Related
I'm following the Heroku scala tutorial at https://devcenter.heroku.com/articles/scala
I was able to get everything working, but I have absolutely no idea where to go from here. I'd like to avoid using a framework (for now) if I can since the point of this is to learn scala and create a website with it. Their webwords example they list as a followup is completely different from the basic hello world example.
Mainly, I have no idea how heroku/scala/sbt know how to actually start the app and respond to requests since the samples are so different. I've looked at some frameworks and they seem pretty similar in that regard.
I'd really just like to know what the standard method for creating routes is (if there is such a thing). Any other tips about how to create a small MVC framework would also be of great help to me. A lot of the tutorials I see seem to make assumptions about what you already know (e.g. you would already know how to create routes and the like) but I can't find any tutorials that are even simpler.
Ultimately, the purpose of creating any web site, regardless of the technology used, is to offer some sort of content or functionality. You can't just say "I want to create a web site." any more than you could say "I want to build a building."
Once you have defined what the web site is supposed to do, then and only then is appropriate to consider how to implement it. The purpose of most frameworks to provide easy to use solutions to common and often difficult problems. For example, using a web application server like Jetty, Tomcat, or Glassfish trivializes most of the "route" issues. Any time that you save by using available tools can then be reinvested in creating better content.
On the other hand, if you really do want to implement an entire web server from scratch, the place to start is with the basic Hello app. In Hello.apply, you can start by looking at the HttpRequest (JBoss JavaDoc). getURI() will give you the request URL, and you can work out, from there, how to handle the different routes that you want to support.
I'm developing a gateway that will be located between mobile web apps and web services on backend systems. The purpose of this gateway is to protect web apps against changes to backend web service api's, to introduce concurrency, transform messages, buffering, etc.
My proposed architecture is as follows:
Platform independent mobile web apps using PhoneGap (done)
Gateway is a web service using Scala for business logic and ZeroMQ for message passing (new)
Backends are existing web services (existing)
The gateway is purely responsible passing, translation, aggregation, etc. of messages and does not need to keep state or do user authentication at this point - it's simply responsible for being a single interface that knows how to talk to mobile apps on the one side and one or more services on the other side.
I'm strongly considering using Scala as the development language because it seems well suited for this type of application, but what would be the correct architecture for such a Scala service? I looked at frameworks such as Lift and Play and also considered doing a simple "java" based web service and just use Scala as to implement my business logic. I believe strongly in keeping things as simple as possible. I'm wary of complicated setups and thousands of lines of dead code in frameworks that may never be used. On the other side, limiting oneself to a 'role your own' solution and creating a lot of work and having to maintain code that may have been part of existing solutions is also not ideal.
Some things to consider: I'm the architect and developer, but my knowledge of Scala is limited to the first half of "Programming in Scala, Second Edition". Also, my time is very limited. Still, I want to get this right the first time.
I'm hoping that some clever gent or dame will provide me with insights to this type of solution and maybe a link or two to get started quick. I really need to get going FAST, but hope that the experience or insights of another professional could help me avoid pitfalls along the way. Any insights to development environments and tools will also be helpful. I have to develop on Mac (company rules) but will be deploying on Ubuntu server. I'm currently juggling between installs of Eclipse or Idea as IDE's and the scala compiler or sbt for building.
UPDATE
Thanks for all the potential answers below. I had a look at each and every suggestion and all of them have merit. The problem is now to bet on the right horse. Spray is possibly the simplest solution to the problem, but I also found Finagle. It seams like a stunning solution to my problem. I'm a bit concerned that it is built on top of Netty instead of Akka. Does anyone see any problem with that. I was hoping to keep my solution as purely Scala as possible, but Finagle appears to be the most mature of the lot. Any ideas?
It might be worth taking a look at Akka, which provides a lightweight framework for writing concurrent, fault-tolerant applications on the JVM, as well as useful built-in abstractions for writing web services. In addition, the Spray project looks like it could be useful for your purposes, providing HTTP server and client libraries on top of Akka (Although, unlike Akka itself, I haven't used this so myself so can't vouch for it).
