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\chapter{Coda}%
-\label{chp:conclusion}
-\todo{Or finale}
-\section{Conclusion}
+\label{chp:conclusion}%
+\ifSubfilesClassLoaded{\glsunsetall}{}%
+\begin{chapterabstract}
+ This chapter concludes the dissertation and reflects on the work.
+\end{chapterabstract}
+\section{Reflections}
+
+This dissertation shed light on orchestrating complete \gls{IOT} systems using \gls{TOP}.
+
+The term \gls{IOT} refers to the interconnected network of physical devices that are connected to each other and the internet.
+The edge, or perception, layer of an \gls{IOT} systems is often powered by microcontrollers.
+These small and cheap computers do not have powerful hardware but are energy efficient and support many sensors and actuators.
+While the term \gls{IOT} has already been known for almost thirty years, only recently, the exponential growth of the number of \gls{IOT} edge devices is really ramping up.
+Programming \gls{IOT} systems is very complex because each layer of the system is built with different computers, hardware architectures, programming languages, programming paradigms, and abstraction levels.
+This generates a lot of semantic friction.
+Furthermore, \gls{IOT} systems become convoluted because they are dynamic, multi-tiered, multi-user, multitasking, interactive, distributed, and collaborative.
+\Gls{TOP} proves a suitable programming paradigm that allows the declarative specification of exactly such systems.
+However, edge devices are often too computationally restricted to be able to run a full-fledged \gls{TOP} system such as \gls{ITASK}.
+
+The dissertation is structured as a purely functional rhapsody in three episodes.
+It shows different techniques that aid crafting the tools required, i.e.\ creating the programming languages.
+Then it shows the tool, \gls{MTASK}, a \gls{TOP} system for \gls{IOT} edge devices.
+Finally it compares how this tool compares to existing tools.
+
+\subsection{Tool craft}
+First some techniques for tool crafting are presented in \cref{prt:dsl} that are useful for creating \gls{TOP} languages for \gls{IOT} edge devices.
+It presents two novel techniques for embedding \glspl{DSL} in \gls{FP} languages:
+Classy deep embedding is a novel \gls{EDSL} embedding technique.
+In \gls{DSL} embedding techniques, one always has to make concessions.
+Either it is easy to extend the language in language constructs or in interpretations but never both.
+Tagless-final embedding offers a way of extending a shallowly embedded \gls{DSL} both in constructs and interpretations.
+Classy deep embedding is the organically grown counterpart for deep embedding a \gls{DSL}.
+It allows orthogonal extension of language constructs and interpretations with minimal boilerplate and no advanced type system extensions.
+
+When embedding a \gls{DSL} in a language, much, but not all, of the machinery is inherited
+For example, data types are not automatically useable in the \gls{DSL} because the interfaces such as constructors, deconstructors and constructor predicates are not inherited.
+I show how to automatically generate boilerplate for \glspl{DSL} in order to make data types first-class citizens in the \gls{DSL}.
+The scaffolding is generated using template metaprogramming and quasiquotation is used to alleviate the programmer from the syntax burden.
+
+\subsection{Tools}
+General-purpose \gls{TOP} systems cannot run on edge devices due to their sizeable hardware requirements.
+However, using advanced \gls{DSL} embedding techniques, \glspl{DSL} can be created that can be executed on edge devices while maintaining the high abstraction level.
+By embedding domain-specific knowledge into the language and execution platform, and leaving out general-purpose functionality \gls{TOP} languages can be made suitable for edge devices.
+
+\Cref{prt:top} contains a complete overview of such a tool: the \gls{MTASK} system.
+Its design, integration with \gls{ITASK}, implementation, and green computing facilities are shown.
+The \gls{MTASK} language is a unique domain-specific \gls{TOP} \gls{EDSL} designed system for edge devices.
+The \gls{MTASK} system is fully integrated with the \gls{ITASK} system, a \gls{TOP} system for programming distributed web applications.
+In the \gls{ITASK} system, there are abstractions for details such as user interfaces, data storage, client-side platforms, and persistent workflows.
+The \gls{MTASK} language abstracts away from edge device specific details such as sensor and actuator access, heterogeneity in hardware, and multitasking and scheduling.
+Tasks in the \gls{MTASK} system are compiled at run time and sent to the device dynamically in order to support create dynamic systems where tasks are tailor-made for the current work requirements.
+This tight integration makes programming full \gls{IOT} systems using \gls{TOP} possible without major compromises.
+Using only three simple functions, devices are connected to \gls{ITASK} servers, \gls{MTASK} tasks are integrated in \gls{ITASK}, and \gls{ITASK} \glspl{SDS} accessed from within \gls{MTASK} tasks.
+
+\subsection{Comparison}
+Previous episodes show that it is possible to program all layers of an \gls{IOT} systems using \gls{TOP}.
+Using tierless programming, many issues that arise with tiered programming are mitigated.
+This has already been observed in web applications.
+The question whether this novel approach to programming tiered systems also reduces the develop grief is answered in \cref{prt:tvt}.
+This episode presents a four-way qualitatively and quantitatively comparison of the following systems:
+\begin{enumerate*}
+ \item \gls{PRS}, a tiered system based on resource-rich edge devices powered by \gls{PYTHON};
+ \item \gls{PWS}, a tiered system based on resource-constrained edge devices by \gls{MICROPYTHON};
+ \item \gls{CRS}, a tierless system based on resource-rich edge devices powered by \gls{ITASK};
+ \item \gls{CWS}, a tierless system based on resource-constrained edge devices powered by \imtask{}.
+\end{enumerate*}
+
+This comparison shows that when using a programming paradigm that is available both for resource-rich and resource-constrained edge devices, there is little difference in developer grief.
+On the other hand, using a tierless system compared to a tiered system reduces the developer grief significantly.
-\section{Future work}
+Using either \imtask{} when dealing with resource-constrained devices such as microcontrollers or just \gls{ITASK} for all layers all layers of the entire \gls{IOT} system are specified in a single source, the same strong type system, and similar high abstraction level.
+The tierless approach results in fewer \gls{SLOC}, files, programming languages and programming paradigms.
+All code is simultaneously checked by a single compiler, reducing interoperability problems.
+Furthermore, all communication and integration is automatically generated, reducing interoperability issues even more.
+%
+However, it is not a silver bullet, there are some disadvantages as well.
+Tierless languages are novel, and hence often lack tooling and community support.
+They contain high-level tierless abstractions that the programmer has to master.
+The low-level specific semantics of the final application may become more difficult to distill from the specification.
+Finally, the system is more monolithic compared to tiered approaches.
+Changing components within the system is easy if it already is supported in the \gls{EDSL}.
+Adding new components to the system requires the programmer to add it to all complex components of the languages such as the compiler, and \gls{RTS}.
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repositories / phd-thesis.git / blobdiff