Tag Archives: Web Applications

Python, Web Applications

Deploying Python apps to Epio

I recently got my beta access to ep.io, the Python application deployment platform. I had the chance today to have a play around and try out some deployments so I thought I would try and give my view on the experience before. I’ve deployed Python apps to Heroku and Gondor before so those services form my reference points here.

So firstly, there’s a command-line client that you install via pip and you effectively deploy to the platform via a client-command, SSH keys and what looks like git on the server-side. This is more like Gondor than Heroku (which is intimately linked to git). It means you have your choice of source control and if you want to be a Python purist you never need to step outside of Python for everything you are doing.

Applications consist of essentially one configuration file that states where the WSGI application is and what the requirements file is. Compared to Gondor it is a very simple setup but it did feel that it could be even simpler if it made convention-based assumptions such as the requirements file being called requirements.txt, for example.

Leveraging WSGI and configuration this way gives a very flexible platform and I was able to get both Flask and Bottle to work (the former very quickly because it has documentation, the latter via trial and error that might require its own blog-post). I didn’t have time to try Django but I felt pretty confident that I could get whatever framework I wanted working once I understood the basic setup.

Unlike Heroku, Epio provides a fixed framework for executing the apps. It seems you will be running behind NGINX and Gunicorn. Both are good choices and I certainly like them but if you want to play around with different servers like Tornado or CherryPy you may prefer Heroku’s more open deployment model. I did like the way that you can use the configuration file to have NGINX serve static content directly.

Epio naturally has less of an ecosystem than Heroku but has Solr, Postgres and Redis out of the box. All solid choices and covering off the majority of what I would need. I was certainly grateful that I didn’t have to grapple with remote database administration and could prototype apps with just Redis.

Deployment and logging have kind of rough edges. Being able to access logs directly from the application page was a win for me, however when I was struggling to define the WSGI entrypoint correctly it seemed as if the application wasn’t being really compiled until the first request comes in. I would see an entry confirming a new deployment but then nothing until I hit the app. I think there should be some kind of sanity check of what you have uploaded to see whether it will even run.

Right now epio is providing a Python-based cloud deployment platform with a sensible set of supplementary services and low opinion about the source control system to you use. It feels like if this had been around at the start of the year it would have blown me away. However now there is more competition and therefore questions of price and ease of use will matter in terms of  how compelling it is to use the service.

If you do Python web development I would definitely recommend you sign up for beta and give it a go yourself as it seems a very solid prototyping platform. If you are not a Ruby and Git fan then you may well love what is on offer here because it is already very convenient, makes few demands on you and gets your web app public in minutes.

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Web Applications

The Browser or the App?

There is an interesting little issue occurring in web development at the moment and it is all being caused by the rise in mobile browsing.

The mobile device has always been a bit a challenge (anyone remember WAP?) but until the iPhone it was an issue that was pretty irrelevant. Web browsing on a phone was so painful that no-one did it. Right now if you check your logs most sites are only going to have a tiny amount of iPhone traffic. However if you live in a major city and you own a phone with a decent screen and browser then you are probably aware of how quickly you start to expect to have access to the same level of information you have at home when on the move. Why should I know more about delayed trains in bed than on the platform?

So the technology is finally reaching the point where the consumer is starting to expect to be able to browse the web on mobile devices. In parallel there is the rise of the app. The prime advantage of the app over mobile web browsing is that the app can sensibly cache data locally and therefore provide a degree of offline tolerant behaviour. You can also simplify some of the UI if your user interacts with your site instead of just consuming the content.

So what do you do? Do you invest in creating a mobile version of your site or instead create an app? Obviously if you can afford it you may want to pursue a web/mobile web/iPhone/Android strategy, i.e. do everything. For most companies though the practicalities lean towards trying to have a main website that more or less works with modern mobile browsers (mostly the iPhone). There are a lot of things that go into that like page load but in essence is a “code and hope” strategy where you hammer any nails that stick up after the event.

What’s interesting about this strategy is that HTML5 has some offline capabilities that allow you to provide some offline capability as long as you as you are happy to ignore the non-Opera/Safari/Chrome users (and frankly why not). This means that can stick to pure web development and have a reasonable mobile experience. Adding a JSON API to your site’s content also opens you up to third-parties developing apps for you.

So what kind of reasons should drive you to develop an app? The first reason is really the customised rich user experience, an app should radically simplify accessing your content. For example for a timetable site a mobile app can make it easier to enter and refine queries, defining search options on mobile web tends to be a pain and you often want to save and reuse search settings rather than re-enter them. Sites with user-generated content may also want to have a rich UI to encourage the user to keep supplying material.

An app should also always be trying to cache content when online and pre-empt the user’s needs. For example it makes sense to try and download timetable information and travel updates for locations I use frequently in my search. If I open my timetable search app and the first thing I see is whether there are delays on my route home are and when the next bus or train is going to be then I may not need to do anything else.

Apps also open sophisticated location service options, although location has been broadened to web browsers too your ability to respond to location based information is very limited on your home PC. A reviews website for example has a strong incentive to invest in an app so it can supply location-based reviews.

