js/pz2.js

   1 /*
   2  * Mine
   3 ** pz2.js - pazpar2's javascript client library.
   4 */
   5
   6 //since explorer is flawed
   7 if (!window['Node']) {
   8     window.Node = new Object();
   9     Node.ELEMENT_NODE = 1;
  10     Node.ATTRIBUTE_NODE = 2;
  11     Node.TEXT_NODE = 3;
  12     Node.CDATA_SECTION_NODE = 4;
  13     Node.ENTITY_REFERENCE_NODE = 5;
  14     Node.ENTITY_NODE = 6;
  15     Node.PROCESSING_INSTRUCTION_NODE = 7;
  16     Node.COMMENT_NODE = 8;
  17     Node.DOCUMENT_NODE = 9;
  18     Node.DOCUMENT_TYPE_NODE = 10;
  19     Node.DOCUMENT_FRAGMENT_NODE = 11;
  20     Node.NOTATION_NODE = 12;
  21 }
  22
  23 // prevent execution of more than once
  24 if(typeof window.pz2 == "undefined") {
  25 window.undefined = window.undefined;
  26
  27 var pz2 = function ( paramArray )
  28 {
  29
  30     // at least one callback required
  31     if ( !paramArray )
  32         throw new Error("Pz2.js: Array with parameters has to be suplied.");
  33
  34     //supported pazpar2's protocol version
  35     this.suppProtoVer = '1';
  36     if (typeof paramArray.pazpar2path != "undefined")
  37         this.pz2String = paramArray.pazpar2path;
  38     else
  39         this.pz2String = "/pazpar2/search.pz2";
  40     this.useSessions = true;
  41
  42     this.stylesheet = paramArray.detailstylesheet || null;
  43     //load stylesheet if required in async mode
  44     if( this.stylesheet ) {
  45         var context = this;
  46         var request = new pzHttpRequest( this.stylesheet );
  47         request.get( {}, function ( doc ) { context.xslDoc = doc; } );
  48     }
  49
  50     this.errorHandler = paramArray.errorhandler || null;
  51     this.showResponseType = paramArray.showResponseType || "xml";
  52
  53     // function callbacks
  54     this.initCallback = paramArray.oninit || null;
  55     this.statCallback = paramArray.onstat || null;
  56     this.showCallback = paramArray.onshow || null;
  57     this.termlistCallback = paramArray.onterm || null;
  58     this.recordCallback = paramArray.onrecord || null;
  59     this.bytargetCallback = paramArray.onbytarget || null;
  60     this.resetCallback = paramArray.onreset || null;
  61
  62     // termlist keys
  63     this.termKeys = paramArray.termlist || "subject";
  64
  65     // some configurational stuff
  66     this.keepAlive = 50000;
  67
  68     if ( paramArray.keepAlive < this.keepAlive )
  69         this.keepAlive = paramArray.keepAlive;
  70
  71     this.sessionID = null;
  72     this.serviceId = paramArray.serviceId || null;
  73     this.initStatusOK = false;
  74     this.pingStatusOK = false;
  75     this.searchStatusOK = false;
  76
  77     // for sorting
  78     this.currentSort = "relevance";
  79
  80     // where are we?
  81     this.currentStart = 0;
  82     this.currentNum = 20;
  83
  84     // last full record retrieved
  85     this.currRecID = null;
  86
  87     // current query
  88     this.currQuery = null;
  89
  90     //current raw record offset
  91     this.currRecOffset = null;
  92
  93     //timers
  94     this.pingTimer = null;
  95     this.statTime = paramArray.stattime || 1000;
  96     this.statTimer = null;
  97     this.termTime = paramArray.termtime || 1000;
  98     this.termTimer = null;
  99     this.showTime = paramArray.showtime || 1000;
 100     this.showTimer = null;
 101     this.showFastCount = 4;
 102     this.bytargetTime = paramArray.bytargettime || 1000;
 103     this.bytargetTimer = null;
 104     this.recordTime = paramArray.recordtime || 500;
 105     this.recordTimer = null;
 106
 107     // counters for each command and applied delay
 108     this.dumpFactor = 500;
 109     this.showCounter = 0;
 110     this.termCounter = 0;
 111     this.statCounter = 0;
 112     this.bytargetCounter = 0;
 113     this.recordCounter = 0;
 114
 115     // active clients, updated by stat and show
 116     // might be an issue since bytarget will poll accordingly
 117     this.activeClients = 1;
 118
 119     // if in proxy mode no need to init
 120     if (paramArray.usesessions != undefined) {
 121          this.useSessions = paramArray.usesessions;
 122         this.initStatusOK = true;
 123     }
 124     // else, auto init session or wait for a user init?
