Java tutorial
/* * Mark Logic Interface to Java * * Copyright 2006 Jason Hunter * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * @author Jason Hunter * @version 1.0 * */ package com.xqdev.jam; import java.io.*; import java.util.*; import java.math.BigDecimal; import java.text.SimpleDateFormat; import javax.servlet.*; import javax.servlet.http.*; import javax.xml.datatype.*; import javax.xml.namespace.QName; import bsh.*; import org.apache.commons.codec.binary.*; import org.apache.commons.codec.DecoderException; /** * TODO: Decide if we want to alter the jam:start() behavior so * it connects to the server as a test. This has the benefit * that any server restart will HUP a client halfway through * something because the context will disappear rather than be * implicitly recreated to an empty state. * TODO: Consider adding a feature so jam:start() can provide a * user-specified stale-out duration for the context. */ public class MLJAM extends HttpServlet { private static HashMap<String, Interpreter> interpreters = new HashMap<String, Interpreter>(); // Need to retire interpreters after some period of inactivity. // Temporary interpreters (those w/ client assigned names) expire faster private static long lastClean = System.currentTimeMillis(); private static long CLEAN_INTERVAL = 5 * 60 * 1000; // five minutes private static long STALE_TIMEOUT = 60 * 60 * 1000; // one hour private static long TEMP_STALE_TIMEOUT = 60 * 60 * 1000; // ten minutes private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SZ"); /* public void init(ServletConfig config) throws ServletException { super.init(config); } */ private static Interpreter getInterpreter(String contextId) throws EvalError { // Get the appropriate interpreter Interpreter i = null; boolean createdInterp = false; synchronized (interpreters) { // serialize two gets of the same name i = interpreters.get(contextId); if (i == null) { i = new Interpreter(); interpreters.put(contextId, i); createdInterp = true; } } if (createdInterp) { Log.log("Created context: " + contextId + " (" + i + ")"); // Now configure stdin and stdout to capture 10k of content // Store references to the circular buffers within the interpreter itself. // This provides a nice place to store them plus theoretically allows // advanced use from within the bsh environment. // On Windows print() outputs \r\n but in XQuery that's normalized to \n // so the 10k of Java buffer may produce less than 10k of content in XQuery! OutputStream circularOutput = new CircularByteArrayOutputStream(10240); PrintStream printOutput = new PrintStream(circularOutput); i.setOut(printOutput); i.set("mljamout", circularOutput); OutputStream circularError = new CircularByteArrayOutputStream(10240); PrintStream printError = new PrintStream(circularError); i.setErr(printError); i.set("mljamerr", circularError); // Capture the built-in System.out and System.err also. // (Commented out since System appears global, can't do per interpreter.) //i.set("mljamprintout", printOutput); //i.set("mljamprinterr", printError); //i.eval("System.setOut(mljamprintout);"); //i.eval("System.setErr(mljamprinterr);"); // Need to expose hexdecode() and base64decode() built-in functions i.eval("hexdecode(String s) { return com.xqdev.jam.MLJAM.hexDecode(s); }"); i.eval("base64decode(String s) { return com.xqdev.jam.MLJAM.base64Decode(s); }"); // Let's tell the context what its id is i.set("mljamid", contextId); } // Update the last accessed time, used for cleaning i.set("mljamlast", System.currentTimeMillis()); // If it's been long enough, go snooping for stale contexts if (System.currentTimeMillis() > lastClean + CLEAN_INTERVAL) { Log.log("Initiated periodic scan for stale context objects"); lastClean = System.currentTimeMillis(); Iterator<Interpreter> itr = interpreters.values().iterator(); while (itr.hasNext()) { Interpreter interp = itr.next(); Long last = (Long) interp.get("mljamlast"); if (System.currentTimeMillis() > last + STALE_TIMEOUT) { itr.remove(); Log.log("Staled context: " + interp.get("mljamid") + " (" + interp + ")"); } else if ((System.currentTimeMillis() > last + TEMP_STALE_TIMEOUT) && ("" + interp.get("mljamid")).startsWith("temp:")) { itr.remove(); Log.log("Staled temp context: " + interp.get("mljamid") + " (" + interp + ")"); } } } return