It is not clear at the moment whether it is more important to develop a mobile web or a mobile application capability. The emergence of capable, enjoyable web browsing on handhelds in an important development, there are many more mobiles than computers. Thinking about how your web content works on those devices is suddenly very relevant. Developing a mobile-capable site is a good defensive strategy but for some businesses being able to enter the mobile app market earlier is going to be much more important as it could potentially form an audience for them that is greater than their current web users.

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Web Applications, Work

The death of MVC

The MVC pattern is so embedded into the concept of modern web development I feel quite the heretic for declaring it over. Yet more and more I think we are moving away from it as a pattern. Views have been boiled down to a special case of templating and now Controllers are the next under the microscope. What does a Controller do? Well it marshalls the model and exposes it to the view.

However with the relentless march of REST how much controlling is the Controller really doing? The HTTP request tells you the format of the data, identifies the resource it is interested in. How much need is there for a controller for each request type? Surely the Uber Controller that responds to the HTTP request is all that’s required.

I have also been using Groovlets recently and when using them I feel like “why not mix your model lookup with the ‘view'”. In my Groovlets I essentially lookup the data for the view either directly via Groovy SQL or via the Service layer that is injected out of Guice. The view is then created using Markup Builder.

Since my scripts end up at around 50 lines of code I think that any benefit I might have in separating things is outweighed by the fact that the entire interaction is in one place and can be found, read and changed very easily.

MVC saved us from really painful web architectures but as we grow more sophisticated in the way we handle HTTP Requests and the more we understand the implications of HTTP and the less ceremonial our languages becomes the less benefit we get from it.

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Groovy, Java, Programming, Scripting, Web Applications

Towards Groovier Projects

My latest project has witnessed an influx of Groovy. The project buildfile is run by Gant, there are Groovlets providing lightweight pages but it is in the test folders that the Groovy has made its most insidious advances.

Markup builder makes fragments of HTML to test, Groovy’s built-in Sql is beginning to setup and check the results of data operations at a functional level. Soon I plan to implement a Groovy Struts 2 result and then it will begin to replace Freemarker.

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Java, Ruby, Web Applications, Work

Working with Rails

I have recently struggled to try and get a prototype web application done with Ruby on Rails. It has been a really great experience and like all such experiences consists of both good and bad moments. Things that are particularly striking coming from a Java Web environment:

  • Integrated console
  • No recompile/build/deploy cycle
  • No mix and match components
  • No real programming language skill required.

It is also remarkable how quickly people revert to the level of thought, planning and execution that you might use for a shell script. Even I have found myself getting caught up in “playing” with the app interactively rather than being focussed on creating behaviour and functionality in a structured way.

Elaborating on these points; in Java web development the first issue is usually building up your component stack. Some people just choose Spring  but those people are idjits! If you are working purely in a web tier without any need for any backend interaction then it is probably a good bet but generally you want to put some thought into how you are going to assemble your various stacks. You tend to have to choose your MVC web framework, your persistence framework and your service framework (if appropriate). You often have to give some thought to your caching and messaging frameworks if they are relevant.

With Rails you just use the appropriate Active Module or Rails built-in features. If there is something that is going to ease some pain for you then it is going be operating as a plugin. That’s it, no framework holy war. It also means that there are a lot of applications that are just not going to be suitable for a Rails application as all those Java components have various strengths for different environments. I certainly wouldn’t want to tackle a legacy database with ActiveRecord for example. Not that it couldn’t be done but I wouldn’t want to do it.

The zero-turnaround is impressive after the build-deploy-check cycle. It was a wow factor last year when I saw the Phobos framework being demonstrated by Sun and its not lost any of its shine. By separating its deployment environments so ruthlessly Rails is able to deliver a really positive developer experience.

The interactive console takes a bit of getting used to in terms of faking browser requests but once you get used to doing so it is another tool that you wonder how you’ve managed without for so long. It’s much more intuitive to use than setting up a remote Java debugging instance (although admittedly you do similar tasks in both). It allows you to scratch those itchy “why?” questions.

And finally that lack of programming skill? A bit controversial perhaps? Well I feel that in recent weeks what I have been learning is how to manipulate Rails. The fact that it is implemented on Ruby may allow a lot of features to be implemented in the way they that they are but you are very rarely called upon to show Ruby madskillz. Instead the majority of the time you are simply plugging little customisations into the Rails framework. It is called Rails for a reason after all, when you are on them you are amazingly productive but if you can’t package your problem into a Rails solution then you are out of luck, you’re going to have to develop your own solution and that is going to be hard work. I have been trying to develop my Ruby skills (that is a whole other story) but the truth is you can bang out something that is acceptable with very little Ruby knowledge. You can go a lot of the way purely by mastering Ruby’s hash syntax.

So have I been converted? Well for all its problems I do have a hankering to get back to my great big Java applications with their holy wars and heavyweight processing. After all being on the Rails is fine for getting things done quickly but it can feel claustrophobic. I am also really glad that after getting distracted by the whole JSF controversy the challenge Rails presents to the status quo of web development means that a lot of the Java frameworks are starting to respond to the real problems faced in web development and ensuring that the easy stuff should be easy.

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