PythonClient

java.lang.Object
- util.PropertyContainer
- - io.AbstractDriver
  - - stella.ow.PythonClient

All Implemented Interfaces:

Driver, Cloneable, OneWireDriver, ExitCleaning, Initializable, PropertySupplying
```
public class PythonClient
extends AbstractDriver
implements ExitCleaning, OneWireDriver
```
This is a work-around to get the one-wire sensors to work. The python client talks via socket to a python server that is responible for issuing the one-wire commands. It uses a very simple ASCII-protocol that understands only three commands, LIST, READ, WRITE, or STOP.
On startup, the client connects to the server on port KEY_PYTHONPORT and keeps the connection open until closed. On init, it sends a list of readable sensors to the server. During normal operation, i.e. when sensors query the client, a read command is issued and the python server returns in plain ascii the most current value of the sensor it has in its cache. If the path issued to the python server was not sent to it previously with a list command, this method returns OneWireDriver.INVALID. Writing of the one-wire switches is accomplished in a similar way by issuing a write command to the python server. These write commands are normally not cached, but forwarded driectly to the underlying onw-wire system. The result returned is writtn by the python server to this python client. Protocol (\n means new-line):
- LIST \n\n...\n: Sends the list of sensor the python server should permanentely query. Each sensorpath has a format similar to /24.0B34086745000/temperature. This path can readily be sent to the one-wire system. It is the reponsibility of this client to send valid paths.
- READ \n: Issues a read from the cache of the python server. The last successful value read in is transferred as plain ASCII to this client. If the sensorpath queried is not in the cache list, OneWireDriver.INVALID is returned.
- WRITE \n: Write-through the requested path to the one-wire bus. The sensorpath need not to be in the cache. The result from the one-wire system, which is always an int, is converted into a plain ASCII string and sent as the response from the one-wire system.
- STOP\n: Stop the caching thread until a new list arrives. The cache is not immediately cleared, thus queries will return values still, though they might be out-of date.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class PythonClient.Test
A test class.

Nested Classes
Modifier and Type	Class and Description
`static class`	`PythonClient.Test` A test class.

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`ADD` The add command string.
`private static String`	`COMMANDSEPARATOR` The separator string between multi-part commands.
`private static long`	`DEFCOOLDOWN` The default cooldown in ms.
`private static String`	`DEFDRIVERNAME` The default python driver name, a serial port name under linux
`private static String`	`DEFPYTHONHOST` The default one-wire server name, a serial port name under linux
`private static int`	`DEFPYTHONPORT` The default python server's listening port.
`private static String`	`DEFSENSORPATH` The default list of sensors.
`private static long`	`DEFTIMEOUT` The default timeout in ms.
`private BufferedReader`	`in` The input reader derived from the client socket.
`static String`	`KEY_COOLDOWN` The default time-out after writing in ms
`static String`	`KEY_PYTHONHOST` The name of the host the python server runs on.
`static String`	`KEY_PYTHONPORT` The port the python server is listening at.
`static String`	`KEY_SENSORPATH` The default list of sensor devices to read as a comma-separated list.
`static String`	`KEY_TIMEOUT` The default time-out for reading in ms
`static String`	`LIST` The list command string.
`private Socket`	`open` The client socket opened on `init()`.
`private BufferedWriter`	`out` The output writer derived from the client socket.
`static String`	`READ` The read command string.
`private boolean`	`stalled` Gets true if reading produced a time-out.
`static String`	`STOP` The stop command string.
`static String`	`WRITE` The write command string.

Fields inherited from class io.AbstractDriver
KEY_DRIVERNAME

Fields inherited from class util.PropertyContainer
KEY_LISTSEPARATOR, KEY_MAPKEYVALUECHAR, KEY_MAPSEPARATOR

Fields inherited from interface stella.ow.OneWireDriver
INVALID, OK, VALID

Fields inherited from interface util.PropertySupplying
CONFIG, KEY_CLASS

Constructor Summary

Constructors
Constructor and Description

PythonClient(Map prop)
Constructs a new python driver.

