presentation start

[msc-thesis1617.git] / results.mtask.tex

diff --git a/results.mtask.tex b/results.mtask.tex
index 50cd1d6..c6adefb 100644 (file)
--- a/results.mtask.tex
+++ b/results.mtask.tex
@@ -1,11 +1,11 @@
-The \glspl{Task} suitable for a client are called \glspl{mTask} and are written
-in the aforementioned \gls{mTask}-\gls{EDSL}. Some functionality of the
-original \gls{mTask}-\gls{EDSL} will not be used in this system. Conversely,
-some functionality needed was not available in the existing \gls{EDSL}. Due to
-the nature of class based shallow embedding this obstacle is very easy to
-solve. A type --- housing the \gls{EDSL} --- does not have to implement all the
-available classes. Moreover, classes can be added at will without interfering
-with the existing views.
+The \glspl{Task} suitable for a client are called \gls{mTask}-\gls{Task} and
+are written in the aforementioned \gls{mTask}-\gls{EDSL}. Some functionality of
+the original \gls{mTask}-\gls{EDSL} will not be used in this system.
+Conversely, some functionality needed was not available in the existing
+\gls{EDSL}. Due to the nature of class based shallow embedding this obstacle is
+easy to solve. A type --- housing the \gls{EDSL} --- does not have to implement
+all the available classes. Moreover, classes can be added at will without
+interfering with the existing views.

 
 \section{\gls{Task} Semantics}
 The current \gls{mTask} engine for devices does not support \glspl{Task} in the
 
 \section{\gls{Task} Semantics}
 The current \gls{mTask} engine for devices does not support \glspl{Task} in the


@@ -25,49 +25,52 @@ reflected in the \CI{MTTask} message type.
                request of a user.
        \item\CI{OnInterval}
 
                request of a user.
        \item\CI{OnInterval}
 

-               \CI{OnInterval} has as a parameter the number of milliseconds to wait
-               in between executions. \Glspl{Task} running with this scheduling method
-               are executed at predetermined intervals.
+               \CI{OnInterval} has the number of milliseconds to wait in between
+               executions as a parameter. \Glspl{Task} running with this scheduling
+               method are executed at predetermined intervals.

        \item\CI{OnInterrupt}
 
                The last scheduling method is running \glspl{Task} on a specific
        \item\CI{OnInterrupt}
 
                The last scheduling method is running \glspl{Task} on a specific

-               interrupt. None of the current client implementations support this.
-               However, registering interrupts on, for example the \gls{Arduino} is
-               very straightforward. Interrupt scheduling is useful for \glspl{Task}
-               that have to react on a certain type of hardware event such as the
-               press of a button.
+               interrupt. Unfortunatly, due to time constraints and focus, none of the
+               current client implementations support this. Interrupt scheduling is
+               useful for \glspl{Task} that have to react on a certain type of
+               hardware event such as the press of a button.

 \end{itemize}
 
 \section{\gls{SDS} semantics}
 \Glspl{SDS} on a client are available on the server as well as regular
 \end{itemize}
 
 \section{\gls{SDS} semantics}
 \Glspl{SDS} on a client are available on the server as well as regular

-\gls{SDS}. However, the same freedom is not given on the \glspl{SDS} that
-reside on the client. Not all types are suitable to be located on a client.
-Moreover, \glspl{SDS} behave a little different on an \gls{mTask} device
-compared to the \gls{iTasks} system. In an \gls{iTasks} system, when the \gls{SDS}
-is updated, a broadcast to everyone in the system watching is made to notify
-them of the update. \glspl{SDS} can update very often and the
-update might not be the final value it will get. This results in a lot of
-expensive unneeded bandwidth usage. Therefore a device must publish the
-\gls{SDS} explicitly to save bandwidth.
+\glspl{SDS}. However, the same freedom is not given for \glspl{SDS} that
+reside on the client. Not all types are suitable to be located on a client,
+simply because it needs to be serializable and representable on clients.
+Moreover, \glspl{SDS} behave a little different in an \gls{mTask} device
+compared to in the \gls{iTasks} system. In an \gls{iTasks} system, when the
+\gls{SDS} is updated, a broadcast to all watching \glspl{Task} in the system
+is made to notify them of the update. \glspl{SDS} can update often and the
+update might not be the final value it will get. Implementing the same
+functionality on the \gls{mTask} client would result in a lot of expensive
+unneeded bandwidth usage. Therefore a device must publish the \gls{SDS}
+explicitly to save bandwidth.

