I use Veins-4a2 and I have modified the scenario of the demo example. I have added a new wsm which is ACK when a node reveives a message, it sends an ACK message to the source node.
I have add this line in onData() function:
sendWSM(prepareWSM("ack", ackLengthBits, type_SCH, ackPriority, sourcenode.idNode, 2));
and I changed certainly the prepareWSM and handleLowerMsg() functions in BaseWaveApplLayer.cc, but when I execute the simulation, it crashes after 10 seconds. This is the error message:
Error in module (Mac1609_4) RSUExampleScenario.node[2].nic.mac1609_4 (id=240) at event #1196, t=9.210177776741: Model error: ASSERT: condition useSCH false in function handleUpperMsg, veins/modules/mac/ieee80211p/Mac1609_4.cc line 259.
Is that I do not have the right to reuse the SCH channel for the ACK message?
How can I correct this problem please?
The 1609.4 MAC layer of Veins 4a2 can be used in one of two operation modes: single channel and multi channel. The behavior can be configured by setting this parameter of the .ned file:
// cycle between an SCH and the CCH (or stay on CCH all the time)
bool useServiceChannel = default(true);
From the error message you are posting it appears you have set this parameter to false, meaning you want the radio to always stay on the Control Channel (CCH). At the same time, the code you posted requests a message to be transmitted over a Service Channel (SCH).
You are thus requesting mutually exclusive behavior.
Veins correctly identified this and aborted your simulation.
Related
We have a PHP app that forwards messages from RabbitMQ to connected devices down a WebSocket connection (PHP AMQP pecl extension v1.7.1 & RabbitMQ 3.6.6).
Messages are consumed from an array of queues (1 per websocket connection), and are acknowledged by the consumer when we receive confirmation over the websocket that the message has been received (so we can requeue messages that are not delivered in an acceptable timeframe). This is done in a non-blocking fashion.
99% of the time, this works perfectly, but very occasionally we receive an error "RabbitMQ PRECONDITION_FAILED - unknown delivery tag ". This closes the channel. In my understanding, this exception is a result of one of the following conditions:
The message has already been acked or rejected.
An ack is attempted over a channel the message was not delivered on.
An ack is attempted after the message timeout (ttl) has expired.
We have implemented protections for each of the above cases but yet the problem continues.
I realise there are number of implementation details that could impact this, but at a conceptual level, are there any other failure cases that we have not considered and should be handling? or is there a better way of achieving the functionality described above?
"PRECONDITION_FAILED - unknown delivery tag" usually happens because of double ack-ing, ack-ing on wrong channels or ack-ing messages that should not be ack-ed.
So in same case you are tying to execute basic.ack two times or basic.ack using another channel
(Solution below)
Quoting Jan Grzegorowski from his blog:
If you are struggling with the 406 error message which is included in
title of this post you may be interested in reading the whole story.
Problem
I was using amqplib for conneting NodeJS based messages processor with
RabbitMQ broker. Everything seems to be working fine, but from time to
time 406 (PRECONDINTION-FAILED) message shows up in the log:
"Error: Channel closed by server: 406 (PRECONDITION-FAILED) with message "PRECONDITION_FAILED - unknown delivery tag 1"
Solution <--
Keeping things simple:
You have to ACK messages in same order as they arrive to your system
You can't ACK messages on a different channel than that they arrive on If you break any of these rules you will face 406
(PRECONDITION-FAILED) error message.
Original answer
It can happen if you set no-ack option of a Consumer to true that means you souldn't call ack function manually:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume.no-ack
The solution: set no-ack flag to false.
If you aknowledge twice the same message you can have this error.
A variation of what they said above about acking it twice:
there is an "obscure" situation where you are acking a message more than once, which is when you ack a message with multiple parameter set to true, which means all previous messages to the one you are trying to ack, will be acked too.
And so if you try to ack one of the messages that were "auto acked" by setting multiple to true then you would be trying to "ack" it multiple times and so the error, confusing but hope you understand it after a few reads.
