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This is a very newbie question.
I want to know how to create a web app to make a telephone call, most likely using VOIP protocol.
What programming languages, both client and server side, do I have to learn?
The primary question you need to answer to get started is are you looking for a computer to computer call or do you want your app to call a telephone number?
Since you specify that you want your "web app to make a call," I suspect you're looking for a way to place automated calls to a user's telephone. If that's the case, you've got a few options.
Install a VoIP server like Asterisk or Freeswitch and write code to have your web app interact with it. For Asterisk, the Adhearsion project can help by allowing you to write Asterisk integrations in Ruby. http://adhearsion.com/
Or you can use a cloud telephony service like Cloudvox or Tropo http://tropo.com (disclosure, I work for Voxeo, the company behind Tropo). These services allow you to use web programming languages and web services to talk to the phone system. You don't need to know anything about Voip to make it happen. A sample Tropo script...
<?php
answer();
say('Yes, it really is this easy.');
hangup();
?>
A side benefit to the cloud services is many of them allow your app to run over other communications channels (Tropo does IM and SMS, too).
The third option is to look into VoiceXML, a W3C standard for creating voice apps. Voxeo provides detailed docs and VoiceXML tutorials at http://vxml.org/. With a VoiceXML (sometimes called VXML) application, you can install a VoiceXML server and the associated VoIP bits or you can use a VoiceXML hosting provider. Voxeo provides both a downloadable server and hosting (both are free for developers), or a search for VoiceXML hosting will reveal a large number of options.
The answer to your question really depends on what you want to do with it. Here are 2 examples of how I have gone about it:
I developed the software for Go2Call.Com (now owned by Deltathree), and it was used for PC-to-Phone calling. In Go2Call's case, it was a Java applet for the dialer frontend that called a Windows DLL written in C++. From there, it spoke a proprietary protocol to talk to the servers which in turn sent the call to regular landlines.
A few years later, I wrote a web-based (ActiveX control) that would allow PC-to-PC or PC-to-Phone calling, and it used the standard H.323 protocol.
I would recommend starting out by figuring out what your end goal is and then looking up the necessary protocols and technologies to accomplish it.
For PC-to-PC, you can do whatever you want if both people use your software. In that case, you can figure out how VOIP works (including compression codecs, etc.) and implement it however you want.
For PC-to-Phone or when you want to call someone else's software, I'd recommend SIP since it's probably the most popular protocol. H.323 is still prevalent, but SIP seems to be taking over.
Sorry this doesn't probably tell you everything, but there's a lot to it. Hopefully, this will get you started in the right direction.
Update: Since you mentioned PC-to-PC, Packetizer has a list of standards and quite a bit of info I used way back when I did a lot of VoIP programming.
As far as books go, the books I've seen so far aren't programming-related but more about using VoIP software and installing VoIP networks.
Gizmo5 has a Flash softphone that runs in the browser: GizmoCall
On the server side, you'd probably link it up with an SIP solution in any language. Asterisk comes to mind, although it may be a bit overkill depending on whether you really wanted a full-blown SIP solution or not.
You may wish to purchase a component which allows you to add SIP functionality to your webpage, (most of these ones are ActiveX based):
http://www.conaito.com/
http://www.vaxvoip.com/
http://www.pcbest.net/
As for the language you have to learn, well what languages have you learned already? Which languages have you developed web apps with? This determines your choice of language. Using components like those listed above take some of the legwork out, but still will require probably vbscript or javascript coding client side, and those that are activeX will only work on Internet Explorer webbrowsers.
If you have no experience then you need to look seriously at what you are trying to do, why, how much time and effort you can and are willing to put in.
Related
I am new in Multiplayer Game Development, I have already developed a offline game and now I want to make it a multiplayer, so with help of my friend we create a server side script in node.js, but I don't know how to integrate this in my c++ project,
I've googled but, can't find anything helpful.
anybody can suggest any tutorial.
Thanks
You've asked a big open-ended question. As Allern suggests there are a lot of things that you can do with networked programs that can extend it well beyond that of a single user game. For instance in my current game there is an access to a version welcome page in html. There are file downloads for campaign/user maps and there are connections to Firebase for leaderboards and other networked resources like ads.
However, I suspect you are referring to the communications between a number of separate user machines all synchronized to keep them coordinated. For this you will need to write some serialization code to transmit to and receive packets from the central server. Typically a serialization package like flatbuffers will be needed to move information from your data structures to a packet and the reverse.