i; } private static void endInterpreter(String contextId) throws EvalError { Interpreter i = interpreters.get(contextId); if (i == null) return; i.eval("clear();"); // can't hurt to tell bsh to clean up internally interpreters.remove(contextId); // now wait for GC Log.log("Destroyed context: " + contextId + " (" + i + ")"); } private static String getBody(HttpServletRequest req) { try { // Try reading the post body using characters. // This might throw an exception if something on the // server side already called getInputStream(). // In that case we'll pull as bytes. Reader reader = null; try { reader = new BufferedReader(req.getReader()); } catch (IOException e) { reader = new BufferedReader(new InputStreamReader(req.getInputStream(), "UTF-8")); } StringBuffer sbuf = new StringBuffer(); char[] cbuf = new char[4096]; int count = 0; while ((count = reader.read(cbuf)) != -1) { sbuf.append(cbuf, 0, count); } return sbuf.toString(); } catch (IOException e2) { throw new ServerProblemException("IOException in reading POST body: " + e2.getMessage()); } } protected void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { doPost(req, res); } protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { try { // A good request looks like /mljam/contextid/verb?name=varname // The extra path info includes the context id and verb String extra = req.getPathInfo(); // "/contextid/verb" if (extra == null || extra.equals("")) { throw new ClientProblemException("Request requires a context id and verb in its extra path info"); } String[] parts = extra.split("/"); // { "", "contextid", "verb" } if (parts.length < 2) { throw new ClientProblemException("Request requires a context id and verb in its extra path info"); } else if (parts.length < 3) { throw new ClientProblemException("Request requires a verb in its extra path info"); } String contextId = parts[1]; String verb = parts[2]; String method = req.getMethod(); if (method.equalsIgnoreCase("get")) { // We have three GET verbs: get, get-stdout, get-stderr. // These are all idempotent, while the POST verbs aren't. The get // verb accept a "name" query string parameter. The get verb returns // either XQuery to evaluate (indicated by x-marklogic/xquery content type) // or a raw binary (indicated by an application/binary-encoded content type). if (verb.equalsIgnoreCase("get")) { String name = req.getParameter("name"); if (name == null || name.equals("")) { throw new ClientProblemException("The get verb requires a name parameter"); } Interpreter i = getInterpreter(contextId); Object o = i.get(name); if (o instanceof byte[]) { sendBinaryResponse(res, (byte[]) o); } else if (o instanceof String) { sendStringResponse(res, (String) o); } else { sendXQueryResponse(res, o); } } else if (verb.equalsIgnoreCase("get-stdout")) { Interpreter i = getInterpreter(contextId); i.getOut().flush(); CircularByteArrayOutputStream circ = (CircularByteArrayOutputStream) i.get("mljamout"); if (circ != null) { sendStringResponse(res, circ.toString()); circ.reset(); } else { throw new ServerProblemException("Could not fetch mljamout from interpreter context"); } } else if (verb.equalsIgnoreCase("get-stderr")) { Interpreter i = getInterpreter(contextId); i.getErr().flush(); CircularByteArrayOutputStream circ = (CircularByteArrayOutputStream) i.get("mljamerr"); if (circ != null) { sendStringResponse(res, circ.toString()); circ.reset(); } else { throw new ServerProblemException("Could not fetch mljamerr from interpreter context"); } } else { throw new ClientProblemException("Unrecognized GET verb: " + verb); } } else if (method.equalsIgnoreCase("post")) { // We have six POST verbs: eval, unset, end, source, set-string, and set-binary. // These are POST verbs because they aren't idempotent. // The set-string, set-binary, unset, and source verbs accept a "name" // query string parameter. The set-string and set-binary verbs accept // a value in their post body. The eval verb accepts code in its post body. if (verb.equalsIgnoreCase("set-string")) { String name = req.getParameter("name"); if (name == null || name.equals("")) { throw new ClientProblemException("The set-string verb requires a name parameter"); } String body = getBody(req); // a value of "" is legit Interpreter i = getInterpreter(contextId); i.unset(name); i.set(name, body); sendNoResponse(res); } else