Scala Plugin for Coming NetBeans 6.5 Official Release
I'm pleased to announce the availability of Scala plugin for coming NetBeans 6.5 official release.
- Much better code-completion
- Two new color themes: Twilight and Emacs Standard
- Various bugs fixes
- It's not perfect, but fairly stable
- Works good with NetBeans Maven plugin
To download, please go to: https://sourceforge.net/project/showfiles.php?group_id=192439&package_id=256544&release_id=641359
For more information, please see http://wiki.netbeans.org/Scala
Bug reports are welcome.
It works also on NetBeans RC2. If you have previous version of Scala plugin installed, you can upgrade to this version.
Posted at 07:11PM Nov 18, 2008 by dcaoyuan in NetBeans | Comments[8]
Scala for NetBeans Screenshot#15: Twilight Color Theme
>>>Updated Nov 11:
Emacs Standard color theme already be there.
======
I'm beginning to write some real thing based on Liftweb. The more code I wrote, the more bugs of Scala plugin were fixed.
Not only bugs are being fixed, I also created a Twilight color theme for this plugin. And an Emacs color theme is also on the road.
When NetBeans 6.5 is official released, I'll put a new Scala plugin too.
Click on the picture to enlarge it
Posted at 10:28PM Nov 09, 2008 by dcaoyuan in NetBeans | Comments[9]
New Scala Plugin for NetBeans 6.5 RC2 Is Packed
I packed a new Scala plugin, and tried several times to upload it to NetBeans' Plugins Portal and could not get job successfully done. So I uploaded it to sourceforge.net instead. The zip file is located at: scala-plugin-081106.zip
NetBeans' trunk has been targeting 7.0 now, the plugin on "Last Development Build" update center is no longer compatible with 6.5 RC2. That is, you should ignore my previous blog talked about installing plugin on 6.5 RC2, if you are using 6.5 RC2, you should download and install this one.
Nightly built version users can get latest plugin via NetBeans' plugin management feature as normal.
For more information, please visit http://wiki.netbeans.org/Scala
This version fixed various bugs, and with some enhancements. The bundling Scala runtime is 2.7.2RC6, with NetBeans' maven plugin, it works on newest Liftweb project.
Bug reports are always welcome.
Click on the picture to enlarge it
Posted at 06:40AM Nov 07, 2008 by dcaoyuan in NetBeans | Comments[6]
Scala for NetBeans Screenshot#14: Refined Color Theme
With more Scala coding experience, I refined color theme of Scala plugin for NetBeans. By desalinating Type name a bit, I found I can concentrate on logic a bit better. And all function calls are highlighted now, so, for multiple-line expression, when error-prone op is put on wrong new line, you can get some hints at once. It also gives you hint if a val/var is with implicit calling, which will be highlighted as a function call.
There are still some bugs when infer var/val's correct type in some cases.
Now the editor is much informative with highlighting and bubble pop display of type information (move mouse on it with CTRL/COMMAND pressed).
You'll need to update to newest 1.9.0 Editing module, please wait for it appealing on Development Update Center.
Click on the picture to enlarge it
Posted at 09:14PM Oct 30, 2008 by dcaoyuan in NetBeans | Comments[3]
Install Scala Plugin for NetBeans 6.5 RC2
>>> Updated Nov 8
Content of this blog is out of date, please look at New Scala Plugin for NetBeans 6.5 RC2 Is Packed
===
NetBeans 6.5 RC2 released. The Scala plugin on NetBeans' Plugins Portal is not compilable with RC2. To get Scala plugin working with RC2, do:
# Open NetBeans 6.5 RC2, go to "Tools" -> "Plugins", check "Setting" -> "Add", add new update center as "Last Development Build" with url: http://deadlock.netbeans.org/hudson/job/nbms-and-javadoc/lastStableBuild/artifact/nbbuild/nbms/updates.xml.gz
# Then in the "Available Plugins" tab, you can find the "Scala" category (or, you can click on "Name" in "Available Plugins" tab to find them. You may need to click "Reload Catalog" to get the latest available modules), check "Scala Kit" and click "Install", following the instructions. Restart IDE.
I'll re-pack a new version of Scala plugin for Plugins Portal when NetBeans 6.5 is officially released.
Posted at 02:10PM Oct 30, 2008 by dcaoyuan in NetBeans | Comments[3]
RPC Server for Erlang, In Scala
There has been Java code in my previous blog: RPC Server for Erlang, In Java, I'm now try to rewrite it in Scala. With the pattern match that I've been familiar with in Erlang, write the Scala version is really a pleasure. You can compare it with the Java version.
I do not try Scala's actor lib yet, maybe late.
And also, I should port Erlang's jinterface to Scala, since OtpErlangTuple, OtpErlangList should be written in Scala's Tuple and List.
