lib/java/src/protocol/TJSONProtocol.java

// Copyright (c) 2006- Facebook
// Distributed under the Thrift Software License
//
// See accompanying file LICENSE or visit the Thrift site at:
// http://developers.facebook.com/thrift/

package com.facebook.thrift.protocol;

import com.facebook.thrift.TException;
import com.facebook.thrift.TByteArrayOutputStream;
import com.facebook.thrift.transport.TTransport;
import java.io.UnsupportedEncodingException;
import java.util.Stack;

/**
 * JSON protocol implementation for thrift.
 *
 * This is a full-featured protocol supporting write and read.
 *
 * Please see the C++ class header for a detailed description of the
 * protocol's wire format.
 *
 * @author Chad Walters <chad@powerset.com>
 */
public class TJSONProtocol extends TProtocol {

  /**
   * Factory for JSON protocol objects
   */
  public static class Factory implements TProtocolFactory {

    public TProtocol getProtocol(TTransport trans) {
      return new TJSONProtocol(trans);
    }

  }

  private static final byte[] COMMA = new byte[] {','};
  private static final byte[] COLON = new byte[] {':'};
  private static final byte[] LBRACE = new byte[] {'{'};
  private static final byte[] RBRACE = new byte[] {'}'};
  private static final byte[] LBRACKET = new byte[] {'['};
  private static final byte[] RBRACKET = new byte[] {']'};
  private static final byte[] QUOTE = new byte[] {'"'};
  private static final byte[] BACKSLASH = new byte[] {'\\'};
  private static final byte[] ZERO = new byte[] {'0'};

  private static final byte[] ESCSEQ = new byte[] {'\\','u','0','0'};

  private static final long  VERSION = 1;

  private static final byte[] JSON_CHAR_TABLE = {
    /*  0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F */
    0,  0,  0,  0,  0,  0,  0,  0,'b','t','n',  0,'f','r',  0,  0, // 0
    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, // 1
    1,  1,'"',  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1, // 2
  };

  private static final String ESCAPE_CHARS = "\"\\bfnrt";

  private static final byte[] ESCAPE_CHAR_VALS = {
    '"', '\\', '\b', '\f', '\n', '\r', '\t',
  };

  private static final int  DEF_STRING_SIZE = 16;

  private static final byte[] NAME_BOOL = new byte[] {'t', 'f'};
  private static final byte[] NAME_BYTE = new byte[] {'i','8'};
  private static final byte[] NAME_I16 = new byte[] {'i','1','6'};
  private static final byte[] NAME_I32 = new byte[] {'i','3','2'};
  private static final byte[] NAME_I64 = new byte[] {'i','6','4'};
  private static final byte[] NAME_DOUBLE = new byte[] {'d','b','l'};
  private static final byte[] NAME_STRUCT = new byte[] {'r','e','c'};
  private static final byte[] NAME_STRING = new byte[] {'s','t','r'};
  private static final byte[] NAME_MAP = new byte[] {'m','a','p'};
  private static final byte[] NAME_LIST = new byte[] {'l','s','t'};
  private static final byte[] NAME_SET = new byte[] {'s','e','t'};

  private static final byte[] getTypeNameForTypeID(byte typeID)
    throws TException {
    switch (typeID) {
    case TType.BOOL:
      return NAME_BOOL;
    case TType.BYTE:
      return NAME_BYTE;
    case TType.I16:
      return NAME_I16;
    case TType.I32:
      return NAME_I32;
    case TType.I64:
      return NAME_I64;
    case TType.DOUBLE:
      return NAME_DOUBLE;
    case TType.STRING:
      return NAME_STRING;
    case TType.STRUCT:
      return NAME_STRUCT;
    case TType.MAP:
      return NAME_MAP;
    case TType.SET:
      return NAME_SET;
    case TType.LIST:
      return NAME_LIST;
    default:
      throw new TProtocolException(TProtocolException.NOT_IMPLEMENTED,
                                   "Unrecognized type");
    }
  }

