This could be either an incredibly easy or horrifically complicated question; but I've started writing code in Scala, and want to run said code on a web server.
There's a few questions that I need answering really, and I apologise for my complete lack of knowledge on the subject, web servers scare me (I'm a PHP developer so all I need to do there is upload to any linux apache server):
How to save and upload files (I know how to use ftp software, do I need to do anything from Eclipse?)
What to do to my server to run the files (at the moment I just have a linux apache server from fasthosts, is that enough?)
Any other advice would be so greatly appreciated; and the less jargon the better - the whole thing blags me a little.
UPDATE: To put the sort of work I'm doing into context, I'm making a rather large, social-media style site that'll have a very large amount of small, regular posts/updates. Also thanks for the answers so far!
Seems like i need to do all of the following:
Learn Scala (I can write in PHP and Java so should be okay)
Install Apache tomcat on my server somehow
Install Lift (and then either Maven or the SBT)
Upload the whole thing?
What do I do about databases?! I need something really serious, with MySQL be okay? Urgh this goes on and on...
Here are the most important points. I'm afraid you will not get this done without lots of reading, but at least you'll know where to start.
You need your own servlet container, e.g. Jetty or Tomcat. Those can be used as stand alone servers or together with apache.
You need to package your web application as a .war file. That is basically a zip file with all the classes and some meta information. Then you upload the .war file to the server.
You should have a look at a web framework for scala, such as Lift.
It also helps to be on good terms with one of the major build tools, sbt or maven.
You are better off using a framework - like Lift as the other answer suggest or...
Play framework has scala support as well - http://scala.playframework.org/
You can look at Play framework "Preparing for Production" page - http://www.playframework.org/documentation/1.0.2.1/guide11
It is not going to be like with PHP where you can just ftp and host.
Lift is a whole web development framework around Scala - might want to try their Getting Started page, or just poke around their docs in general.
But in general, you'll be using any of the java-based web application serving solutions, e.g. Jetty, Tomcat.
You have not said what exactly you want to do with Scala on the web. In addition to the Lift and Play frameworks there are some interesting alternatives like Unfiltered:
http://unfiltered.databinder.net/Unfiltered.html
https://github.com/n8han/Unfiltered
It is also easy to start without any kind of framework by directly writing Servlets:
Here is a interesting example that uses Jetty, websocktes and the Scala interpreter to create a web based Scala REPL:
https://github.com/TiarkRompf/replhtml
Also the excellent Akka framework has a http module:
http://akka.io/docs/akka/1.1.2/scala/http.html
Scalate
- http://scalate.fusesource.org/
To start with Scala without too much to read, you may give G-WAN v3.9 (that's the September beta, the release is expected in October) a try.
G-WAN runs Scala source code files without configuration (you just copy a file and call it) and it lets you run other languages the same way.
Related
I'm a student. For my Distributed Systems project, I'm expected to create a gRPC project. I'm creating the project in Eclipse.
Two service implementation are to be coded in Java and the other is to be done in another coding language.
I've tried searching for help online but the results I'm getting are related to gRPC and how gRPC works, not about the coding or using other coding.
Ideally, I would like to use Python as the other language and to create it in Eclipse if possible. Does anyone have any information, documentation or examples I could look at, so I could can reference it?
I am able to see online searches for both Java and Python, but I'm not sure how to use both in one project.
Thank you.
So I got a lot of feedback for lecturers and classmates.
The server doesn't care what programming language is used.
So Java, Python, Node.js etc, could all be sent to the server.
A generalised simplistic idea of how I was able to understand is: Python converts its code to binary and sends it to the server. Same with Java and Node.js.
I don't know why, but I was digging myself deeper trying to figure out what code (i.e. the binary) that needed to be the communication between the server and code. I was trying to encapsulate Python into Java and vice versa.
Why did I think this? Your guess is as good as mine.
I have been trying to decide if my web project is a candidate for implementation using PSGI, but I don't really see what good it would do for my application at this stage.
I don't really understand all the fuss. To me PSGI seems like a framework that provides a common interface between different Apache modules which lets you move your application between them. e.g Easily move your application from running on mod_perl to fastcgi, and provide the application support for running on both options.
