I'm trying to learn how to do some very simple client-server application programming.
Basically, I want to make a program (the server) that listens and waits, and when a commend is sent it will run a batch file or execute a line of code.
The client will just ask for the ip and send the command when a button is pushed.
Shouldn't be too hard right? So what are some good resources that you've used to get started?
You probably want to dig into WCF, the Windows Communication Foundation. That's the state-of-the art for writing .NET components that need to communicate over some kind of network. Googling for wcf introduction yields various tutorials and examples to this topic.
Related
Advanced Attacks Detection in a Platform-as-a-Service(PaaS) Environment
In the first part of this project, i'm supposed to monitor incoming packets
in a web service, accept only HTTP & HTTPS (TCP)packets for later analysis and, drop the rest.
I was thinking doing this in JAVA, because i think it's a very flexible and
complete language and, it's present in every PaaS Environment! So, my idea is
to build a simple web page in JSP/JSF with a bean to attend this first step
of the project.
This is where i need some guidance! Because i've started considering
libpcap JAVA wrappers like jNetPcap, Jpcap and Pcap4J. But none of them is able to drop packets!
Forgetting JAVA, i also have red about other libraries like: libnet, libdnet and libcrafter.
libnet can not handle the task!
libdnet has network firewall rule manipulation capabilities, but it's a very old library and, i'm not sure it can handle integration with iptables!
libcrafter is the best! Because it's an actual updated project and, it allows the use of iptables rules in the code.
And, of course, working directly with netfilter would be the ideal scenario!
But working with libcrafter or netfilter, to follow my simple idea of a web service with a JAVA bean, i would have to write my own java wrapper by JNI! Which i assume NOT to be a simple task!
Now, what is raising many doubts in my mind, is the fact that this has to be
done in a PaaS environment! None of them (PaaS providers) seem to have the
same restrictions. There are some more flexible like AWS and Microsoft Azure that let you choose and manage a VM with the OS distro you want. Others like OpenShift, BlueMix or Cloud Foundry, in a project, only give you the option of defining the programming language, application server and, that's it! So, one might not have permissions to install libraries and control network & transport layers to manage the packets! Since the hole OS administration is handled by the provider.
Considering only the main purpose of this project, which is managing the packet flow pointed to a domain located in a PaaS environment, without the help of other servers like tcp proxies, i am desperately in need of someone pointing me a direction to start from! Because with that, i can dig as deep as needed to get a solution. Please HELP!
Thank you very much for your time and consideration.
I am developing applications and c#, I at the moment, I work on projects for Windows Platform only. However, I am planning to move into using C# mono to make my programs be able to work with linux, mac-os and windows.
One of the feature I am implementing in my program is the ability to communicate between them (ie. A Console type program that can communicate and interact with GUI Program by sending commands and receiving reply messages, logging messages, signals,.etc). Back in windows dotnet framework, I am looking at anonymous pipes, but now, I am checking if Mono.Unix.UnixPipes will do the job for me and will let me implement inter process messaging with very little to no adjustments at all under linux, mac-os and windows.
I am a little bit new to this kind of feature, and i am now reading into the documentations (however, class and objects documentations are not helping me so much yet). I am also browsing to some of the inter process messaging questions that are posted here in stackoverflow.
If anyone has a link to a tutorial kind of document or example on how to do this, it will be a great help. please help?
thank you.
I highly recommend running a mongodb (easly scalable from a dev boxes to hundreds of servers) and using the library https://github.com/dominionenterprises/mongo-queue-csharp on top of it for the messaging. It has the ability to query for messages which enables some really nice patterns. Also its compatible with mono ! Also has some other languages if needed down the road.
I am looking for a tool capable of generating multiple Xmpp connections to load-test a XMPP server with a secure connection, especially starttls.
For a xmpp plain text authentication I had used jab_simul(followed this tutorial) and tsung both with success.
But I was unable to use the tolls above for the starttls,I peeked into the code of both tools and tried different configurations of the tools.
Another option I am pondering is using a xmpp library like eXmpp and make a specific load-testing tool myself with, instead of altering jab_simul (C software with comments in language i do not understand) or altering tsung(all purpose load-testing tool, so lots of place where you can go wrong).
short-story - I am looking for a tool or advice to stress-testing/load-testing a xmpp server.