If you're using a web service that is purely for other services, then an Akka based service like Spray or Blueeyes is probably your best bet. You can use Jerkson to do the JSON mapping to and from your case classes and use Akka-Camel to link to ZeroMQ.
As mistertim says, Akka is a good option. I'm biased, but I think Lift and its RestHelper is a fantastic way to go also (I've built several APIs for iPhone apps using Lift). Beyond those, I know several people who are very happy with Unfiltered.
Unfiltered is very interesting option if you want to keep it lightweight, as is not a full blown web framework.
To be honest, the documentation can use more detail, but to provide a web service you just write:
object MyService extends unfiltered.filter.Plan {
def intent = {
case req # GET(Path ("/myendpoint")& Params(params)) =>
for {
param1<-params("param1")
param2<-params("param2")
} yield ResponseString(yourMethod(param1,param2))
}
override def main(args:Array[String]) = unfiltered.jetty.Http.anylocal.filter(MyService).run();
}
Very useful if you don't want to use a framework and don't want to mix java/java annotations with Scala (otherwise, you have the usual java solutions)
Still, I would recommend to look into Akka if you think you think actors will fit your problem
If your system is middle-ware and get the things done quickly, then Spray will be a best. Spray was developed on top of Akka. Akka has ZeroMQ support.
in future if you are going to add some other web like module along with your middle-ware, then choosing Lift + Akka will be better because, Lift also provides Spray like web service stuff + it will be easy to start developing other modules.
You can choose SBT as your build, there are some project templates, template generation tools available, so you can get the project build very quickly.
In my experience , SBT + InteliJ Idea works well, have a look on sbt-idea plugin
Spray Project Template
Lift Project Template Generator
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
Questions asking us to recommend or find a book, tool, software library, tutorial or other off-site resource are off-topic for Stack Overflow as they tend to attract opinionated answers and spam. Instead, describe the problem and what has been done so far to solve it.
Closed 8 years ago.
Improve this question
I've just started learning Scala, and the first thing I'm going to implement is a tiny web application. I've been using Erlang for the last year to implement server-side software, but I've never wrote web applications before. It will be a great experience.
Are there web-frameworks for Scala except for Lift?
Don't get me wrong, Lift looks awesome. I just want to know how many frameworks there are so that I can then choose between them. It's always a good to have a choice, but I the only thing I found was Lift.
I'm very interested in Scala, but I have not used it yet, so with that caveat, the frameworks I am aware of that are not mentioned in HRJ's answer (Lift, Sweet, Slinky) are:
Scalatra, previously Step (on GitHub)
Play 2 (on GitHub)
Pinky
I wrote a blog post about this.
To summarise, some of the options are:
Lift
Sweet
Slinky
I finally found that none were suitable for me, and developed my own little "framework". (It is not open-source yet).
I like Lift ;-)
Play is my second choice for Scala-friendly web frameworks.
Wicket is my third choice.
Following is a dump of frameworks. It doesn't mean I actually used them:
Coeus. A traditional MVC web framework for Scala.
Unfiltered. A toolkit for servicing HTTP requests in Scala.
Uniscala Granite.
Gardel
Mondo
Amore. A Scala port of the Ruby web framework Sinatra
Scales XML. Flexible approach to XML handling and a simplified way of interacting with XML.
Belt. A Rack-like interface for web applications built on top of Scalaz-HTTP
Frank. Web application DSL built on top of Scalaz/Belt
MixedBits. A framework for the Scala progamming language to help build web sites
Circumflex. Unites several self-contained open source projects for application development using the Scala programming language.
Scala Webmachine. Port of Basho's webmachine in Scala, a REST-based system for building web applications
Bowler. A RESTful, multi-channel ready Scala web framework
Try Play Framework, which also support Scala.
One very interesting web framework with commercial deployment is Scalatra, inspired by Ruby's Sinatra. Here's an InfoQ article about it.
