org.vishia.msgDispatch

Class MsgRecvCommFile

java.lang.Object

org.vishia.msgDispatch.MsgRecvCommFile

All Implemented Interfaces:

InterProcessComm

public class MsgRecvCommFile
extends java.lang.Object
implements InterProcessComm

This class receives messages via a simple file transfer. The file contains some message items in binary format. A file with changed timestamp is recognized as a new message packet. The source should open, write and close the files with messages in an lower time cycle than this class reads the file.
It is able to use for an connection which can transfer files but not free ethernet telegrams. The class implements the InterProcessComm interface because it is used as any form of InterProcessComm independent of its implementation via file transfer.

Field Summary

Fields

Modifier and Type	Field and Description
private java.io.File	fileMsgBin The only one file which is checked.
(package private) long	lastTimestamp

Fields inherited from interface org.vishia.communication.InterProcessComm

receiverShouldbeBlocking, receiverShouldbePolling, version

Constructor Summary

Constructors

Constructor and Description
MsgRecvCommFile(java.lang.String file)

Method Summary

Modifier and Type	Method and Description
int	abortReceive() Abort receiving function
int	capacityToSendWithoutBlocking(int nrofBytesToSend) Tests wether a next send is done without blocking.
int	checkConnection() Checks the connection.
int	close() Closes the mailbox, only to be called on shutdown of the application.
Address_InterProcessComm	createAddress() Creates an empty instance for a address information, especially for the sender.
Address_InterProcessComm	createAddress(int p1, int p2)
Address_InterProcessComm	createAddress(java.lang.String address)
Address_InterProcessComm	createAddress(java.lang.String p1, int p2)
int	dataAvailable() Tests wether data are available to receive.
boolean	equals(Address_InterProcessComm address1p, Address_InterProcessComm address2p) Compare the address to another address, returns true if it is the same address.
int	flush() Flushs send data to destination.
void	freeData(byte[] data) Relinguishes the data buffer, after it is evaluated.
java.lang.String	getName()
Address_InterProcessComm	getOwnAddress() Gets the own address of this interProcessComm, it are the receive parameters.
byte[]	getSendBuffer(int len) Gets a buffer for send.
int	open(Address_InterProcessComm ownAddress, boolean shouldBlock) Opens the Communication.
byte[]	receive(int[] result, Address_InterProcessComm sender) Receives a Datagram.
byte[]	receiveData(int[] nrofBytes, byte[] buffer, Address_InterProcessComm sender)
int	send(byte[] data, int nBytes, Address_InterProcessComm addressee) Sends Data.
java.lang.String	translateErrorMsg(int nError)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

fileMsgBin

private final java.io.File fileMsgBin

The only one file which is checked.

lastTimestamp

long lastTimestamp

Constructor Detail

MsgRecvCommFile

public MsgRecvCommFile(java.lang.String file)

Method Detail

abortReceive

public int abortReceive()

Description copied from interface: InterProcessComm

Abort receiving function

Specified by:

abortReceive in interface InterProcessComm

capacityToSendWithoutBlocking

public int capacityToSendWithoutBlocking(int nrofBytesToSend)

Description copied from interface: InterProcessComm

Tests wether a next send is done without blocking. If the transfer medium supports this test and it has a limited capacity, the method is helpfull to use. If the medium doesnot support such quest, the nrofBytes is returned. It means, it has a capacity. send is possible but it is not guarented that the send doesnot block.

Specified by:

capacityToSendWithoutBlocking in interface InterProcessComm

Returns:

nrofBytes of capacity to send without blocking, but not greater than argument nrofBytesToSend. 0 if the next send call will be blocked. negativ value if any error.

checkConnection

public int checkConnection()

Description copied from interface: InterProcessComm

Checks the connection. This is the alternativ method for polling instead of the callback methods errorConnection() and readyConnection().

Specified by:

checkConnection in interface InterProcessComm

Returns:

value less 0: error code, the connection is not available. If the value is >=0, the connection is established.

close

public int close()

Description copied from interface: InterProcessComm

Closes the mailbox, only to be called on shutdown of the application.

Specified by:

close in interface InterProcessComm

dataAvailable

public int dataAvailable()

Description copied from interface: InterProcessComm

Tests wether data are available to receive. This is the alternativ method for polling instead of the callback methods dataAvailable() from the callback interface. This method can return 0 also if data are receiveable, if the implementation donot support such quest.