The code is auto-formatted by NetBeans' Scala plugin, and the syntax highlighting is the same as in NetBeans, oh, not exactly.
/*
* RpcMsg.scala
*
*/
package net.lightpole.rpcnode
import com.ericsson.otp.erlang.{OtpErlangAtom, OtpErlangList, OtpErlangObject, OtpErlangPid, OtpErlangRef, OtpErlangTuple}
class RpcMsg(val call:OtpErlangAtom,
val mod :OtpErlangAtom,
val fun :OtpErlangAtom,
val args:OtpErlangList,
val user:OtpErlangPid,
val to :OtpErlangPid,
val tag :OtpErlangRef) {
}
object RpcMsg {
def apply(msg:OtpErlangObject) : Option[RpcMsg] = msg match {
case tMsg:OtpErlangTuple =>
tMsg.elements() match {
/* {'$gen_call', {To, Tag}, {call, Mod, Fun, Args, User}} */
case Array(head:OtpErlangAtom, from:OtpErlangTuple, request:OtpErlangTuple) =>
if (head.atomValue.equals("$gen_call")) {
(from.elements, request.elements) match {
case (Array(to :OtpErlangPid,
tag:OtpErlangRef), Array(call:OtpErlangAtom,
mod :OtpErlangAtom,
fun :OtpErlangAtom,
args:OtpErlangList,
user:OtpErlangPid)) =>
if (call.atomValue.equals("call")) {
Some(new RpcMsg(call, mod, fun, args, user, to, tag))
} else None
case _ => None
}
} else None
case _ => None
}
case _ => None
}
}
/*
* RpcNode.scala
*
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
*/
package net.lightpole.rpcnode
import com.ericsson.otp.erlang.{OtpAuthException, OtpConnection, OtpErlangAtom, OtpErlangExit, OtpErlangObject, OtpErlangString, OtpErlangTuple, OtpSelf}
import java.io.IOException
import java.net.InetAddress
import java.net.UnknownHostException
import java.util.concurrent.ExecutorService
import java.util.concurrent.Executors
import java.util.logging.Level
import java.util.logging.Logger
trait Cons {
val OK = new OtpErlangAtom("ok")
val ERROR = new OtpErlangAtom("error")
val STOPED = new OtpErlangAtom("stoped")
val THREAD_POOL_SIZE = 100
}
/**
*
* Usage:
* $ erl -sname clientnode -setcookie mycookie
* (clientnode@cmac)> rpc:call(xnodename@cmac, xnode, parse, []).
*
* @author Caoyuan Deng
*/
abstract class RpcNode(xnodeName:String, cookie:String, threadPoolSize:Int) extends Cons {
def this(xnodeName:String, cookie:String) = this(xnodeName, cookie, 100)
private var xSelf:OtpSelf = _
private var sConnection:OtpConnection = _
private var execService:ExecutorService = Executors.newFixedThreadPool(threadPoolSize)
private val flags = Array(0)
startServerConnection(xnodeName, cookie)
loop
def startServerConnection(xnodeName:String, cookie:String ) = {
try {
xSelf = new OtpSelf(xnodeName, cookie);
// The node then publishes its port to the Erlang Port Mapper Daemon.
// This registers the node name and port, making it available to a remote client process.
// When the port is published it is important to immediately invoke the accept method.
// Forgetting to accept a connection after publishing the port would be the programmatic
// equivalent of false advertising
val registered = xSelf.publishPort();
if (registered) {
System.out.println(xSelf.node() + " is ready.");
/**
* Accept an incoming connection from a remote node. A call to this
* method will block until an incoming connection is at least
* attempted.
*/
sConnection = xSelf.accept();
} else {
System.out.println("There should be an epmd running, start an epmd by running 'erl'.");
}
} catch {
case ex:IOException =>
case ex:OtpAuthException =>
}
}
def loop : Unit = {
try {
val msg = sConnection.receive
val task = new Runnable() {
override
def run = RpcMsg(msg) match {
case None =>
try {
sConnection.send(sConnection.peer.node, new OtpErlangString("unknown request"));
} catch {
case ex:IOException =>
}
case Some(call) =>
val t0 = System.currentTimeMillis
flag(0) = processRpcCall(call)
System.out.println("Rpc time: " + (System.currentTimeMillis() - t0) / 1000.0)
}
}
execService.execute(task)
if (flag(0) == -1) {
System.out.println("Exited")
} else loop
} catch {
case ex:IOException => loop
case ex:OtpErlangExit =>
case ex:OtpAuthException =>
}
}
/** @throws IOException */
def sendRpcResult(call:RpcMsg, head:OtpErlangAtom, result:OtpErlangObject) = {
val tResult = new OtpErlangTuple(Array(head, result))
// Should specify call.tag here
val msg = new OtpErlangTuple(Array(call.tag, tResult))
// Should specify call.to here
sConnection.send(call.to, msg, 1024 * 1024 * 10)
}
/** @abstact */
def processRpcCall(call:RpcMsg) : Int
}
object RpcCall {
def getShortLocalHost : String = getLocalHost(false)
def getLongLocalHost : String = getLocalHost(true)
def getLocalHost(longName:Boolean) : String = {
var localHost = "localhost"
try {
localHost = InetAddress.getLocalHost.getHostName;
if (!longName) {
/* Make sure it's a short name, i.e. strip of everything after first '.' */
val dot = localHost.indexOf(".")