 
 To add this functionality, the \CI{sds} class could be extended. However, this
 would result in having to update all existing views that use the \CI{sds}
 class. Therefore, an extra class is added that contains the extra
 
 To add this functionality, the \CI{sds} class could be extended. However, this
 would result in having to update all existing views that use the \CI{sds}
 class. Therefore, an extra class is added that contains the extra

-functionality. The existing views can choose to implement it in the future but
-are not obliged to. The publication function has the following signature:
+functionality. Programmers can choose to implement it for existing views in the
+future but are not obliged to. The publication function has the following
+signature:

 \begin{lstlisting}[caption={The \texttt{sdspub} class}]
 class sdspub v where
   pub :: (v t Upd) -> v t Expr | type t
 \end{lstlisting}
 
 \section{Bytecode compilation view}\label{sec:compiler}
 \begin{lstlisting}[caption={The \texttt{sdspub} class}]
 class sdspub v where
   pub :: (v t Upd) -> v t Expr | type t
 \end{lstlisting}
 
 \section{Bytecode compilation view}\label{sec:compiler}

-The \glspl{mTask} are sent to the device in bytecode and are saved in the
-memory of the device. To compile the \gls{EDSL} code to bytecode, a view is
-added to the \gls{mTask}-system encapsulated in the type \CI{ByteCode}. As
+The \gls{mTask}-\glspl{Task} are sent to the device in bytecode and are saved
+in the memory of the device. To compile the \gls{EDSL} code to bytecode, a view
+is added to the \gls{mTask}-system encapsulated in the type \CI{ByteCode}. As

 shown in Listing~\ref{lst:bcview}, the \CI{ByteCode} view is a boxed \gls{RWST}
 shown in Listing~\ref{lst:bcview}, the \CI{ByteCode} view is a boxed \gls{RWST}

-that writes bytecode instructions (\CI{BC}) while carrying around a
-\CI{BCState}. The state is kept between compilations and is unique to a device.
-The state contains fresh variable names and a register of \glspl{SDS} used.
+that writes bytecode instructions (\CI{BC}, Subsection~\ref{sec:instruction})
+while carrying around a \CI{BCState}. The state is kept between compilations
+and is unique to a device.  The state contains fresh variable names and a
+register of \glspl{SDS} that are used.

 
 Types implementing the \gls{mTask} classes must have two free type variables.
 Therefore the \gls{RWST} is wrapped with a constructor and two phantom type
 
 Types implementing the \gls{mTask} classes must have two free type variables.
 Therefore the \gls{RWST} is wrapped with a constructor and two phantom type


@@ -113,10 +116,10 @@ instance arith ByteCode
 instance serial ByteCode
 \end{lstlisting}
 
 instance serial ByteCode
 \end{lstlisting}
 

-\subsection{Instruction Set}
+\subsection{Instruction Set}\label{sec:instruction}

 The instruction set is given in Listing~\ref{bc:instr}. The instruction set is
 The instruction set is given in Listing~\ref{bc:instr}. The instruction set is

-kept large, but under $255$, to get the highest expressively while keeping all
-instruction one byte. 
+kept large, but under $255$, to get as much expressieve power as possible while
+keeping all instruction within one byte.

