\begin{document}
\input{subfileprefix}
-\chapter{Integration of \texorpdfstring{\gls{MTASK}}{mTask} and \texorpdfstring{\gls{ITASK}}{iTask}}%
+\chapter{Integration of mTask and iTask}%
\label{chp:integration_with_itask}
\begin{chapterabstract}
This chapter shows the integration of \gls{MTASK} and \gls{ITASK} by showing:
\end{chapterabstract}
The \gls{MTASK} language is a multi-view \gls{DSL}, there are multiple interpretations possible for a single \gls{MTASK} term.
-When using the byte code compiler (\cleaninline{BCInterpret}) \gls{DSL} interpretation, \gls{MTASK} tasks are fully integrated in \gls{ITASK}.
+When using the byte code compiler (\cleaninline{:: BCInterpret a}) \gls{DSL} interpretation, \gls{MTASK} tasks are fully integrated in \gls{ITASK}.
They execute as regular \gls{ITASK} tasks and they can access \glspl{SDS} from \gls{ITASK}.
Devices in the \gls{MTASK} system are set up with a domain-specific \gls{OS} and become little \gls{TOP} engines in their own respect, being able to execute tasks.
failover [] _ = throw "Exhausted device pool"
failover [d:ds] mtask = try (withDevice d (liftmTask mtask)) except
where except MTEUnexpectedDisconnect = failover ds mtask
- except _ = throw e
+ except _ = throw e
\end{lstClean}
-\section{Lifting \texorpdfstring{\gls{MTASK}}{mTask} tasks}\label{sec:liftmtask}
+\section{Lifting mTask tasks}\label{sec:liftmtask}
Once the connection with the device is established, \gls{MTASK} tasks are lifted to \gls{ITASK} tasks using the \cleaninline{liftmTask} function (see \cref{lst:liftmtask}).
Given an \gls{MTASK} task in the \cleaninline{BCInterpret} view and a device handle obtained from \cleaninline{withDevice}, an \gls{ITASK} task is returned.
This \gls{ITASK} task proxies the \gls{MTASK} task that is executed on the microcontroller.
preloadTask :: (Main (MTask BCInterpret a)) -> Task String
\end{lstClean}
-\section{Lowering \texorpdfstring{\gls{ITASK}}{iTask} \texorpdfstring{\glsxtrlongpl{SDS}}{shared data sources}}\label{sec:liftsds}
+\section{Lowering iTask shared data sources}\label{sec:liftsds}
Lowering \gls{ITASK} \glspl{SDS} to \gls{MTASK} \glspl{SDS} is something that mostly happens at the \gls{DSL} level using the \cleaninline{lowerSds} function (see \cref{lst:mtask_itasksds}).
Lowering \pgls{SDS} proxies the \gls{ITASK} \gls{SDS} for use in \gls{MTASK}.
\Glspl{SDS} in \gls{MTASK} always have an initial value.
On the device, there is just one difference between lowered \glspl{SDS} and regular \glspl{SDS}: after changing a lowered \gls{SDS}, a message is sent to the server containing this new value.
The \cleaninline{withDevice} task (see \cref{sec:withdevice}) receives and processes this message by writing to the \gls{ITASK} \gls{SDS}.
Tasks watching this \gls{SDS} get notified then through the normal notification mechanism of \gls{ITASK}.
+\Cref{lst:imp_sds} shows the implementation of this type class for the byte code compiler.
\begin{lstClean}[label={lst:mtask_itasksds},caption={Lowered \gls{ITASK} \glspl{SDS} in \gls{MTASK}.}]
class lowerSds v where
In {main=f true}
\end{lstClean}
-\subsection{Implementation}
-The compilation of the code and the serialisation of the data throws away all typing information.
-\Glspl{SDS} are stored in the compiler state as a map from identifiers to either an initial value or an \cleaninline{MTLens}.
-The \cleaninline{MTLens} is a type synonym for \pgls{SDS} that represents the typeless serialised value of the underlying \gls{SDS}.