if (dot != -1) localHost = localHost.substring(0, dot)
}
} catch {
case ex:UnknownHostException =>
}
localHost
}
}
Posted at 08:25PM Oct 27, 2008 by dcaoyuan in Erlang |
FOR, WHILE Is Too Easy, Let's Go Looping
With several 10k code in Erlang, I'm familiar with functional style coding, and I found I can almost rewrite any functions in Erlang to Scala, in syntax meaning.
Now, I have some piece of code written in Java, which I need to translate them to Scala. Since "for", "while", or "do" statement is so easy in Java, I can find a lot of them in Java code. The problem is, should I keep them in the corresponding "for", "while", "do" in Scala, or, as what I do in Erlang, use recursive function call, or, "loop"?
I sure choose to loop, and since Scala supports recursive function call on functions defined in function body (Erlang doesn't), I choose define these functions' name as "loop", and I tried to write code let "loop" looks like a replacement of "for", "while" etc.
Here's a piece of code that is used to read number string and convert to double, only piece of them.
The Java code:
public class ReadNum {
private double readNumber(int fstChar, boolean isNeg) {
StringBuilder out = new StringBuilder(22);
out.append(fstChar);
double v = '0' - fstChar;
// the maxima length of number stirng won't exceed 22
for (int i = 0; i < 22; i++) {
int c = getChar();
switch (c) {
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
v = v * 10 - (c - '0');
out.append(c);
continue;
case '.':
out.append('.');
return readFrac(out, 22 - i);
case 'e':
case 'E':
out.append(c);
return readExp(out, 22 - i);
default:
if (c != -1) backup(1);
if (!isNeg) return v; else return -v
}
}
return 0;
}
}
The Scala code:
class ReadNum {
private
def readNumber(fstChar:Char, isNeg:Boolean) :Double = {
val out = new StringBuilder(22)
out.append(fstChar)
val v:Double = '0' - fstChar
def loop(c:Char, v:Double, i:Int) :Double = c match {
// the maxima length of number stirng won't exceed 22
case _ if i > 21 =>
0
case '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' =>
out.append(c)
val v1 = v * 10 - (c - '0')
loop(getChar, v1, i + 1)
case '.' =>
out.append('.')
readFrac(out, 22 - i)
case 'e' | 'E' =>
out.append(c)
readExp(out, 22 - i)
case _ =>
if (c != -1) backup(1)
if (isNeg) v else -v
}; loop(getChar, v, 1)
}
}
As you can see in line 25, the loop call is put at the position immediately after the "loop" definition, following "}; ", I don't put it to another new line, it makes me aware of the "loop" function is just used for this call.
And yes, I named all these embedded looping function as "loop", every where.
Posted at 09:47PM Oct 21, 2008 by dcaoyuan in Java | Comments[6]
An Example Syntax in Haskell, Erlang and Scala
>>> Updated Oct 16:
I found some conventions of coding style make code more readable for Scala. For example, use
{ x => something } instead of (x => dosomething) for anonymous function; Use x, y, z as the names of arguments of anonymous functions; Put all modifiers to the ahead line etc. That makes me can pick up these functions by eyes quickly. ======
It's actually my first time to write true Scala code, sounds strange? Before I write Scala code, I wrote a Scala IDE first, and am a bit familiar with Scala syntax now. And I've got about 1.5 year experience on Erlang, it began after I wrote ErlyBird.
Now it's time to write some real world Scala code, I choose to port Paul R. Brown's perpubplat blog engine, which is written in Haskell. And I have also some curiosities on how the syntax looks in Erlang, so I tried some Erlang code too.
Here's some code piece of entry module in Haskell, Erlang and Scala:
Original Haskell code piece
empty :: Model
empty = Model M.empty M.empty M.empty [] 0
build_model :: [Item] -> Model
build_model [] = empty
build_model items = Model (map_by permatitle sorted_items)
bid
(build_child_map sorted_items)
(sorted_items)
(n+1)
where
sorted_items = sort_by_created_reverse items
bid = (map_by internal_id sorted_items)
n = fst . M.findMax $ bid
build_child_map :: [Item] -> M.Map Int [Int]
build_child_map i = build_child_map_ (M.fromList $ (map (\x -> (internal_id x,[])) i)) i
-- Constructed to take advantage of the input being in sorted order.
build_child_map_ :: M.Map Int [Int] -> [Item] -> M.Map Int [Int]
build_child_map_ m [] = m
build_child_map_ m (i:is) = if (parent i == Nothing) then
build_child_map_ m is
else
build_child_map_ (M.insertWith (++) (unwrap $ parent i) [internal_id i] m) is
sort_by_created_reverse :: [Item] -> [Item]
sort_by_created_reverse = sortBy created_sort_reverse
created_sort_reverse :: Item -> Item -> Ordering
created_sort_reverse a b = compare (created b) (created a)
In Erlang:
% @spec empty :: Model
empty() -> #model{}.