 125     if (this.useSessions && paramArray.autoInit !== false) {
 126         this.init(this.sessionId, this.serviceId);
 127     }
 128 };
 129
 130 pz2.prototype =
 131 {
 132     //error handler for async error throws
 133    throwError: function (errMsg, errCode)
 134    {
 135         var err = new Error(errMsg);
 136         if (errCode) err.code = errCode;
 137
 138         if (this.errorHandler) {
 139             this.errorHandler(err);
 140         }
 141         else {
 142             throw err;
 143         }
 144    },
 145
 146     // stop activity by clearing tiemouts
 147    stop: function ()
 148    {
 149        clearTimeout(this.statTimer);
 150        clearTimeout(this.showTimer);
 151        clearTimeout(this.termTimer);
 152        clearTimeout(this.bytargetTimer);
 153     },
 154
 155     // reset status variables
 156     reset: function ()
 157     {
 158         if ( this.useSessions ) {
 159             this.sessionID = null;
 160             this.initStatusOK = false;
 161             this.pingStatusOK = false;
 162             clearTimeout(this.pingTimer);
 163         }
 164         this.searchStatusOK = false;
 165         this.stop();
 166
 167         if ( this.resetCallback )
 168                 this.resetCallback();
 169     },
 170
 171     init: function (sessionId, serviceId)
 172     {
 173         this.reset();
 174
 175         // session id as a param
 176         if (sessionId && this.useSessions ) {
 177             this.initStatusOK = true;
 178             this.sessionID = sessionId;
 179             this.ping();
 180         // old school direct pazpar2 init
 181         } else if (this.useSessions) {
 182             var context = this;
 183             var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 184             var opts = {'command' : 'init'};
 185             if (serviceId) opts.service = serviceId;
 186             request.safeGet(
 187                 opts,
 188                 function(data) {
 189                     if ( data.getElementsByTagName("status")[0]
 190                             .childNodes[0].nodeValue == "OK" ) {
 191                         if ( data.getElementsByTagName("protocol")[0]
 192                                 .childNodes[0].nodeValue
 193                             != context.suppProtoVer )
 194                             throw new Error(
 195                                 "Server's protocol not supported by the client"
 196                             );
 197                         context.initStatusOK = true;
 198                         context.sessionID =
 199                             data.getElementsByTagName("session")[0]
 200                                 .childNodes[0].nodeValue;
 201                         context.pingTimer =
 202                             setTimeout(
 203                                 function () {
 204                                     context.ping();
 205                                 },
 206                                 context.keepAlive
 207                             );
 208                         if ( context.initCallback )
 209                             context.initCallback();
 210                     }
 211                     else
 212                         context.throwError('Init failed. Malformed WS resonse.',
 213                                             110);
 214                 }
 215             );
 216         // when through proxy no need to init
 217         } else {
 218             this.initStatusOK = true;
 219         }
 220     },
 221     // no need to ping explicitly
 222     ping: function ()
 223     {
 224         // pinging only makes sense when using pazpar2 directly
 225         if( !this.initStatusOK || !this.useSessions )
 226             throw new Error(
 227             'Pz2.js: Ping not allowed (proxy mode) or session not initialized.'
