I'd like to ask for your help on creating a user-defined application in ns-2.
I tried to create a new application for simulating scheduling policies by modifying the code of CBR traffic application.
I've finished c++ files and tried to do the simulation with the oTcl script. When I run the ns, it turns out that the application does not transmit any packet. To make sure that my Tcl script is correct, I change the application to CBR and then the program can indeed transmit packets.
It seems that the Tcl commands could not access the functions which I define in the c++ domain.
Should I do anything else in the oTcl domain?
I'm wondering if there is anyone who has ever came across the similar situation.
The following are what I've done so far:
Create a new application class in c++ domain.
Create a static shadow object by deriving from TclClass
Create instprocs by defining the function "int command(argc, argv)" in c++ domain.
In oTcl domain: define an instproc init and use -superclass to declare that the new application is a derived class from "Application" class.
Thank you very much for your generous help.
Related
I have created a program that extracts data from a racing game and sends it to a speed gauge cluster. I call it the transfer program.
I need a simple user-friendly User Interface to start the transfer program, set some variables and choose a COM Port. At the moment I'm trying to do it with a C++ Windows Forms Application in a CLR Project on Microsoft Visual Studio 2015. When I tried to do it directly (creating the UI in the same project as the transfer program) I just get too many errors that I have no idea where they come from or why they are there.
So I've decided maybe I could try creating some sort of launcher, i.e. a completely different program that is only the UI to start the transfer program and send a few user-set variables to it on startup as well as choose a COM Port to communicate on.
Any idea on how to start on this? How do I execute the transfer program from the Launcher? How do I send variables and data to it?
Thank you very much!
There are basically two ways to pass information to your transfer program.
For simple use cases, just pass the values along on the command line. If you're still using the CLR, this is done using System.Diagnostics.Process. A nice example can be found in this answer: https://stackoverflow.com/a/33633148/127826
Use a shared configuration file. So the user interface loads the values from the config and also saves the file before executing the transfer program. The transfer program then reads the same configuration file to get the values it needs.
The second approach is far more flexible and is what I would use.
I'm currently working on a little project in C++. I'm fairly new to C++/Programming and wanted to ask how my classes should be designed.
To be specific: I want to write a little program for chatting. Just simple communication between two programs/computers. For that I want to use a good class design because, although it is only a small project (just for the sake of learning), I want it to be well designed and extensible.
My program should have about 5 classes (Handlers etc, the Updater and App - the main class only for this program).
I'll give you a few examples of ideas I have how I could design one part of the program. The first part should be the connection part (handled by Connection). The task is to build up a connection between the two programs. It will also set up local files, which will hold the information to print, and connect it to the 'server' file. Later in the program there should be access to the File_Handler class so it can edit/read the local file and read/request to write to the 'server' file. (How exactly it's gonna do it is already figured out, so as long as it is not necessary I'd like to keep this system as it is ;) ). But now let's get to the ideas I have:
Idea 1
App creates an instance of Connection to set up the connection.
Connection then creates an instance of File_Handler which will set up the files (in this case File_Hanlder would hold the paths with static variables) and then destroy that instance because it is no longer needed by Connection.
Another class (instance is held by App) then creats an own instance of File_Hanlder later and could work with the files since the variable for the path is static.
Idea 2
App creates an Instance of Connection and File_Handler (lets call them con and fil).
To set up the connection, fil is passed per reference to con to set up the variable paths for the files and create the files etc. .
For working with the files later, App would pass around fil to manage all the file handling for the other classes which would, for example, update the chat etc.
That would require a lot of classes to have a constructor or (a) function(s) which needs to have a File_Handler parameter and the same variable would be passed around a lot of times.
Idea 3
The last idea I have is that Connection, File_Handler and the other classes would be created very general without any or near to zero relation to other classes.
App then creates a lot of functions (or even 'subclasses') to work with these classes almost like working with Frameworks which were developed independently and thus could, theoraticly, be used in another program without any problems.
Which solution do you think would be the best? Or is there another solution you have for me which would be even better?
I have a Windows local service that may spawn off a process to execute a JScript script (in a .js file) via the Windows Script Host. The issue is that I need to notify my service of the results generated by the script in the .js file. A transfer or a simple 32-bit integer, or a string would suffice. What would be the way to do this?
PS. The code must run on Windows XP SP3 or later OS.
Your best bet is to create an out of process COM object that executes within your service. Just implement the necessary scripting interfaces and provide a member function to match the notification and call it from your script as such:
newObj = new ActiveXObject("localserver.mynotify");
newObj.Notify("finished");
Would the exit code of the process be enough?
Windows Scripting host has has a .Quit(errorCode) method that allows you to set the exit code.