% @spec build_model :: [Item] -> Model
build_model([]) -> empty();
build_model(Is) ->
SortedIs = sort_by_created_reverse(Is),
Bid = dict:from_list([{I#item.internal_id, I} || I <- SortedIs]),
N = lists:max(dict:fetch_keys(Bid)),
#model{by_permatitle = dict:from_list([{X#item.permatitle, X} || X <- SortedIs]),
by_int_id = Bid,
child_map = build_child_map(SortedIs),
all_items = SortedIs,
next_id = N + 1}.
% @spec build_child_map :: [Item] -> M.Map Int [Int]
build_child_map(Is) -> build_child_map_(dict:from_list(lists:map(fun (X) -> {X#item.internal_id, []} end), Is), Is).
%% Constructed to take advantage of the input being in sorted order.
% @spec build_child_map_ :: M.Map Int [Int] -> [Item] -> M.Map Int [Int]
build_child_map_(D, []) -> D;
build_child_map_(D, [I|Is]) ->
case I#item.parent of
undefined ->
build_child_map_(D, Is);
P_Id ->
build_child_map_(dict:append(unwrap(P_Id), I#item.internal_id, D), Is)
end.
% @spec sort_by_created_reverse :: [Item] -> [Item]
sort_by_created_reverse(Is) -> lists:sort(fun created_sort_reverse/2, Is).
% @spec created_sort_reverse :: Item -> Item -> Ordering
created_sort_reverse(A, B) -> compare(B#item.created, A#item.created).
In Scala
object Entry {
def empty = new Model()
def build_model(is:List[Item]) = is match {
case Nil => empty
case _ =>
val sortedIs = sortByCreatedReverse(is)
val bid = Map() ++ sortedIs.map{ x => (x.internalId -> x) }
val n = bid.keys.toList.sort{ (x, y) => x > y }.head // max
new Model(Map() ++ sortedIs.map{ x => (x.permatitle -> x) },
bid,
buildChildMap(sortedIs),
sortedIs,
n + 1)
}
def buildChildMap(is:List[Item]) = buildChildMap_(Map() ++ is.map{ x => (x.internalId -> Nil) }, is)
private
def buildChildMap_(map:Map[Int, List[Int]], is:List[Item]) = {
map ++ (for (i <- is if i.parent.isDefined; pid = i.parent.get; cids = map.getOrElse(pid, Nil))
yield (pid -> (cids + i.internalId)))
}
def sortByCreatedReverse(is:List[Item]) = is.sort{ (x, y) => x.created before y.created }
}
>>> Updated Oct 16: Per Martin's suggestion, the above code can be written more Scala style (the reasons are in the comments). Thanks, Martin.
object Entry {
def empty = new Model()
def build_model(is:List[Item]) = is match {
case Nil => empty
case _ =>
val sortedIs = sortByCreatedReverse(is)
val bid = Map() ++ sortedIs.map{ x => (x.internalId -> x) }
// use predefined max in Iterable
val n = Iterable.max(bid.keys.toList)
new Model(Map() ++ sortedIs.map{ x => (x.permatitle -> x) },
bid,
buildChildMap(sortedIs),
sortedIs,
n + 1)
}
// you can use a wildcard anonymousfunction here
def buildChildMap(is:List[Item]) = buildChildMap_(Map() ++ is.map(_.internalId -> Nil), is)
private
def buildChildMap_(map:Map[Int, List[Int]], is:List[Item]) =
map ++ { // rewrite for so that definitions go into body -- it's more efficient.
for (i <- is if i.parent.isDefined) yield {
val pid = i.parent.get
val cids = map.getOrElse(pid, Nil)
pid -> (cids + i.internalId)
}
}
// you can use a wildcard anonymous function here
def sortByCreatedReverse(is:List[Item]) = is.sort{ _.created before _.created }
}
======
I use ErlyBird for Erlang coding, and Scala for NetBeans for Scala coding. The experience seems that IDE is much aware of Scala, and I can get the typing a bit faster than writing Erlang code.
If you are not familiar with all these 3 languages, which one looks more understandable?