 
 The interpreter running in the client is a stack machine. The virtual
 instruction \CI{BCLab} is added to allow for an easy implementation of jumping.
 
 The interpreter running in the client is a stack machine. The virtual
 instruction \CI{BCLab} is added to allow for an easy implementation of jumping.


@@ -150,20 +153,21 @@ and avoid label lookups at runtime.
        | BCReturn
 \end{lstlisting}
 
        | BCReturn
 \end{lstlisting}
 

-All single byte instructions are converted automatically using the generic
-function \CI{consIndex} which returns the index of the constructor. The index
-of the constructor is the byte value for all instructions. The last step of the
+All single byte instructions are converted automatically using a generic
+function which returns the index of the constructor. The index of the
+constructor is the byte value for all instructions. Added to this single byte
+value are the encoded parameters of the instruction. The last step of the

 compilation is transforming the list of bytecode instructions to actual bytes.
 
 \subsection{Helper functions}
 compilation is transforming the list of bytecode instructions to actual bytes.
 
 \subsection{Helper functions}

-The \CI{ByteCode} type is just a boxed \gls{RWST} and that gives us access to
-the whole range of \gls{RWST} functions. However, to apply a function the type
-must be unboxed. After application the type must be boxed again. To achieve
-this, several helper functions have been created. They are listed in
-Listing~\ref{lst:helpers}. The \CI{op} and \CI{op2} function is crafted to make
-operators that pop one or two values off the stack respectively. The \CI{tell`}
-is a wrapper around the \gls{RWST} function \CI{tell} that appends the argument
-to the \emph{Writer} value.
+Since the \CI{ByteCode} type is just a boxed \gls{RWST}, access to the whole
+range of \gls{RWST} functions is available. However, to use this, the type must
+be unboxed. After application the type must be boxed again. To achieve this,
+several helper functions have been created. They are given in
+Listing~\ref{lst:helpers}. The \CI{op} and \CI{op2} functions is hand-crafted
+to make operators that pop one or two values off the stack respectively. The
+\CI{tell`} function is a wrapper around the \gls{RWST} function \CI{tell} that
+appends the argument to the \emph{Writer} value.

 
 \begin{lstlisting}[label={lst:helpers},caption={Some helper functions}]
 op2 :: (ByteCode a p1) (ByteCode a p2) BC -> ByteCode b Expr
 
 \begin{lstlisting}[label={lst:helpers},caption={Some helper functions}]
 op2 :: (ByteCode a p1) (ByteCode a p2) BC -> ByteCode b Expr


@@ -180,10 +184,10 @@ unBC (BC x) = x
 \end{lstlisting}
 
 \subsection{Arithmetics \& Peripherals}
 \end{lstlisting}
 
 \subsection{Arithmetics \& Peripherals}

-Almost all of the code from the simple classes use exclusively helper
-functions. Listing~\ref{lst:arithview} shows some implementations. The classes
-\CI{boolExpr} and the classes for the peripherals are implemented using the
-same strategy.
+Almost all of the code from the simple classes exclusively use helper
+functions. Listing~\ref{lst:arithview} shows some implementations. The
+\CI{boolExpr} class and the classes for the peripherals are implemented using
+the same strategy.

 
 \begin{lstlisting}[label={lst:arithview},caption={%
        Bytecode view implementation for arithmetic and peripheral classes}]
 
 \begin{lstlisting}[label={lst:arithview},caption={%
        Bytecode view implementation for arithmetic and peripheral classes}]


@@ -199,16 +203,15 @@ instance userLed ByteCode where
 
 \subsection{Control Flow}
 Implementing the sequence operator is very straightforward in the bytecode
 
 \subsection{Control Flow}
 Implementing the sequence operator is very straightforward in the bytecode

