I have a project in which I need to write an LSP server in OCaml for a developing language.
So I did a lot of research on this but I'm having a bit of a hard time getting through it.
The Microsoft tutorial https://microsoft.github.io/language-server-protocol/specification speaks sometimes on the server side, sometimes on the client side, sometimes JSON RPC through which requests and notifications must pass between the client and the server, and all of that mixed up, plus TypeScript and not OCaml, what I want to use as a language confuses me a bit, I feel like I don't understand anything.
So I turned to code. I saw a lot of code like the one from https://github.com/facebook/flow/tree/master/src/lsp, the one from https://github.com/ocaml/ocaml-lsp but I don't understand really the code, there are a lot of files with a lot of lines, I don't know what does what.
Can you show me an example of how to initiate connection with the first initiate request, send notification in OCaml. I will use Emacs as client but I know how to do that when the server is ready. I think a little example will help me do the rest.
Related
It's something totally new for me, and since it seems to be something trivial, I can't find any response with our beloved friend ggle...
My question is : I have to create a webapp that can work if the client have nothing on his computer but a browser. My question is : is it possible to include to my project an external library (here I want to use PCL (Point Cloud library), a C++ library), and make it works even if the client have nothing installed? If I use QtWebKit for example, will I be able to create this kind of webapp?
Thanks a lot, and sorry for the (maybe) stupid question, I never did web dev before, it's my first time. ...
Have a nice day!
Wow, that question is as broad as the day is long, but here goes (you don't give too much about your background so I apologise if I am going too basic).
A web browser is just a piece of software that knows how to process HTML, CSS and Javascript passed over HTTP from a TCP socket.
So, on a most basic level, to get something to work in a browser all you need is to write a program that listens on a TCP socket and passes headers and HTML in the body of the response as per the HTTP protocol.
So, leaving aside the socket part, your method may look something like this:
std::cout << "<h1>Hello, world!</h1>" << std::endl;
In fact, the vast majority of the original dynamic web sites worked just like this: they were just C programs that just happened to produce HTML as output in the old days (cgi-bin).
The main issue with this approach is it's very tedious and time consuming to write code to that level of detail to generate HTML, especially when you factor in CSS and JavaScript.
This is one of the key reasons that most web applications these days are implemented in Java, .Net, Ruby, PHP etc as there is a wealth of fully-featured, stable and mature frameworks for web development that take the grunt work out of creating dynamic web sites (and C/C++ is much rarer).
However there are a couple of good frameworks out there for C++ if that is definitely the language you want to use.
Wikipedia has a limited section on C++ frameworks but it covers the 2 I would suggest investigating (CppCMS and Wt):
https://en.wikipedia.org/wiki/Comparison_of_web_frameworks#C.2B.2B
Of these, I've only had direct experience of CppCMS but I can recommend it - it's approach is idiomatic C++ (to my eyes at least, but I must confess I am more often a Java web developer than C++)
Also, there is quite a useful if slightly dogmatic SO discussion on this thread that may be relevant:
How popular is C++ for making websites/web applications?
First of all, a big thank you to anyone willing to help!
You can skip the following wall of text if you want.
Background
I am trying to make a proxy program for my own minecraft server network. I wish to use multiple servers to allow people to play creative and survival on separate servers (to reduce serverload and increase my capacity). I am planning on using the transporter plugin for the server side of things, but I'd like to prevent having to install a clientpatch.
I discovered bungeecord, but it didn't do what I needed it to (namely, forge support for a modded server I plan on adding.) for mc 1.4.7 (which I need to use due to the server I plan on adding).
At the moment the system is running using a bungeecord proxy. However, md_5 told me that I'd need to write my own proxy (or mod his) to make it work the way I want. However, I really can't wrap my head around java (I just don't get it). So I decided to write my own.
The problem
After some research I discovered this to be doable. The hardest part would be to parse the packets. So I dug around for a library to do it for me. I came across libmcnet, which seemed to be what I wanted, but all the data it produced was garbled.
