A few years ago I did a lot of work with CGI.pm. I'm evaluating using it again for a quick project. Can someone bring me up to speed on the current state of developing with CGI.pm in the "Web 2.0" world? What are the best libraries on CPAN to use with it? Are there clean ways to include jQuery, YUI, other CSS libs, etc, and do some AJAX. There are of course lots of libraries on CPAN but what works and what is commonly used?
We aren't still doing this?
$JSCRIPT<<EOF;
...
EOF
I realize people are going to offer Catalyst as an answer. However, many people may have legacy CGI.pm apps they simply want to enhance. Is starting over really the best answer?
Personally, I'm no fan of Catalyst (too heavy for my taste) or Mason (mixing code and HTML is bad ju-ju), but I do quite well using CGI.pm for input[1], HTML::Template for output, and CGI::Ajax to provide AJAX functionality where called for.
If you're looking at frameworks, you may also want to consider CGI::Application, which is a widely-used and lighter-weight alternative to Catalyst/Mason.
[1] I can't recall the last time I called anything other than $q->param or $q->cookie from CGI.pm. There are still a lot of tutorials out there saying to use its HTML-generation functions, but that's still mixing code and HTML in a way that's just as bad as using here docs, if not worse.
Consider using something more modern, for example Catalyst. It will make your life much easier and you won't have to reinvent the wheel. I understand that it is just a small project, but from my experience many small projects in time become large ones :)
The "web 2.0" apps that I've worked with usually use client-side JavaScript to request JSON data from the server, then use that data to update the page in-place via DOM.
The JSON module is useful for returning structured data to a browser.
As far as including JavaScript, HTML, or whatever in a here doc - that was never a good idea, and still isn't. Instead, use one of the plethora of template modules to be found on CPAN. For a CGI, I'd avoid "heavy" modules like Mason or Template Toolkit, and use a lighter module for quicker startup, such as Text::Template, or Template::Simple.
Yes, you can write perfect web2.0 web applications WITHOUT using any framework on the server side in any language Perl, Python, Java, etc and WITHOUT using any JavaScript libraries/framework on the client side. The definition of web 2.0 is kind of a loose definition, and I'm guessing by web2.0, you mean Ajax or partial page refresh, then all you would really need is to focus on the following:
Know about the XmlHttpRequest object.
Know how to return JSON object from the server to the client.
Know how to safely evaluate/parse the JSON object using JavaScript and know to manipulate the DOM. Also, at least know about innerHTML. InnerHTML is helpful occasioanally.
Know CSS.
Having said that, it's a lot easier to use some framework on the server side, but not because it's required by web2.0 and it's a lot easier to use some JavaScript on the client like jQuery, mootools, YUI. And you can mix-and-match depends on your needs and your tastes. Most JavaScript provides wrapper around the XmlHttpRequest so that it works across all browsers. No one write "naked" XmlHttpRequest anymore, unless you want to show some samples.
It's perfectly possible to write "Web 2.0" apps using CGI.pm, but you'll have to do the work yourself. From what I've seen, the focus in the Perl development community has been on developing successor frameworks to CGI, not on writing helper modules to let legacy apps get bootstrapped into modern paradigms. So you're somewhat on your own.
As to whether to start over, what are you really trying to accomplish? Everyone's definition of "Web 2.0" is somewhat different.
If you're trying to introduce a few modern features (like AJAX) to a legacy app, then there's no reason you need to start over.
On the other hand if you're trying to write something that truly looks, feels, and works like a modern web app (for example, moving away from the page-load is app-state model), you should probably consider starting from the ground up. Trying to make that much of a transformation happen after the fact is going to be more trouble than it's worth for anything but the most trivial of apps.
I agree with Adam's answer, you probably want to use Catalyst. That being said, if you really don't want to, there's nothing preventing you from using only CGI.pm. The thing is, Catalyst is a collection of packages that do the things you want to make Web 2.0 easy. It combines the various templating engines such as Template Toolkit or Mason with the various ORM interfaces like DBIx::Class and Class::DBI.
Certainly you don't have to use these things to write Web 2.0 apps, it's just a good idea. Part of your question is wondering if javascript and CSS frameworks like jQuery, or prototype require anything from the server-side code. They don't, you can use them with any kind of server-side code you want.
For new apps, if you don't find Catalyst to your taste, Dancer is another lightweight framework you may like. There are also plenty of others, including CGI::Simple, Mojo/Mojolicious, Squatting...
Any of these lightweight frameworks can take care of the boring parts of web programming for you, and let you get on with writing the fun parts the way you want to.