  private static final byte getTypeIDForTypeName(byte[] name)
    throws TException {
    byte result = TType.STOP;
    if (name.length > 1) {
      switch (name[0]) {
      case 'd':
        result = TType.DOUBLE;
        break;
      case 'i':
        switch (name[1]) {
        case '8':
          result = TType.BYTE;
          break;
        case '1':
          result = TType.I16;
          break;
        case '3':
          result = TType.I32;
          break;
        case '6':
          result = TType.I64;
          break;
        }
        break;
      case 'l':
        result = TType.LIST;
        break;
      case 'm':
        result = TType.MAP;
        break;
      case 'r':
        result = TType.STRUCT;
        break;
      case 's':
        if (name[1] == 't') {
          result = TType.STRING;
        }
        else if (name[1] == 'e') {
          result = TType.SET;
        }
        break;
      case 't':
        result = TType.BOOL;
        break;
      }
    }
    if (result == TType.STOP) {
      throw new TProtocolException(TProtocolException.NOT_IMPLEMENTED,
                                   "Unrecognized type");
    }
    return result;
  }

  // Base class for tracking JSON contexts that may require inserting/reading
  // additional JSON syntax characters
  // This base context does nothing.
  protected class JSONBaseContext {
    protected void write() throws TException {}

    protected void read() throws TException {}

    protected boolean escapeNum() { return false; }
  }

  // Context for JSON lists. Will insert/read commas before each item except
  // for the first one
  protected class JSONListContext extends JSONBaseContext {
    private boolean first_ = true;

    @Override
    protected void write() throws TException {
      if (first_) {
        first_ = false;
      } else {
        trans_.write(COMMA);
      }
    }

    @Override
    protected void read() throws TException {
      if (first_) {
        first_ = false;
      } else {
        readJSONSyntaxChar(COMMA);
      }
    }
  }

  // Context for JSON records. Will insert/read colons before the value portion
  // of each record pair, and commas before each key except the first. In
  // addition, will indicate that numbers in the key position need to be
  // escaped in quotes (since JSON keys must be strings).
  protected class JSONPairContext extends JSONBaseContext {
    private boolean first_ = true;
    private boolean colon_ = true;

    @Override
    protected void write() throws TException {
      if (first_) {
        first_ = false;
        colon_ = true;
      } else {
        trans_.write(colon_ ? COLON : COMMA);
        colon_ = !colon_;
      }
    }

    @Override
    protected void read() throws TException {
      if (first_) {
        first_ = false;
        colon_ = true;
      } else {
        readJSONSyntaxChar(colon_ ? COLON : COMMA);
        colon_ = !colon_;
      }
    }

    @Override
    protected boolean escapeNum() {
      return colon_;
    }
  }

  // Holds up to one byte from the transport
  protected class LookaheadReader {

    private boolean hasData_;
    private byte[] data_ = new byte[1];

    // Return and consume the next byte to be read, either taking it from the
    // data buffer if present or getting it from the transport otherwise.
    protected byte read() throws TException {
      if (hasData_) {
        hasData_ = false;
      }
      else {
        trans_.readAll(data_, 0, 1);
      }
      return data_[0];
    }

    // Return the next byte to be read without consuming, filling the data
    // buffer if it has not been filled already.
    protected byte peek() throws TException {
      if (!hasData_) {
        trans_.readAll(data_, 0, 1);
      }
      hasData_ = true;
      return data_[0];
    }
  }

  // Stack of nested contexts that we may be in
  private Stack<JSONBaseContext> contextStack_ = new Stack<JSONBaseContext>();

  // Current context that we are in
  private JSONBaseContext context_ = new JSONBaseContext();

  // Reader that manages a 1-byte buffer
  private LookaheadReader reader_ = new LookaheadReader();

  // Push a new JSON context onto the stack.
  private void pushContext(JSONBaseContext c) {
    contextStack_.push(context_);
    context_ = c;
  }

  // Pop the last JSON context off the stack
  private void popContext() {
    context_ = contextStack_.pop();
  }

  /**
   * Constructor
   */
  public TJSONProtocol(TTransport trans) {
    super(trans);
  }

  // Temporary buffer used by several methods
  private byte[] tmpbuf_ = new byte[4];

  // Read a byte that must match b[0]; otherwise an excpetion is thrown.
  // Marked protected to avoid synthetic accessor in JSONListContext.read
  // and JSONPairContext.read
  protected void readJSONSyntaxChar(byte[] b) throws TException {
    byte ch = reader_.read();
    if (ch != b[0]) {
      throw new TProtocolException(TProtocolException.INVALID_DATA,
                                   "Unexpected character:" + (char)ch);
    }
  }