Looking over some packet dumps, and referencing it with wiki.vg, I discovered that libmcnet was giving me big-endian. However, my code and computers assume little-endian.
What I have done about it
After some thinking and looking over the code I thought it easier to write my own parser using some defines from libmcnet (namely include/mcnet/packets.h). So I copied the packets.h and read.h/read.c (both of which were heavily modified) and started recoding it. I did well enough, I think, as my system can successfully parse the server's 0xff (kick) packet during the server ping.
New problems
The next hurdle proved to be decrypting the client's data. It doesn't seem to use the same data standards as the server. For instance, the packet id the server transmits is 16 bit while the client's seems to be 8 bit.
So what I want to know:
Why does my code work fine on data from the server, but fail miserably when the client sends data? I'm pretty sure that libmcnet's code (on which I based it) is wrong as well.
Can anybody help me make this code work?
Code: http://pastebin.com/jg26yity (I figured this'd be cleaner)
Thank you all for your help!
*I'll add information if anybody requests more...
PS. First question asked here, so my post is a bit messy...
I figured it out, apparently I can't assume a library written to parse the minecraft protocol actually has proper code to read the protocol...
I was digging around and verifying what was read versus manually reading it... Appearantly a byte isn't a byte with minecraft and I thought the library had it covered.
I can't decide which way I should take so instead of trying all options I would like to get expert's or more knowlageable people's ideas since I'm a C++ newbie. (After frustration with php for years I understood C,C++ is the way to go )
Extra info: I'm only linux user for a year :)
--Here is what I want to do: Webapp that people can register and chat and be friends. Like facebookchat but no less ability than it (should be realtime all the way) (For instance: If a friend closes the browser it should be seem unavailable).
--Options I have I guess: Using boost:asio, using BSD directly, using opensource server like nginx,lighttpd with fcgi (I din't like libev, libevent.)
--Here is main questions:
1) Is Nginx+fcgi+CPP spawning a new Cpp programme for each request (Performance would be bad)
2) Would using a ready server+FCGI make it impossible or harder the chat thing i stated above.
3) Would you choose BSD, asio or tweaking a ready server for such thing?(with a short why)
(Scability for development is main concern. I mean if it requires new implementations it should be done in future)(blaa blaa must be done)
What would you do?
I think I'd step back a bit, and consider a few questions. First and foremost, it's not apparent from your question whether you're basically trying to set up a web site (or something on that order) that provides this service, or you want to write software that (or example) others could incorporate into their web sites.
Second, it's not entirely clear whether you're interested primarily in the client side, the server side, or both. Most of what you talk about is on the server side, but the features you talk about providing are mostly on the client side.
Third, is the question of whether you're willing to write a closed system that requires your client to work with your server, or you want to use something like XMPP to provide compatibility with existing software.
To summarize: you seem to be jumping directly into nitty-gritty details of how to do things; before you can figure out how very well, you first have to decide exactly what you're going to do. Until those are answered, many of the "how" questions can't be -- and after they're answered, many of the "how" questions may easily disappear.
I would start playing with Wt (http://www.webtoolkit.eu/wt) which is a framework for Web applications, or Qt (http://qt.nokia.com/products/) which offer good http and https support
I have an Android application in the market which connects and send POST and GET queries to a REST API, and then stores the results in a DB which are then queries and displayed in an appropriate manner in the application.
I'm interested in speeding up the application and have noticed quite a lot of lag between the time of receiving the data back from the api and the data being ready to use. I'd like to investigate if and how I can write similar code in c++ using the NDK to connect to the REST API, process the results and store in a DB or raise an error. I've no previous c++ experience and need to know firstly if I can access the same DB in the C++ as the Java, secondly if there are any other caveats which I should be aware of?
Also I guess I should ask - is it worth doing this? Will I notice any difference?
Any links to similar code, or an overview of where I should look to get started in c++ would be greatly appreciated.