-This is done so that the \cleaninline{withDevice} task can write the received \gls{SDS} updates to the according \gls{SDS} while the \gls{SDS} is not in scope.
-The \gls{ITASK} notification mechanism then takes care of the rest.
-Such \pgls{SDS} is created by using the \cleaninline{mapReadWriteError} which, given a pair of read and write functions with error handling, produces \pgls{SDS} with the lens embedded.
-The read function transforms converts the typed value to a typeless serialised value.
-The write function will, given a new serialised value and the old typed value, produce a new typed value.
-It tries to decode the serialised value, if that succeeds, it is written to the underlying \gls{SDS}, an error is thrown otherwise.
-\Cref{lst:mtask_itasksds_lens} shows the implementation for this.
-
-% VimTeX: SynIgnore on
-\begin{lstClean}[label={lst:mtask_itasksds_lens},caption={Lens applied to lowered \gls{ITASK} \glspl{SDS} in \gls{MTASK}.}]
-lens :: (Shared sds a) -> MTLens | type a & RWShared sds
-lens sds = mapReadWriteError
- ( \r-> Ok (fromString (toByteCode{|*|} r)
- , \w r-> ?Just <$> iTasksDecode (toString w)
- ) ?None sds
-\end{lstClean}
-% VimTeX: SynIgnore off
-
-\Cref{lst:mtask_itasksds_lift} shows the code for the implementation of \cleaninline{lowerSds} that uses the \cleaninline{lens} function shown earlier.
-First, the \gls{SDS} to be lowered is extracted from the expression by bootstrapping the fixed point with a dummy value.
-This is safe because the expression on the right-hand side of the \cleaninline{In} is never evaluated.
-Then, using \cleaninline{addSdsIfNotExist}, the identifier for this particular \gls{SDS} is either retrieved from the compiler state or generated freshly.
-This identifier is then used to provide a reference to the \cleaninline{def} definition to evaluate the main expression.
-
-% VimTeX: SynIgnore on
-\begin{lstClean}[label={lst:mtask_itasksds_lift},caption={The implementation for lowering \glspl{SDS} in \gls{MTASK}.}]
-instance lowerSds BCInterpret where
- lowerSds def = {main =
- let (t In _) = def (abort "lowerSds: expression too strict")
- in addSdsIfNotExist (Right $ lens t)
- >>= \sdsi->let (_ In e) = def (pure (Sds sdsi)) in e.main
- }\end{lstClean}
-% VimTeX: SynIgnore off
-
\section{Conclusion}
When \gls{IOT} edge devices run the \gls{MTASK} \gls{RTS}, they become little \gls{TOP} engines of their own.
Using just three \gls{ITASK} functions, \gls{MTASK} devices are integrated in \gls{ITASK} seamlessly.
All details regarding interoperation are automatically taken care of.
The following section contains an elaborate example using all integration functions that has deliberately been placed after the conclusion so that the code listing and description are on facing pages.
-\begin{figure}[p]
- \begin{leftfullpage}
- \vspace{\headsep}
-\section{Home automation}
-This section presents an interactive home automation program (\cref{lst:example_home_automation}) to illustrate the integration of the \gls{MTASK} language and the \gls{ITASK} system.
-It consists of a web interface for the user to control which tasks are executed on either one of two connected devices: an \gls{ARDUINO} UNO, connected via a serial port; and an ESP8266 based prototyping board called NodeMCU, connected via \gls{TCP} over \gls{WIFI}.
-
-\Crefrange{lst:example:spec1}{lst:example:spec2} show the specification for the devices.
-The UNO is connected via serial using the unix filepath \path{/dev/ttyACM0} and the default serial port settings.
-The NodeMCU is connected via \gls{WIFI} and hence the \cleaninline{TCPSettings} record is used.
-Both types have \cleaninline{channelSync} instances.
-
-The code consists of an \gls{ITASK} part and several \gls{MTASK} parts.
-\Crefrange{lst:example:task1}{lst:example:task2} contains the \gls{ITASK} task that coordinates the \gls{IOT} application.
