Opa: A new language aiming to make web programming transparent

http://lambda-the-ultimate.org/node/4336

by hbbio • 15 years ago

116 62 15 years ago

I hope I'm not the only one that is now picturing a bunch of Greeks destroying plates...

adelevie2• 15 years ago

The project itself looks great. Novel idea, excellent documentation, etc. But the title of the OP seems a bit off: how does adding an extra layer between the developer and the application code (server code, client-side js) create more transparency? It's kind of like saying Coffeescript makes Javascript more transparent.

joelhaasnoot2• 15 years ago

Now functional programming languages are scary to any student who sees them for the first time, but I admit, this kind of thing really scared me. Took a CS Introduction to Functional Programming course at university, taught using Clean, a pure and lazy functional language developed at the university. Most of their research currently is related to iTasks (see http://wiki.clean.cs.ru.nl/ITasks) which also does web apps, but focused on workflows. As a web dev however, it totally stripped the layers between model and browser, which is actually the harder part most of the time where the customization happens, and became this (all too simple) mess of models and functions. It was too early stage software too, various server bugs in the built-in HTTP server, and lacking JS/frontend implemantation. Only one of the 15 weeks needed iTasks, which was a good thing, for students and TA sanity.

adelevie2• 15 years ago

Interesting story, though it's tough to gather what your overall point is. You're saying that abstracting server and client logic into monolithic functional code gave you headaches?

calloc• 15 years ago

Opa translated from Dutch to English means Grandpa ...

hernan7• 15 years ago

Opa is Argentinian slang for "retarded" :-(

crazygringo• 15 years ago

Opa translated from Portuguese to English means wow, or whoops ...

mortain• 15 years ago

Opa! ... lol

zzzmarcus• 15 years ago

Same in Mexican Spanish.

julius2• 15 years ago

Also grandpa in german.

simcop2387• 15 years ago

It apparently means Ulcer in "Lithuanian". http://translate.google.com/#lt|en|Opa

reinhardt• 15 years ago

Also a greek exclamation common in songs, e.g. http://www.youtube.com/watch?v=bmeCC53FKes

onedognight• 15 years ago

It means "older brother" in Korean.

Yoric14• 15 years ago

Just in case anybody wonders: roughly half of the Opa team speaks German, at least one speaks Argentinian Spanish, at least one speaks Greek. So, yeah, we are aware of most of the puns.

Guess what? We like them :)

necubi• 15 years ago

Unfortunately it's AGPL licensed so it can't be used for commercial development (without obtaining a commercial license). It looks neat though, and it's great to see people rethinking the normal way of doing things on the web.

pygy_• 15 years ago

s/commercial/closed source/...

Also, I may be wrong, but I don't think that the code run by a GPLed interpreter has to conform to the license. Native libraries linked to the runtime would have to, though.

Yoric14• 15 years ago

Caveat: Opa is not an interpreter, it's a native code compiler, with native libraries. Consequently, the previous poster is right: AGPL is fully contagious here.

Note: I'm part of the Opa team.

anonymoushn2• 15 years ago

You can't even open source your code using a license that doesn't restrict the rights of others. You would have to pay for a commercial license to be able to release your code under WTFPL, zlib, or MIT license.

julius2• 15 years ago

here is a blog post about the license: http://blog.opalang.org/2011/08/opa-license-contributions.ht...

mlinksva• 15 years ago

Regardless of license requirements, I think the following built in feature is interesting:

"way for your users to download the sources of the application. In fact Opa facilitates that by automatically enriching the server (in release mode) to serve the source code of the application at a special /_internal_/src_code URL."

felixhummel• 15 years ago

I do not believe "automatically generating client-side Javascript and handling communication and session control", in short: hiding redundancy and complexity, can "make web programming transparent". IMHO, making something as complex as web programming transparent requires a lot of knowledge transfer. Making web development more easily accessible would be a fitting description. The idea is not new - see Ruby on Rails, even though it takes a different approach.