I'm doing the EXACT same thing, and trust me: if you have no previous C++ experience, this might be a bit too costly for little benefit.
In my case, after some profiling, I reordered things around and had an initial jump in performance only by dropping DOM and using SAX. All the rest is only making things marginally better, like processing the response while packets are still being transmitted (i.e. not wait for the full response to start processing), and multiplexing requests on the same thread instead of starting a new thread for each.
What you should be looking for in Google is POSIX sockets, HTTP and REST codes, if you wish to do it all by hand. A better option might be using CURL or something similar for the Socket/HTTP part. I did it all myself, but only because I have already done this a few times.
Is there a relatively easy way to display the output of a C++ program on a webpage? And I don't mean manually, in other words, you see it on a webpage as it runs not as in I make a code tag and write it in myself.
EDIT: Just so everybody can get this clear I am going to post this up here. I am NOT trying to make a webpage in C++. Please excuse me if this sounds spiteful or anything but I am getting a lot of answers relating to that.
Step one, get yourself a server-side language. Be that PHP, ASP, Python, Ruby, whatever. Get it set up so you can serve it.
Step two, find your language's exec equivalent. Practically all of them have them. It'll let you run a command as if it were from the command line, usually with arguments and capture the output. Here's PHP's:
http://php.net/manual/en/function.exec.php
Of course, if you're passing user-input as arguments, sanitise!
I've just seen that you accepted Scott's answer. I usually wouldn't chase up a SO thread so persistently but I fear you're about to make a mistake that you'll come to regret down the line. Giving direct access to your program and its own built-in server is a terrible idea for two reasons:
You waste a day implementing this built-in server and then getting it to persist and testing it
More importantly, you've just opened up another attack vector into your server. When it comes to security, keep it simple.
You're far better having your C++ app running behind another (mature) server side language as all the work is done for you and it can filter the input to keep things safe.
You could write a CGI app in C++, or you could use an existing web server language to execute the command and send the output to the client.
You want to use Witty.
Wt (pronounced 'witty') is a C++
library for developing interactive web
applications.
The API is widget-centric and similar
to desktop GUI APIs. To the developer,
it offers complete abstraction of any
web-specific implementation details,
including event handling, graphics
support, graceful degradation (or
progressive enhancement), and pretty
URLs.
Unlike many page-based frameworks, Wt
was designed for creating stateful
applications that are at the same time
highly interactive (leveraging
techinques such as AJAX to their
fullest) and accessible (supporting
plain HTML browsers), using automatic
graceful degradation or progressive
enhancement.
The library comes with an application
server that acts as a stand-alone web
server or integrates through FastCGI
with other web servers.
I am not sure this is what you are looking for but you may want CGI You may want to look at this SO question, C++ may not be the best language for what you want to do.
based off the questions you posted Writing a web app like what you want is no simple task. What I would recommend is use some other library (this is one i found with a quick google) to get a web console on your server and give the user it is running under execute deny permissions on every folder except the folder you have your app installed.
This is still is a risky method if you don't set up the security correctly but it is the easiest solution without digging around too much on existing libraries to just have the application interactive.
EDIT --
The "Best" solution is learn AJAX and have your program post its own pages with it but like I said, it will not be easy.
It sounds like you want something like a telnet session embedded in a webpage. A quick google turns up many Java telnet apps, though I'm not qualified to evaluate which would be most ideal to embed in html.
You would set up the login script on the host machine to run your c++ app and the user would interact with it through the shell window. Note though that this will only work for pure command line apps. If you want to use a GUI app in this way, then you should look into remote desktop software or VNC.
It may be worth looking into Adobe's "Alchemy" project on Adobe Labs
This may help you with what you're trying to achieve.
:)
Are you looking for something like what codepad.org does? I believe they explain how they did it here.
There is a library called C++ Server Pages - Poco. I used it for one of my college project, its pretty good. There is also good documentation to get started with, u can find it here http://pocoproject.org/docs/