You might also require communication/network software to asynchronously send and receive those packets (this may be included in whatever game engine you might be using). Boost.asio might help otherwise. There are numerous other networking packages and libraries all the way down to the bare-bones unix/POSIX calls (or Windows OS calls).
You will also need software on the server side to log users in, deal with players disconnecting and doing the main work of passing the game packets around. This software may also implement the logic of your game (game rules) and might do saves on the data if you want users to be able to play the game in multiple sessions (like a big dungeon crawl). There might be packages out there that do most of the server side stuff. If so, please post what you find out.
Cocos2dx does have some networking software built in but it isn't very functional as far as I'm concerned. It does have facilities to display web pages and download files fairly easy but the async communication seems a little weak. You can try the Network module in the API Docs which may have what you are looking for.
Since the type of game and how you want to implement your player interaction will dictate how the software is to be built I'm afraid this answer is a little vague. Good luck. Share your insights.
you can use public tools , as a sample is websocket,it can support C++ and javasc
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I want to develop real time web application like chatting & real time message conversion. I searched the internet and got confused with few technology
erlang ejabberd nodejs openfire
Right now im in java domain but won't hesitate to learn new things. So can anyone explain what is these technology in a very simple words and what technology i will need to achieve my target ? Does all these do the same thing ? and new technology suggestion from your side will be appriciated.
These are entirely different things :)
At the lowest level you have:
Erlang/OTP is piece of technology, that lets you built low latency, fault tolerant systems. It includes Erlang programming language, Erlang VM and OTP, which is set of patterns, libraries and good practices for writing those systems.
nodejs is a platform, that lets you code JavaScript on server side. It makes your life a little bit easier, when dealing with events, but Erlang is still better saving you from callback hell with actors and messages between them.
At the higher level you have xmpp:
xmpp is eXtensible Messaging and Presence Protocol. This is great for implementing chats like facebook chat, but because it is extensible, you can use it for any kind of messaging.
ejabberd is implementation of xmpp in erlang. There is also fork of ejabberd called MongooseIM. Those will give you great start at developing your messaging application. They implement not only basic xmpp, but also couple of extensions (called xeps in xmpp community).
openfire is solution based on xmpp, so it is even higher level. For chatting and message conversion, this might be overkill, but it depends on your specific needs.
Totally an opinion post:
Erlang: Doing this from scratch with yaws and Erlang is the most straightforward way (its even a code sample in "Programming Erlang" 2nd ed.).
Ejabberd is famously undocumented (and overkill for most webchat services), but it and its better documented/saner cousin (MongooseIM) are robust and already written.
node.js is a cosmic joke played on monolingual ex-frontend web developers.
I've never heard of openfire.
None of these things are bad to learn -- but that's because nothing is ever bad to learn (though some things aren't worth the time you would spend learning them).
The basic problem, I think, is that your goal is probably more broad than you realize, at least in terms of methods by which you can achieve the goal of "develop a web-based chat and communication service". There are a hundred web servers out there, each with its own way of doing active content service, each with a hundred more back-end plugins to a thousand more chat/conversation/comments/blather service frameworks. Any given "technology stack" will often involve a dozen languages throughout it (consider service pages written in PHP from an Apache server which proxies to a Tomcat webserver for pluggable content which calls out to a tiny scheme chat service which stores data in Postgres...).
The situation with most web stacks is, in my opinion, laughable. That is at the core of the Node.js idea, actually: pick a language most people know and stick with it throughout. The problem there is that not every language is well suited to every task (or any task...). But the basic idea that cutting the web tech clutter down is quite sound.
That said, I sincerely think the easiest place to get started is with a relatively tiny language with a small, hyper-knowledgable community around it, and focus on doing everything you can in that language. For this particular task (live web comms) I prefer Erlang and Yaws, writing the service from scratch until some element of it obviously is in need of some pre-written framework treatment. (That is not the right choice of tools for everything, though, so keep an open mind and learn to hate every language, at least a little -- they all suck, just some less than others.)