-First the devices are connected (\crefrange{lst:example:conn1}{lst:example:conn2}) followed by launching a \cleaninline{parallel} task, visualized as a tabbed window, and a shutdown button to terminate the program (\crefrange{lst:example:par1}{lst:example:par2}).
-This parallel task is the controller of the tasks that run on the edge devices.
-It contains one task that allows adding new tasks (using \cleaninline{appendTask}) and all other tasks in the process list will be \gls{MTASK} tasks once they are added by the user.
-The controller task, \cleaninline{chooseTask} as shown in \crefrange{lst:example:ct1}{lst:example:ct2}, allows the user to pick a task, and sending it to the specified device.
-Tasks are picked by index from the \cleaninline{tasks} list (\crefrange{lst:example:tasks1}{lst:example:tasks2}) using \cleaninline{enterChoice}.
-The interface that is generated for this is seen in \cref{fig:example_screenshots1}.
-After selecting the task, a device is selected (see \cref{fig:example_screenshots2,lst:example:selectdev}).
-When both a task and a device are selected, an \gls{ITASK} task is added to the process list using \cleaninline{appendTask}.
-Using the helper function \cleaninline{mkTask}, the actual task is selected from the \cleaninline{tasks} list and executed by providing it the device argument.
-For example, when selecting the \cleaninline{temperature} task, the current temperature is shown to the user (\cref{fig:example_screenshots3}).
-This task just sends a simple temperature monitoring task to the device using \cleaninline{liftmTask} and provides a view on its task value using the \cleaninline{>\&>} \gls{ITASK} combinator.
-This combinator allows the observation of the left-hand side task's value through \pgls{SDS}.
-The light switch task at \crefrange{lst:example:ls1}{lst:example:ls2} is a task that has bidirectional interaction using the definition of \cleaninline{lightswitch} shown in \cref{lst:mtask_liftsds_ex}.
-Using \cleaninline{liftsds}, the status of the light switch is synchronised with the user.
-Finally, a task that calculates the factorial of a user-provided number is shown in the list.
-
- \vspace{4ex}
- \begin{center}
- \begin{subfigure}[b]{.3\linewidth}
- \includegraphics[width=\linewidth]{home_auto1}
- \caption{Select task.}%
- \label{fig:example_screenshots1}
- \end{subfigure}
- \begin{subfigure}[b]{.3\linewidth}
- \includegraphics[width=\linewidth]{home_auto2}
- \caption{Select device.}%
- \label{fig:example_screenshots2}
- \end{subfigure}
- \begin{subfigure}[b]{.3\linewidth}
- \includegraphics[width=\linewidth]{home_auto3}
- \caption{View result.}%
- \label{fig:example_screenshots3}
- \end{subfigure}
- \caption{Screenshots of the home automation example program in action.}%
- \label{fig:example_screenshots}
- \end{center}
- \end{leftfullpage}
-\end{figure}
-
-\begin{figure}[p]
- \begin{fullpage}
- \cleaninputlisting[firstline=12,lastline=50,numbers=left,belowskip=0pt]{lst/example.icl}
- \begin{lstClean}[numbers=left,firstnumber=40,aboveskip=0pt,caption={An example of a home automation program.},label={lst:example_home_automation}]
- , ...][+\label{lst:example:tasks2}+]\end{lstClean}
- \end{fullpage}
-\end{figure}
+%\begin{figure}[p]
+% \begin{leftfullpage}
+% \vspace{\headsep}
+%\section{Home automation}
+%This section presents an interactive home automation program (\cref{lst:example_home_automation}) to illustrate the integration of the \gls{MTASK} language and the \gls{ITASK} system.
+%It consists of a web interface for the user to control which tasks are executed on either one of two connected devices: an \gls{ARDUINO} UNO, connected via a serial port; and an ESP8266 based prototyping board called NodeMCU, connected via \gls{TCP} over \gls{WIFI}.
+%
+%\Crefrange{lst:example:spec1}{lst:example:spec2} show the specification for the devices.
