatdate{2022}{10}{13}}.
+ These devices, together with all the scaffolding and integration such as the various networks providing the communication, (cloud) computers realising the back end or administration and the devices in our pockets providing us with a view on the system are called the \gls{IOT}.
+ \Gls{IOT} systems can be seen as layered systems, where each layer is powered by different types of computers; programming languages and even programming paradigms.
+ This thesis shows a novel way of orchestrating these brobdingnagian systems using the \gls{TOP} paradigm.
It does so by giving a proof-of-concept implementation for a \gls{TOP} system specifically designed for the \gls{IOT}: \gls{MTASK}.
At the core of the \gls{MTASK} system is a \gls{DSL}, embedded in the general purpose \gls{TOP} system \gls{ITASK}.
Using the \gls{MTASK} system, all layers of an \gls{IOT} system can be programmed from a single declarative specification.
- This chapter provides the required background material, detail regarding the contributions and a reading guide.
+ This chapter provides the required background material, an overview of the concrete contributions and a reading guide.
\end{chapterabstract}
\todo{Introduction in the abstract doen zoals nu?}
CISCO states that the \gls{IOT} only started when there where as many connected devices as there were people on the globe, i.e.\ around 2008~\citep{evans_internet_2011}.
Today, the \gls{IOT} is the term for a system of devices that sense the environment, act upon it and communicate with each other and the world.
-These connected devices are already in everyone's household in the form of smart electricity meters, smart fridges, smartphones, smart watches, home automation, \etc.
+These connected devices are already in households all around us in the form of smart electricity meters, fridges, phones, watches, home automation, \etc.
-When describing \gls{IOT} systems layered---or tiered---architecture is often used to compartmentalize the technology.
+When describing \gls{IOT} systems, a tiered---or layered---architecture is often used to compartmentalize the technology.
The number of tiers heavily depends on the required complexity of the model but for the intents and purposes of the thesis, the four layer architecture shown in \cref{fig:iot-layers} is used.
\begin{figure}[ht]
\label{fig:iot-layers}
\end{figure}
-The presentation layer provides the interface between the user and the \gls{IOT} application.
-For example, in home automation, this is a web interface or a mobile app used on the phone or a mounted tablet to interact with the edge devices.
+Closest to the end-user is the presentation layer, it provides the interface between the user and the \gls{IOT} application.
+In home automation this may be a web interface or a app used on a phone or mounted tablet to interact with the edge devices and view the sensor data.
The application layer provides the \glspl{API}, interfaces and data storage.
-In home automation, this would be the cloud service or local server.
+A cloud service or local server provides this layer in a typical home automation application.
All layers are connected using the network layer.
-In many applications this is implemented using conventional networking techniques such as WiFi or wired networks.
-However, networks and layers on top of itt tailored to the needs of \gls{IOT} applications have been increasingly popular such as \gls{BLE}, LoRa, ZigBee, LTE-M, or \gls{MQTT}.
+In many applications this is implemented using conventional networking techniques such as WiFi or Ethernet.
+However, networks or layers on top of it tailored to the needs of \gls{IOT} applications have been increasingly popular such as \gls{BLE}, LoRa, ZigBee, LTE-M, or \gls{MQTT}.
-The perception layer---also called edge layer---collects the data, interacts with the environment, and consists of (edge) devices equipped with various sensors and actuators.
-%As a special type of device, it may also contain a \gls{SN}.
-%A \gls{SN} is a collection of sensors connected by a mesh network or central hub.
-In home automation this layer consists of all the microprocessors in the sensors, for example in the smart lightbulbs, actuators to open doors and sensors.
+The perception layer---also called edge layer---collects the data and interacts with the environment.
+It consists of edge devices such as microprocessors equipped with various sensors and actuators.
+In home automation this layer consists of all the devices hosting the sensors and actuators such as in a smart lightbulb, an actuator to open a door or a temperature and humidity sensor.
-Spanning all layers, the devices are a large heterogeneous collection of different platforms, protocols, paradigms and programming languages resulting in impedance problems or semantic friction between layers~\citep{ireland_classification_2009}.
-Furthermore, specifically the perception layer often is a heterogeneous collections of microprocessors in itself as well, each having their own peculiarities, language of choice and hardware interfaces.
-As the hardware needs to be cheap, small-scale, and energy efficient, the \glspl{MCU} used to power these devices do not have a lot of computational power, only a soup\c{c}on of memory, and little communication bandwidth.
+Across the layers, the devices are a large heterogeneous collection of different platforms, protocols, paradigms, and programming languages often resulting in impedance problems or semantic friction between layers when programming \citep{ireland_classification_2009}.
+Even more so, perception layer specifically often is a heterogeneous collections of microprocessors in itself as well, each having their own peculiarities, language of choice and hardware interfaces.
+As the edge hardware needs to be cheap, small-scale, and energy efficient, the microprocessors used to power these devices do not have a lot of computational power, only a soup\c{c}on of memory, and little communication bandwidth.