Make sure you have the correct application.properties:
If you use the RabbitTemplate without any channel configuration, use "simple":
spring.rabbitmq.listener.simple.acknowledge-mode=manual
In this case, if you use "direct" instead of "simple", you will get the same error message. Another one looks like this:
spring.rabbitmq.listener.direct.acknowledge-mode=manual
I have a sensor network where nodes exchange messages and calculate some parameters on which we decide if a clone has been inserted into the network or not. If it is the case, I call the endSimulation() instruction in order to stop the simulation. But I noticed that some messages continue to be exchanged after the instruction endsimulation() and I got the message:
undisposed object: (omnetpp::cMessage) Drones.clone.app.event2 -- check module destructor"
Although I have a finish() method where I cancelAndDelete(event2). I want to know how to delete event after calling endSimulation().
I have two programs running in separated sessions. I want to send a event from program A and catch this event in program B.
How can I do that ?
Using class-based events is not really an option, as these cannot be used to communicate between user sessions.
There is a mechanism that you can use to send messages between sessions: ABAP Messaging Channels. You can send anything that is either a text string, a byte string or can be serialised in any of the above.
You will need to create such a message channel using the repository browser SE80 (Create > Connectivity > ABAP Messaging Channel) or with the Eclipse ADT (New > ABAP Messaging Channel Application).
In there, you will have to define:
The message type (text vs binary)
The ABAP programs that are authorised to access the message channel.
The scope of the messages (i.e. do you want to send messages between users? or just for the same user? what about between application servers?)
The message channels work through a publish - subscribe mechanism. You will have to use specialised classes to publish to the channel (inside report A) and to read from the channel (inside report B). In order to wait for a message to arrive once you have subscribed, you can use the statement WAIT FOR MESSAGE CHANNELS.
Example code:
" publishing a message
CAST if_amc_message_producer_text(
cl_amc_channel_manager=>create_message_producer(
i_application_id = 'DEMO_AMC'
i_channel_id = '/demo_text'
i_suppress_echo = abap_true )
)->send( i_message = text_message ).
" subscribing to a channel
DATA(lo_receiver) = NEW message_receiver( ).
cl_amc_channel_manager=>create_message_consumer(
i_application_id = 'DEMO_AMC'
i_channel_id = '/demo_text'
)->start_message_delivery( i_receiver = lo_receiver )
" waiting for a message
WAIT FOR MESSAGING CHANNELS
UNTIL lo_receiver->text_message IS NOT INITIAL
UP TO time SECONDS.
If you want to avoid waiting inside your subscriber report B and to do something else in the meanwhile, then you can wrap the WAIT FOR... statement inside a RFC and call this RFC using the aRFC variant. This would allow you to continue doing stuff inside report B while waiting for an event to happen. When this event happens, the aRFC callback method that you defined inside your report when calling the RFC would be executed.
Inside the RFC, you would simply have the subscription part and the WAIT statement plus an assignment of the message itself to an EXPORTING parameter. In your report, you could have something like:
CALL FUNCTION 'ZMY_AMC_WRAPPER' STARTING NEW TASK 'MY_TASK'
CALLING lo_listener->my_method ON END OF TASK.
" inside your 'listener' class implementation
METHOD my_method.
DATA lv_message TYPE my_message_type.
RECEIVE RESULTS FROM FUNCTION 'ZMY_AMC_WRAPPER'
IMPORTING ev_message = lv_message.
" do something with the lv_message
ENDMETHOD.
You could emulate it by checking in program B if a parameter in SAP memory has changed. program A will set this parameter to send the event. (ie SET/ GET PARAMETER ...). In effect you're polling event in B.