Is that right, or have I missed something?
As I and the team I am a part of not only develop the application, but also pretty much do maintenance and setup of servers I don't see the value for us of being able to run on fastcgi, cgi, and mod_perl, we do just fine with just mod_perl.
Have I misunderstood the PSGI functionality, or is it just not suitable for my project?
Forget the Apache bit. It's a way of writing your application so that the choice of webserver becomes less relevant. At $work we switched to Plack/PSGI after finding our app running with very high CPU load after upgrading to Apache2 - benchmarking various Apache configs and NYTProf'ing were unable to determine the reason, and using PSGI and the Starman webserver worked out much better for us.
Now everything is handled in one place by our PSGI app (URL re-writes, static content, expiry headers, etc) rather than Apache configuration, so it's a) Perl, and b) easily tested via our standard /t/ scripts. Also our tests are now testing exactly what a user sees, rather than just the basic app itself.
It may well not be relevant to you if you're happy with Apache and mod_perl, and I'm sure others will be able to give much better answers, but for us not having to deal with anything Apache-related again is such a relief in itself. The ease of testing, and the ability to just stick in a Data::Dumper and see what's going on rather than wrestling with ModRewrite and friends, is a great boon.
Borrowing from a recent blog post by chromatic, Why PSGI/Plack Matters (Testing), here's what it is:
It's a good idea borrowed from Python's WSGI and Ruby's Rack but made Perlish; it's a simple formalizing of a pattern of web application development, where the entry point into the application is a function reference and the exit point is a tuple of header information and a response body.
That's it. That's as simple as it can be, and that simplicity deceives a lot of people who want to learn it.
An important benefit is, ibid.,
Given a Plack application, you don't have to deploy to a web server—even locally—to test your application as if it were deployed … Plack and TWMP (and Plack::Test) use the well-defined Plack pattern to make something which was previously difficult into something amazingly easy. They're not the first and they won't be the last, but they do demonstrate the value of Plack.
Started wrote an answer and after 50 lines I deleted it. Simply because it is impossible tell (in short) why is PSGI extremely cool. I'm new in PSGI too, but zilion things now are much easier as before in my apache/mod_perl era.
I can give you next advices:
read the Plack advent calendar - all days, step-by-step. You must understand the basic philosophy, what is good on onions and so on... :)
search CPAN for "Plack::Middleware::" - and read the first few lines in each. Here are MANY. (Really should be somewhere some short overview for each one, unfortunately don't know any faster way. Simply it is good to know, what middlewares are already developed. (For example, you sure will need the Plack::Middleware::Session, or Plack::Middleware::Static and so on...)
read about Plack::Builder (already done, when you done with the advent calendar) :)
try write some apps with it and will find than Plack is like the first sex - now you didn't understand that you could live without it.
ps:
If was here something like "Perl Oscar", will sure nominating MyiagavaSan. :)
I am about to start on a college project (a web application) and I have never used a full-fledged IDE such as Eclipse.
Turbo C/C++, Visual Basic 6,Java Basic, a bit of SQL, ASP, etc is the sort of exposure I have.
What things should I keep in mind before starting my project using Eclipse? Are the tools mentioned appropriate for the project?(If not please give a detailed answer)
Designing - UML (Rational Rose)
Language - Google Web Toolkit
Server - Google App Engine
IDE - Eclipse
Version Control - Subversion or Mercurial?
I would definitely recommend Googling first. There are a number of tutorials regarding Eclipse as it is a very popular IDE. A quick Google search of my own brought up all these results: developing web applications in eclipse
As for other things to consider, if you are developing a web application, you'll need:
web server (Tomcat is a popular one)
possibly a database (MySQL is an open source, easy to use DB)
language (I'm assuming you're going with Java since you are using Eclipse)
Of course, you'll also need to consider how you hook everything together and what technologies you want to use to do that. (Hibernate, Spring, etc) Eclipse itself has a ton of plugins to help bring together all these various aspects.
That list from Wikipedia is a good and comprehensive list, but if you are learning or developing on your own machine, you may not necessarily need all of that.