Constructors
Constructor and Description
`PythonClient(Map prop)` Constructs a new python driver.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`close()` Closes the driver.
`private boolean`	`closeSocket()` Closes the socket without sending a stop to the Python server.
`void`	`exit()` On exit we close the client socket to the server and do not care about any possible failures.
`void`	`init()` Initializing never fails as all relevant keys have default values.
`boolean`	`isOpen()` Checks if the connection is open.
`int`	`issue(String sensorpath, String what)` Sends a write command to the python server.
`boolean`	`open()` Initializes the driver.
`private boolean`	`openSocket()` Opens the socket connetion, but does not send any sensor lists.
`private String`	`readLine()` Reads a line from the input stream, and blocks if no bytes are available.
`String`	`retrieve(String sensorpath)` Send a read command to the python server.
`boolean`	`sendList(List sensorlist)` Send a list to the python server.
`boolean`	`sendStop()` Sends the stop command.
`private boolean`	`writeLine(String what)` Sends the given line to the socket's output stream.

Methods inherited from class io.AbstractDriver
createDriver, equals, getDriverName, hashCode

Methods inherited from class util.PropertyContainer
augment, augment, augment, augment, augment, clone, defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsEnums, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, initProperties, isNew, parseObject, parseObject, reload, reload, removeProperty, requires, rescanned, setObject, setProperties, setProperty, stringProperties, toString

Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface io.Driver
getDriverName

- Field Detail
  - KEY_PYTHONHOST
```
public static final String KEY_PYTHONHOST
```
    The name of the host the python server runs on.
    
    See Also:
    
    Constant Field Values
  - KEY_PYTHONPORT
```
public static final String KEY_PYTHONPORT
```
    The port the python server is listening at.
    
    See Also:
    
    Constant Field Values
  - KEY_SENSORPATH
```
public static final String KEY_SENSORPATH
```
    The default list of sensor devices to read as a comma-separated list.
    
    See Also:
    
    Constant Field Values
  - KEY_COOLDOWN
```
public static final String KEY_COOLDOWN
```
    The default time-out after writing in ms
    
    See Also:
    
    Constant Field Values
  - KEY_TIMEOUT
```
public static final String KEY_TIMEOUT
```
    The default time-out for reading in ms
    
    See Also:
    
    Constant Field Values
  - DEFDRIVERNAME
```
private static final String DEFDRIVERNAME
```
    The default python driver name, a serial port name under linux
    
    See Also:
    
    Constant Field Values
  - DEFPYTHONHOST
```
private static final String DEFPYTHONHOST
```
    The default one-wire server name, a serial port name under linux
    
    See Also:
    
    Constant Field Values
  - DEFPYTHONPORT
```
private static final int DEFPYTHONPORT
```
    The default python server's listening port.
    
    See Also:
    
    Constant Field Values
  - DEFSENSORPATH
```
private static final String DEFSENSORPATH
```
    The default list of sensors.
    
    See Also:
    
    Constant Field Values
  - DEFCOOLDOWN
```
private static final long DEFCOOLDOWN
```
    The default cooldown in ms.
    
    See Also:
    
    Constant Field Values
  - DEFTIMEOUT
```
private static final long DEFTIMEOUT
```
    The default timeout in ms.
    
    See Also:
    
    Constant Field Values
  - LIST
```
public static final String LIST
```
    The list command string.
    
    See Also:
    
    Constant Field Values
  - ADD
```
public static final String ADD
```
    The add command string.
    
    See Also:
    
    Constant Field Values
  - READ
```
public static final String READ
```
    The read command string.
    
    See Also:
    
    Constant Field Values
  - WRITE
```
public static final String WRITE
```
    The write command string.
    
    See Also:
    
    Constant Field Values
  - STOP
```
public static final String STOP
```
    The stop command string.
    
    See Also:
    
    Constant Field Values
  - COMMANDSEPARATOR
```
private static final String COMMANDSEPARATOR
```
    The separator string between multi-part commands.
    
    See Also:
    
    Constant Field Values
  - open
```
private Socket open
```
    The client socket opened on init().
  - in
```
private BufferedReader in
```
    The input reader derived from the client socket.
  - out
```
private BufferedWriter out
```
    The output writer derived from the client socket.
  - stalled
```
private boolean stalled
```
    Gets true if reading produced a time-out.
- Constructor Detail
  - PythonClient
```
public PythonClient(Map prop)
```
    Constructs a new python driver. Initially, only the sensor pathes described in the list KEY_SENSORPATH are sent to the python server.
- Method Detail
  - init
```
public void init()
```
    Initializing never fails as all relevant keys have default values.
    
