ltkc_win32/src/ltkc_connection.c File Reference

Functions to communicate using LLRP messages over a socket. More...

#include <assert.h>
#include "ltkc_platform.h"
#include "ltkc_base.h"
#include "ltkc_frame.h"
#include "ltkc_connection.h"

Functions
LLRP_tSConnection *	LLRP_Conn_construct (const LLRP_tSTypeRegistry *pTypeRegistry, unsigned int nBufferSize)
	Construct a new LLRP connection instance.
void	LLRP_Conn_destruct (LLRP_tSConnection *pConn)
	Destruct a LLRP connection instance.
int	LLRP_Conn_openConnectionToReader (LLRP_tSConnection pConn, const char pReaderHostName)
	Open the connection to the reader.
const char *	LLRP_Conn_getConnectError (LLRP_tSConnection *pConn)
	Get the string that explains LLRP_Conn_openReaderConnection() error.
int	LLRP_Conn_closeConnectionToReader (LLRP_tSConnection *pConn)
	Close connection to reader, allow reuse of instance.
LLRP_tSMessage *	LLRP_Conn_transact (LLRP_tSConnection pConn, LLRP_tSMessage pSendMessage, int nMaxMS)
	Transact a LLRP request and response to a connection.
const LLRP_tSErrorDetails *	LLRP_Conn_getTransactError (LLRP_tSConnection *pConn)
	Get the details that explains LLRP_Conn_transact() error.
LLRP_tResultCode	LLRP_Conn_sendMessage (LLRP_tSConnection pConn, LLRP_tSMessage pMessage)
	Send a LLRP message to a connection.
const LLRP_tSErrorDetails *	LLRP_Conn_getSendError (LLRP_tSConnection *pConn)
	Get the details that explains LLRP_Conn_sendMessage() error.
LLRP_tSMessage *	LLRP_Conn_recvMessage (LLRP_tSConnection *pConn, int nMaxMS)
	Receive a message from a connection.
const LLRP_tSErrorDetails *	LLRP_Conn_getRecvError (LLRP_tSConnection *pConn)
	Get the details that explains LLRP_Conn_recvMessage() or LLRP_Conn_recvResponse() error.
LLRP_tSMessage *	LLRP_Conn_recvResponse (LLRP_tSConnection pConn, int nMaxMS, const LLRP_tSTypeDescriptor pResponseType, llrp_u32_t ResponseMessageID)
	Receive a specific message from a connection.

Detailed Description

Functions to communicate using LLRP messages over a socket.

This provides a simple interface to send and receive LLRP messages using a network socket.

This is simplified. It is possible, even likely, that some applications could require much more sophistication. To that end this source file serves as an example to illustrate how framing, encoding, decoding, and response matching are done.

Function Documentation

int LLRP_Conn_closeConnectionToReader ( LLRP_tSConnection * pConn )

Close connection to reader, allow reuse of instance.

Parameters:

[in] pConn Pointer to the connection instance.

Returns:: ==0 Connected OK, ready for business !=0 Error, check getConnectError() for reason

LLRP_tSConnection* LLRP_Conn_construct	(	const LLRP_tSTypeRegistry *	pTypeRegistry,
		unsigned int	nBufferSize
	)

Construct a new LLRP connection instance.

Parameters:

`[in]`	pTypeRegistry	The LLRP registry of known message/parameter types. Includes standard and custom. Used during decode.
`[in]`	nBufferSize	Size of each the receive and send buffers. Use size larger than the largest frame you expect. 0 selects a default value.

Returns:: !=NULL Pointer to connection instance ==NULL Error, always an allocation failure most likely nBufferSize is weird

void LLRP_Conn_destruct ( LLRP_tSConnection * pConn )

Destruct a LLRP connection instance.

Parameters:

[in] pConn Pointer to the connection instance.

Returns:: void

const char* LLRP_Conn_getConnectError ( LLRP_tSConnection * pConn )

Get the string that explains LLRP_Conn_openReaderConnection() error.

Parameters:

[in] pConn Pointer to the connection instance.

Returns:: ==NULL No error !=NULL Short string description of error

const LLRP_tSErrorDetails* LLRP_Conn_getRecvError ( LLRP_tSConnection * pConn )

Get the details that explains LLRP_Conn_recvMessage() or LLRP_Conn_recvResponse() error.

Parameters:

[in] pConn Pointer to the connection instance.

Returns:: Pointer to const error details

const LLRP_tSErrorDetails* LLRP_Conn_getSendError ( LLRP_tSConnection * pConn )

Get the details that explains LLRP_Conn_sendMessage() error.