Hope that helps.
Since it is a web application, then start with the looks of it.
First, layout a template of how your pages should look, that is what users see. If it does not look good, the users will think the application (in its entirety) is also not good (it does not matter if the code behind the view is perfect; it will just make a first bad impression).
Start with that and be consistent with the design in all your pages. SiteMesh is a nice tool to dissociate the looks of the page from the functionality you put in it.
Then think what the application will do and what it will use:
you have a database? (use something like MySQL). With what are you going to access it? (IBatis is nice; Hibernate I think is a bit heavy weight for a first project)
you need a server: Tomcat is easy to use;
are you going for a simple Servlet/JSP approach or you want to use a framework (look at Spring or Struts);
try to find the good ways of writing the application, look at service layers, DAO pattern, DTO, MVC. Also, you must understand how HTTP works.
A lot more could be said.
Ah.. and also use a source repository. It’s a must (even if you work alone on this project).
Eclipse can handle all of these tools, but then so can Netbeans.
For your first project with GWT you should read through this tutorial:
http://code.google.com/webtoolkit/tutorials/1.6/gettingstarted.html
If you don't know Java then you will have some learning to do, and unlike Visual Studio your UI won't be just drag and drop, so it will be a bit harder than you are used to.
Subversion is fine, it is a nice source control, and any IDE will work with it.
Depending on your project would determine if GWT is the best choice though.
I expect UML may be overkill, and if you were following an agile methodology you wouldn't use it.
Your best bet is to get the UI done first, just have it appear as you want, and have some fake results, until you are happy with the look and feel.
Then, start to do the wiring to whatever you need on the backend.
Don't mean to be harping on you, but is Eclipse a must? For myself, in the beginning NetBeans turned out to be a really painless introduction to getting a web project up a running fast. I believe in the beginning one will spend a lot less time fighting the IDE with NetBeans.
A lot of the items from your bullet list NB makes super easy to ramp up as well. Just my $0.2
I'm writing an application to do proxying and rewriting of webpages on the fly and am pretty settled on using mod_perl2 - there is an existing implementation using mod_perl (v1) that I'm working from. In mod_perl2, there's this idea of APR::Brigades and APR::Buckets which, from my vague understanding, are an efficient way to do the sort of filtering & rewriting that I want. I can't, however, find anything but the Perldoc pages for these modules, so I'm really quite unsure how to utilize them.
Can anyone explain mod_perl2 Bucket Brigades to me, point me to a tutorial, or even show me some open-source app that uses mod_perl2 that I could learn from?
Buckets and Brigades are native concept to the Apache Portable Runtime. You'll find ample examples of the native API, with a HTTP-specific slant, in the source code for Apache HTTP Server modules like mod_proxy, mod_deflate, and mod_substitute.
See the filter info here:
http://www.apachetutor.org/dev/#filter
Then take a peek at the previously mentioned Apache HTTP Server modules.
There seems to be a simple perl-specific filter here:
http://perl.apache.org/docs/2.0/user/handlers/filters.html#Bucket_Brigade_based_Output_Filters
Every time I see Ruby or Python discussed in the context of web development, it's always with a framework (Rails for Ruby, Django for Python). Are these frameworks necessary? If not, is there a reason why these languages are often used within a framework, while Perl and PHP are not?
I can only speak towards Ruby - but, no, you don't need a framework to run Ruby based pages on the web. You do need a ruby enabled server, such as Apache running eruby/erb. But, once you do, you can create .rhtml files just like RoR, where it processes the inline ruby code.
The short answer is no, they are not necessary. In ruby you have .erb templates that can be used in a similar way as you use PHP pages. You can write a site in ruby or Python using several technologies (Rails-like frameworks, Templates or even talking directly with the HTTP library and building the page CGI-style).
Web frameworks like Python's Django or Ruby's Rails (there are many) just raise the level of abstraction from the PHP's or ASP's, and automate several process (like login, database interaction, REST API's) which is always a good thing.
"Need" is a strong word. You can certainly write Python without one, but I wouldn't want to.