Posted at 11:14AM Oct 15, 2008 by dcaoyuan in Erlang | Comments[11]
RPC Server for Erlang, In Java
We are using Erlang to do some serious things, one of them is indeed part of a banking system. Erlang is a perfect language in concurrent and syntax (yes, I like its syntax), but lacks static typing (I hope new added -spec and -type attributes may be a bit helping), and, is not suitable for processing massive data (performance, memory etc). I tried parsing a 10M size XML file with xmerl, the lib for XML in OTP/Erlang, which causes terrible memory disk-swap and I can never get the parsed tree out.
It's really a need to get some massive data processed in other languages, for example, C, Java etc. That's why I tried to write RPC server for Erlang, in Java.
There is a jinterface lib with OTP/Erlang, which is for communication between Erlang and Java. And there are docs for how to get it to work. But, for a RPC server that is called from Erlang, there are still some tips for real world:
1. When you send back the result to caller, you need set the result as a tuple, with caller's tag Ref as the first element, and the destination should be the caller's Pid. It's something like:
OtpErlangTuple msg = new OtpErlangTuple(new OtpErlangObject[] {call.tag, tResult});
sConnection.send(call.to, msg);
where, call.tag is a OtpErlangRef, and tResult can be any OtpErlangObject, call.to is a OtpErlangPid.
2. If you need to send back a massive data back to caller, the default buffer size of OtpErlangOutputStream is not good, I set it to 1024 * 1024 * 10
3. Since there may be a lot of concurrent callers call your RPC server, you have to consider the concurrent performance of your server, I choose using thread pool here.
The RPC server in Java has two class, RpcNode.java, and RpcMsg.java:
package net.lightpole.rpcnode;
import com.ericsson.otp.erlang.OtpErlangAtom;
import com.ericsson.otp.erlang.OtpErlangList;
import com.ericsson.otp.erlang.OtpErlangObject;
import com.ericsson.otp.erlang.OtpErlangPid;
import com.ericsson.otp.erlang.OtpErlangRef;
import com.ericsson.otp.erlang.OtpErlangTuple;
/**
*
* @author Caoyuan Deng
*/
public class RpcMsg {
public OtpErlangAtom call;
public OtpErlangAtom mod;
public OtpErlangAtom fun;
public OtpErlangList args;
public OtpErlangPid user;
public OtpErlangPid to;
public OtpErlangRef tag;
public RpcMsg(OtpErlangTuple from, OtpErlangTuple request) throws IllegalArgumentException {
if (request.arity() != 5) {
throw new IllegalArgumentException("Not a rpc call");
}
/* {call, Mod, Fun, Args, userPid} */
if (request.elementAt(0) instanceof OtpErlangAtom && ((OtpErlangAtom) request.elementAt(0)).atomValue().equals("call") &&
request.elementAt(1) instanceof OtpErlangAtom &&
request.elementAt(2) instanceof OtpErlangAtom &&
request.elementAt(3) instanceof OtpErlangList &&
request.elementAt(4) instanceof OtpErlangPid &&
from.elementAt(0) instanceof OtpErlangPid &&
from.elementAt(1) instanceof OtpErlangRef) {
call = (OtpErlangAtom) request.elementAt(0);
mod = (OtpErlangAtom) request.elementAt(1);
fun = (OtpErlangAtom) request.elementAt(2);
args = (OtpErlangList) request.elementAt(3);
user = (OtpErlangPid) request.elementAt(4);
to = (OtpErlangPid) from.elementAt(0);
tag = (OtpErlangRef) from.elementAt(1);
} else {
throw new IllegalArgumentException("Not a rpc call.");
}
}
/* {'$gen_call', {To, Tag}, {call, Mod, Fun, Args, User}} */
public static RpcMsg tryToResolveRcpCall(OtpErlangObject msg) {
if (msg instanceof OtpErlangTuple) {
OtpErlangTuple tMsg = (OtpErlangTuple) msg;
if (tMsg.arity() == 3) {
OtpErlangObject[] o = tMsg.elements();
if (o[0] instanceof OtpErlangAtom && ((OtpErlangAtom) o[0]).atomValue().equals("$gen_call") &&
o[1] instanceof OtpErlangTuple && ((OtpErlangTuple) o[1]).arity() == 2 &&
o[2] instanceof OtpErlangTuple && ((OtpErlangTuple) o[2]).arity() == 5) {
OtpErlangTuple from = (OtpErlangTuple) o[1];
OtpErlangTuple request = (OtpErlangTuple) o[2];
try {
return new RpcMsg(from, request);
} catch (IllegalArgumentException ex) {
ex.printStackTrace();
}
}
}
}
return null;
}
}
package net.lightpole.rpcnode;
import com.ericsson.otp.erlang.OtpAuthException;
import com.ericsson.otp.erlang.OtpConnection;
import com.ericsson.otp.erlang.OtpErlangAtom;
import com.ericsson.otp.erlang.OtpErlangExit;
import com.ericsson.otp.erlang.OtpErlangObject;
import com.ericsson.otp.erlang.OtpErlangString;
import com.ericsson.otp.erlang.OtpErlangTuple;
import com.ericsson.otp.erlang.OtpSelf;
import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
*
* Usage:
* $ erl -sname clientnode -setcookie mycookie
* (clientnode@cmac)> rpc:call(xnodename@cmac, 'System', currentTimeMillis, []).