Specified by:

dataAvailable in interface InterProcessComm

Returns:

value less 0: error code, the connection is not available. If the value is >0, data are available. If 0, no data are available.

equals

public boolean equals(Address_InterProcessComm address1p,
                      Address_InterProcessComm address2p)

Description copied from interface: InterProcessComm

Compare the address to another address, returns true if it is the same address. This method can used to compare a known address with a sender address from InterProcessComm::receive().

Specified by:

equals in interface InterProcessComm

flush

public int flush()

Description copied from interface: InterProcessComm

Flushs send data to destination.

Specified by:

flush in interface InterProcessComm

freeData

public void freeData(byte[] data)

Description copied from interface: InterProcessComm

Relinguishes the data buffer, after it is evaluated.

Specified by:

freeData in interface InterProcessComm

Parameters:

data - The buffer delivered from receive!

getName

public java.lang.String getName()

Specified by:

getName in interface InterProcessComm

getOwnAddress

public Address_InterProcessComm getOwnAddress()

Description copied from interface: InterProcessComm

Gets the own address of this interProcessComm, it are the receive parameters. The knowledge of receive address may be necessary at user level if the information about a other receive adress should be communicate to the partner. In most cases the partner knows the sender adress (back-info-argument of receive) from the implementation level, but in some cases (2-simplex-Ports TCP/UDP) the receive adress is the address getted here.

Specified by:

getOwnAddress in interface InterProcessComm

getSendBuffer

public byte[] getSendBuffer(int len)

Description copied from interface: InterProcessComm

Gets a buffer for send.

Specified by:

getSendBuffer in interface InterProcessComm

open

public int open(Address_InterProcessComm ownAddress,
                boolean shouldBlock)

Description copied from interface: InterProcessComm

Opens the Communication. Only called at startup.

Specified by:

open in interface InterProcessComm

Parameters:

ownAddress - The own address to which this interprocess-port is assigned. This address is also used when calling send() as information about the sender of the data.

Returns:

true if success, false if it failed. Use getReceiveErrorMsg() to detect the cause manually.

receive

public byte[] receive(int[] result,
                      Address_InterProcessComm sender)

Description copied from interface: InterProcessComm

Receives a Datagram. This method blocks until a Datagram is received. If a Datagram is received, the content of the Datagram will copied into the appropriated buffer.

Specified by:

receive in interface InterProcessComm

Parameters:

result - result[0] = Nr of Bytes sendet, if >=0. If <0 its an error code.

sender - Buffer for the sender of the message.

Returns:

The reference to the buffer containing data. On error, the content of this reference is not valid, but the user must call relinguishData() with this reference .

receiveData

public byte[] receiveData(int[] nrofBytes,
                          byte[] buffer,
                          Address_InterProcessComm sender)

Specified by:

receiveData in interface InterProcessComm

Returns:

send

public int send(byte[] data,
                int nBytes,
                Address_InterProcessComm addressee)

Description copied from interface: InterProcessComm

Sends Data. The destination adress is defined on open. If a listener is associated with this class, the data will be forwarded to the users evaluation method defined in the implementation of the listener. So a evaluation may be execute directly without consideration of the users software and without consideration of the realization in this class. If no listener is associated, the data will be sent in the kind of realization of this class.

Specified by:

send in interface InterProcessComm

Parameters:

data - The data to be sent. The user should not touch the buffer after calling here.

nBytes - The number of bytes to be send.

addressee - The addressee, the receiver of the message. If it is a fix connection (TCP), then this parameter should be null. It isn't used. The addressee is given on #open(Address_InterProcessComm, int)-request.

Returns:

number of Bytes sent, if >=0. If <0 its an error code.

translateErrorMsg

public java.lang.String translateErrorMsg(int nError)

Specified by:

translateErrorMsg in interface InterProcessComm

createAddress

public Address_InterProcessComm createAddress()

Description copied from interface: InterProcessComm

Creates an empty instance for a address information, especially for the sender.

Specified by:

createAddress in interface InterProcessComm

Returns:

An empty new instance apropriate to the kind of communication.

createAddress

public Address_InterProcessComm createAddress(int p1,
                                              int p2)

Specified by:

createAddress in interface InterProcessComm

createAddress

public Address_InterProcessComm createAddress(java.lang.String p1,
                                              int p2)

Specified by:

createAddress in interface InterProcessComm

createAddress

public Address_InterProcessComm createAddress(java.lang.String address)

Specified by:

createAddress in interface InterProcessComm