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().
Related
I am writing a state machine with the following functionality.
start State -> Lambda1 which calls external service Describe API endpoint to get State attribute of item example "isOKay" or "isNotOkay" -> Choice state((depending on the state received) if "IsOkay" move to next state and if "isNotOkay" again call lambda1. This happens until it gets a IsOkay state. How can put a limit to this custom retry loop so that I dont get stuck if I never receive a IsOkay response.
You can use input your step in a form of counter, which incremented by lambda. Which when return in retry can be checked for a limit, if crosses one fail lambda with custom exception. Describe separate step for handling the exception.
https://docs.aws.amazon.com/step-functions/latest/dg/input-output-inputpath-params.html
https://docs.aws.amazon.com/step-functions/latest/dg/concepts-error-handling.html
I am working on a wireless routing protocol. I have created a Queue at every node. In this queue, every node kept packet which it already transmitted. If packet is not transmitted by nexthop then previous node will retransmit the packet after timeout. The problem is that when node is trying to retransmitt the packet by calling postRotingHook in handle function to retransmit then it is not doing anything. This postRoutingHook is created locally so it is not actually sending the packet. So how to connect this packet with network for retransmission?
Example: Suppose We have 3 nodes A, B and C. A is source, B is intermediate and C is destination. Node A sent a packet initially. Now node B will forward it to node C. At this time node A will overhear this packet and it will cancel the timer and delete this packet from its Queue. (in normal condition)
Suppose node B could not forward the packet because of some reason then node A should re-transmit the packet after time out. I am unable to achieve this functionality.
My programming scenario is:
I have modified GPSR protocol. Where header file have definition of these 5 INetfilterHooks methods. I didn't use any control packet e.g. request, response, beacon etc. I am directly dealing with data packet which contains some control information. I have implemented my logic in datagramPreRoutingHook() method (when data is received from lower layer) and datagramLocalOutHook() method (when data is received from upper layer).
Source node (at network layer) receives packet from upper layer at IPv4.cc using handlePacketFromHL() ->datagramLocalOutHook(datagram, destIE, nextHopAddr) == INetfilter::IHook::ACCEPT) when it calls datagramLocalOutHook(datagram, destIE, nextHopAddr) then control goes to my routing protocol. It makes necessary changes, Adds source, destination address, creates options and keeps the packet in Queue (for retransmission by scheduling timer) then return ACCEP. Then control again goes to IPv4.cc.
After this process, if time out occurs at my protocol then I am unable to send packet to IPv4.cc. I called postRoutingHook to retransmit the packet then it simly return ACCEPT (as defined in header file) and does nothing. I have tried to call some methods of IPv4.cc by making object of IPv4 in my protocol but these methods are protected so I couldn't access these methods.
I tried with making some public methods of IPv4.cc but it is giving error at further stage.
I have tried to make the object of INetfilter::IHook for calling its postRoutingHook() but is also providing error as object of abstract class can not be created.
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 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.
Using MS Visual Studio 2008 C++ for Windows 32 (XP brand), I try to construct a POP3 client managed from a modeless dialog box.
Te first step is create a persistent object -say pop3- with all that Boost.asio stuff to do asynchronous connections, in the WM_INITDIALOG message of the dialog-box-procedure. Some like:
case WM_INITDIALOG:
return (iniPop3Dlg (hDlg, lParam));
Here we assume that iniPop3Dlg() create the pop3 heap object -say pointed out by pop3p-. Then connect with the remote server, and a session is initiated with the client’s id and password (USER and PASS commands). Here we assume that the server is in TRANSACTION state.
Then, in response to some user input, the dialog-box-procedure, call the appropriate function. Say:
case IDS_TOTAL: // get how many emails in the server
total (pop3p);
return FALSE;
case IDS_DETAIL: // get date, sender and subject for each email in the server
detail (pop3p);
return FALSE;
Note that total() uses the POP3’s STAT command to get how many emails in the server, while detail() uses two commands consecutively; first STAT to get the total and then a loop with the GET command to retrieve the content of each message.
As an aside: detail() and total() share the same subroutines -the STAT handle routine-, and when finished, both leaves the session as-is. That is, without closing the connection; the socket remains opened an the server in TRANSACTION state.
When any option is selected by the first time, the things run as expected, obtaining the desired results. But when making the second chance, the connection hangs.
A closer inspection show that the first time that the statement
socket_.get_io_service().run();
Is used, never ends.
Note that all asynchronous write and read routines uses the same io_service, and each routine uses socket_.get_io_service().reset() prior to any run()
Not also that all R/W operations also uses the same timer, who is reseted to zero wait after each operation is completed:
dTimer_.expires_from_now (boost::posix_time::seconds(0));
I suspect that the problem is in the io_service or in the timer, and the fact that subsequent executions occurs in a different load of the routine.
As a first approach to my problem, I hope that someone would bring some light in it, prior to a more detailed exposition of the -very few and simple- routines involved.
Have you looked at the asio examples and studied them? There are several asynchronous examples that should help you understand the basic control flow. Pay particular importance to the main event loop started by invoking io_service::run, it's important to understand control is not expected to return to the caller until the io_service has no more remaining work to do.