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i am a senior developer and I'm trying to advance my knowledge of security to a deeper level. That is to say that i know what these hackers can do/what the risks are, but I'd like to know how they do it in general. On that note, if anyone can enlighten me on the following items, i would be most grateful:
Packet sniffing: I know that packets can be sniffed out and analyzed, but how do they do it? my understanding was that in order to do this, there would need to be actual software running on the server itself since it needs access to the network card to do so... is that accurate? If not, how can they remotely capture incoming packets to a server without access to that box directly?
Session Hijacking: Once again, i am confused here. I know they can do it, but how? The session ID is issues by the server itself, and then returned to the browser based on what? the caller's ip address? mac address? what is used by these hackers to capture the session id from a web session? is it software on a pc that is infected?
Site Hijacking: again, i know they can do this, but from my current knowledge, this would mean that they would have to have hijacked/infected a DNS publishing server and redirecting queries for that site to their choice of IP address... again: is that accurate?
Hijacking a server: how is this possible? how can an open port, for example, allow any hacker to gain full fledged access yo a box so that they can infect it or install some piece of software that would enable 1, 2 and 3 above? My current understanding is that ports are used to communicate, but that unless some software/service is monitoring that port and waiting for commands, nothing would come of that port being open... is that accurate? and if so, why is so much importance given to ports being closed and such?
Hijacking some super secure site: i work every day with security in mind, and constantly use things like: SSL, RSA, SHA512, SSL TOKENS, IP restriction, etc... my question is: how in the crapper are they STILL able to get in with all of these things enabled?
i know that's a lot of stuff, but i really am curious and want to take my security knowledge to the next level. If you're a developer with the same mindset as me, you have issues just using some pre-built library or control without knowing what it does in the background in details, and you'll understand why I'm not happy just knowing which protocols, libraries or encryption methods to implement.
Know the enemy, right?
First of all, I love hacking (only for good), and I think the more people are educated about it the safer we all will be, so I applaud you for your curiosity.
These are great questions, but a good answer would literally require an entire book or two. I have read all of these books in my studies and I personally recommend them. I recommend the following to get you started:
This will get you started with basic tools and techniques. This book doesn't go very deep so if you're looking for the meat, skip it and read the other three unless you are very new to security: The Basics of Hacking and Penetration Testing: Ethical Hacking and Penetration Testing Made Easy, Patrick Engebretson (Full disclosure, the author was a professor of mine at DSU. The book rocks though)
For a relatively deep introduction to security, including an excellent background in OSes and networking:Counter Hack Reloaded: A Step-by-Step Guide to Computer Attacks and Effective Defenses (2nd Edition), Edward Skoudis (probably my favorite book of all time)
To dive very deep (Assembly language level) into how the attacks work:Hacking, The Art of Exploitation, Jon Erickson
To dive deeply into the Web app side of things:The Web Application Hacker's Handbook: Finding and Exploiting Security Flaws, Dafydd Stuttard, Marcus Pinto (Full disclosure, the technical editor was a professor of mine at DSU)
I am faced with the following problem. I get calls from my customers thou a voip line. And then i need to ask them who they are and look them up. All of this takes the most time in the phone call so i want to speed that up abit.
Basicly i want something that catches the caller id and sends it to a (web) server. Idealy i would put that at the phone server but that part is outsourced. So my question comes down to: Is there an easy way to do this? I can write my own software but i would like something of a voip client that does this for me since i would like the quick solution.
I searched the internet for a view hours but i am not that familiure with voip technologie so any help would be useful.
I don't know of any softphones could do it although I do have a hazy memory of another stackoverflow question where someone asked about sending a HTTP request triggered by an incoming SIP call. Unfortunately I can't find the question sorry.
Apart from softphones I do know of at least three ways you could do it on a server and there are probably more.
First there's my own software (doable with a free accounts and open source), sipsorcery.com, where you could receive the SIP call from your provider and in your Ruby dialplan send an HTTP request to your web server to get whatever info you wanted.
Secondly there's tropo.com who also have highly extensible dialplan type functionality and in lots of different languages. Their dialplans support sending HTTP requests.
Finally there's anveo.com who have HTTP tools available in their graphical call flow builder.
Open source softphones should be extendable, I know twinkle can be configured with scripts, should be well suited for your personal needs.
If this is something you want to centralize, create a SIP proxy to intercept all calls and do what it needs to. Sailfin is a robust development environment for something like this if you like Java.
Let me introduce myself a bit.
I have 7 years of C++ (most MFC) experience, 1 year C#.NET and 2 years Java experience.
