I have to create a particular simulation for a college project. The simulation should feature several mobile nodes cyclically switch between 802.11 access point and station modes. While in station mode, nodes should read the SSIDs of access points around them, and then they should change their SSID in AP mode accordingly. There is no need for connections or data exchange between the nodes beside the SSID reading.
Now, I've been through Omnet/Inet tutorials/documentation (all two of them), and I feel pretty much stuck.
What I could use right now is someone confirming my understanding of the framework giving me some directions on how exactly I should proceed.
From what I understand is Inet does not implement any direct/easy way to do what I'm trying to do. Most examples have fixed connections declared in NED files and hosts with a fixed status (AP or STA) defined in the .ini file.
So my question is basically how do I do that: do I need to extend a module (say, wirelessHost), modifying its runtime behaviour, or should I implement a new application (like UDPApp) to have my node read other SSIDs and change his accordingly? And what is the best way to access an host's SSID?
You may utilize two radios for each mobile node e.g. **.mobilenode[*].numRadios = 2 (see also example in /inet/examples/wireless/multiradio/).
The first radio operates as AP **.mobilenode[*].wlan[0].mgmtType = "Ieee80211MgmtAPSimplified" which has to adapt its SSID.
The second radio serves as STA **.mobilenode[*].wlan[1].mgmtType = "Ieee80211MgmtSTA". Now, you have to sub-class Ieee80211AgentSTA which handles the SSID scanning procedure and has to change the first radio's SSID upon new SSID detection. Then you utilize the adopted sub-class within the simulation. Finally, active scanning has to be activated **.mobilenode[*].wlan[1].agent.activeScan = true.
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I am an Engineering Student and as part of my diploma thesis, I am simulating the passenger changeover process in metros using the Anylogic Pedestrian Library.
In the simulation, it often happens that standing passengers "leave" the standing area and somehow get into the sitting places, blocking the way from other peds that would like to occupy the seat.
All passengers come from the Passenger Agent, where they have a boolean variable wantToSit. If wantToSit = false, they are routed into the standing area, with wantToSit = true they go to take their seats.
Now, I would like to restrict the access of peds with wantToSit = false into the area drown using polygonal nodes around the seat groups, so that the phenomenon written above cannot occur, thus only sitting passengers will enter this area.
However, when I try to define the condition for the access restriction in the polygonal Node, I always get the error "... cannot be resolved to a variable".
Here is the variable from the Agent "Passenger":
On the Agent "Main", where the Polygonal Node is, the auto code complete does not recommend anything for want or for ped. . For the word Passenger, see the picture below:
Is there a way to use the access restriction feature in this case? I don't know how to access this parameter of Passenger from Main, which is a different agent.
Thank you in advance for your help!
If you do the code complete action in the condition field before you type anything, you will see that the local variables available for you to use in the condition field is agent and self
And then if you choose agent you will see that the fields within your custom Pedestrian agent will become available.
Try not to type anything without code complete. It can save you a lot of time.
In Order use a PLC as a Client (formerly “Slave”), one has to configure the PDO channels, since the default values of the manufacturer are often not suitable. In my case, I need the PDOs so send INT valued instead of the default UNSIGNED8 (see. Picture).
Therefore my question: What kind of workflow would you recommend, to map the CANopen Client PDO channels?
I found the following workflow suitable, however I appreciate any improvements and recommendations from your side!
Start by locating the .eds file from the manufacturer. The image show this in the B&R Automation Studio Programming Environment
Open the file in a eds. Editor. I found the free Vector CANEds Editor very useful. Delete all RxPODs and RxPDO mappings that you don’t need.
Assign the needed Data Type (e.g. INTEGER16) and Channel Name (“1 Byte In (1)”).
Add the necessary PDOs and PDO mapping from the database. (This might actually be a bug, but if you just edit the PDOs without deleting and recreating them, I always receive error messages)
Map the Date to the Channels
Don't forget to write the number of channels in the first entry (in this image: 1601sub0)
Check the eds file for Errors (press F5) and copy&paste the eds file to the original location point 1.)
