#clojure – 2008-04-03

2008-04-03

11:11	cgrand	It seems that when calling a method on a type hinted value, the object is cast to the declaring class of the method not to the hinted class. Am I right? Can I rely on this behavior or is it an implementation detail?
11:12	rhickey	when does distinguishing it become important?
11:13	cgrand	out is tagged as an OutputStreamWriter and I bind it to a PrintWriter (in a servelt)
11:13	cgrand	Right now it works
11:14	rhickey	hmm...
11:15	rhickey	it probably should just be hinted Writer
11:16	rhickey	I can't promise it will never cast to hinted type
11:16	cgrand	and I would not have to worry :-)
11:16	Chouser	cgrand: are you using webjure?
11:18	cgrand	casting to the hinted type can provide some performance gains (methods declared final... or final classes... hey does it means that actually Strings are cast to CarSequence?)
11:18	cgrand	chouser: no writing write a minimal servlet wrapper
11:19	cgrand	chouser: (delete "write")
11:20	rhickey	cgrand: the hints are just used to find resolve methods, the casts are based upon the methods themselves right now
11:22	cgrand	rhichey: ok
11:23	rhickey	cgrand: out type hint now Writer
11:23	cgrand	rhickey: thanks
11:29	Chouser	cgrand: I'm currently writing a minimal webserver that may or may not be able to load and run servlets eventually.
11:30	Chouser	cgrand: are you writing Java code to run clojure in a standard Java server, or some other piece?
11:33	cgrand	chouser: a simple servlet which setup clojure and delegates everything to clojure code with nearly no wrapping of java objects (request & response)
11:36	cgrand	chouser: are you building your webserver from scratch?
11:37	Chouser	cgrand: yeah, I just want something that's super-easy to deploy, esp. in a development environment.
11:41	Chouser	so you're passing the servlet req and resp directly into clojure code?
11:42	Chouser	will the clojure code register some kind of handler with the servlet, or will it be more hard-wired?
11:43	cgrand	chouser: yes, I bing them to servlet/request and response (and in and out to their reader/writer)
11:43	cgrand	chouser: s/bing/bind/
11:43	rhickey	cgrand: it's easy, right?
11:44	Chouser	ok, cool.
11:44	cgrand	really easy and I tak the name of the boot script for the app from a servlet parameter
11:44	rhickey	I'll eventually put a servlet stub class in Clojure
11:44	rhickey	to make even easier and standardize
11:47	cgrand	rhickey: how would you dispatch requests to clojure code? with a map (http-method => handler), with a single clojure function "service" or several functions (one by http method)?
11:47	Chouser	isn't the input stream already in the request? Sorry, I'm new to servlets.
11:49	rhickey	cgrand: probably a single service fn, to allow the most flexibility, since the advantages of overriding them separately on the Java side are lost once you override them all
11:50	rhickey	the idea of the stub would be to get out of Java ASAP
11:51	cgrand	chouser: it is, I just think it's fairly common to want to bind out to the response outputstream so that print works.
11:51	Chouser	yeah, ok.
11:59	cgrand	chouser: did you consider Jetty? http://docs.codehaus.org/display/JETTY/Embedding+Jetty
11:59	Chouser	yes I did
12:01	Chouser	I started trying to install and configure Jetty. I got maven installed ok, but then it was pulling in all sorts of libraries to build Jetty. The binary installation of Jetty was over 20MB.
12:02	cgrand	lightweight :-)
12:02	Chouser	I don't mean to whine, but I don't really want all that just for playing around with development.
12:03	Chouser	I expect to have a minimal web server .clj file to weigh in at around 150 LOC. With minimal servlet support, maybe add another 100.
12:04	Chouser	Sure, if I'm going to deploy a production server I can expect signicant installation work, and I can compare Jetty and TomCat and whatever, and do what makes sense.
12:05	Chouser	But I've played with a few web "frameworks" in a few languages (python, C++/Qt, ruby (guess which one!)) and being able to install a small framework and run a command to get your sample site running in a little webserver is just really pleasant.
12:05	Chouser	I think it's a good way to help get a newbie hooked on any particular framework.
12:06	Chouser	or maybe my little webserver will be useless for anything but helping me learn Clojure and servlets. That's ok too. :-)
12:06	rhickey	yeah, until people realize the built-in webservers for those frameworks are not so hot.
12:06	rhickey	Once you have a servlet host installed, everything else is easy
12:07	rhickey	but you've built on an architecture that lets you swap in Tomcat/Jetty/Resin/GlassFish...
12:07	rhickey	grows into authentication, JDBC connection pooling
12:07	Chouser	but what if the code you write for the built-in webserver can be dropped directly into a standerd servlet host?
12:08	rhickey	your clients can get support for the servers from Sun/IBM/JBoss
12:08	Chouser	what's the downside then?
12:08	rhickey	as I said before, you'd have to provide all of the features of servlets, accurately
12:09	Chouser	so you really think this is a dead end.
12:09	rhickey	When Webjure was released, I was on a client site and had no servlet host on my laptop...
12:10	rhickey	I downloaded Jetty into a directory, started it, dumped webjure into the deploy directory, fired up a browser and it worked - 10 minutes
12:11	rhickey	Chouser: yes, while J2EE is overkill, servlets are sweet, and all of those servlet containers are really nice open source tech - to good to ignore
12:11	Chouser	Do you have a recommendation for a low-cost hosting service that includes servlet support? Ususally that one feature seems to crank the monthly price up significantly.
12:13	rhickey	not offhand - most of my clients are self-hosted/internal
12:13	cgrand	rhickey: would you mind making RT.loadResourceScript public?
12:13	Chouser	yeah. Makes sense for most businesses, I suppose.
12:15	rhickey	cgrand: done
12:15	cgrand	rhickey: thanks
12:25	Chouser	So no love from the Java folks for FastCGI or SCGI. Makes me sad.
12:25	Chouser	I guess I'll try to find a work-around.
12:29	Chouser	cgrand: do you plan on putting your wrapper in clojure-contrib?
13:15	Chouser	ok, I seem to have tomcat running. I guess I'll use webjure until cgrand's wrapper is done, if he feels like sharing.
14:28	cgrand	Chouser: sorry, I was away. I'll put in in the grop asap.
14:52	Chouser	cgrand: cool! I'm stumbling along fine with webjure for now, but a more minimal solution will be great.
14:52	Chouser	Ugh, I'm so bad at dealing with the Java libs.
15:33	abrooks	rhickey: Will you ever be open to having platform support code as part of a general Clojure distribution? (i.e. JNI via "(. posix.something (mumble...))") There are some generally useful OS interfaces and some more specific (RDMA / various hardware MPI assist for HPC for example) interfaces which would be interesting for various domains.
15:34	rhickey	abrooks: I think the core should be pure Java
15:35	abrooks	Agreed. I was more asking about side libraries that could be bundled with the sources and be available on supported platforms. I wasn't imagining that this would in any way be in the core language implementation (however we're both defining "core" ;).
15:38	rhickey	abrooks: I don't see it, at present
16:00	abrooks	rhickey: That's understandable. :) Just testing the waters.
16:00	rhickey	abrooks: never say never :)
22:25	ericthor	what is the painless way to deal with the equivalent of function that takes Object[] ? Like new Object[] { new SomeType(),2,new SomOtherType()}
22:25	ericthor	nevermind...i just thought of something