We are facing exactly the same challenge right now. After deep consideration we found out that only especially build software can deliver the load we want to test. (Remember, you can configure ejabberd to something very specific :-)
For that we developed a small library called xmpp_talker https://github.com/burinov/xmpp_talker (Apache Licence) which is a kind of xmpp client made as a gen_server. I find it is a very nice starting point to build any kind of load simulation software. There is also echo_worker example included. So, you have good base to start. At the moment xmpp_talker is suited for exmpp 0.9.7. As far as I know in a few days will be out version 1.0.0. (or 0.9.9?) There are many bug fixes (trust me you don't want to know about them). On monday I will release xmpp_talker for exmpp 0.9.8 with proper service interruption handling.
In case you deside to go the same way xmpp_talker could be useful for you.
Added: Here is also great article that is realted to the topic: https://support.process-one.net/doc/display/EXMPP/Scalable+XMPP+bots+with+erlang+and+exmpp
There's also the recently started XMPP benchmarking project called xmppench which aims to be a high-performance benchmarking tool simulating some reasonable use cases of XMPP servers. It's written in C++, based on Swiften and boost.
I am working on a project that involves an embedded system which runs a non-microsoft OS with a C program for the application and am developing .NET software for its end user applications. For remote configuring with the .NET software (which can go across firewalls), I am considering using WCF. I know only a little about WCF so far but I've read that it is supposed to be interoperable with environments other than .NET. The embedded environment has an HTTP stack but no built in support for web services. Does anyone have any experience with this kind of thing or know if it would be appropriate at all? If so please provide some advice or point me in the right direction.
Thanks!
WCF is interoperable because it's accessed over HTTP. Visual Studio can help you build client libraries very quickly for WCF, but client access to WCF doesn't require anything other than HTTP calls with the proper payload. If you're looking at a remote server call and your built-in support in your embedded environment is basic HTTP, look at building your server-side as REST-formatted methods. Your debugger will thank you.
What kinds of data are you planning on transferring back and forth? For something this low level and proprietary I would recommend sticking with good old fashioned Sockets.
I will be passing configuration data back and forth...basically to enable technical support staff to remotely program the device. If I were using sockets this could be binary data, but there is a requirement that customers with firewalls shouldn't need to open any ports. Because of this I was thinking of sending XML over HTTP. So, is it better to use WCF or REST on the server side? Or WCF with REST?
I'm curious about your "customers with firewalls" requirement. Sockets with binary data or XML over HTTP can use any port (not just port 80), and I'm curious if your device will be "listening" on the network, or just making an outbound connection. If your device is listening, you will need to open a port on the firewall. Making an outbound connection ("phoning home") is much easier on the firewall.
So I think you could use sockets and binary data. However, I have faced similar issues on the last two projects, and I really wanted to implement WCF using REST on the embedded device, but no one else wanted to do it - I'm hoping someone else will be first, and publish some results!
Good Luck! (and post your results!)
I've created a service for one of my apps. How do i create a system tray component in VB.net that can be used to monitor the progress of the service? Is there a way to have this installed via tcpip on multiple client machines such as those that are for our employees?
We do exactly that here, with the server running a really basic HTTP server on a configurable port on a separate thread that returns status in an XML format (nothing else, just that) -- the client just uses a web request to get the XML, before parsing it and displaying it appropriately.
This approach also allows for future extensibility (detailed status, sending service control commands, adding an association to an XSLT file elsewhere for use with a normal web browser, etc.)
You could use WCF for this. Using WCF your service would open up an EndPoint which would expose status information to callers. You could then build a tray icon application that can be deployed to the employees workstations. The tray icon application could periodically poll the WCF service the your Windows Service is hosting and get status information. I know #Johan mentioned Remoting already and this is a similar approach. I'd recommend WCF though as the programming API is more simple, IMHO, and WCF will give you more flexibility with regards to network transports, etc.
I guess your question is not about how to actually do the "traybar"-thing, but how to communicate with the service to get the information you want to show in the monitor/traybar-program?
It can be done in many ways, API is one way, use sendmessage/postmessage/getmessage is one way to make 2 running programs communicate with each other without having to store anything in files or databases first.
DDE is another way. If it needs to do the stuff via net then there is something called NetDDE, but I havent done anything with NetDDE I cant help anything there.
But about the API and DDE, feel free to ask more questions if you want some clarification.
I'll take the second question: Is there a way to remotely install software on client machines?
Yes. However it is very dependent on your environment. For example, if you have an Active Directory domain, you can use group policy to force installation of software on the client boxes.
If you don't like that or if you aren't on active directory, you can buy something like Altiris to push installs down.
Another option would be to use login scripts which would run a custom program to detect if your program is installed and take appropriate action. But then you are probably better off buying Altiris.
For the comunication part, i have used remoting before, and this works very well. With a little bit of configuration, you can even get it working to another machine.