if (verb.equalsIgnoreCase("set-binary")) { String name = req.getParameter("name"); if (name == null || name.equals("")) { throw new ClientProblemException("The set-binary verb requires a name parameter"); } String body = getBody(req); // a value of "" is legit byte[] bodyBytes = hexDecode(body); // later could do this streaming for speed Interpreter i = getInterpreter(contextId); i.unset(name); i.set(name, bodyBytes); sendNoResponse(res); } else if (verb.equalsIgnoreCase("eval")) { String body = getBody(req); if (body == null || body.equals("")) { throw new ClientProblemException( "The eval verb requires a post body containing code to eval"); } Interpreter i = getInterpreter(contextId); i.eval(body); sendNoResponse(res); } else if (verb.equalsIgnoreCase("eval-get")) { String body = getBody(req); if (body == null || body.equals("")) { throw new ClientProblemException( "The eval-get verb requires a post body containing code to eval"); } Interpreter i = getInterpreter(contextId); Object o = i.eval(body); if (o instanceof byte[]) { sendBinaryResponse(res, (byte[]) o); } else if (o instanceof String) { sendStringResponse(res, (String) o); } else { sendXQueryResponse(res, o); } } else if (verb.equalsIgnoreCase("unset")) { String name = req.getParameter("name"); if (name == null || name.equals("")) { throw new ClientProblemException("The unset verb requires a name parameter"); } Interpreter i = getInterpreter(contextId); i.unset(name); sendNoResponse(res); } else if (verb.equalsIgnoreCase("end")) { endInterpreter(contextId); sendNoResponse(res); } else if (verb.equalsIgnoreCase("source")) { String name = req.getParameter("name"); if (name == null || name.equals("")) { throw new ClientProblemException("The source verb requires a name parameter"); } Interpreter i = getInterpreter(contextId); i.source(name); sendNoResponse(res); } else { throw new ClientProblemException("Unrecognized POST verb: " + verb); } } } catch (TargetError e) { Throwable target = e.getTarget(); Log.log(e); Log.log("Target: " + target); sendServerProblemResponse(res, target.getClass().getName() + ": " + target.getMessage() + " when executing Java code: " + e.getErrorText()); // include full trace? } catch (EvalError e) { Log.log(e); sendServerProblemResponse(res, e.getClass().getName() + ": " + e.getMessage()); // include full trace? } catch (ClientProblemException e) { Log.log(e); sendClientProblemResponse(res, e.getMessage()); } catch (ServerProblemException e) { Log.log(e); sendServerProblemResponse(res, e.getMessage()); } } private static String escapeSingleQuotes(String s) { return s.replaceAll("'", "''"); } public static byte[] hexDecode(String s) { try { return Hex.decodeHex(s.toCharArray()); } catch (DecoderException e) { throw new ClientProblemException("Hex content is not valid hex: " + e.getMessage() + ": " + s); } } private static String hexEncode(byte[] bytes) { return new String(Hex.encodeHex(bytes)); } public static byte[] base64Decode(String s) { try { return Base64.decodeBase64(s.getBytes("ISO-8859-1")); } catch (UnsupportedEncodingException e) { throw new ServerProblemException("Server does not recognize ISO-8859-1 encoding"); } } private static void sendClientProblemResponse(HttpServletResponse res, String s) throws IOException { // Commenting out the status code because we want the client to eval the error() call //res.setStatus(HttpServletResponse.SC_BAD_REQUEST); if (s != null && s.length() > 4096) { // Cap super long errors s = s.substring(0, 2048) + " ...[trimmed]... " + s.substring(s.length() - 2048); } res.setContentType("x-marklogic/xquery; charset=UTF-8"); Writer writer = res.getWriter(); writer.write("error('" + escapeSingleQuotes(s) + "')"); writer.flush(); } private static void sendServerProblemResponse(HttpServletResponse res, String s) throws IOException { // Commenting out the status code because we want the client to eval the error() call //res.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR); res.setContentType("x-marklogic/xquery; charset=UTF-8"); if (s != null && s.length() > 4096) { // Cap super long errors s = s.substring(0, 2048) + " ...