There a a lot of unknown in your desription. For example is the event a one-shot operation or can A send several event ? if so B will have to clear the parameter when done treating the event so that A know it's OK to send a new one (and A will have to wait for the parameter to clear after having set it)...
edited : removed the part about having no messaging in ABAP, since Seban shown i was wrong
I'm doing a scenario where there is 1 route at the beginning and then it splits into 3, then merges into 1 again. I'm stopping the car in the first lane, the second car stops also, the third one reroutes in the middle lane, the fourth goes to the queue, the fifth reroutes, the sixth goes to the queue, the seventh reroutes.....why is it behaving like that? I can't understand where to change this "balancing" or "threshold". Any suggestion?
The Veins 4.6 sample application behaves as follows:
if a vehicle is stopped (and has been driving) and has not yet sent a warning message, it sends a message containing its current road (TraCIDemo11p.cc, line 82)
if a vehicle receives a warning message, it tries to find a new route through the road network that avoids this road (TraCIDemo11p.cc, line 48); in addition, if it has not yet sent a warning message, it re-sends the received message (TraCIDemo11p.cc, line 54)
So, if you use this sample application and observe that some vehicles do not change their route, this can be attributed (among others) to either of the following effects:
they never received a message that told them about the congestion
they received a message, but couldn't find a route through the road network that would avoid the congestion
Why a vehicle did not receive a message can again be attributed (among others) to any of the following:
a warning message was transmitted to them, but they could not receive it (e.g., due to interference)
a warning message was transmitted through the network before they started their trip (remember, warning messages are not repeated by the example application)
I am using Arduino to control an SM5100B GSM device, everything works except when I want to send an SMS after receiving another. I get this,
Error code:
O K > + C M G S : 2 5 O K + C M E E R R O R : 4
My code for handling the aforementioned received SMS:
#include <SoftwareSerial.h> //Include the NewSoftSerial library to send serial commands to the cellular module.
char inchar; //Will hold the incoming character from the Serial Port.
SoftwareSerial cell(2,3);
char mobilenumber[] = "0597010129";
void setup() {
//GSM
Serial.begin(9600); // opens serial port, sets data rate to 9600 bps
Serial.println("Initialize GSM module serial port for communication.");
cell.begin(9600);
delay(35000); // give time for GSM module to register on network etc.
Serial.println("delay off");
cell.println("AT+CMGF=1"); // set SMS mode to text
delay(200);
cell.println("AT+CNMI=3,3,0,0"); // set module to send SMS data to serial out upon receipt
delay(200);
}
void loop() {
if(cell.available() >0)//If a character comes in, from the cellular module
{
inchar=cell.read();
Serial.println(inchar);
if (inchar=='#'){ // OK - the start of our command
delay(10);
inchar=cell.read();
Serial.println(inchar);
if (inchar=='a'){
delay(10);
Serial.println("The folowing SMS : \n");
inchar=cell.read();
Serial.println(inchar);
if (inchar=='0'){ //sequance = #a0
Serial.println("#a0 was received");
}
else if (inchar=='1'){//sequance = #a1
Serial.println("#a1 was received ");
sendSms();
}
}
cell.println("AT+CMGD=1,4");// AT command to delete all msgs
Serial.println(" delete all SMS");
}
}//end of if(cell.available() >0) {...}
}
void sendSms(){
//cell.println("AT+CMGF=1"); // set SMS mode to text
cell.print("AT+CMGS="); // now send message...
cell.print((char)34); // ASCII equivalent of "
cell.print(mobilenumber);
cell.println((char)34); // ASCII equivalent of "
delay(500); // give the module some thinking time
cell.print(":D hello m3alleg :D"); // our message to send
cell.println((char)26); // ASCII equivalent of Ctrl-Z
delay(20000);
}
General note about your handling of AT commands.
No, no, no! This way of doing it will never work reliably. You MUST
wait for the > character to be received before sending "text
to send". Or actually it is not just the > character, it is four
characters. Quote from 3GPP specification 27.005:
the TA shall send a four character sequence
<CR><LF><greater_than><space> (IRA 13, 10, 62, 32) after command line
is terminated with <CR>; after that text can be entered from TE to
ME/TA.