  // Convert a byte containing a hex char ('0'-'9' or 'a'-'f') into its
  // corresponding hex value
  private static final byte hexVal(byte ch) throws TException {
    if ((ch >= '0') && (ch <= '9')) {
      return (byte)((char)ch - '0');
    }
    else if ((ch >= 'a') && (ch <= 'f')) {
      return (byte)((char)ch - 'a');
    }
    else {
      throw new TProtocolException(TProtocolException.INVALID_DATA,
                                   "Expected hex character");
    }
  }

  // Convert a byte containing a hex value to its corresponding hex character
  private static final byte hexChar(byte val) {
    val &= 0x0F;
    if (val < 10) {
      return (byte)((char)val + '0');
    }
    else {
      return (byte)((char)val + 'a');
    }
  }

  // Write the bytes in array buf as a JSON characters, escaping as needed
  private void writeJSONString(byte[] b) throws TException {
    context_.write();
    trans_.write(QUOTE);
    int len = b.length;
    for (int i = 0; i < len; i++) {
      if ((b[i] & 0x00FF) >= 0x30) {
        if (b[i] == BACKSLASH[0]) {
          trans_.write(BACKSLASH);
          trans_.write(BACKSLASH);
        }
        else {
          trans_.write(b, i, 1);
        }
      }
      else {
        tmpbuf_[0] = JSON_CHAR_TABLE[b[i]];
        if (tmpbuf_[0] == 1) {
          trans_.write(b, i, 1);
        }
        else if (tmpbuf_[0] > 1) {
          trans_.write(BACKSLASH);
          trans_.write(tmpbuf_, 0, 1);
        }
        else {
          trans_.write(ESCSEQ);
          tmpbuf_[0] = hexChar((byte)(b[i] >> 4));
          tmpbuf_[1] = hexChar(b[i]);
          trans_.write(tmpbuf_, 0, 2);
        }
      }
    }
    trans_.write(QUOTE);
  }

  // Write out number as a JSON value. If the context dictates so, it will be
  // wrapped in quotes to output as a JSON string.
  private void writeJSONInteger(long num) throws TException {
    context_.write();
    String str = Long.toString(num);
    boolean escapeNum = context_.escapeNum();
    if (escapeNum) {
      trans_.write(QUOTE);
    }
    try {
      byte[] buf = str.getBytes("UTF-8");
      trans_.write(buf);
    } catch (UnsupportedEncodingException uex) {
      throw new TException("JVM DOES NOT SUPPORT UTF-8");
    }
    if (escapeNum) {
      trans_.write(QUOTE);
    }
  }

  // Write out a double as a JSON value. If it is NaN or infinity or if the
  // context dictates escaping, write out as JSON string.
  private void writeJSONDouble(double num) throws TException {
    context_.write();
    String str = Double.toString(num);
    boolean special = false;
    switch (str.charAt(0)) {
    case 'N': // NaN
    case 'I': // Infinity
      special = true;
      break;
    case '-':
      if (str.charAt(1) == 'I') { // -Infinity
        special = true;
      }
      break;
    }

    boolean escapeNum = special || context_.escapeNum();
    if (escapeNum) {
      trans_.write(QUOTE);
    }
    try {
      byte[] b = str.getBytes("UTF-8");
      trans_.write(b, 0, b.length);
    } catch (UnsupportedEncodingException uex) {
      throw new TException("JVM DOES NOT SUPPORT UTF-8");
    }
    if (escapeNum) {
      trans_.write(QUOTE);
    }
  }

  // Write out contents of byte array b as a JSON string with base-64 encoded
  // data
  private void writeJSONBase64(byte[] b) throws TException {
    context_.write();
    trans_.write(QUOTE);
    int len = b.length;
    int off = 0;
    while (len >= 3) {
      // Encode 3 bytes at a time
      TBase64Utils.encode(b, off, 3, tmpbuf_, 0);
      trans_.write(tmpbuf_, 0, 4);
      off += 3;
      len -= 3;
    }
    if (len > 0) {
      // Encode remainder
      TBase64Utils.encode(b, off, len, tmpbuf_, 0);
      trans_.write(tmpbuf_, 0, len + 1);
    }
    trans_.write(QUOTE);
  }

  private void writeJSONObjectStart() throws TException {
    context_.write();
    trans_.write(LBRACE);
    pushContext(new JSONPairContext());
  }

  private void writeJSONObjectEnd() throws TException {
    popContext();
    trans_.write(RBRACE);
  }

  private void writeJSONArrayStart() throws TException {
    context_.write();
    trans_.write(LBRACKET);
    pushContext(new JSONListContext());
  }

  private void writeJSONArrayEnd() throws TException {
    popContext();
    trans_.write(RBRACKET);
  }