*
* @author Caoyuan Deng
*/
public abstract class RpcNode {
public static final OtpErlangAtom OK = new OtpErlangAtom("ok");
public static final OtpErlangAtom ERROR = new OtpErlangAtom("error");
public static final OtpErlangAtom STOPED = new OtpErlangAtom("stoped");
private static final int THREAD_POOL_SIZE = 100;
private OtpSelf xSelf;
private OtpConnection sConnection;
private ExecutorService execService;
public RpcNode(String xnodeName, String cookie) {
this(xnodeName, cookie, THREAD_POOL_SIZE);
}
public RpcNode(String xnodeName, String cookie, int threadPoolSize) {
execService = Executors.newFixedThreadPool(threadPoolSize);
startServerConnection(xnodeName, cookie);
loop();
}
private void startServerConnection(String xnodeName, String cookie) {
try {
xSelf = new OtpSelf(xnodeName, cookie);
boolean registered = xSelf.publishPort();
if (registered) {
System.out.println(xSelf.node() + " is ready.");
/**
* Accept an incoming connection from a remote node. A call to this
* method will block until an incoming connection is at least
* attempted.
*/
sConnection = xSelf.accept();
} else {
System.out.println("There should be an epmd running, start an epmd by running 'erl'.");
}
} catch (IOException ex) {
Logger.getLogger(RpcNode.class.getName()).log(Level.SEVERE, null, ex);
} catch (OtpAuthException ex) {
Logger.getLogger(RpcNode.class.getName()).log(Level.SEVERE, null, ex);
}
}
private void loop() {
while (true) {
try {
final int[] flag = {0};
final OtpErlangTuple msg = (OtpErlangTuple) sConnection.receive();
Runnable task = new Runnable() {
public void run() {
RpcMsg call = RpcMsg.tryToResolveRcpCall(msg);
if (call != null) {
long t0 = System.currentTimeMillis();
flag[0] = processRpcCall(call);
System.out.println("Rpc time: " + (System.currentTimeMillis() - t0) / 1000.0);
} else {
try {
sConnection.send(sConnection.peer().node(), new OtpErlangString("unknown request"));
} catch (IOException ex) {
Logger.getLogger(RpcNode.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
};
execService.execute(task);
if (flag[0] == -1) {
System.out.println("Exited");
break;
}
} catch (OtpErlangExit ex) {
Logger.getLogger(RpcNode.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(RpcNode.class.getName()).log(Level.SEVERE, null, ex);
} catch (OtpAuthException ex) {
Logger.getLogger(RpcNode.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
protected void sendRpcResult(RpcMsg call, OtpErlangAtom head, OtpErlangObject result) throws IOException {
OtpErlangTuple tResult = new OtpErlangTuple(new OtpErlangObject[] {head, result});
// Should specify call.tag here
OtpErlangTuple msg = new OtpErlangTuple(new OtpErlangObject[]{call.tag, tResult});
// Should specify call.to here
sConnection.send(call.to, msg, 1024 * 1024 * 10);
}
public abstract int processRpcCall(RpcMsg call);
// ------ helper
public static String getShortLocalHost() {
return getLocalHost(false);
}
public static String getLongLocalHost() {
return getLocalHost(true);
}
private static String getLocalHost(boolean longName) {
String localHost;
try {
localHost = InetAddress.getLocalHost().getHostName();
if (!longName) {
/* Make sure it's a short name, i.e. strip of everything after first '.' */
int dot = localHost.indexOf(".");
if (dot != -1) {
localHost = localHost.substring(0, dot);
}
}
} catch (UnknownHostException e) {
localHost = "localhost";
}
return localHost;
}
}
As you can see, the RpcNode is an abstract class, by implement int processRpcCall(RpcMsg call), you can get your what ever wanted features. For example:
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package net.lightpole.xmlnode;
import basexnode.Main;
import com.ericsson.otp.erlang.OtpErlangAtom;
import com.ericsson.otp.erlang.OtpErlangList;
import com.ericsson.otp.erlang.OtpErlangObject;
import com.ericsson.otp.erlang.OtpErlangString;
import java.io.IOException;
import net.lightpole.rpcnode.RpcMsg;
import net.lightpole.rpcnode.RpcNode;
/**
*
* @author dcaoyuan
*/
public class MyNode extends RpcNode {
public MyNode(String xnodeName, String cookie, int threadPoolSize) {
super(xnodeName, cookie, threadPoolSize);
}
@Override
public int processRpcCall(RpcMsg call) {
final String modStr = call.mod.atomValue();
final String funStr = call.fun.atomValue();
final OtpErlangList args = call.args;
try {
OtpErlangAtom head = ERROR;
OtpErlangObject result = null;
if (modStr.equals("xnode") && funStr.equals("stop")) {
head = OK;
sendRpcResult(call, head, STOPED);
return -1;
}
if (modStr.equals("System") && funStr.equals("currentTimeMillis")) {
head = OK;
long t = System.currentTimeMillis();
result = new OtpErlangLong(t);
} else {
result = new OtpErlangString("{undef,{" + modStr + "," + funStr + "}}");
}
if (result == null) {
result = new OtpErlangAtom("undefined");
}
sendRpcResult(call, head, result);
} catch (IOException ex) {
ex.printStackTrace();
} catch (Exception ex) {
}
return 0;
}
}
I tested MyNode by:
$ erl -sname clientnode -setcookie mycookie ... (clientnode@cmac)> rpc:call(xnodename@cmac, 'System', currentTimeMillis, []).