Python wasn't designed (like PHP was, for example) as a direct web scripting language, so common web-ish things like connecting to databases isn't native, and frameworks are handy.
EDIT: mod_python exists for Apache, so if you're merely looking to write some scripts, then Python doesn't need a framework. If you want to build an entire site, I'd recommend using one.
From a Pythonic point of view, you'd absolutely want to use one of the frameworks. Yes, it might be possible to write a web app without them, but it's not going to be pretty. Here's a few things you'll (probably) end up writing from scratch:
Templating: unless you're writing a really really quick hack, you don't want to be generating all of your HTML within your Python code -- this is a really poor design that becomes a maintainability nightmare.
URL Processing: splitting a URL and identifying which code to run isn't a trivial task. Django (for example) provides a fantastic mechanism to map from a set of regular expressions to a set of view functions.
Authentication: rolling your own login/logout/session management code is a pain, especially when there's already pre-written (and tested) code available
Error handling: frameworks already have a good mechanism in place to a) help you debug your app, and b) help redirect to proper 404 and 500 pages.
To add to this, all of the framework libraries are all heavily tested (and fire tested). Additionally, there are communities of people who are developing using the same code base, so if you have any questions, you can probably find help.
In summary, you don't have to, but unless your project is "a new web framework", you're probably better off using one of the existing ones instead.
Framework? Heck, you don't even need a web server if you're using Python, you can make one in around three lines of code.
As to the why:
The most plausible thing I can think of is that Perl and PHP were developed before the notion of using frameworks for web apps became popular. Hence, the "old" way of doing things has stuck around in those cultures. Ruby and Python became popular after frameworks became popular, hence they developed together. If your language has a good framework (or more than one) that's well supported by the community, there's not much reason to try to write a Web App without one.
A framework isn't necessary per se, but it can certainly speed development and help you write "better" code. In PHP, there are definitely frameworks that get used like CakePHP, and in Perl there are many as well like Mason and Catalyst.
The frameworks aren't necessary. However, a lot of developers think frameworks ease development by automating a lot of things. For example, Django will create a production-ready backend for you based on your database structure. It also has lets you incorporate various plugins if you choose. I don't know too much about Rails or Perl frameworks, but PHP frameworks such as Zend, Symfony, Code Igniter, CakePHP, etc are used widely.
Where I work at we rolled our own PHP framework.
Are these frameworks necessary?
No. They, like any 'framework', are simply for speeding up development time and making the programmer's job easier.
If not, is there a reason why these languages are often used within a framework, while Perl and PHP are not?
PHP and Perl were popular languages for building web sites well before the idea of using frameworks was. Frameworks like Rails are what gave Ruby it's following. I'm not sure that Python or Ruby were that common as web languages before they were backed by frameworks.
These days, even PHP/Perl web developement should be backed by a framework (of which there are now many).
By no means are those development frameworks required. But as with most development environments, your productivity will increase exponentially if you have a supported framework to reference and build your applications on. It also decreases the training needed to bring others up to speed on your applications if they already have a core understanding of the framework that you use.
For python, the answer is No you don't have to. You can write python directly behind your web server very easily, take a look at mod_python for how to do it.
A lot of people like frameworks because they supply a lot of the boilerplate code in a reliable form so you don't have to write it yourself. But, like any code project, you should choose the tools and frameworks on their merit for your problem.
You can certainly write CGI scripts in either language and do things "raw".
The frameworks (ideally) save the trouble of writing a pile of code for things that other people have already handled (session handling, etc.).
The decision probably comes down to what you need to do. If the framework has the features you need, why not use it. If the framework is going to require extensive modifications, it might be easier to roll your own stuff. Or check out a different framework.
The python library has numerous modules for doing cgi, parsing html, cookies, WSGI, etc:
http://docs.python.org/library/index.html
PHP has a lot of frameworks. Probably more then most. In Ruby most use Rails so thats what you hear, and Django for Python is mentioned more then not.
But with PHP you have many to choose from.
List of web application frameworks
Any language that can "print" can be used to generate web pages, but frameworks handle a lot of the HTML generation for you. They let you concentrate more on the content and less on the details of coding the raw HTML.