+%The UNO is connected via serial using the unix filepath \path{/dev/ttyACM0} and the default serial port settings.
+%The NodeMCU is connected via \gls{WIFI} and hence the \cleaninline{TCPSettings} record is used.
+%Both types have \cleaninline{channelSync} instances.
+%
+%The code consists of an \gls{ITASK} part and several \gls{MTASK} parts.
+%\Crefrange{lst:example:task1}{lst:example:task2} contains the \gls{ITASK} task that coordinates the \gls{IOT} application.
+%First the devices are connected (\crefrange{lst:example:conn1}{lst:example:conn2}) followed by launching a \cleaninline{parallel} task, visualized as a tabbed window, and a shutdown button to terminate the program (\crefrange{lst:example:par1}{lst:example:par2}).
+%This parallel task is the controller of the tasks that run on the edge devices.
+%It contains one task that allows adding new tasks (using \cleaninline{appendTask}) and all other tasks in the process list will be \gls{MTASK} tasks once they are added by the user.
+%The controller task, \cleaninline{chooseTask} as shown in \crefrange{lst:example:ct1}{lst:example:ct2}, allows the user to pick a task, and sending it to the specified device.
+%Tasks are picked by index from the \cleaninline{tasks} list (\crefrange{lst:example:tasks1}{lst:example:tasks2}) using \cleaninline{enterChoice}.
+%The interface that is generated for this is seen in \cref{fig:example_screenshots1}.
+%After selecting the task, a device is selected (see \cref{fig:example_screenshots2,lst:example:selectdev}).
+%When both a task and a device are selected, an \gls{ITASK} task is added to the process list using \cleaninline{appendTask}.
+%Using the helper function \cleaninline{mkTask}, the actual task is selected from the \cleaninline{tasks} list and executed by providing it the device argument.
+%For example, when selecting the \cleaninline{temperature} task, the current temperature is shown to the user (\cref{fig:example_screenshots3}).
+%This task just sends a simple temperature monitoring task to the device using \cleaninline{liftmTask} and provides a view on its task value using the \cleaninline{>\&>} \gls{ITASK} combinator.
+%This combinator allows the observation of the left-hand side task's value through \pgls{SDS}.
+%The light switch task at \crefrange{lst:example:ls1}{lst:example:ls2} is a task that has bidirectional interaction using the definition of \cleaninline{lightswitch} shown in \cref{lst:mtask_liftsds_ex}.
+%Using \cleaninline{lowerSds}, the status of the light switch is synchronised with the user.
+%Finally, a task that calculates the factorial of a user-provided number is shown in the list.
+%
+% \vspace{4ex}
+% \begin{center}
+% \begin{subfigure}[b]{.3\linewidth}
+% \includegraphics[width=\linewidth]{home_auto1}
+% \caption{Select task.}%
+% \label{fig:example_screenshots1}
+% \end{subfigure}
+% \begin{subfigure}[b]{.3\linewidth}
+% \includegraphics[width=\linewidth]{home_auto2}
+% \caption{Select device.}%
+% \label{fig:example_screenshots2}
+% \end{subfigure}
+% \begin{subfigure}[b]{.3\linewidth}
+% \includegraphics[width=\linewidth]{home_auto3}
+% \caption{View result.}%
+% \label{fig:example_screenshots3}
+% \end{subfigure}
+% \caption{Screenshots of the home automation example program in action.}%
+% \label{fig:example_screenshots}
+% \end{center}
+% \end{leftfullpage}
+%\end{figure}
+%
+%\begin{figure}[p]
+% \begin{fullpage}
+% \cleaninputlisting[firstline=12,lastline=50,numbers=left,belowskip=0pt]{lst/example.icl}
+% \begin{lstClean}[numbers=left,firstnumber=40,aboveskip=0pt,caption={An example of a home automation program.},label={lst:example_home_automation}]
+% , ...][+\label{lst:example:tasks2}+]\end{lstClean}
+% \end{fullpage}
+%\end{figure}
\input{subfilepostamble}
\end{document}
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