There is a lot of transparency in web programming if you are willing to learn. Roy Fielding's dissertation comes to mind as well as the book "RESTful Web Services", RFC 2068, RFC 2616 and ECMA-262. In the end it's "some server stuff" -- HTTP -- "some client stuff" where "some client stuff" is mostly Javascript.

Off topic: Does Blizzard's World of Warcraft client count as web development or is web development limited to the way Joel Spolsky describes it? [1]

PS: This comment is based solely on the introductory paragraph of OPA's home page.

[1] https://plus.google.com/117114202722218150209/posts/KhMRNmgG...

Yoric14• 15 years ago

Yeah, 'transparent' might be the wrong formulation. Still, Opa is great :)

Note: I'm part of the Opa team.

hbbio4• 15 years ago

Fully agreed that current web programming is complex and that was the driving force behind making Opa. What might not be clear in the presentation of Opa is that it's not some new glue on top of existing components. It's instead a whole new, clean, technology for writing and running web applications.

And given that the language is statically typed (with inference in most cases, so it's easy for the programmer) with first-class web values, the whole point of Opa is that the compiler knows quite a lot about your application when generating the binaries. The typing system determines wether part of the code will run on the client side, on the server side (or both) for instance. This mechanism is very different from Ruby on Rails for instance, although both approaches share the goal of making the programmer's life easy.

Building RESTful services is exactly where Opa excels. Have a look at http://doc.opalang.org/index.html#_hello_web_services and the following chapter.

grandalf• 15 years ago

Does the chat work?

http://chat.opalang.org/

koper• 15 years ago

I believe it does, it doesn't for you?

Yoric14• 15 years ago

Works for me.

ww520• 15 years ago

Similar to GWT?

Yoric14• 15 years ago

There are common points. However, Opa goes much further than Gwt (and its toolchain supersets) in terms of automation, concurrency, distribution and security.

Automation: by default, you do not have to give the compiler any hint as to whether code should be compiled towards the client, the server, the database, etc. The compiler solves all of this automatically, inserting whichever Ajax/Comet calls wherever needed. You can, however, provide annotations for optimization and/or security purposes.

Concurrency/distribution: at its heart, Opa is based on an actor model (although you do not need to use actors for simple applications). This actor model lets you connect easily clients, servers, etc. or subsystems through a very simple paradigm.

Security: every Ajax/Comet call inserted is checked for a number of criteria. In particular, the structure of messages is checked automatically, entry points generated dynamically for one single client can only be used by that client, etc.

Note: I'm one of the authors of Opa.

FuzzyDunlop• 15 years ago

I am the music man, I come from down your way and I can plaaay (what can you play?)

I play the trombone.

Opa opa opa-pa opa-pa opa-pa

Opa opa opa-pa opa opa-pa

dgreensp2• 15 years ago

Looks interesting, from skimming the docs.

Only a few obvious downsides/open questions to me:

* License prohibits making closed-source things in it.

* How efficient is the generated client-side code? Language mismatch is a major cause of slow generated code (see GWT). In Opa's case, having no arrays (only linked lists) sounds like a disaster for compiling to JS.

* I've never seen the model work before where you "don't even need to think about what's running on the client or server." I like features like sharing code (same language) and easy transport (serializable data structures), but frameworks that blur the client/server distinction usually download all of your code, or none of it, or little snippets on demand, or some other strategy that's worse than a manual distinction.

* What's development like? Do you really have to recompile your app after every change? My favorite frameworks just let you change the code and reload the web page.

* I've seen many, and even written one, tutorial that goes: "Making a chat room in a web browser is hard. But here's a demo that does it in 20 lines!" With all the frameworks and libraries out there these days, it's not that hard.

* Tons of dependencies (a personal gripe). Coming from the Java world, where lots of things like reading images are built-in, it's comical to see that Opa requires Java, AND libjpeg and a dozen other things (it doesn't actually run on the JVM I don't think).

hbbio4• 15 years ago

Partial answers/tidbits:

The JS code is not as optimized as what you can write manually, although a lot of work was put in making it work "fast enough" (thanks Mathieu). However, we have many ideas on how to reach native performance. Look for instance at how Java got sometimes even faster than C!