I find Unfiltered very interesting https://github.com/unfiltered/unfiltered.
It's mentioned in IttayD's list.
Here is a presentation about it http://unfiltered.lessis.me/#0
and the video http://code.technically.us/post/942531598/doug-tangren-presents-the-unfiltered-toolkit-for
Also here there is an article with more info http://code.technically.us/post/998251172/holding-the-parameter
It must be noted that there is also a considerable interest in Wicket and Scala. Wicket fits Scala suprisingly well. If you want to take advantage of the very mature Wicket project and its ecosystem (extensions) plus the concise syntax and productivity advantage of Scala, this one may be for you!
See also:
Some prosa
Presentation
Some experience with Wicket and Scala
Announcments with reference to the project for the glue code to bind Scala closures to models
Play is pretty sweet.
It is now production ready. It incorporates: a cool template framework,automatic reloading of source files upon safe, a composable action system, akka awesomeness, etc.
Its part of the Typesafe Stack.
Having used it for two projects, I can say that it works pretty smoothly and it should be something to consider next time you are looking to learn new web frameworks.
I tend to use JAX-RS using Jersey (you can write nice resource beans in Scala, Java or Groovy) to write RESTul web applications. Then I use Scalate for the rendering the views using one of the various template languages (JADE, Scaml, Ssp (Scala Server Pages), Mustache, etc.).
There's a new web framework, called Scala Web Pages. From the site:
Target Audience
The Scala Pages web framework is likely to appeal to web programmers who come from a Java background and want to program web applications in Scala. The emphasis is on OOP rather than functional programming.
Characteristics And Features
Adheres to model-view-controller paradigm
Text-based template engine
Simple syntax: $variable and <?scp-instruction?>
Encoding/content detection, able to handle international text encodings
Snippets instead of custom tags
URL Rewriting
Prikrutil, I think we're on the same boat. I also come to Scala from Erlang. I like Nitrogen a lot so I decided to created a Scala web framework inspired by it.
Take a look at Xitrum. Its doc is quite extensive. From README:
Xitrum is an async and clustered Scala web framework and web server on top of Netty and Hazelcast:
It fills the gap between Scalatra and Lift: more powerful than Scalatra and easier to use than Lift. You can easily create both RESTful APIs and postbacks. Xitrum is controller-first like Scalatra, not view-first like Lift.
Annotation is used for URL routes, in the spirit of JAX-RS. You don't have to declare all routes in a single place.
Typesafe, in the spirit of Scala.
Async, in the spirit of Netty.
Sessions can be stored in cookies or clustered Hazelcast.
jQuery Validation is integrated for browser side and server side validation.
i18n using GNU gettext, which means unlike most other solutions, both singular and plural forms are supported.
Conditional GET using ETag.
Hazelcast also gives:
In-process and clustered cache, you don't need separate cache servers.
In-process and clustered Comet, you can scale Comet to multiple web servers.
Follow the tutorial for a quick start.
There's also Pinky, which used to be on bitbucket but got transfered to github.
By the way, github is a great place to search for Scala projects, as there's a lot being put there.
I'd like to add my own efforts to this list. You can find out more information here:
brzy framework
It's in early development and I'm still working on it aggressively. It includes features like:
A focus on simplicity and extensibility.
Integrated build tool.
Modular design; some initial modules includes support for scalate, email, jms, jpa, squeryl, cassandra, cron services and more.
Simple RESTful controllers and actions.
Any and all feedback is much appreciated.
UPDATE: 2011-09-078, I just posted a major update to version 0.9.1. There's more info at http://brzy.org which includes a screencast.
Both Sweet and Slinky seem to be unmaintanted for about a year. Sweet Maven repo sweetsoftwaredesign.com is dead so there's even no way to download dependencies.
Note: Spiffy is outdated.