    Specified by:
    
    init in interface Initializable
  - open
```
public boolean open()
             throws IOException
```
    Initializes the driver. This requires that the python server is up and running. On init, we open a socket connection to the python server on port KEY_PYTHONPORT. If the open is successful, we parse the initial list of sensors to query and send it to the server.
    
    Specified by:
    
    open in interface Driver
    
    Returns:
    
    True if initialization was successful.
    
    Throws:
    
    IOException
  - openSocket
```
private boolean openSocket()
                    throws IOException
```
    Opens the socket connetion, but does not send any sensor lists. This method may be used on re-opening.
    
    Throws:
    
    IOException
  - closeSocket
```
private boolean closeSocket()
                     throws IOException
```
    Closes the socket without sending a stop to the Python server.
    
    Throws:
    
    IOException
  - isOpen
```
public boolean isOpen()
```
    Checks if the connection is open. We consider everything o.k. if we have the I/O streams and the client socket.
    
    Specified by:
    
    isOpen in interface Driver
    
    Returns:
    
    True, if a previous initialization was successful
  - close
```
public boolean close()
```
    Closes the driver. We send a STOP to the python server and then close the socket's I/O-streams and the socket itself. If anything in this process fails, we return false. If the socket was already closed, we return true.
    
    Specified by:
    
    close in interface Driver
    
    Returns:
    
    True if clean-up was successful.
  - exit
```
public void exit()
```
    On exit we close the client socket to the server and do not care about any possible failures.
    
    Specified by:
    
    exit in interface ExitCleaning
  - sendList
```
public boolean sendList(List sensorlist)
```
    Send a list to the python server. The connection must be open for success. On receive, this list is cached for re-opening re-sends.
  - retrieve
```
public String retrieve(String sensorpath)
```
    Send a read command to the python server. The argument must be a valid sensor path, i.e. a sensor that is in the python server's cache.
    
    Specified by:
    
    retrieve in interface OneWireDriver
    
    Parameters:
    
    sensorpath - The path to the one-wire sensor.
  - issue
```
public int issue(String sensorpath,
                 String what)
```
    Sends a write command to the python server. The sensor path is not bound to be in the python server's cache, but it should nevertheless be a valid one. The python server's return, which is an int as a string is returned and must be interpreted from the caller's side.
    
    Specified by:
    
    issue in interface OneWireDriver
    
    Parameters:
    
    sensorpath - The path to the one-wire sensor.
    
    what - The command to send to the one-wire sensor.
  - sendStop
```
public boolean sendStop()
```
    Sends the stop command. This will block further updating of the cache in the python server until a new list was sent with LIST.
  - writeLine
```
private boolean writeLine(String what)
```
    Sends the given line to the socket's output stream. The connection is NOT checked for openess, this must be ensured by the caller if desired. After each write we wait a KEY_COOLDOWN time to ensure that reading the line is possible immediately as the write returns. This is no elegant solution, but there is actually no case where we write and not read immediately afterwards.
    We had mysterious dissappearance of sensor threads, which I believe is a buffer overflow in the out stream. Thus, on occasions where we're stalled, we re-open the connection, not really hoping for a cure, but trying to keep the thing alive.
    
    Returns:
    
    true if writing was successful.
  - readLine
```
private String readLine()
```
    Reads a line from the input stream, and blocks if no bytes are available.

Class PythonClient

Nested Class Summary

Field Summary

Fields inherited from class io.AbstractDriver

Fields inherited from class util.PropertyContainer

Fields inherited from interface stella.ow.OneWireDriver

Fields inherited from interface util.PropertySupplying

Constructor Summary

Method Summary

Methods inherited from class io.AbstractDriver

Methods inherited from class util.PropertyContainer

Methods inherited from class java.lang.Object

Methods inherited from interface io.Driver

Field Detail

KEY_PYTHONHOST

KEY_PYTHONPORT

KEY_SENSORPATH

KEY_COOLDOWN

KEY_TIMEOUT

DEFDRIVERNAME

DEFPYTHONHOST

DEFPYTHONPORT

DEFSENSORPATH

DEFCOOLDOWN

DEFTIMEOUT

LIST

ADD

READ

WRITE

STOP

COMMANDSEPARATOR

open

in

out

stalled

Constructor Detail

PythonClient

Method Detail

init

open

openSocket

closeSocket

isOpen

close

exit

sendList

retrieve

issue

sendStop

writeLine

readLine