I know little about web application, what I did and am doing is Windows desktop applications.
I start to do some (minor) (freelance) side projects in the past half year and uses C# mostly as it's more "rapid" than MFC. But seems there's more web projects in this market than desktop projects. And I do not feel good as long as I do not know web development.
So, should I touch the new web filed for me or just stay focus in desktop application but learn more e.g Python, or Frameworks/Libraries such as Qt or Boost?
My gut feeling is that more and more people/companies are moving their projects to the web. My company, for example, has added numerous web applications since I have been there. Another prime example of this is Microsoft (yes, even them) providing a web-based version of Office, their flagship product.
There will always be a need for desktop applications, but I see more web-based projects in the future. It's always good to learn something new, anyway.
EDIT: Oh, and you don't lose anything by being aware of "desktop-based" processes. You may be doing more server-side programming, even if it is web-based. So, in other words, it doesn't hurt to continue expanding your knowledge in that arena, as well.
There will most likely still be a market for desktop applications for many years to come. However, web development seems to have taken over a large share of the development market from what I can see. I would recommend definitely getting familiar with web development as it definitely can't hurt to increase the number of skills you have even if you never stop writing desktop apps.
Since you have experience with C# you might want to consider doing some ASP.NET work. Or if you feel the need to learn a new technology then maybe consider a framework like Ruby on Rails.
I'd really suggest looking into web development - like you said, there are many more web application projects - and you already know C#.NET and Java, and both of those languages have really good API's / frameworks for web development. ASP.NET for C# and Java Servlets/JSPs.
I'd first suggest learning some really basic HTML to learn how pages are rendered, then try to make dynamic versions using the language of your choice. Then I'd learn some other web technologies like CSS/Javascript/some Javascript libraries - then I'd start looking at frameworks that build on top of the basics in the language of your choice.
Oh, and some further suggestions - there are web frameworks that are component-based rather than request-based - you may be tempted to learn these as a shortcut to web development since most claim that developing in them is similar to desktop development. I really wouldn't suggest this - as in practice you really do need to know how the web works at a lower level to develop custom components, include things that the framework doesn't do, or to debug them when things go wrong even when using these frameworks. If you jump right in you can get lost/confused pretty quickly.
Microsoft Office 2010 will have an online version. To me this is a watershed moment for Web applications. Office apps are an important litmus test as once you can do Office on the Web (which has been the case with Google Documents for some time but Office has important symbolic meaning) you can do most things that most users care about.
Desktop apps won't die but I definitely think they're going to take more and more of a backseat.
I'd highly suggest you read How Microsoft Lost the API War if you haven't already. One of the things that's particularly amazing about this post is that it was written in 2004.
I honestly believe that with maybe the exception of OSs and browsers, everything will be a web app within the next 10 years. Having said that, let me clarify that by everything I mean everything that a) involves a UI of some kind and b) can be guaranteed secure.
User-interfaced apps will always at some point need a backend, which will at some level require code that is not being interfaced by humans and not being executed via HTTP. I am always reminding myself that things like 'cat' in Unix are actually programs that the OS is calling, not just a function built into the OS. MySQL won't be a web app (as far as I know), but app that powers web apps. We may get to a point where these apps are fully developed via a web interface, written, audited, uploaded and called all via a browser, but at some level its still running behind the scenes.
On that second point, about guaranteed security, I can very easily imagine a large corporation or government office running 95 percent of their daily routines via web apps, but mandating that certain high-security operations be done on a machine directly interfaced with some sort of mainframe, after passing through the cool doors with the retinal scans and what not. Or simply because they can't risk moving certain mission-critical apps over to the web, from fear of it breaking our losing data in the process.
But with those two things aside, I honestly believe everything will be web-based. With the advancement of Web Services and XML in general, it will be possible to not only access and interact with our data, but to plug our custom apps into another app and extend that interaction further and in any environment we want.
It's like that Apple ad "There's an app for that." Except once people get the real picture, it won't be an app written for your iPhone, but a URL. "There's a site for that."
I recommend learning the Lift framework. It's as easy to use as Rails, and it's based on a statically-typed language for the JVM, Scala. From the perspective of your background, Scala should be middling to easy to learn, and you'll be more likely to be comfortable with it than with a dynamic language.
In my opinion, you have a good chance of picking it up quickly, learn a lot about good practices in web development, and even expanding your programming horizons a bit.