If the jump from CGI.pm to Catalyst seems too daunting then perhaps something like Squatting might be more appropriate?
Squatting is a web microframework and I have found it ideal for quick prototyping and for replacing/upgrading my old CGI scripts.
I have recently built a small "web 2.0" app with Squatting using jQuery with no issues at all. Inside the CPAN distribution there is an example directory which contains some programs using jQuery and AJAX including a very interesting [COMET](http://en.wikipedia.org/wiki/Comet_(programming)) example which makes use of Continuity (which Squatting "squats" on by default).
NB. If required then you can later "squat" your app onto Catalyst with Squatting::On::Catalyst
There is also CGI::Ajax.
Related
I have a client who wants me to design a new web app from scratch
The problem is that he wants me to use only core modules that come with perl (5.10 or 5.12)
Is there a way to write MVC apps with just CGI?
I know about Catalyst, Mojolicious and Dancer and how easy it is to do MVC with them, but I have no clue on how to do it with CGI alone
Are there any code examples that I could see and inspire from? (I've already googled but didn't find anything that I could use)
Also, like with Mojo and Dancer, is there any way I can generate links (Routes from Mojo, and Rails) from CGI?
Thanks
First off, what's the reason for the "core modules only" restriction? Does that also mean that you can't write any new modules of your own? The most effective solution would undoubtedly be to convince the client to let you use CPAN.
If you're allowed to write your own non-core modules, would you be able to get away with including a new module named "Prancer" which looks suspiciously like Dancer? (i.e., Grab the Dancer source tree and s/Dancer/Prancer/g across the whole thing, then add it to your project.)
But, if all else fails... yes, it's possible to at least use MVC principles and strong separation of concerns under CGI.pm, although you won't have an actual framework helping you with it unless you write that framework yourself. You'll also have to write any database abstraction layer and templating engine yourself, too. I know this is possible because I was doing it myself 5-10 years ago, back in the Dark Ages before I switched to Dancer. I can't offer any examples, though, because I've successfully forgotten where I buried those bodies.
I am looking to start Web Programming in Perl (Perl is the only language I know). The problem is, I have no prior knowledge of anything to do with the web, except surfing it. I have no idea where to start.
So my question(s) is...
Where do I start learning Web Programming? What should I know? What should I use?
I thank everybody in advance for answering and helping.
The key things to understand are:
What you can send to browsers
… or rather, the things you intend to send to browsers, but having an awareness of what else is out there is useful (since, in complex web applications in particular, you will need to select appropriate data formats).
e.g.
HTML
CSS
JavaScript
Images
JSON
XML
PDFs
When you are generating data dynamically, you should also understand the available tools (e.g. the Perl community has a strong preference for TT for generating HTML, but there are other options such as Mason, while JSON::Any tends to be my goto for JSON).
Transport mechanisms
HTTP (including what status codes to use and when, how to do redirects, what methods (POST, GET, PUT, etc) to use and when).
HTTPS (HTTP with SSL encryption)
How to get a webserver to talk to your Perl
PSGI/Plack if you want modern and efficient
CGI for very simple
mod_perl if you want crazy levels of power (I've seen someone turn then Apache HTTPD into an SMTP spam filter using it).
Security
How to guard against malicious input (which basically comes down to knowing how to take data in one format (such as submitted form data) and convert it to another (such as HTML or SQL).
Web Frameworks
You can push a lot of work off to frameworks, which provide structured ways to organise a web applications.
Web::Simple is simple
Dancer seems to be holding the middle ground (although I have to confess that I haven't had a chance to use it yet)
Catalyst probably has the steepest learning curve but comes with a lot of power and plugins.
Dependent on complexity of your project, you could have a look at Catalyst MVC. This is a good framework, messing up with the most request stuff, but gives you enough in deep view whats going on.
There is a good tutorial in CPAN
If you want to start with mod_perl or CGI, there are also some Tutorials :
mod_perl
CGI Doc
If you're looking to try some web programming in Perl, you could try hosting a Dancer app for free on OpenShift Express.
There's even a "Dancer on OpenShift Express" repo to get you started: https://github.com/openshift/dancer-example
I learn best by taking apart something that already does something and figuring out why decisions were made in which manner.
Recently I've started working with Perl's CGI::Application framework, but found i don't really get along well with the documentation (too little information on how to best structure an application with it). There are some examples of small applications on the cgi-app website, but they're mostly structured such that they demonstrate a small feature, but contain mostly of code that one would never actually use in production. Other examples are massively huge and would require way too much time to dig through. And most of them are just stuff that runs on cgiapp, but isn't open source.
