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Stanford Parser processes raw text in English, Chinese, German, Arabic, and French, and extracts constituency parse trees.
package edu.stanford.nlp.parser.server;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Collection;
import java.util.List;
import edu.stanford.nlp.ling.CoreLabel;
import edu.stanford.nlp.ling.HasWord;
import edu.stanford.nlp.parser.common.ParserGrammar;
import edu.stanford.nlp.parser.lexparser.LexicalizedParser;
import edu.stanford.nlp.parser.lexparser.TreeBinarizer;
import edu.stanford.nlp.trees.GrammaticalStructure;
import edu.stanford.nlp.trees.Tree;
import edu.stanford.nlp.trees.TypedDependency;
import edu.stanford.nlp.util.Filters;
/**
* Serves requests to the given parser model on the given port.
* See processRequest for a description of the query formats that are
* handled.
*/
public class LexicalizedParserServer {
final int port;
final ServerSocket serverSocket;
final ParserGrammar parser;
final TreeBinarizer binarizer;
//static final Charset utf8Charset = Charset.forName("utf-8");
boolean stillRunning = true;
public LexicalizedParserServer(int port, String parserModel)
throws IOException
{
this(port, loadModel(parserModel, null));
}
public LexicalizedParserServer(int port, String parserModel, String taggerModel)
throws IOException
{
this(port, loadModel(parserModel, taggerModel));
}
public LexicalizedParserServer(int port, ParserGrammar parser)
throws IOException
{
this.port = port;
this.serverSocket = new ServerSocket(port);
this.parser = parser;
this.binarizer = TreeBinarizer.simpleTreeBinarizer(parser.getTLPParams().headFinder(), parser.treebankLanguagePack());
}
private static ParserGrammar loadModel(String parserModel, String taggerModel) {
ParserGrammar model;
if (taggerModel == null) {
model = ParserGrammar.loadModel(parserModel);
} else {
model = ParserGrammar.loadModel(parserModel, "-preTag", "-taggerSerializedFile", taggerModel);
// preload tagger so the first query doesn't take forever
model.loadTagger();
}
model.setOptionFlags(model.defaultCoreNLPFlags());
return model;
}
/**
* Runs in a loop, getting requests from new clients until a client
* tells us to exit.
*/
public void listen()
throws IOException
{
while (stillRunning) {
Socket clientSocket = null;
try {
clientSocket = serverSocket.accept();
System.err.println("Got a connection");
processRequest(clientSocket);
System.err.println("Goodbye!");
System.err.println();
} catch (IOException e) {
// accidental multiple closes don't seem to have any bad effect
clientSocket.close();
System.err.println(e);
continue;
}
}
serverSocket.close();
}
// TODO: handle multiple requests in one connection? why not?
/**
* Possible commands are of the form:
* quit
* parse query: returns a String of the parsed query
* tree query: returns a serialized Tree of the parsed query
*/
public void processRequest(Socket clientSocket)
throws IOException
{
BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream(), "utf-8"));
String line = reader.readLine();
System.err.println(line);
if (line == null)
return;
line = line.trim();
String[] pieces = line.split(" ", 2);
String[] commandPieces = pieces[0].split(":", 2);
String command = commandPieces[0];
String commandArgs = "";
if (commandPieces.length > 1) {
commandArgs = commandPieces[1];
}
String arg = null;
if (pieces.length > 1) {
arg = pieces[1];
}
System.err.println("Got the command " + command);
if (arg != null) {
System.err.println(" ... with argument " + arg);
}
switch (command) {
case "quit":
handleQuit();
break;
case "parse":
handleParse(arg, clientSocket.getOutputStream(), commandArgs.equals("binarized"));
break;
case "dependencies":
handleDependencies(arg, clientSocket.getOutputStream(), commandArgs);
break;
case "tree":
handleTree(arg, clientSocket.getOutputStream());
break;
case "tokenize":
handleTokenize(arg, clientSocket.getOutputStream());
break;
case "lemma":
handleLemma(arg, clientSocket.getOutputStream());
break;
}
System.err.println("Handled request");
clientSocket.close();
}
/**
* Tells the server to exit.