<plug>
Spiffy:
is written in Scala
uses the fantastic Akka library and actors to scale
uses servlet API 3.0 for asynchronous request handling
is modular (replacing components is straight forward)
uses DSLs to cut down on code where you don't want it
supports Scalate and Freemarker for templating
Spiffy is a web framework using Scala, Akka (a Scala actor implementation), and the Java Servlet 3.0 API. It makes use of the the async interface and aims to provide a massively parallel and scalable environment for web applications. Spiffy's various components are all based on the idea that they need to be independent minimalistic modules that do small amounts of work very quickly and hand off the request to the next component in the pipeline. After the last component is done processing the request it signals the servlet container by "completing" the request and sending it back to the client.
https://github.com/mardambey/spiffy
</plug>
You could also try Context. It was designed to be a Java-framework but I have successfully used it with Scala also without difficulties. It is a component based framework and has similar properties as Lift or Tapestry.
I have stumbled upon your question a few weeks back, but since then also learned about Circumflex. This is a nice, minimal framework that is therefore easy to learn, and it has pretty good documentation available as well.
Beside it's minimal-ness, it also claims to work well with other libraries and lets you use your own implementation of things when you need it.
I am looking into something lightweight, that, at a minimum should support the following features:
Support for easy definition of actions through metadata
Wrapper that extracts parameters from request into clojure map, or as function parameters
Support for multiple forms of authentication (basic, form, cookie)
basic authorization based of api method metadata
session object wrapped in clojure map
live coding from REPL (no need to restart server)
automatic serialization of return value to json and xml
have nice (pluggable) url parameter handling (eg /action/par1/par2 instead of /action?par1=val1&par2=val2)
I know it is relatively easy to roll my own micro-framework for each one of these options, but why reinvent the wheel if something like that already exists? Especially if it is:
Active project with rising number of contributors/users
Have at least basic documentation and tutorial online.
First of all, I think that you are unlikely to find a single shrinkwrapped solution to do all this in Clojure (except in the form of a Java library to be used through interop). What is becoming Clojure's standard Web stack comprises a number of libraries which people mix and match in all sorts of ways (since they happily tend to be perfectly compatible).1
Here's a list of some building blocks which you might find useful:
Ring -- Clojure's basic HTTP request handling library; all the other webby libraries (for writing routes &c.) that I know of are compatible with Ring. Ring is being actively developed, has a robust community, is very well-written and has a nice SPEC document detailing its design philosophy. This blog post provides a nice example of how it might be used (reacting to GitHub commits).
Sandbar -- currently an authentication library, more types of functionality planned; under development.
Compojure -- a mature and robust library which provides a nice DSL for writing routes to be used on top of Ring. This will give you the nice URL parameter handling.
Compojure-rest -- "a library for building RESTful applications on top of Compojure". Compojure-rest is, as far as I can tell, in its early stages of development; perhaps you might see this as an opportunity to influence its design. :-)
For dealing with XML, there's clojure.contrib.lazy-xml (and the helper library clojure.contrib.zip-filter.xml) and Enlive (the built-in clojure.xml namespace is currently not very usable); these would be used in tandem (though for your purposes the former might suffice).
For JSON, there a library in contrib and clojure-json (and I think there was at least one other lib I seem to be forgetting now...); pick the one you like best.
All of will be perfectly happy with a REPL-driven development style (see the accepted answer to this SO question for a Ring trick which is very much to the purpose here). I suppose the above collection of links does leave a few blind spots (in particular, the authentication story is still being ironed out, as far as I can tell), but hopefully it's a good start.
1The only single-package solution for building webapps in Clojure that I know of is Conjure, inspired by Rails; unfortunately I have to admit that I don't know much about it, so if you feel interested, follow the link and look around the sources, wiki &c.
While building my first Clojure rest service I found myself asking often the same question. The Clojure Toolbox helped me a lot: http://www.clojure-toolbox.com/
If you are looking for some sample, real-world, illustrative code to get you started, then you could study this clojure-news-feed on github project which demonstrates how to implement a non-trivial RESTful web service with compojure/ring that wraps both SQL (postgresql or mysql) and NoSQL (cassandra), search (solr), caching (redis), event logging (kafka), connection pooling (c3po), and real-time metrics via JMX.