  @Override
  public void writeMessageBegin(TMessage message) throws TException {
    writeJSONArrayStart();
    writeJSONInteger(VERSION);
    try {
      byte[] b = message.name.getBytes("UTF-8");
      writeJSONString(b);
    } catch (UnsupportedEncodingException uex) {
      throw new TException("JVM DOES NOT SUPPORT UTF-8");
    }
    writeJSONInteger(message.type);
    writeJSONInteger(message.seqid);
  }

  @Override
  public void writeMessageEnd() throws TException {
    writeJSONArrayEnd();
  }

  @Override
  public void writeStructBegin(TStruct struct) throws TException {
    writeJSONObjectStart();
  }

  @Override
  public void writeStructEnd() throws TException {
    writeJSONObjectEnd();
  }

  @Override
  public void writeFieldBegin(TField field) throws TException {
    writeJSONInteger(field.id);
    writeJSONObjectStart();
    writeJSONString(getTypeNameForTypeID(field.type));
  }

  @Override
  public void writeFieldEnd() throws TException {
    writeJSONObjectEnd();
  }

  @Override
  public void writeFieldStop() {}

  @Override
  public void writeMapBegin(TMap map) throws TException {
    writeJSONArrayStart();
    writeJSONString(getTypeNameForTypeID(map.keyType));
    writeJSONString(getTypeNameForTypeID(map.valueType));
    writeJSONInteger(map.size);
    writeJSONObjectStart();
  }

  @Override
  public void writeMapEnd() throws TException {
    writeJSONObjectEnd();
    writeJSONArrayEnd();
  }

  @Override
  public void writeListBegin(TList list) throws TException {
    writeJSONArrayStart();
    writeJSONString(getTypeNameForTypeID(list.elemType));
    writeJSONInteger(list.size);
  }

  @Override
  public void writeListEnd() throws TException {
    writeJSONArrayEnd();
  }

  @Override
  public void writeSetBegin(TSet set) throws TException {
    writeJSONArrayStart();
    writeJSONString(getTypeNameForTypeID(set.elemType));
    writeJSONInteger(set.size);
  }

  @Override
  public void writeSetEnd() throws TException {
    writeJSONArrayEnd();
  }

  @Override
  public void writeBool(boolean b) throws TException {
    writeJSONInteger(b ? (long)1 : (long)0);
  }

  @Override
  public void writeByte(byte b) throws TException {
    writeJSONInteger((long)b);
  }

  @Override
  public void writeI16(short i16) throws TException {
    writeJSONInteger((long)i16);
  }

  @Override
  public void writeI32(int i32) throws TException {
    writeJSONInteger((long)i32);
  }

  @Override
  public void writeI64(long i64) throws TException {
    writeJSONInteger(i64);
  }

  @Override
  public void writeDouble(double dub) throws TException {
    writeJSONDouble(dub);
  }

  @Override
  public void writeString(String str) throws TException {
    try {
      byte[] b = str.getBytes("UTF-8");
      writeJSONString(b);
    } catch (UnsupportedEncodingException uex) {
      throw new TException("JVM DOES NOT SUPPORT UTF-8");
    }
  }

  @Override
  public void writeBinary(byte[] bin) throws TException {
    writeJSONBase64(bin);
  }