[trimmed]... " + s.substring(s.length() - 2048); } Writer writer = res.getWriter(); writer.write("error('" + escapeSingleQuotes(s) + "')"); writer.flush(); } private static void sendNoResponse(HttpServletResponse res) { res.setStatus(HttpServletResponse.SC_NO_CONTENT); } private static void sendBinaryResponse(HttpServletResponse res, byte[] bytes) throws IOException { res.setContentType("application/binary-encoded"); OutputStream out = res.getOutputStream(); // care to handle errors later? out.write(bytes); out.flush(); } private static void sendStringResponse(HttpServletResponse res, String s) throws IOException { res.setContentType("text/plain; charset=UTF-8"); Writer w = res.getWriter(); w.write(s); w.flush(); } private static void sendXQueryResponse(HttpServletResponse res, Object o) throws IOException { // Make sure to leave the status code alone. It defaults to 200, but sometimes // callers of this method will have set it to a custom code. res.setContentType("x-marklogic/xquery; charset=UTF-8"); //res.setContentType("text/plain"); Writer writer = res.getWriter(); // care to handle errors later? if (o == null) { writer.write("()"); } else if (o instanceof byte[]) { writer.write("binary {'"); writer.write(hexEncode((byte[]) o)); writer.write("'}"); } else if (o instanceof Object[]) { Object[] arr = (Object[]) o; writer.write("("); for (int i = 0; i < arr.length; i++) { sendXQueryResponse(res, arr[i]); if (i + 1 < arr.length) writer.write(", "); } writer.write(")"); } else if (o instanceof String) { writer.write("'"); writer.write(escapeSingleQuotes(o.toString())); writer.write("'"); } else if (o instanceof Integer) { writer.write("xs:int("); writer.write(o.toString()); writer.write(")"); } else if (o instanceof Long) { writer.write("xs:integer("); writer.write(o.toString()); writer.write(")"); } else if (o instanceof Float) { Float flt = (Float) o; writer.write("xs:float("); if (flt.equals(Float.POSITIVE_INFINITY)) { writer.write("'INF'"); } else if (flt.equals(Float.NEGATIVE_INFINITY)) { writer.write("'-INF'"); } else if (flt.equals(Float.NaN)) { writer.write("fn:number(())"); // poor man's way to write NaN } else { writer.write(o.toString()); } writer.write(")"); } else if (o instanceof Double) { Double dbl = (Double) o; writer.write("xs:double("); if (dbl.equals(Double.POSITIVE_INFINITY)) { writer.write("'INF'"); } else if (dbl.equals(Double.NEGATIVE_INFINITY)) { writer.write("'-INF'"); } else if (dbl.equals(Double.NaN)) { writer.write("fn:number(())"); // poor man's way to write NaN } else { writer.write(o.toString()); } writer.write(")"); } else if (o instanceof Boolean) { writer.write("xs:boolean('"); writer.write(o.toString()); writer.write("')"); } else if (o instanceof BigDecimal) { writer.write("xs:decimal("); writer.write(o.toString()); writer.write(")"); } else if (o instanceof Date) { // We want something like: 2006-04-30T01:28:30.499-07:00 // We format to get: 2006-04-30T01:28:30.499-0700 // Then we add in the colon writer.write("xs:dateTime('"); String d = dateFormat.format((Date) o); writer.write(d.substring(0, d.length() - 2)); writer.write(":"); writer.write(d.substring(d.length() - 2)); writer.write("')"); } else if (o instanceof XMLGregorianCalendar) { XMLGregorianCalendar greg = (XMLGregorianCalendar) o; QName type = greg.getXMLSchemaType(); if (type.equals(DatatypeConstants.DATETIME)) { writer.write("xs:dateTime('"); } else if (type.equals(DatatypeConstants.DATE)) { writer.write("xs:date('"); } else if (type.equals(DatatypeConstants.TIME)) { writer.write("xs:time('"); } else if (type.equals(DatatypeConstants.GYEARMONTH)) { writer.write("xs:gYearMonth('"); } else if (type.equals(DatatypeConstants.GMONTHDAY)) { writer.write("xs:gMonthDay('"); } else if (type.equals(DatatypeConstants.GYEAR)) { writer.write("xs:gYear('"); } else if (type.equals(DatatypeConstants.GMONTH)) { writer.write("xs:gMonth('"); } else if (type.equals(DatatypeConstants.GDAY)) { writer.write("xs:gDay('"); } writer.write(greg.toXMLFormat()); writer.write("')"); } else if (o instanceof Duration) { Duration dur = (Duration) o; /* // The following fails on Xerces QName type = dur.getXMLSchemaType(); if (type.equals(DatatypeConstants.DURATION)) { writer.write("xs:duration('"); } else if (type.equals(DatatypeConstants.DURATION_DAYTIME)) { writer.write("xdt:dayTimeDuration('"); } else if (type.equals(DatatypeConstants.DURATION_YEARMONTH)) { writer.write("xdt:yearMonthDuration('"); } */ // If no years or months, must be DURATION_DAYTIME if (dur.getYears() == 0 && dur.getMonths() == 0) { writer.write("xdt:dayTimeDuration('"); } // If has years or months but nothing else, must be DURATION_YEARMONTH else if (dur.getDays() == 0 && dur.getHours() == 0 && dur.getMinutes() == 0 && dur.getSeconds() == 0) { writer.write("xdt:yearMonthDuration('"); } else { writer.write("xs:duration('"); } writer.write(dur.toString()); writer.write("')"); } else if (o instanceof org.jdom.Element) { org.jdom.Element elt = (org.jdom.Element) o; writer.write("xdmp:unquote('"); // Because "<" in XQuery is the same as "<" I need to double escape any ampersands writer.write(new org.jdom.output.XMLOutputter().outputString(elt).replaceAll("&", "&") .replaceAll("'", "''")); writer.write("')/*"); // make sure to return the root elt } else if (o instanceof org.jdom.Document) { org.jdom.Document doc = (org.jdom.Document) o; writer.write("xdmp:unquote('"); writer.write(new org.jdom.output.XMLOutputter().outputString(doc).replaceAll("&", "&") .replaceAll("'", "''")); writer.write("')"); } else if (o instanceof org.jdom.Text) { org.jdom.Text text = (org.jdom.Text) o; writer.write("text {'"); writer.write(escapeSingleQuotes(text.getText())); writer.write("'}"); } else if (o instanceof org.jdom.Attribute) { // <fake xmlns:pref="http://uri.com" pref:attrname="attrvalue"/>/@*:attrname // <fake xmlns="http://uri.com" attrname="attrvalue"/>/@*:attrname org.jdom.Attribute attr = (org.jdom.Attribute) o; writer.write("<fake xmlns"); if ("".equals(attr.getNamespacePrefix())) { writer.write("=\""); } else { writer.write(":" + attr.getNamespacePrefix() + "=\""); } writer.write(attr.getNamespaceURI()); writer.write("\" "); writer.write(attr.getQualifiedName()); writer.write("=\""); writer.write(escapeSingleQuotes(attr.getValue())); writer.write("\"/>/@*:"); writer.write(attr.getName()); } else if (o instanceof org.jdom.Comment) { org.jdom.Comment com = (org.jdom.Comment) o; writer.write("comment {'"); writer.write(escapeSingleQuotes(com.getText())); writer.write("'}"); } else if (o instanceof org.jdom.ProcessingInstruction) { org.jdom.ProcessingInstruction pi = (org.jdom.ProcessingInstruction) o; writer.write("processing-instruction "); writer.write(pi.getTarget()); writer.write(" {'"); writer.write(escapeSingleQuotes(pi.getData())); writer.write("'}"); } else if (o instanceof QName) { QName q = (QName) o; writer.write("fn:expanded-QName('"); writer.write(escapeSingleQuotes(q.getNamespaceURI())); writer.write("','"); writer.write(q.getLocalPart()); writer.write("')"); } else { writer.write("error('XQuery tried to retrieve unsupported type: " + o.getClass().getName() + "')"); } writer.flush(); } } class CircularByteArrayOutputStream extends OutputStream { protected byte buf[]; protected int position = 0; protected boolean wrapped = false; public CircularByteArrayOutputStream(int maxSize) { buf = new byte[maxSize]; } public synchronized void write(int b) { buf[position] = (byte) b; position++; if (position == buf.length) { position = 0; wrapped = true; } } public byte[] toByteArray() { byte[] newBuf = null; if (!wrapped) { // We haven't wrapped yet so copy up to the current position newBuf = new byte[position]; System.arraycopy(buf, 0, newBuf, 0, position); } else { // We'll have wrapped, so it's a two step process. // Copy everything following the position, then everything before newBuf = new byte[buf.length]; // "position" is where we'd write next so it's the oldest byte. // So copy starting there for as many as are between there and the end. System.arraycopy(buf, position, newBuf, 0, (buf.length - position)); // Now copy starting at 0, placing into the end of the last copy, up to position. System.arraycopy(buf, 0, newBuf, (buf.length - position), position); } return newBuf; } public String toString() { // We don't specify a charset since we assume the // console received bytes in the default platform encoding. return new String(toByteArray()); } public void reset() { // Fetching resets the circular buffer position = 0; wrapped = false; } } class ClientProblemException extends RuntimeException { ClientProblemException(String s) { super(s); } } class ServerProblemException extends RuntimeException { ServerProblemException(String s) { super(s); } }