Add the PLC Client device in Automation Studio and you should see the correct mappings.
(PS: I couldn't make the images smaller ... any recommendations about formating this question are welcome!)
I am using Oendaylight (carbon) to develop an SDN application consisting of multiple switches that connect to a controller. I want to be able to deploy different applications on different switches when they connect. How can I specify this? For example when openflow:1 connects, I want to deploy an L2 switch on it and when openflow:2 connects, I want to deploy a different application on it. Thanks.
First of all, you do not deploy applications on switches. Applications run on controller, you can add a logic which programs selected switches only.
What you essentially want to do is reactive programming; wait for events and act accordingly. This can be easily achieved by hooking the event listeners to the nodes in YANG model of the application. Any change in these nodes will be then notified to your application which can then do selective network programming.
In the example mentioned, you will need to use "InstanceIdentifier" object to identify which data model's events you are interested in listening.
InstanceIdentifier<Node> nodeID = InstanceIdentifier.builder(Nodes.class).child(Node.class, new NodeKey(node.getId())) .augmentation(FlowCapableNode.class)
.build();
Now simply register a listener to this IID by using DataBroker object's registerDataChangeListener method.
db.registerDataChangeListener(LogicalDatastoreType.CONFIGURATION, nodeID, this, AsyncDataBroker.DataChangeScope.SUBTREE);
At this point in time, you will be notified of any update (addition/modifification/deletion) of the switches you have registered for.
Finally to catch the event use/override DataChangeListener interface's onDataChanged method and add your fancy logic.
The similar logic can be fine grained to listen to activities on particular flow tables, flow rules, etc on the switch.
While going through upnp spec I got the following doubts .
Can I define a basic upnp device with all mandatory fields and with no servicelist and
when providing the description xml I will modify my description xml to advertise my service based to different conditions.
eg: services may playmusic OR switch light OR playfootball.
Can i modify the xml per device basis on run time to inlcude completely different and random services?
I hope the description and service xmls are not static .
Just like almost everything else in UPnP Device Arch document this is not 100% clearly defined, but the idea of dynamic device/service descriptions is mentioned:
If a device needs to
change one of these descriptions, it MUST cancel its outstanding
advertisements and re-advertise. Consequently, control points SHOULD
NOT assume that device and service descriptions are unchanged if a
device re-appears on the network, but they can detect whether
descriptions changed if a changed CONFIGID.UPNP.ORG field value is
present in the announcements.
So descriptions are not static, but you do need need to cancel and re-advertize.
That said, abusing this does not sound useful (Why not use separate root devices or at least sub-devices for totally unrelated services) and is bound to lead to compatibility issues.
Is there an API or way to programmatically turn off an individual, external monitor via Objective-C on a Mac?
I'm looking to write a small menubar application that can control a secondary display (without a physical power button), but still keep the primary monitor in use.
Hunting around the API documentation, I can't seem to find anything, other then reading states. So hoping someone else might have an idea.
You can't "programmatically turn off an individual monitor", it's not physically possible. The most you can do is tell the OS to not use the monitor, but I don't think you can change system-wide settings like that, especially not at the level you're working on (Obj-C).
Looking at the Core Graphics API mentioned in #Halley's comment, try starting with the CGBeginDisplayConfiguration method and see if you can set a display configuration to your liking.
EDIT: Alternatively, you could also use CGDisplayCapture(displayID), which by default fills the captured display with black. You can then
call CGDisplayRelease(displayID) when you want to turn it back on.
It seems to be possible to sleep display so by I/O Kit:
https://web.archive.org/web/20161106204726/http://www.cocoabuilder.com/archive/cocoa/191807-sleep-display.html
http://explanatorygap.net/2009/01/31/a-screensaver-to-send-your-display-to-sleep/
But I am not sure whether it can control single monitors.