Typically the devices do not run a full fledged \gls{OS} but a compiled firmware.
This firmware is often written in an imperative language that needs to be flashed to the program memory.
Program memory typically is flash based and only lasts a couple of thousand writes before it wears out.
While devices are getting a bit faster, smaller, and cheaper, they keep these properties to an extent, greatly reducing the flexibility for dynamic systems where tasks are created on the fly, executed on demand, or require parallel execution.
-These problems can be mitigated by dynamically sending code to be interpreted to the \gls{MCU}.
+These problems can be mitigated by dynamically sending code to be interpreted to the microprocessor.
With interpretation, a specialized interpreter is flashed in the program memory once that receives the program code to execute at runtime.
%weiser_computer_1991
For example, \citep{elliott_compiling_2003} describe the language Pan, for which the final representation in the host language is a compiler that will, when executed, generate code for a completely different target platform.
In fact, \gls{ITASK} and \gls{MTASK} are both heterogeneous \glspl{EDSL} and \gls{MTASK} specifically is a compiling \gls{DSL}.
-\section{Task-oriented programming}
-\Gls{TOP} is a declarative programming paradigm designed to model interactive systems~\citep{plasmeijer_task-oriented_2012}.
+\section{\texorpdfstring{\Glsxtrlong{TOP}}{Task-oriented programming}}
+\Gls{TOP} is a declarative programming paradigm designed to model interactive systems \citep{plasmeijer_task-oriented_2012}.
Instead of dividing problems into layers or tiers, as is done in \gls{IOT} architectures as well, it deals with separation of concerns in a novel way.
-From the data types, utilising various \emph{type-parametrised} concepts, all other aspects are handled (see \cref{fig:tosd}).
+From the data types, utilising various \emph{type-parametrised} concepts, all other aspects are handled automatically (see \cref{fig:tosd}).
This approach to software development is called \gls{TOSD}~\citep{wang_maintaining_2018}.
\begin{figure}[ht]
\end{figure}
\begin{description}
- \item[Presentation layer (\gls{UI})]
+ \item[\Glsxtrshort{UI} (presentation layer):]
The \gls{UI} of the system is automatically generated from the representation of the type.
% For instance, \gls{TOP} languages implemented in an \gls{FP} language often use generic programming or template metaprogramming to automatically achieve this.
% \Gls{TOP} languages embedded in imperative programming languages may use introspection\todo{Do I want this sentence here?}.
Even though the \gls{UI} is generated from the structure of the datatypes, in practical \gls{TOP} systems it can be tweaked afterwards to suit the specific needs of the application.
- \item[Business layer (tasks):]
+ \item[Tasks (business layer):]
A task is an abstract representation of a piece of work that needs to be done.
It provides an intuitive abstraction over work in the real world.
Just as with real-life tasks and workflow, tasks can be combined in various ways such as in parallel or in sequence.
Furthermore, a task is observable which means it is possible to observe a---partial---result during execution and act upon it by for example starting new tasks.
Examples of tasks are filling in a form, sending an email, reading a sensor or even doing a physical task.
- \item[Resource access (\glspl{SDS}):]
+ \item[\Glsxtrshortpl{SDS} (resource access):]
Tasks can communicate using task values but this imposes a problem in many collaboration patterns where tasks that are not necessarily related need to share data.
Tasks can also share data using \glspl{SDS}, an abstraction over any data.
An \gls{SDS} can represent typed data stored in a file, a chunk of memory, a database \etc.
\Glspl{SDS} can also represent external impure data such as the time, random numbers or sensory data.
Similar to tasks, transformation and combination of \glspl{SDS} is possible.
- \item[\Gls{UOD} (programming language):]
+ \item[Programming language (\glsxtrshort{UOD}):]
The \gls{UOD} from the business layer is explicitly and separately modelled by the relations that exist in the functions of the host language.
\end{description}
The concept of \gls{TOP} originated from the \gls{ITASK} framework, a declarative workflow language for defining multi-user distributed web applications implemented as an \gls{EDSL} in the lazy pure \gls{FP} language \gls{CLEAN}~\citep{plasmeijer_itasks:_2007,plasmeijer_task-oriented_2012}.
While \gls{ITASK} conceived \gls{TOP}, it is not the only \gls{TOP} language.
-\Gls{TOPHAT} is a fully formally specified \gls{TOP} language designed to capture the essence of \gls{TOP} formally~\citep{steenvoorden_tophat_2019}.
-\citet{piers_task-oriented_2016} created \textmu{}Task, a \gls{TOP} language for specifying non-interruptible embedded systems implemented as an \gls{EDSL} in \gls{HASKELL}.
+Some \gls{TOP} languages arose from Master's and Bachelor's thesis projects (e.g.\ \textmu{}Task \citep{piers_task-oriented_2016} and LTasks \citep{van_gemert_task_2022}) or were created to solve a practical problem (e.g.\ Toppyt \citep{lijnse_toppyt_2022} and hTask \citep{lubbers_htask_2022}).