-view. The function just sequences the two \glspl{RWST}. The \emph{If} statement
-requires some detailed explanation since labels come into play. The
-implementation speaks for itself in Listing~\ref{lst:controlflow}. First, all
-the labels are gathered and then they are placed in the correct order in the
-bytecode sequence. It can happen that multiple labels appear consecutively in
-the code. This is not a problem since the labels are resolved to real addresses
-later on anyway.
+view. The function just sequences the two \glspl{RWST}. The
+implementation for the \emph{If} statement speaks for itself in
+Listing~\ref{lst:controlflow}. First, all the labels are gathered after which
+they are placed in the correct order in the bytecode sequence. It can happen
+that multiple labels appear consecutively in the code. This is not a problem
+since the labels are resolved to real addresses later on anyway.

 
 \begin{lstlisting}[label={lst:controlflow},%
 
 \begin{lstlisting}[label={lst:controlflow},%

-       caption={Bytecode view for \texttt{arith}}]
+       caption={Bytecode view for \texttt{arith} class}]

 freshlabel = get >>= \st=:{freshl}->put {st & freshl=freshl+1} >>| pure freshl
 
 instance If ByteCode Stmt Stmt Stmt where If b t e = BCIfStmt b t e
 freshlabel = get >>= \st=:{freshl}->put {st & freshl=freshl+1} >>| pure freshl
 
 instance If ByteCode Stmt Stmt Stmt where If b t e = BCIfStmt b t e


@@ -229,13 +232,13 @@ instance noOp ByteCode where
        noOp = tell` [BCNop]
 \end{lstlisting}
 
        noOp = tell` [BCNop]
 \end{lstlisting}
 

-The semantics for the \glspl{mTask} bytecode view are different than the
-semantics for the \gls{C} view. \glspl{Task} in the \gls{C} view can start new
-\gls{Task} or themselves to continue, while in the bytecode view, \gls{Task}
-run idefinitly, one-shot or on interrupt. To allow interval and interrupt
-\glspl{Task} to terminate, a return instruction is added. This class was not
-available in the original system and is thus added. It just writes a single
-instruction so that the interpreter knows to stop execution.
+The semantics for the \gls{mTask}-\glspl{Task} bytecode view are different from
+the semantics of the \gls{C} view. \glspl{Task} in the \gls{C} view can start
+new \glspl{Task} or even start themselves to continue, while in the bytecode
+view, \glspl{Task} run indefinitly, one-shot or on interrupt. To allow interval
+and interrupt \glspl{Task} to terminate, a return instruction is added. This
+class was not available in the original system and is thus added. It just
+writes a single instruction so that the interpreter knows to stop execution.

 Listing~\ref{lst:return} shows the classes and implementation for the return
 expression.
 
 Listing~\ref{lst:return} shows the classes and implementation for the return
 expression.
 


@@ -249,9 +252,9 @@ instance retrn ByteCode where
 \end{lstlisting}
 
 \subsection{Shared Data Sources \& Assignment}
 \end{lstlisting}
 
 \subsection{Shared Data Sources \& Assignment}

-Shared data sources must be acquired from the state and constructing one
-involves multiple steps. First, a fresh identifier is grabbed from the state.
-Then a \CI{BCShare} record is created with that identifier. A \CI{BCSdsFetch}
+Fresh \gls{SDS} are generated using the state and constructing one involves
+multiple steps.  First, a fresh identifier is grabbed from the state.  Then a
+\CI{BCShare} record is created with that identifier. A \CI{BCSdsFetch}

 instruction is written and the body is generated to finally add the \gls{SDS}
 to the actual state with the value obtained from the function. The exact
 implementation is shown in Listing~\ref{lst:shareview}.
 instruction is written and the body is generated to finally add the \gls{SDS}
 to the actual state with the value obtained from the function. The exact
 implementation is shown in Listing~\ref{lst:shareview}.