There are hints @server and @client to specify a side for running a bit of your code. Since, as you say, there are things you know and the machine doesn't.

Opa being a compiler, updated projects have to be recompiled. You gain a lot in quality, consistency with this (especially associated to the very advanced type system of Opa). And as we know that compilers are annoying, we made our best to make the compile time short. You probably won't have to take a coffee, sorry.

The chat example does not rely on predefined libraries -- that's the difference. You can also look at bigger chat applications like https://github.com/hbbio/OpaChat and compare with https://github.com/ry/node_chat.

Opa requires Java for building from source - if the package does, that's something you can report at https://github.com/mlstate/opalang/issues?sort=created&d...

Groxx• 15 years ago

>Look for instance at how Java got sometimes even faster than C!

I don't think browsers are going to let you build a hot-spot compiler in Javascript. Nor do I think that an online, optimizing interpreter in javascript stands much of a chance of improving performance.

Yoric14• 15 years ago

I've never seen the model work before where you "don't even need to think about what's running on the client or server." I like features like sharing code (same language) and easy transport (serializable data structures), but frameworks that blur the client/server distinction usually download all of your code, or none of it, or little snippets on demand, or some other strategy that's worse than a manual distinction.

There are two things here. For prototyping, Opa will automatically decide what goes to the client and what goes to the server. We are very much aware that this may not yield the best performance. So, when you move from prototyping to optimization, using your knowledge of the application security policy, you can add security hints that the compiler will use to optimize client-server placement, knowing that this does not break the policy. And finally, if you want even better control, you can annotate any piece of code to instruct the compiler to place it on the client, or on the server, or both. In any case, the compiler will inform you if the set of constraints you put has no solution.

Tons of dependencies (a personal gripe). Coming from the Java world, where lots of things like reading images are built-in, it's comical to see that Opa requires Java, AND libjpeg and a dozen other things (it doesn't actually run on the JVM I don't think).

I concur that the dependencies are a (minor) annoyance. Just one point: Java is used only to build Opa from source. More precisely, during Opa compilation, we run the (very nice) Java-based Google Closure Compiler as a measure of the quality of our JavaScript libraries. If I recall correctly, that build step is optional, too.

alexro• 15 years ago

Opa is definitely something, but isn't going anywhere without the support of existing database servers. I don't really need that much of automation to create a prototype - and that's what Opa is only good at in it's current form, unfortunately.

vinodkd• 15 years ago

Seems like an interesting stab at fixing the drudgery that web app development has become. Some questions, however:

1. When you go through the pains of integrating everything else, why not go for gold and exclude x/html and css as well? These are as "glue, antagonistic" as the other bits that make up the current webapp quagmire.

2. When ideas like PaaS are emerging, wouldnt it be better to bundle everything that makes up the app separate from everything that makes up the platform? I know that this sounds like the antithesis of your "one executable" idea - and I love single executables where appropriate - but it seems like webapp deployment could do with some economies of scale on the underlying container in the sense that the difference between App A and App B is primarily in the functionality, not in the way those functions are accessed, used, etc.

Yoric14• 15 years ago

> 1. When you go through the pains of integrating everything else, why not go for gold and exclude x/html and css as well? These are as "glue, antagonistic" as the other bits that make up the current webapp quagmire.

Actually, the x/html and (most of the) css that you see in our examples is syntactic sugar for higher-level constructions.

> 2. When ideas like PaaS are emerging, wouldnt it be better to bundle everything that makes up the app separate from everything that makes up the platform? [...]

Certainly feasible, but I'm not sure what would be gained, and it would make deployment a little harder.

thesorrow• 15 years ago

I thought this OPA thing was closed already.

I have quit java/j2ee to avoid recompiling/redeploying all the time ! So the compiling part is a no go for me !

asymmetric• 15 years ago

really like the web page design (especially the 'secure' tab). was it made at MLstate?

hbbio4• 15 years ago

Made internally: Congrats go to Ida.

Opa: A new language aiming to make web programming transparent

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