  /**
   * Reading methods.
   */

  // Read in a JSON string, unescaping as appropriate.. Skip reading from the
  // context if skipContext is true.
  private TByteArrayOutputStream readJSONString(boolean skipContext)
    throws TException {
    TByteArrayOutputStream arr = new TByteArrayOutputStream(DEF_STRING_SIZE);
    if (!skipContext) {
      context_.read();
    }
    readJSONSyntaxChar(QUOTE);
    while (true) {
      byte ch = reader_.read();
      if (ch == QUOTE[0]) {
        break;
      }
      if (ch == ESCSEQ[0]) {
        ch = reader_.read();
        if (ch == ESCSEQ[1]) {
          readJSONSyntaxChar(ZERO);
          readJSONSyntaxChar(ZERO);
          trans_.readAll(tmpbuf_, 0, 2);
          ch = (byte)((hexVal((byte)tmpbuf_[0]) << 4) + hexVal(tmpbuf_[1]));
        }
        else {
          int off = ESCAPE_CHARS.indexOf(ch);
          if (off == -1) {
            throw new TProtocolException(TProtocolException.INVALID_DATA,
                                         "Expected control char");
          }
          ch = ESCAPE_CHAR_VALS[off];
        }
      }
      arr.write(ch);
    }
    return arr;
  }

  // Return true if the given byte could be a valid part of a JSON number.
  private boolean isJSONNumeric(byte b) {
    switch (b) {
    case '+':
    case '-':
    case '.':
    case '0':
    case '1':
    case '2':
    case '3':
    case '4':
    case '5':
    case '6':
    case '7':
    case '8':
    case '9':
    case 'E':
    case 'e':
      return true;
    }
    return false;
  }

  // Read in a sequence of characters that are all valid in JSON numbers. Does
  // not do a complete regex check to validate that this is actually a number.
  private String readJSONNumericChars() throws TException {
    StringBuilder strbld = new StringBuilder();
    while (true) {
      byte ch = reader_.peek();
      if (!isJSONNumeric(ch)) {
        break;
      }
      strbld.append((char)reader_.read());
    }
    return strbld.toString();
  }

  // Read in a JSON number. If the context dictates, read in enclosing quotes.
  private long readJSONInteger() throws TException {
    context_.read();
    if (context_.escapeNum()) {
      readJSONSyntaxChar(QUOTE);
    }
    String str = readJSONNumericChars();
    if (context_.escapeNum()) {
      readJSONSyntaxChar(QUOTE);
    }
    try {
      return Long.valueOf(str);
    }
    catch (NumberFormatException ex) {
      throw new TProtocolException(TProtocolException.INVALID_DATA,
                                   "Bad data encounted in numeric data");
    }
  }

  // Read in a JSON double value. Throw if the value is not wrapped in quotes
  // when expected or if wrapped in quotes when not expected.
  private double readJSONDouble() throws TException {
    context_.read();
    if (reader_.peek() == QUOTE[0]) {
      TByteArrayOutputStream arr = readJSONString(true);
      try {
        double dub = Double.valueOf(arr.toString("UTF-8"));
        if (!context_.escapeNum() && !Double.isNaN(dub) &&
            !Double.isInfinite(dub)) {
          // Throw exception -- we should not be in a string in this case
          throw new TProtocolException(TProtocolException.INVALID_DATA,
                                       "Numeric data unexpectedly quoted");
        }
        return dub;
      }
      catch (UnsupportedEncodingException ex) {
        throw new TException("JVM DOES NOT SUPPORT UTF-8");
      }
    }
    else {
      if (context_.escapeNum()) {
        // This will throw - we should have had a quote if escapeNum == true
        readJSONSyntaxChar(QUOTE);
      }
      try {
        return Double.valueOf(readJSONNumericChars());
      }
      catch (NumberFormatException ex) {
        throw new TProtocolException(TProtocolException.INVALID_DATA,
                                     "Bad data encounted in numeric data");
      }
    }
  }

  // Read in a JSON string containing base-64 encoded data and decode it.
  private byte[] readJSONBase64() throws TException {
    TByteArrayOutputStream arr = readJSONString(false);
    byte[] b = arr.get();
    int len = arr.len();
    int off = 0;
    int size = 0;
    while (len >= 4) {
      // Decode 4 bytes at a time
      TBase64Utils.decode(b, off, 4, b, size); // NB: decoded in place
      off += 4;
      len -= 4;
      size += 3;
    }
    // Don't decode if we hit the end or got a single leftover byte (invalid
    // base64 but legal for skip of regular string type)
    if (len > 1) {
      // Decode remainder
      TBase64Utils.decode(b, off, len, b, size); // NB: decoded in place
      size += len - 1;
    }
    // Sadly we must copy the byte[] (any way around this?)
    byte [] result = new byte[size];
    System.arraycopy(b, 0, result, 0, size);
    return result;
  }