As such I am looking for something that has most base functionality like user logins, db access, some processing, etc.; is actually used for something but not so big that it would take hours to even set them up.
Does something like that exist or am i out of luck?
CGI::Application tends to be used for small, rapid-development web applications (much like Dancer, Maypole and other related modules). I haven't seen any real examples of open-source web apps built on top of it, though perhaps I'm not looking hard enough.
You could look at Catalyst. The wiki has a list of Catalyst-powered software and there are a large number of apps there - poke around, see if you like the look of the framework. Of this, this is Perl, so some of those apps will be using Template::Toolkit, some will use HTML::Mason... still, you'll get a general idea.
Try looking at Miril CMS. Although I don't know in which state it is.
I am the same with code, and had the same request. When I did not find a solution I created my own. which is https://github.com/alexxroche/Notice
I hope that it is a good solution to this request.
Notice demonstrates:
CGI::Application
CGI::Application::Plugin::ConfigAuto
CGI::Application::Plugin::AutoRunmode
CGI::Application::Plugin::DBH
CGI::Application::Plugin::Session;
CGI::Application::Plugin::Authentication
CGI::Application::Plugin::Redirect
CGI::Application::Plugin::DBIC::Schema
CGI::Application::Plugin::Forward
CGI::Application::Plugin::TT
It comes with an example mysql schema, but because of DBIC::Schema it can be used with PostgreSQL, (or anything else that DBIx::Class supports.)
I use Notice in all of my real life applications since 2007. The version in github is everything except the branding and the content.
Check out the Krang CMS.
I've been having an agruement with a friend that Mason (Perl) is not a framework, but a templating language. I feel Mason for Perl does what JSP does for Java (as an analogy, not pure technical comparison). From what I know, JSP is not a framework and I feel neither is Mason. When I looked up wikipedia Mason (Perl), I see that the main site says it is a web application framework written in Perl while the discussion page contests it.
Any pointers on why it is/ it is not a framework?
Update based on comments from ysth:
For a framework, I feel it should at least make db access easy, manage sessions, basic security that a webapp would need, templating and code reuse (or libraries that make basic tasks easy).
Mason is an 'M' short of being a MVC (Model-View-Controller) framework. It provides extensive rendering (View) features, which is why people think of Mason as being a templating language. However it also provides quite a few dispatch mechanisms (epsecially in the form of dhandlers), and control mechanisms (which fit naturally into autohandlers).
A few years ago I wrote an on-line tutorial (in Mason) to show off some of these features. It's optimised for full-screen display, and needs javascript enabled.
What Mason doesn't give you is a database abstraction layer, so you have to bring your own Model.
To the best of my knowledge amazon.com is written in Mason, along with many other sites.
If you enjoy working with Mason, but you'd like to have a Model, more toys, and a pony, then you may consider looking at Jifty as a web application framework.
A templating system would be something like HTML::Template, that is, a module that only does templating.
I feel that Mason does more, it has somehow a routing mechanism, it provides argument handling though %ARGS, intialisations through %INIT.
It also provides interfaces to mod_perl, CGI...
Now, it does not talk to the database, as if you want a clean way to do it, you'll have to use Class::DBI, DBIx::Perlish or one of the other hundred perl modules that does object mapping, or whatever else...
It is not an Model-View-Controller type of framework, it is probably closer to PHP than Ruby on Rails for example (and just as bad from what I have seen of it).
Can't answer the question to whether HTML::Mason is or isn't a framework without looking at it but I'm always happy with the following definition....
"a framework calls your program whereas your program calls a library"
Looking at Embedded Perl in HTML with Mason view of its competition, I'd say it is a template language. Otherwise Catalyst and Maypole would be on the list. Also, I think I read somewhere that you can use Mason as the View portion in a Catalyst application.
I guess I can see where you can use it like a framework, but it seems to be more complete if you view it as a template language.
Mason alone is not a framework it's just a template system BUT with some very cool features. It's got it's own structure and you can embed perl code very easely in it also it's got cache support. I've seen people who use Mason alone for developing a large application, but I guess it works better in an MVC framework.
Take care!
The following definition of a framework is taken from the Gamma book on Design Patterns. "A framework is a set of cooperating classes that make up a reusable design for a specific class of software." Mason, by that definition, is a framework. An MVC framework is only one type of framework.
HTML::Mason is what frameworks want to become when they get older. With HTML::Mason you get:
a dispatcher
templating
caching
logging
extremely flexible modularization
It was designed for high performance multi-tiered web applications, not for pleasing the fans of design patterns borrowed from desktop programming (such as MVC was).
Depends of your definition of framework.
You can apply name framework to any library if it does more than one thing.
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.