@@ -273,15 +276,16 @@ instance sdspub ByteCode where
 addSDS sds v s = {s & sdss=[{sds & sdsval=BCValue v}:s.sdss]}
 \end{lstlisting}
 
 addSDS sds v s = {s & sdss=[{sds & sdsval=BCValue v}:s.sdss]}
 \end{lstlisting}
 

-All assignable types compile to a \gls{RWST} that writes one fetch instruction.
-For example, using a \gls{SDS} always results in an expression of the form
-\CI{sds \x=4 In ...}. The actual \CI{x} is the \gls{RWST} that always writes
-one \CI{BCSdsFetch} instruction with the correct \gls{SDS} embedded. Assigning
-to an analog pin will result in the \gls{RWST} containing the \CI{BCAnalogRead}
-instruction. When the assignable is not a read from but assigned to, the
-instruction will be rewritten as a store instruction. Resulting in an
-\CI{BCSdsStore} or \CI{BCAnalogWrite} instruction respectively. The
-implementation for this is given in Listing~\ref{lst:assignmentview}.
+All assignable types compile to a \gls{RWST} which writes the specific fetch
+instruction(s). For example, using an \gls{SDS} always results in an expression
+of the form \CI{sds \x=4 In ...}. The actual \CI{x} is the \gls{RWST} that
+always writes one \CI{BCSdsFetch} instruction with the correctly embedded
+\gls{SDS}.  Assigning to an analog pin will result in the \gls{RWST} containing
+the \CI{BCAnalogRead} instruction. When the operation on the assignable is not
+a read operation from but an assign operation, the instruction(s) will be
+rewritten accordingly. This results in a \CI{BCSdsStore} or \CI{BCAnalogWrite}
+instruction respectively. The implementation for this is given in
+Listing~\ref{lst:assignmentview}.

 
 \begin{lstlisting}[label={lst:assignmentview},%
        caption={Bytecode view implementation for assignment.}]
 
 \begin{lstlisting}[label={lst:assignmentview},%
        caption={Bytecode view implementation for assignment.}]


@@ -295,15 +299,15 @@ makeStore [...]             = [...]
 
 \subsection{Actual Compilation}
 All the previous functions are tied together with the \CI{toMessages} function.
 
 \subsection{Actual Compilation}
 All the previous functions are tied together with the \CI{toMessages} function.

-This function compiles the bytecode and transforms the \gls{Task} in a message.
+This function compiles the bytecode and transforms the \gls{Task} to a message.

 The \glspl{SDS} that were not already sent to the device are also added as
 The \glspl{SDS} that were not already sent to the device are also added as

-messages to be sent to the device. This functionality is listed in
+messages to be sent to the device. This functionality is shown in

 Listing~\ref{lst:compilation}. The compilation process consists of two steps.
 First, the \gls{RWST} is executed. Then, the \emph{Jump} statements that
 jump to labels are transformed to jump to program memory addresses. The
 Listing~\ref{lst:compilation}. The compilation process consists of two steps.
 First, the \gls{RWST} is executed. Then, the \emph{Jump} statements that
 jump to labels are transformed to jump to program memory addresses. The

-translation of labels is possible in one sweep because no labels are reused.
+translation of labels is possible in one sweep because fresh labels are reused.

 Reusing labels would not give a speed improvement since the labels are removed
 Reusing labels would not give a speed improvement since the labels are removed

-anyway in the end.
+in the end.

 
 \begin{lstlisting}[label={lst:compilation},%
        caption={Actual compilation.}]
 
 \begin{lstlisting}[label={lst:compilation},%
        caption={Actual compilation.}]


@@ -331,7 +335,7 @@ toMessages interval x oldstate
 \end{lstlisting}
 
 \section{Examples}
 \end{lstlisting}
 
 \section{Examples}

-The heating example given previously in Listing~\ref{lst:exmtask} would be
+The thermostat example given previously in Listing~\ref{lst:exmtask} would be

 compiled to the following code. The left column indicates the
 position in the program memory.
 
 compiled to the following code. The left column indicates the
 position in the program memory.