And you can try to test its concurrent performance by:
%% $ erl -sname clientnode -setcookie mycookie
%% > xnode_test:test(10000)
-module(xnode_test).
-export([test/1]).
test(ProcN) ->
Workers = [spawn_worker(self(), fun rpc_parse/1, {})
|| I <- lists:seq(0, ProcN - 1)],
Results = [wait_result(Worker) || Worker <- Workers].
rpc_parse({}) ->
rpc:call(xnodename@cmac, 'System', currentTimeMillis, []).
spawn_worker(Parent, F, A) ->
erlang:spawn_monitor(fun() -> Parent ! {self(), F(A)} end).
wait_result({Pid, Ref}) ->
receive
{'DOWN', Ref, _, _, normal} -> receive {Pid, Result} -> Result end;
{'DOWN', Ref, _, _, Reason} -> exit(Reason)
end.
I spawned 10000 calls to it, and it run smoothly.
I'm also considering to write a more general-purpose RPC server in Java, which can dynamically call any existed methods of Java class.
Posted at 06:59PM Oct 10, 2008 by dcaoyuan in Erlang | Comments[2]
Things To Do in Coming Months
As the beta of Scala for NetBeans released, I found I have several things to do in the coming months.
First, I'll keep the Scala plugins going on, I'll try to re-implement the Project supporting, which, may be an extension of current NetBeans' plain Java Project, that is, you just create plain JSE or JEE project, then add Scala source files to this project, you may mix Java/Scala in one project. Another perception is, it's time to re-write whole things in Scala itself? I have a featured Scala IDE now, or, the chicken, I should make eggs via this chicken instead of duck.
Second, we get some contracts on mobile application for Banking, which, will be implemented via our current Atom/Atom Publish Protocol web service platform. The platform is written in Erlang, but, with more and more business logical requirements, maybe we should consider some Scala things?
Third, oh, it's about AIOTrade, I'v left it at corner for almost one and half year, I said it would be re-written in Scala someday, I really hope I have time. I got some requests to support drawing charts for web application, it actually can, if you understand the source code, I just wrote an example recently, I may post an article on how to do that.
Posted at 10:30AM Sep 06, 2008 by dcaoyuan in Java | Comments[4]
Scala for Netbeans Beta Is Ready, Working with NetBeans 6.5 Beta
>>> Updated Aug 15:
For Windows Vista users:
There is a known bug #135547 that may have been fixed in trunk but not for NetBeans 6.5 Beta, which causes exception of "NullPointerException at org.openide.filesystems.FileUtil.normalizeFileOnWindows" when create Scala project. If you are Vista user and like to have a try on Scala plugins, you may need to download a recent nightly build version of NetBeans. Since I have none Vista environment, I'm not sure about above message.
======
I'm pleased to announce that the first beta of Scala for NetBeans is released, followed NetBeans 6.5 beta releasing. The availability and installation instructions can be found at http://wiki.netbeans.org/Scala.
Features:
- Full featured Scala editor
- syntax and semantic coloring
- outline navigator
- code folding
- mark occurrences
- go to declaration
- instant rename
- indentation
- formatting
- pair matching
- error annotations
- code completion
- Project management (build/run/debug project)
- Debugger
- Interactive console
- JUnit integration
- Maven integration (works with Lift Web Framework)
There are some known issues. Bug reports are welcome.
Installation on NetBeans 6.5 beta:
- Get the NetBeans 6.5 beta or later version from: http://download.netbeans.org/netbeans/6.5/beta/
- Get the Scala plugins beta binary from: http://plugins.netbeans.org/PluginPortal/faces/PluginDetailPage.jsp?pluginid=11854
- Unzip Scala plugin binary to somewhere
- Open NetBeans, go to "Tools" -> "Plugins", click on "Downloaded" tab title, click on "Add Plugins..." button, choose the directory where the Scala plugins are unzipped, select all listed *.nbm files, following the instructions. Restart IDE.