You should be able to call WSH directly from the service and get the return code with GetProcessExitCode() by passing the process handle that you received after spawning it.
Note that almost everything you can do from a JScript file can also be done with native code.
Do you have to execute the .js file as an external process? Windows Scripting has COM objects that an app can use to run scripts within its own process. I use this to execute script files within my service processes, and it works fine. The hosting process can even implement its own IDispatch-based classes and pass them to the scripting engine to expose to scripts as global objects so the scripts can communicate with the hosting process without having to use new ActiveXObject or CreateObject() to access those objects.
I see your script is written in JScript and your app in C++.
Perhaps the easiest way to accomplish what you want is by writing a file, say, to programdata folder which your service should have access to. Maybe use a GUID for the particular request, pass that to the JScript so it's guaranteed to be a unique file. Not ideal.
Another way to get JScript output ... Can you call out to managed code (C#)? If so, you could use a .NET-based or .NET-callable JavaScript compiler/interpreter. This would allow you to avoid IActiveScript and also to grab the values right out of the script context or from function return. I've used Jurassic and JavaScriptDotNet, both very easy to use and extend.
This might open a problem if you heavily rely on ActiveXObject calls (ie: FileSystemObject) and don't want to write components. JuraScript wraps the Jurassic engine and add ActiveXObject support to it for COM automation.
I am a C++ newb, so I don't know how much of a leap this is for you although I know it's possible to interop between managed/C++.
Just thought I'd mention these scenarios as I didn't see them listed in answers.
I'm reading through a tutorial on using voice commands to control applications and, in an example of controlling rhythmbox, it suggests commands such as the following can be executed:
rhythmbox-client --play
rhythmbox-client --pause
Why does this not simply open a new instance of the program, and how can I emulate the functionality in my own programs? For example, how could I pass a string to a particular instance of a program?
Thanks
Rhythmbox uses inter-process communictation to achieve this type of functionality, and this can be implemented in a number of different ways. One of them is to use D-Bus, like Rhythmbox does.
Using D-Bus is not very easy, but the basic idea is that you register your application in D-Bus, so other applications can call different procedures your app exports (for example play/stop actions), and then in the same application implement a client. This way, if arguments like --play are passed, you don't run the usual code, but just check for an instance of the running app and send a command to your already running program.
On the other hand, when no arguments are passed, your program just starts and registers the proper triggers, so that a later called instance can control it.
Here is a tutorial on dbus, and the DBus homepage
There are several techniques to have only one application instance running. In these terms calling yyy --play would generally mean the same as
INSTANCE = GET_RUNNING_INSTANCE()
IF INSTANCE == NULL
INSTANCE = CREATE_NEW_INSTANCE()
SEND_MESSAGE(INSTANCE, PLAY)
For example, how could I pass a string to a particular instance of a program?
You'll need to use whatever interprocess communication facilities your operating system offers. Sockets or named pipes, for example, or messages.
I'm trying to read variables from memory. Variables, that doesn't belong to my own program. For instance, let's say I have this Adobe Shockwave (.dcr) application running in browser and I want to read different variables from it. How it's being done? Do I need to hook the process? But it's running under virtual machine, so I don't know how to do it.
This task is pretty much trivial in normal w32 applications (as it is mainly just
CBT-hooking / subclassing), but as I mentioned before, I've got no idea how it's being
done with flash / shockwave.
I'm using C++ (VS9) as my development-environment, in case you wish to know.
Any hints would be highly appreciated, so thank you in advance.
Best regards,
nhaa123
If you're trying to do it manually just for one or two experiments, it's easy.
Try a tool like Cheat engine which is like a free and quick and simple process peeker. Basically it scans the process's memory space for given key values. You can then filter those initial search hits later as well. You can also change those values you do find, live. The link above shows a quick example of using it to find a score or money value in a game, and editing it live as the game runs.
without having debug Binaries/DLLs of the Apps, your only chance is asking some hackers.
Normally you can connect to a process with a debugger, but without the debugging symbols of the binaries you don't see any variable names - just memory addresses.
Further the Flash/Shockwave code runs inside a sandbox inside the browser to prevent security holes by manipulated Flash code. So you don't have a real chance to get access to the running Flash code / to the plugin executing the Flash code - except you have a manipulated version of such a plugin.
So your task is quite hard to solve without using less legal methods. The next hard thing is the virtual machine - this could be solved by implementing your app as a client/server solution, where the "inspector" / watchdog runs as server inside the virtual machine and the client requesting the variable status/content running on your normal host. The communication could be done as simple socket connection.
If you have the chance to write your own Flash/Shockwave plugin, you maybe could be able to see contents of variables.
Sorry, that I cannot help you any further.
ciao,
3DH