Parameters:

[in] pConn Pointer to the connection instance.

Returns:: Pointer to const error details

const LLRP_tSErrorDetails* LLRP_Conn_getTransactError ( LLRP_tSConnection * pConn )

Get the details that explains LLRP_Conn_transact() error.

This is not 100% reliable. It looks at the send error and if that seems OK it uses the recv error. Uses of LLRP_Conn_sendMessage(), LLRP_Conn_recvMessage() or LLRP_CONN_recvResponse() since LLRP_Conn_transact() will distort the error.

Returns:: Pointer to const error details

int LLRP_Conn_openConnectionToReader	(	LLRP_tSConnection *	pConn,
		const char *	pReaderHostName
	)

Open the connection to the reader.

The steps:

Look up the host name
Create a socket
Connect to the host address
Condition the socket (set options)

Parameters:

`[in]`	pConn	Pointer to the connection instance.
`[in]`	pReaderHostName	String containing the reader host name

Returns:: ==0 Connected OK, ready for business !=0 Error, check LLRP_Conn_getConnectError() for reason

LLRP_tSMessage* LLRP_Conn_recvMessage	(	LLRP_tSConnection *	pConn,
		int	nMaxMS
	)

Receive a message from a connection.

The message could have already arrived and be pending on the input queue.

Parameters:

`[in]`	pConn	Pointer to the connection instance.
`[in]`	nMaxMS	-1 => block indefinitely 0 => just peek at input queue and socket queue, return immediately no matter what >0 => ms to await complete frame

Returns:: ==NULL No message available per parameters. Check LLRP_Conn_getRecvErrot() for why !=NULL Input message

LLRP_tSMessage* LLRP_Conn_recvResponse	(	LLRP_tSConnection *	pConn,
		int	nMaxMS,
		const LLRP_tSTypeDescriptor *	pResponseType,
		llrp_u32_t	ResponseMessageID
	)

Receive a specific message from a connection.

The message is identified by type and message ID.

This is used to receive a response to a request, but could be used for other things, too. A message matches and is returned if the type matches AND if the message ID matches. Either or both can be wildcards.

The sought message could have already arrived and be pending on the input queue. While we are looking for the response notifications might arrive. They are held in the input queue while we continue to look for the sought message.

About timeLimit.... The timeLimit is the last time() we'll try to receive the sought message and prevents "spinning". It is conceivable that a steady stream of messages other than the one sought could arrive, and the time between those messages could be smaller the nMaxMS. When that happens, recvAdvance() would not time out during its poll/select. It could "spin". The time out must be detected by other means and that's the purpose of timeLimit.

Parameters:

`[in]`	pConn	Pointer to the connection instance.
`[in]`	nMaxMS	-1 => block indefinitely 0 => just peek at input queue and socket queue, return immediately no matter what >0 => ms to await complete frame
`[in]`	pResponseType	The type descriptor of the sought or NULL to match all messages. If not NULL, ERROR_MESSAGE will also match.
`[in]`	ResponseMessageID	The MessageID of sought message or 0 to match all messages.

Returns:: ==NULL No message available per parameters. Check LLRP_Conn_getRecvErrot() for why !=NULL Input message

LLRP_tResultCode LLRP_Conn_sendMessage	(	LLRP_tSConnection *	pConn,
		LLRP_tSMessage *	pMessage
	)

Send a LLRP message to a connection.

Parameters:

`[in]`	pConn	Pointer to the connection instance.
`[in]`	pMessage	Pointer to the LLRP message to send.

Returns:: LLRP_RC_OK Frame sent LLRP_RC_SendIOError I/O error in write(). Probably means fd is bad. LLRP_RC_... Encoder error. Check LLRP_Conn_getSendError() for why.

LLRP_tSMessage* LLRP_Conn_transact	(	LLRP_tSConnection *	pConn,
		LLRP_tSMessage *	pSendMessage,
		int	nMaxMS
	)

Transact a LLRP request and response to a connection.

This is a combination of LLRP_Conn_sendMessage() and LLRP_Conn_recvResponse(). The MessageID is taken from the outgoing messages. It's best to not use MessageID 0. The expected response type is also taken from the outgoing message. ERROR_MESSAGE is also deemed a response;

Parameters:

`[in]`	pConn	Pointer to the connection instance.
`[in]`	pSendMessage	Pointer to the LLRP message to send.
`[in]`	nMaxMS	-1 => block indefinitely 0 => just peek at input queue and socket queue, return immediately no matter what >0 => ms to await complete frame

Returns:: ==NULL Something failed. Use LLRP_Conn_getTransactError() for best guess at what went wrong. !=NULL Response message