Posted at 01:53AM Aug 14, 2008 by dcaoyuan in NetBeans | Comments[11]
Run/Debug Lift Web App Using Scala/Maven Plugin for NetBeans
I'm a newbie to Maven, so I encountered some issues when run/debug Lift apps. The following are tips that I got, it may not be perfect, but at least work.
1. When pom.xml is changed, and classes not found errors happen on editor, you can close and reopen the project
This is a known issue, that I didn't refresh compiling context when pom.xml changed, thus the classpath dependency may be not refreshed at once, I'll fix this issue in the near future.2. Run project by external Maven instead of embedded Maven of NetBeans plugin
I encountered "java.lang.NoClassDefFoundError org/codehaus/plexus/util/DirectoryScanner" when use embedded NetBeans Maven plugin (3.1.3) when invoke "Run" project, but fortunately, you can custom the binding actions in NetBeans Maven. The steps are:- Right click project node, choose "Properties"
- Click on "Actions" in left-pane, choose "Use external Maven for build execution", and "set external Maven home"
- Choose "Run project" in right-pane, input "jetty:run"
- Choose "Debug project" in right-pane, input "jetty:run"
3. How to debug project
I'm a bit stupid here, since I don't like to change MAVEN_OPTS frequently. So I choose to do:
$ cd $MAVEN_HOME$/bin $ cp mvn mvn.run $ cp mvnDebug mvn
Then I invoke "Debug" action from NetBeans toolbar, and get NetBeans' output window saying:
WARNING: You are running Maven builds externally, some UI functionality will not be available. Executing:/Users/dcaoyuan/apps/apache-maven-2.0.9/bin/mvn jetty:run Preparing to Execute Maven in Debug Mode Listening for transport dt_socket at address: 8000
Open menu "Debug" -> "Attach Debugger...", in the popped window, for "Port:", input "8000". Everything goes smoothly then. You add/remove breakpoints just as you are doing for a regular Scala project.
Of course, if you want to turn back to "Run" from "Debug", you have to "cp mvn.run mvn" back.
Anybody can give me hints on how to get this setting simple? in NetBeans Maven plugin.
Here's a snapshot: (click to enlarge it)
Posted at 03:10PM Jul 29, 2008 by dcaoyuan in NetBeans | Comments[2]
Scala, NetBeans, Maven, and yes, Lift now
Per recent changes, Scala for NetBeans can live with Maven for NetBeans, and yes, Lift web framework.
The Maven for NetBeans has done an excellent work for Maven's project integration, with proper classpath supporting and indexing. So the Scala editor is well aware of auto-completion, types etc.
Here's a snapshot: (click to enlarge it)
To get above features, you have to download the latest NetBeans daily build, then install Scala's plugins and Maven plugins.
For Scala plugins, see http://wiki.netbeans.org/Scala; For Maven plugins, see http://wiki.netbeans.org/MavenBestPractices.
Posted at 08:18PM Jul 28, 2008 by dcaoyuan in NetBeans | Comments[2]
Implementation of Scala for NetBeans based on GSF
The Scala for NetBeans is under pre-beta stage, other than bug-fixes, I'm preparing some documentations for it too. If you are interested in how to write language supporting under GSF's framework, you can take a look at this working documentation.
Implementation of Scala for NetBeans
And also:
Proposal of Scala for NetBeans
Progressing of Scala for NetBeans
Posted at 10:54AM Jul 26, 2008 by dcaoyuan in NetBeans | Comments[1]
Scala for NetBeans Screenshot#12: JUnit integration
There is a Scala JUnit Test template in Scala for NetBeans now, you can create Scala JUnit testing and run testing, see testing result.
Here is an example test file:
/*
* DogTest.scala
*
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
*/
package scalajunit
import org.junit.After
import org.junit.Before
import org.junit.Test
import org.junit.Assert._
class DogTest {
@Before
def setUp() = {
}
@After
def tearDown() = {
}
@Test
def testHello() = {
val dog = new Dog()
dog.talk("Mr. Foo")
assert(true)
}
@Test
def testAdding() = {
assertEquals(4, 2 + 3)
}
}
To get JUnit working, upgrade to Scala Project Module version 1.2.14, and re-create a new project for exist old project (if there has been one). Under the "Test Packages", create your testing packages, right click on package node, select create "Scala JUnit Test".
To run tests, right-click on project node, choose "Test".
And also, the beta-release is feature frozen, I'll concentrate on bug-fixes in next 1-2 weeks, and get it ready for public release as beta.
Posted at 05:50PM Jul 25, 2008 by dcaoyuan in NetBeans |