  private void readJSONObjectStart() throws TException {
    context_.read();
    readJSONSyntaxChar(LBRACE);
    pushContext(new JSONPairContext());
  }

  private void readJSONObjectEnd() throws TException {
    readJSONSyntaxChar(RBRACE);
    popContext();
  }

  private void readJSONArrayStart() throws TException {
    context_.read();
    readJSONSyntaxChar(LBRACKET);
    pushContext(new JSONListContext());
  }

  private void readJSONArrayEnd() throws TException {
    readJSONSyntaxChar(RBRACKET);
    popContext();
  }

  @Override
  public TMessage readMessageBegin() throws TException {
    TMessage message = new TMessage();
    readJSONArrayStart();
    if (readJSONInteger() != VERSION) {
      throw new TProtocolException(TProtocolException.BAD_VERSION,
                                   "Message contained bad version.");
    }
    try {
      message.name = readJSONString(false).toString("UTF-8");
    }
    catch (UnsupportedEncodingException ex) {
      throw new TException("JVM DOES NOT SUPPORT UTF-8");
    }
    message.type = (byte) readJSONInteger();
    message.seqid = (int) readJSONInteger();
    return message;
  }

  @Override
  public void readMessageEnd() throws TException {
    readJSONArrayEnd();
  }

  @Override
  public TStruct readStructBegin() throws TException {
    readJSONObjectStart();
    return new TStruct();
  }

  @Override
  public void readStructEnd() throws TException {
    readJSONObjectEnd();
  }

  @Override
  public TField readFieldBegin() throws TException {
    TField field = new TField();
    byte ch = reader_.peek();
    if (ch == RBRACE[0]) {
      field.type = TType.STOP;
    }
    else {
      field.id = (short) readJSONInteger();
      readJSONObjectStart();
      field.type = getTypeIDForTypeName(readJSONString(false).get());
    }
    return field;
  }

  @Override
  public void readFieldEnd() throws TException {
    readJSONObjectEnd();
  }

  @Override
  public TMap readMapBegin() throws TException {
    TMap map = new TMap();
    readJSONArrayStart();
    map.keyType = getTypeIDForTypeName(readJSONString(false).get());
    map.valueType = getTypeIDForTypeName(readJSONString(false).get());
    map.size = (int)readJSONInteger();
    readJSONObjectStart();
    return map;
  }

  @Override
  public void readMapEnd() throws TException {
    readJSONObjectEnd();
    readJSONArrayEnd();
  }

  @Override
  public TList readListBegin() throws TException {
    TList list = new TList();
    readJSONArrayStart();
    list.elemType = getTypeIDForTypeName(readJSONString(false).get());
    list.size = (int)readJSONInteger();
    return list;
  }

  @Override
  public void readListEnd() throws TException {
    readJSONArrayEnd();
  }

  @Override
  public TSet readSetBegin() throws TException {
    TSet set = new TSet();
    readJSONArrayStart();
    set.elemType = getTypeIDForTypeName(readJSONString(false).get());
    set.size = (int)readJSONInteger();
    return set;
  }

  @Override
  public void readSetEnd() throws TException {
    readJSONArrayEnd();
  }

  @Override
  public boolean readBool() throws TException {
    return (readJSONInteger() == 0 ? false : true);
  }

  @Override
  public byte readByte() throws TException {
    return (byte) readJSONInteger();
  }

  @Override
  public short readI16() throws TException {
    return (short) readJSONInteger();
  }

  @Override
  public int readI32() throws TException {
    return (int) readJSONInteger();
  }

  @Override
  public long readI64() throws TException {
    return (long) readJSONInteger();
  }

  @Override
  public double readDouble() throws TException {
    return readJSONDouble();
  }

  @Override
  public String readString() throws TException {
    try {
      return readJSONString(false).toString("UTF-8");
    }
    catch (UnsupportedEncodingException ex) {
      throw new TException("JVM DOES NOT SUPPORT UTF-8");
    }
  }

  @Override
  public byte[] readBinary() throws TException {
    return readJSONBase64();
  }

}