+
+Furthermore, \gls{TOPHAT} is a fully formally specified \gls{TOP} language designed to capture the essence of \gls{TOP} formally~\citep{steenvoorden_tophat_2019}.
+ created \textmu{}Task, a \gls{TOP} language for specifying non-interruptible embedded systems implemented as an \gls{EDSL} in \gls{HASKELL}.
\citet{van_gemert_task_2022} created LTasks, a \gls{TOP} language for interactive terminal applications implemented in LUA, a dynamically typed imperative language.
\citet{lijnse_toppyt_2022} created Toppyt, a \gls{TOP} language based on \gls{ITASK}, implemented in \gls{PYTHON}, but designed to be simpler and smaller.
Finally there is \gls{MTASK}, \gls{TOP} language designed for defining workflow for \gls{IOT} devices~\cite{koopman_task-based_2018}.
This part is a monograph focussing on \glspl{TOP} for the \gls{IOT} and hence are the chapters best read in order.
The monograph is compiled from the following papers and revised lecture notes.
-\newcommand{\citeentry}[1]{\begin{NoHyper}\bibentry{#1}\end{NoHyper}. \citep{#1}}
\begin{itemize}
\item \citeentry{koopman_task-based_2018}
It shows how a simple imperative variant of \gls{MTASK} was integrated with \gls{ITASK}.
While the language was a lot different than later versions, the integration mechanism is still used in \gls{MTASK} today.
The research in this paper and writing the paper was performed by me, though there were weekly meetings with Pieter Koopman and Rinus Plasmeijer in which we discussed and refined the ideas.
- \item \citeentry{lubbers_multitasking_2019}
+ \item \citeentry{lubbers_multitasking_2019}\footnote{%
+ This work acknowledges the support of the ERASMUS+ project ``Focusing Education on Composability, Comprehensibility and Correctness of Working Software'', no. 2017--1--SK01--KA203--035402
+ }
This paper was a short paper on the multitasking capabilities of \gls{MTASK} in contrast to traditional multitasking methods for \gls{ARDUINO}.
The research in this paper and writing the paper was performed by me, though there were weekly meetings with Pieter Koopman and Rinus Plasmeijer.
- \item \citeentry{koopman_simulation_2018}\todo{change when published}
+ \item \citeentry{koopman_simulation_2018}\footnotemark[\value{footnote}]\todo{change when published}
- These revised lecture notes are from a course on the \gls{MTASK} simulator was provided at the 2018 CEFP/3COWS winter school in Ko\v{s}ice, Slovakia.
+ These revised lecture notes are from a course on the \gls{MTASK} simulator was provided at the 2018 \gls{CEFP}/\gls{3COWS} winter school in Ko\v{s}ice, Slovakia.
Pieter Koopman wrote and taught it, I helped with the software and research.
- \item \citeentry{lubbers_writing_2019}\todo{change when published}
+ \item \citeentry{lubbers_writing_2019}\footnotemark[\value{footnote}]\todo{change when published}
- These revised lecture notes are from a course on programming in \gls{MTASK} provided at the 2019 CEFP/3COWS summer school in Budapest, Hungary.
+ These revised lecture notes are from a course on programming in \gls{MTASK} provided at the 2019 \gls{CEFP}/\gls{3COWS} summer school in Budapest, Hungary.
Pieter Koopman prepared and taught half of the lecture and supervised the practical session.
I taught the other half of the lecture, wrote the lecture notes, made the assignments and supervised the practical session.
Furthermore, it shows how to integrate hardware interrupts into \gls{MTASK}.
The research was carried out by \citet{crooijmans_reducing_2021} during his Master's thesis.
I did the daily supervision and helped with the research, Pieter Koopman was the formal supervisor and wrote most of the paper.
- \item \emph{Green Computing for the Internet of Things}\todo{change when published}
+ \item \emph{Green Computing for the Internet of Things}\footnote{
+ This work acknowledges the support of the Erasmus+ project ``SusTrainable---Promoting Sustainability as a Fundamental Driver in Software Development Training and Education'', no. 2020--1--PT01--KA203--078646}\todo{change when published}
These revised lecture notes are from a course on sustainable programming using \gls{MTASK} provided at the 2022 SusTrainable summer school in Rijeka, Croatia.
\end{itemize}
\subsection*{\nameref{prt:tvt}}
-This chapter is based on the journal paper: \citeentry{lubbers_could_2022}\footnote{The journal paper is an extension of the conference article: \citeentry{lubbers_tiered_2020}\footnotemark{}}.
+This chapter is based on the journal paper: \citeentry{lubbers_could_2022}\footnote{This work is an extension of the conference article: \citeentry{lubbers_tiered_2020}\footnotemark{}}.
\footnotetext{This paper was partly funded by the Radboud-Glasgow Collaboration Fund.}
It compares programming traditional tiered architectures to tierless architectures by showing a qualitative and a quantitative four-way comparison of a smart campus application.
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