This blog about Building a Scalable News Feed Web Service in Clojure provides a good introduction. I ran some load tests against this service on a humble AWS deployment and got about eighty transactions per second with less than a half second average latency per transaction.
Take a look at liberator library http://clojure-liberator.github.io/liberator/ It's noy a standalone solution, buy very good for rest service definition.
Just to provide an updated answer to this old question, currently (in 2018) I think Luminus provides an excellent starting point. It's using many of the libraries (ring, compojure, etc.) mentioned in previous answers, is modular and as close to "single package" as you can get with Clojure. Specifically for REST, take a look at compojure-api. Luminus recommends buddy for authentication, I've had good success using it both for traditional session-based auth as well as Oauth and stateless JWTs.
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
Questions asking us to recommend or find a book, tool, software library, tutorial or other off-site resource are off-topic for Stack Overflow as they tend to attract opinionated answers and spam. Instead, describe the problem and what has been done so far to solve it.
Closed 8 years ago.
Improve this question
I've just started learning Scala, and the first thing I'm going to implement is a tiny web application. I've been using Erlang for the last year to implement server-side software, but I've never wrote web applications before. It will be a great experience.
Are there web-frameworks for Scala except for Lift?
Don't get me wrong, Lift looks awesome. I just want to know how many frameworks there are so that I can then choose between them. It's always a good to have a choice, but I the only thing I found was Lift.
I'm very interested in Scala, but I have not used it yet, so with that caveat, the frameworks I am aware of that are not mentioned in HRJ's answer (Lift, Sweet, Slinky) are:
Scalatra, previously Step (on GitHub)
Play 2 (on GitHub)
Pinky
I wrote a blog post about this.
To summarise, some of the options are:
Lift
Sweet
Slinky
I finally found that none were suitable for me, and developed my own little "framework". (It is not open-source yet).
I like Lift ;-)
Play is my second choice for Scala-friendly web frameworks.
Wicket is my third choice.
Following is a dump of frameworks. It doesn't mean I actually used them:
Coeus. A traditional MVC web framework for Scala.
Unfiltered. A toolkit for servicing HTTP requests in Scala.
Uniscala Granite.
Gardel
Mondo
Amore. A Scala port of the Ruby web framework Sinatra
Scales XML. Flexible approach to XML handling and a simplified way of interacting with XML.
Belt. A Rack-like interface for web applications built on top of Scalaz-HTTP
Frank. Web application DSL built on top of Scalaz/Belt
MixedBits. A framework for the Scala progamming language to help build web sites
Circumflex. Unites several self-contained open source projects for application development using the Scala programming language.
Scala Webmachine. Port of Basho's webmachine in Scala, a REST-based system for building web applications
Bowler. A RESTful, multi-channel ready Scala web framework
Try Play Framework, which also support Scala.
One very interesting web framework with commercial deployment is Scalatra, inspired by Ruby's Sinatra. Here's an InfoQ article about it.
I find Unfiltered very interesting https://github.com/unfiltered/unfiltered.
It's mentioned in IttayD's list.
Here is a presentation about it http://unfiltered.lessis.me/#0
and the video http://code.technically.us/post/942531598/doug-tangren-presents-the-unfiltered-toolkit-for
Also here there is an article with more info http://code.technically.us/post/998251172/holding-the-parameter
It must be noted that there is also a considerable interest in Wicket and Scala. Wicket fits Scala suprisingly well. If you want to take advantage of the very mature Wicket project and its ecosystem (extensions) plus the concise syntax and productivity advantage of Scala, this one may be for you!
See also:
Some prosa
Presentation
Some experience with Wicket and Scala
Announcments with reference to the project for the glue code to bind Scala closures to models
Play is pretty sweet.
It is now production ready. It incorporates: a cool template framework,automatic reloading of source files upon safe, a composable action system, akka awesomeness, etc.
Its part of the Typesafe Stack.