(TA (terminal adapter) here means modem and TE (terminal equipment) the sender of AT commands)
For any abortable AT command (and 27.005 clearly states for AT+CMGS
This command should be abortable.) the sending of any character will
abort the operation of the command. To quote ITU V.250:
5.6.1 Aborting commands
...
Aborting
of commands is accomplished by the
transmission from the DTE to the DCE
of any character.
(DCE (data communication equipment) here means modem and DTE (data terminal equipment) the sender of AT commands)
This means that when you send "text to send" before "\r\n> " is sent
by the modem the command will be aborted. There is no way to wait "long
enough" for expecting the response be send. You MUST read and parse
the response text you get back from the modem.
The same applies for the final result code after each command (e.g. OK,
ERROR, CME ERROR and a few more). For instance sending "AT+CMGF=1"
and then sending the next command without first waiting for OK is begging
for problems. So always when sending AT commands, you MUST wait
for the final result code before sending the next command.
Please never, never use delay to wait for any AT command response. It's
as useful as kicking dogs that stand in your way in order to get them
to move. Yes it might actually work some times, but at some point you
will be sorry for taking that approach...
Answer to your question.
Based on the response you get, I can see that your problem is not command
abortion (although your parsing have serious problems as described above
that you should fix), and the CME ERROR is your best clue. From section
"9.2.1 General errors" in 27.007 it gives operation not supported as
description for value 4.
27.005 states that:
If sending fails in a network or an ME error, final result code +CMS ERROR: is returned.
Notice that this is +CMS ERROR and not +CME ERROR, but it is applicable, see below.
I guess that sequence of actions is as following:
The AT command handling part of the SM100B GSM modem accepts the sms data
and formats it in an appropriate format and sends it of to the part of the
modem that communicates with the GSM network. It successfully send the
sms data to the network and reports this back to the AT command handling
part which then prints +CMGS: 25 and final result code OK. However
after a short time the network sends back a rejection message for the sms,
which is then given as the +CME ERROR response.
If my guess above is correct, should the response have been delivered
as +CMS ERROR instead? No, because the final response
has for the AT+CMGS command has already been given (OK), and
returning multiple final result codes for a command should never be done
(except by mistake (note 1)).
And while +CME ERROR can replace the ERROR final result code,
it is not only a final result code. From the AT+CMEE command description:
Set command disables or enables the use of result code +CME ERROR: as an indication of an error relating to
the functionality of the MT. When enabled, MT related errors cause +CME ERROR: final result code instead
of the regular ERROR final result code. ERROR is returned normally when error is related to syntax, invalid parameters,
or TA functionality.
Thus +CME ERROR can both be an final result code as well as an unsolicited
result code (possibly also an intermediate result code).
But could not the AT+CMGS command have waited to receive the network
rejection and returned +CMS ERROR? Probably not. Without knowing too
much about the network details of sms sending, it might be the case
that rejection today might occur at a much later time than before. Such
changes are sometimes a problem with GSM related AT commands which have
an old heritage that was originally tightly tied to GSM behaviour which
some times becomes less and less true as the technology moves to GPRS,
UMTS, LTE, etc.
Note 1:
One of my former colleagues used to complain about the way the standard
have specified voice call handling, because after a ATD1234; command
you first get the final result code OK, and then later when the call is
ended you get a new final result code NO CARRIER. This just horribly
bad design, the call end indication should have been a specific unsolicited
response and not a final response.
So to summarise
Your sms seems to be rejected by the network. Try to find out why.
You also have some serious problems with your AT command handling
that you should fix; there is no way to handle AT commands without
reading and parsing the response text from the modem.
cell.println("AT+CNMI=3,3,0,0"); // set module to send SMS data to
serial out upon receipt
For anyone who is looking for answer to the same problem I had:
I was trying to wake up gsm module from sleep mode by sending sms and it didn't work right away. Phone call goes straight to UART, but for sms you have to use this command to set module to send SMS data to serial port upon receipt .
AT+CNMI=3,3,0,0