\section{Discussion \& Future Research}
The system is still a crude prototype and a proof of concept. Improvements and
extension for the system are amply available in several fields of study.

\subsection{Simulation}
An additional simulation view to the \gls{mTask}-\gls{EDSL} could be added that
works in the same way as the existing \gls{C}-backed simulation. It simulates
the bytecode interpretation. Moreover would be possible to let the simulator
function as a real device, thus handling all communication through the
existing \gls{SDS}-based systems and behave like a real device. At the moment
the \emph{POSIX}-client is the reference client and contains debugging code.
Adding a simulation view to the system allows for easy interactive debugging.
However, it might not be easy to devise a simulation tool that accurately
simulates the \gls{mTask} system accurately on some levels. The semantics can
be simulated but timing and peripheral input/output are more difficult to
simulate properly.

\subsection{Optimization}
\paragraph{Multitasking on the client:}
True multitasking could be added to the client software. This allows
\gls{mTask}-\glspl{Task} to run truly parallel. All \glspl{mTask} get slices
of execution time and will each have their own interpreter state instead of one
system-wide one that is reset after am \gls{mTask} finishes. This does require
separate stacks for each \gls{Task} and therefore increases the system
requirements of the client software. However, it could be implemented as a
compile-time option and exchanged during the handshake so that the server knows
the multithreading capabilities of the client.

\paragraph{Optimizing the interpreter:}
Hardly any work has been done in the interpreter. The current interpreter is a
no nonsense stack machine. A lot of improvements can be done in this part. For
example, precomputed \emph{gotos} can improve jumping to the correct part of
the code corresponding to the correct instruction. Moreover, the stack
currently consists of 16-bit values. All operations work on 16-bit values and
this simplifies the interpreter implementation. A memory improvement can be
made by converting the stack to 8-bit values. This does pose some problems
since an equality instruction must work on single-byte booleans \emph{and}
two-byte integers. Adding specialized instructions per word size could overcome
this problem.

\subsection{Resources}
\paragraph{Resource analysis: }
Resource analysis during compilation can be useful to determine if an
\gls{mTask}-\gls{Task} is suitable for a specific device. If the device does
not contain the correct peripherals --- such as an \gls{LCD} --- then the
\gls{mTask}-\gls{Task} should be rejected and feedback to the user must be
given. It might even be possible to do this statically on the type level.

\paragraph{Extended resource analysis: }
The previous idea could be extended to the analysis of stack size and possibly
communication bandwidth. With this functionality ever more reliable fail-over
systems can be designed. When the system knows precise bounds it can allocate
more \glspl{Task} on a device whilst staying within safe memory bounds. The
resource allocation can be done at runtime within the backend itself or a
general backend can be devices that can calculate the resources needed for a
given \gls{mTask}. A specific \gls{mTask} cannot have multiple views at the
same time due to the restrictions of class based shallow embedding. It might
even be possible to encode the resource allocation in the type system itself
using forms of dependant types.

\subsection{Functionality}
\paragraph{Add more combinators: }
More \gls{Task}-combinators --- already existing in the \gls{iTasks}-system ---
could be added to the \gls{mTask}-system to allow for more fine-grained control
flow between \gls{mTask}-\glspl{Task}. In this way the new system follows the
\gls{TOP} paradigm even more and makes programming \glspl{mTask} for
\gls{TOP}-programmers more seamless. Some of the combinators require previously
mentioned extension such as the parallel combinator. Others might be achieved
using simple syntactic transformations.

\paragraph{Launch \glspl{Task} from a \gls{Task}: }
Currently the \gls{C}-view allows \glspl{Task} to launch other \glspl{Task}. In
the current system this type of logic has to take place server side. Adding
this functionality to the bytecode-view allows greater flexibility, easier
programming and less communication resources. Adding these semantics requires
modifications to the client software and extensions to the communication
protocol since relations between \glspl{Task} also need to be encoded and
communicated.

The \gls{SDS} functionality in the current system is bare. There is no easy way
of reusing a \gls{SDS} for another \gls{Task} on the same device or on another
device. Such functionality can be implemented in a crude way by tying the
\glspl{SDS} together in the \gls{iTasks} environment. However, this will result
in a slow updating system. Functionality for reusing shares from a device
should be added. This requires rethinking the storage because some typedness is
lost when the \gls{SDS} is stored after compilation. A possibility would be to
use runtime typing with \CI{Dynamic}s or the encoding technique currently used
for \CI{BCValue}s. Using \glspl{SDS} for multiple \glspl{Task} within one
device is solved when the previous point at paragraph~\ref{par:tasklaunch} is
implemented.

\subsection{Robustness}
\paragraph{Reconnect with lost devices:}
The robustness of the system can be greatly improved. Devices that lose
connection are in the current system not well supported. The device will stop
functioning and have to be emptied for a reconnect. \Glspl{Task} residing on a
device that disconnected should be kept on the server to allow a swift
reconnect and restoration of the \glspl{Task}. This holds the same for the
client software. The client drops all existing \glspl{Task} on a shutdown
request. An extra specialization of the shutdown could be added that drops the
connection but keeps the \glspl{Task} in memory. During the downtime the
\glspl{Task} can still be executed but publications need to be delayed. If the
same server connects to the client the delayed publications can be sent
anyways.

\paragraph{Reverse \gls{Task} sending:}
Moreover, devices could send their current \glspl{Task} back at the
server to synchronize it. This allows interchanging servers without
interrupting the client. Allowing the client to send \glspl{Task} to the server
is something to handle with care because it can easily cause high bandwidth
usage.

\section{Conclusion}
This thesis introduces a novel system for add \gls{IoT} functionality to
the \gls{TOP} implementation \gls{iTasks}. A new view for the existing
\gls{mTask}-\gls{EDSL} has been created which compiles the program
into bytecode that can be interpreted by a client. Clients have
been written for several microcontrollers and consumer architectures which can
be connected through various means of communication such as serial port,
bluetooth, wifi and wired network communication. The bytecode on the devices is
interpreted using a stack machine and provides the programmer interfaces
to the peripherals. The semantics of the \glspl{mTask} tries to resemble the
\gls{iTasks} semantics as close as possible.

The host language has a very efficient compiler and code generator. Therefore,
compiling \glspl{mTask} is also fast. Compiling \glspl{mTask} is nothing
more than running some functions native to the host language.

The dynamic nature allows the microcontroller to be programmed once and used
many times. The program memory of microcontrollers often guarantees around
$10.000$ write or upload cycles and therefore existing techniques such as
generating \gls{C} code are not usable for dynamic \gls{Task} environments.
The dynamic nature also allows the programmer to design fail-over mechanisms.
When a device is assigned a \gls{Task} but another device suddenly becomes
unusable, the \gls{iTasks} system can reassign a new \gls{mTask}-\gls{Task} to
the first device that possibly takes over some of the functionality of the
broken device without needing to recompile the code.