Having used it for two projects, I can say that it works pretty smoothly and it should be something to consider next time you are looking to learn new web frameworks.
I tend to use JAX-RS using Jersey (you can write nice resource beans in Scala, Java or Groovy) to write RESTul web applications. Then I use Scalate for the rendering the views using one of the various template languages (JADE, Scaml, Ssp (Scala Server Pages), Mustache, etc.).
There's a new web framework, called Scala Web Pages. From the site:
Target Audience
The Scala Pages web framework is likely to appeal to web programmers who come from a Java background and want to program web applications in Scala. The emphasis is on OOP rather than functional programming.
Characteristics And Features
Adheres to model-view-controller paradigm
Text-based template engine
Simple syntax: $variable and <?scp-instruction?>
Encoding/content detection, able to handle international text encodings
Snippets instead of custom tags
URL Rewriting
Prikrutil, I think we're on the same boat. I also come to Scala from Erlang. I like Nitrogen a lot so I decided to created a Scala web framework inspired by it.
Take a look at Xitrum. Its doc is quite extensive. From README:
Xitrum is an async and clustered Scala web framework and web server on top of Netty and Hazelcast:
It fills the gap between Scalatra and Lift: more powerful than Scalatra and easier to use than Lift. You can easily create both RESTful APIs and postbacks. Xitrum is controller-first like Scalatra, not view-first like Lift.
Annotation is used for URL routes, in the spirit of JAX-RS. You don't have to declare all routes in a single place.
Typesafe, in the spirit of Scala.
Async, in the spirit of Netty.
Sessions can be stored in cookies or clustered Hazelcast.
jQuery Validation is integrated for browser side and server side validation.
i18n using GNU gettext, which means unlike most other solutions, both singular and plural forms are supported.
Conditional GET using ETag.
Hazelcast also gives:
In-process and clustered cache, you don't need separate cache servers.
In-process and clustered Comet, you can scale Comet to multiple web servers.
Follow the tutorial for a quick start.
There's also Pinky, which used to be on bitbucket but got transfered to github.
By the way, github is a great place to search for Scala projects, as there's a lot being put there.
I'd like to add my own efforts to this list. You can find out more information here:
brzy framework
It's in early development and I'm still working on it aggressively. It includes features like:
A focus on simplicity and extensibility.
Integrated build tool.
Modular design; some initial modules includes support for scalate, email, jms, jpa, squeryl, cassandra, cron services and more.
Simple RESTful controllers and actions.
Any and all feedback is much appreciated.
UPDATE: 2011-09-078, I just posted a major update to version 0.9.1. There's more info at http://brzy.org which includes a screencast.
Both Sweet and Slinky seem to be unmaintanted for about a year. Sweet Maven repo sweetsoftwaredesign.com is dead so there's even no way to download dependencies.
Note: Spiffy is outdated.
<plug>
Spiffy:
is written in Scala
uses the fantastic Akka library and actors to scale
uses servlet API 3.0 for asynchronous request handling
is modular (replacing components is straight forward)
uses DSLs to cut down on code where you don't want it
supports Scalate and Freemarker for templating
Spiffy is a web framework using Scala, Akka (a Scala actor implementation), and the Java Servlet 3.0 API. It makes use of the the async interface and aims to provide a massively parallel and scalable environment for web applications. Spiffy's various components are all based on the idea that they need to be independent minimalistic modules that do small amounts of work very quickly and hand off the request to the next component in the pipeline. After the last component is done processing the request it signals the servlet container by "completing" the request and sending it back to the client.
https://github.com/mardambey/spiffy
</plug>
You could also try Context. It was designed to be a Java-framework but I have successfully used it with Scala also without difficulties. It is a component based framework and has similar properties as Lift or Tapestry.
I have stumbled upon your question a few weeks back, but since then also learned about Circumflex. This is a nice, minimal framework that is therefore easy to learn, and it has pretty good documentation available as well.
Beside it's minimal-ness, it also claims to work well with other libraries and lets you use your own implementation of things when you need it.