Tynamo is model-driven, full-stack web framework based on Apache Tapestry 5

Tynamo's mission is to provide implementations for different aspects of a full web application stack that offer reasonable out-of-the-box functionality and are easy to customize. We are intent on proving that web applications based on Java can simultaneously be high performing, easy to implement and fun to develop. We leverage existing technologies where possible and provide integrations with proven, clean and compact libraries rather than limit ourselves only to standard Java (JSRs). Tynamo is both comprehensive and modular so you are free to choose the parts you like from our full stack. And finally, we like Tapestry and our modules use Tapestry IoC extensively.

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RememberMe with rolling tokens

Why is it that I cannot find a definition of a rolling authentication token anywhere? Let me provide my own then: a rolling token is a security (authentication) token that can only be used for a single successful authentication. After a successful authentication, the used token is always replaced by a new one, therefore the token is said to be rolling. There, now we can talk. I’ve always disliked typical rememberMe implementations for the weak security they provide and I still admire this eight year old blog post by Charles Miller. Let me quote from “Persistent Login Cookie Best Practice”:

Persistent login cookies are the cookies that are stored with your browser when you click the “remember me” button on the login form. I would like to be able to say that such cookies are obselete, and we have a better way of handling user logins, but they aren’t, and we don’t.

The following recipe for persistent cookies requires no crypto more powerful than a good random number generator.

Premises

  1. Cookies are vulnerable. Between common browser cookie-theft vulnerabilities and cross-site scripting attacks, we must accept that cookies are not safe
  2. Persistent login cookies are on their own sufficient authentication to access a website. They are the equivalent of both a valid username and password rolled into one
  3. Users reuse passwords. Hence, any login cookie from which you can recover the user’s password holds significantly more potential for harm than one from which you can not
  4. Binding persistent cookies to a particular IP address makes them not particularly persistent in many common cases
  5. A user may wish to have persistent cookies on multiple web browsers on different machines simultaneously

With all this in mind, I’ve always implemented rememberMe based on rolling tokens in the various web applications I’ve worked on. However, I’ve never attempted to provide it as a reusable module until one day a few months ago while I was working on federatedaccounts it hit me: rolling tokens can be thought of as just another “remote” authentication provider that can be federated with the main account. For some months now, we’ve happily been using tynamo-federatedaccounts-rollingtokens in production. I added some quick documentation for it at the end of the generic tynamo-federatedaccounts guide, have (secure) fun with it!

Why Tapestry?

Lately, I’ve had noticeably more people asking me about Tapestry and why one should choose it over the other (Java) web frameworks. To me, Tapestry is a good compromise, just like Java is. Linus Torvalds, my fellow country man, has famously said “performance almost always matters”. There are so many aspects to web development, and performance is often seen as one of the smallest of your problems because in the end “it always comes down to the database”. However, a high performing framework solves many other problems. Today, a typical, reasonably well-implemented Java web application on a modest hardware can serve hundreds of concurrent requests, thousands of concurrent users and tens of thousands of users a day from a single server. Most start-ups never need to worry about the scaling out problem until they actually have the money to pay for it. Unfortunately, you can also easily make the implementation horribly slow, suffering from scalability problems from the get-go and even more unfortunately, it’s easier to go wrong with some Java frameworks than with others. For what Tapestry offers, the performance of the framework itself, both in terms of cpu and memory consumption is simply phenomenal. Performance matters.

However, I really don’t want to make this post about Tapestry’s performance. As soon as you mention one thing about a particular framework, people tend to place it in that category and forget about everything else. What I really like to give as an answer to people who ask why one should use Tapestry is this: because it is well-balanced and comprehensive. There are a lot of other web frameworks that are optimized with a certain thing in mind and in that narrow field, they typically beat the competition. It’s difficult though to be a good all-around contender but that’s exactly what Tapestry is all about. Tapestry doesn’t force you to a certain development model - such as using sessions, always post, single url, ajax-only, thick RIA etc. If you just need to handle a specific case, such as building a single-page, desktop-like application for web, you could pick GWT, Flex or Vaadin, but if you are a building a generic, mixed static/dynamic content site with multiple pages you’d undoubtedly pick entirely different set of tools. Tapestry though, is an “enabling” technology - you could use it together with all three aforementioned RIA frameworks. You could also use and people have used Tapestry-IoC alone in non-web desktop applications. Not a whole lot of other “web” frameworks can claim suitability for such diverse use cases. Sadly, comprehensiveness of a framework can be a somewhat difficult area to objectively compare so each framework usually resorts to toting their best features to prove their superiority over others.

One criteria I personally use a lot in comparing effectiveness of competing solutions is their expressiveness and succinctness. Now, everybody knows that Java is a butt-ugly language (though it makes up on other departments, like performance and comprehensiveness). Today’s Java is far from your grandfather’s Java a few years back and Tapestry makes the best use of the more advanced, modern JVM techniques available today, such as bytecode manipulation, annotation-based meta programming and introspection without reflection. Tapestry code is purposefully remarkably succinct. Minimal effort required for creating Tapestry components makes it easy to refactor your application logic into reusable elements, rather than having to repeat yourself. Patterns in object-oriented languages are a well studied and accepted principle, but only a few (IoC) frameworks besides Tapestry IoC manages to have a framework level support for implementing common ones, such as chain of command, strategy and pipelines.

For Tynamo, I’ve said it before but I just don’t think we could have achieved the same CRUD functionality with any other framework. Certainly anything can be done, but the cost of it would have both been far higher and we would have needed to build much more infrastructure. When we moved from Tapestry 4 to Tapestry 5 (and from Trails to Tynamo), it was amazing to see how we were able to simplify our implementation and remove huge amounts of code while keeping the concept unchanged and making it all more modular at the same time. Using a different stack, you could probably get closest to what tapestry-model is with a combination of Wicket and Spring, but allowing the same level of extensibility would undoubtedly be more cumbersome. Back in Trails, we actually had one person working on a pure Spring (MVC + core) implementation of the same concept but it died a slow death. As the documentation states, tapestry-model produced “default model is highly customizable, you can change pretty much anything you need, and make the changes specific to type, page or instance - a feature that very few other CRUD frameworks offer”. The big difference is that when you need to customize the model, you don’t have to rewrite it all, you’ll be just customizing the pages and overriding components as needed.

Perhaps we’ve gone a bit overboard with modularity, but since it’s just that simple with Tapestry, most of our modules are independently usable but seamlessly work together in the same web application as soon as you add them to the classpath. Today, Tynamo is much more than just tapestry-model, the CRUD framework. Tapestry-security, tapestry-conversations and tapestry-resteasy are all steadily gaining popularity and based on the page views, it seems that tapestry-security is poised to become our most popular module offering at some point. On that note, I have a few new supplemental modules for tapestry-security coming up which should be of interest to others as well, but more on that in a separate post. For now, I hope I’ve been able to give some answers to why at Tynamo, we think we’ve made the right choice with Tapestry and I’m confident that 2011 will be the best year yet both for Tapestry and Tynamo!