*/
public void handleQuit() {
stillRunning = false;
}
public void handleTokenize(String arg, OutputStream outStream)
throws IOException
{
if (arg == null) {
return;
}
List tokens = parser.tokenize(arg);
OutputStreamWriter osw = new OutputStreamWriter(outStream, "utf-8");
for (int i = 0; i < tokens.size(); ++i) {
HasWord word = tokens.get(i);
if (i > 0) {
osw.write(" ");
}
osw.write(word.toString());
}
osw.write("\n");
osw.flush();
}
public void handleLemma(String arg, OutputStream outStream)
throws IOException
{
if (arg == null) {
return;
}
List tokens = parser.lemmatize(arg);
OutputStreamWriter osw = new OutputStreamWriter(outStream, "utf-8");
for (int i = 0; i < tokens.size(); ++i) {
CoreLabel word = tokens.get(i);
if (i > 0) {
osw.write(" ");
}
osw.write(word.lemma());
}
osw.write("\n");
osw.flush();
}
// TODO: when this method throws an exception (for whatever reason)
// a waiting client might hang. There should be some graceful
// handling of that.
public void handleDependencies(String arg, OutputStream outStream, String commandArgs)
throws IOException
{
Tree tree = parse(arg, false);
if (tree == null) {
return;
}
// TODO: this might throw an exception if the parser doesn't support dependencies. Handle that cleaner?
GrammaticalStructure gs = parser.getTLPParams().getGrammaticalStructure(tree, parser.treebankLanguagePack().punctuationWordRejectFilter(), parser.getTLPParams().typedDependencyHeadFinder());
Collection deps = null;
switch (commandArgs.toUpperCase()) {
case "COLLAPSED_TREE":
deps = gs.typedDependenciesCollapsedTree();
break;
default:
throw new UnsupportedOperationException("Dependencies type not implemented: " + commandArgs);
}
OutputStreamWriter osw = new OutputStreamWriter(outStream, "utf-8");
for (TypedDependency dep : deps) {
osw.write(dep.toString());
osw.write("\n");
}
osw.flush();
}
/**
* Returns the result of applying the parser to arg as a serialized tree.
*/
public void handleTree(String arg, OutputStream outStream)
throws IOException
{
Tree tree = parse(arg, false);
if (tree == null) {
return;
}
System.err.println(tree);
if (tree != null) {
ObjectOutputStream oos = new ObjectOutputStream(outStream);
oos.writeObject(tree);
oos.flush();
}
}
/**
* Returns the result of applying the parser to arg as a string.
*/
public void handleParse(String arg, OutputStream outStream, boolean binarized)
throws IOException
{
Tree tree = parse(arg, binarized);
if (tree == null) {
return;
}
System.err.println(tree);
if (tree != null) {
OutputStreamWriter osw = new OutputStreamWriter(outStream, "utf-8");
osw.write(tree.toString());
osw.write("\n");
osw.flush();
}
}
private Tree parse(String arg, boolean binarized) {
if (arg == null) {
return null;
}
Tree tree = parser.parse(arg);
if (binarized) {
tree = binarizer.transformTree(tree);
}
return tree;
}
private static void help() {
System.err.println("-help: display this message");
System.err.println("-model: load this parser (default englishPCFG.ser.gz)");
System.err.println("-tagger: pretag with this tagger model");
System.err.println("-port: run on this port (default 4466)");
}
static final int DEFAULT_PORT = 4466;
public static void main(String[] args)
throws IOException
{
System.setOut(new PrintStream(System.out, true, "utf-8"));
System.setErr(new PrintStream(System.err, true, "utf-8"));
int port = DEFAULT_PORT;
String model = LexicalizedParser.DEFAULT_PARSER_LOC;
String tagger = null;
// TODO: rewrite this a bit to allow for passing flags to the parser
for (int i = 0; i < args.length; i += 2) {
if (i + 1 >= args.length) {
System.err.println("Unspecified argument " + args[i]);
System.exit(2);
}
String arg = args[i];
if (arg.startsWith("--")) {
arg = arg.substring(2);
} else if (arg.startsWith("-")) {
arg = arg.substring(1);
}
if (arg.equalsIgnoreCase("model")) {
model = args[i + 1];
} else if (arg.equalsIgnoreCase("port")) {
port = Integer.valueOf(args[i + 1]);
} else if (arg.equalsIgnoreCase("tagger")) {
tagger = args[i + 1];
} else if (arg.equalsIgnoreCase("help")) {
help();
System.exit(0);
}
}
LexicalizedParserServer server = new LexicalizedParserServer(port, model, tagger);
System.err.println("Server ready!");
server.listen();
}
}