 228             );
 229         var context = this;
 230
 231         clearTimeout(context.pingTimer);
 232
 233         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 234         request.safeGet(
 235             { "command": "ping", "session": this.sessionID, "windowid" : window.name },
 236             function(data) {
 237                 if ( data.getElementsByTagName("status")[0]
 238                         .childNodes[0].nodeValue == "OK" ) {
 239                     context.pingStatusOK = true;
 240                     context.pingTimer =
 241                         setTimeout(
 242                             function () {
 243                                 context.ping();
 244                             },
 245                             context.keepAlive
 246                         );
 247                 }
 248                 else
 249                     context.throwError('Ping failed. Malformed WS resonse.',
 250                                         111);
 251             }
 252         );
 253     },
 254     search: function (query, num, sort, filter, showfrom, addParamsArr)
 255     {
 256         clearTimeout(this.statTimer);
 257         clearTimeout(this.showTimer);
 258         clearTimeout(this.termTimer);
 259         clearTimeout(this.bytargetTimer);
 260
 261         this.showCounter = 0;
 262         this.termCounter = 0;
 263         this.bytargetCounter = 0;
 264         this.statCounter = 0;
 265         this.activeClients = 1;
 266
 267         // no proxy mode
 268         if( !this.initStatusOK )
 269             throw new Error('Pz2.js: session not initialized.');
 270
 271         if( query !== undefined )
 272             this.currQuery = query;
 273         else
 274             throw new Error("Pz2.js: no query supplied to the search command.");
 275
 276         if ( showfrom !== undefined )
 277             var start = showfrom;
 278         else
 279             var start = 0;
 280
 281               var searchParams = {
 282           "command": "search",
 283           "query": this.currQuery,
 284           "session": this.sessionID,
 285           "windowid" : window.name
 286         };
 287
 288         if (filter !== undefined)
 289                 searchParams["filter"] = filter;
 290
 291         // copy additional parmeters, do not overwrite
 292         if (addParamsArr != undefined) {
 293             for (var prop in addParamsArr) {
 294                 if (!searchParams.hasOwnProperty(prop))
 295                     searchParams[prop] = addParamsArr[prop];
 296             }
 297         }
 298
 299         var context = this;
 300         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 301         request.safeGet(
 302             searchParams,
 303             function(data) {
 304                 if ( data.getElementsByTagName("status")[0]
 305                         .childNodes[0].nodeValue == "OK" ) {
 306                     context.searchStatusOK = true;
 307                     //piggyback search
 308                     context.show(start, num, sort);
 309                     if (context.statCallback)
 310                         context.stat();
 311                     if (context.termlistCallback)
 312                         context.termlist();
 313                     if (context.bytargetCallback)
 314                         context.bytarget();
 315                 }
 316                 else
 317                     context.throwError('Search failed. Malformed WS resonse.',
 318                                         112);
 319             }
 320         );
 321     },
 322     stat: function()
 323     {
 324         if( !this.initStatusOK )
 325             throw new Error('Pz2.js: session not initialized.');
 326
 327         // if called explicitly takes precedence
 328         clearTimeout(this.statTimer);
 329
 330         var context = this;
 331         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 332         request.safeGet(
 333             { "command": "stat", "session": this.sessionID, "windowid" : window.name },
 334             function(data) {
 335                 if ( data.getElementsByTagName("stat") ) {
 336                     var activeClients =
 337                         Number( data.getElementsByTagName("activeclients")[0]
 338                                     .childNodes[0].nodeValue );
 339                     context.activeClients = activeClients;
 340
 341                     var stat = Element_parseChildNodes(data.documentElement);
 342
 343                     context.statCounter++;
 344                     var delay = context.statTime
 345                         + context.statCounter * context.dumpFactor;
 346
 347                     if ( activeClients > 0 )
 348                         context.statTimer =
 349                             setTimeout(
 350                                 function () {
 351                                     context.stat();
 352                                 },
 353                                 delay
 354                             );
 355                     context.statCallback(stat);
 356                 }
 357                 else
 358                     context.throwError('Stat failed. Malformed WS resonse.',
 359                                         113);
 360             }
 361         );
 362     },
 363     show: function(start, num, sort)
 364     {
 365         if( !this.searchStatusOK && this.useSessions )
 366             throw new Error(
 367                 'Pz2.js: show command has to be preceded with a search command.'
 368             );
 369
 370         // if called explicitly takes precedence
 371         clearTimeout(this.showTimer);
 372
 373         if( sort !== undefined )
 374             this.currentSort = sort;
 375         if( start !== undefined )
 376             this.currentStart = Number( start );
 377         if( num !== undefined )
 378             this.currentNum = Number( num );
 379
 380         var context = this;
 381         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 382         request.safeGet(
 383           {
 384             "command": "show",
 385             "session": this.sessionID,
 386             "start": this.currentStart,
 387             "num": this.currentNum,
 388             "sort": this.currentSort,
 389             "block": 1,
 390             "type": this.showResponseType,
 391             "windowid" : window.name
 392           },
 393           function(data, type) {
 394             var show = null;
 395             var activeClients = 0;
 396             if (type === "json") {
 397               show = {};
 398               activeClients = Number(data.activeclients[0]);
 399               show.activeclients = activeClients;
 400               show.merged = Number(data.merged[0]);
 401               show.total = Number(data.total[0]);
 402               show.start = Number(data.start[0]);
 403               show.num = Number(data.num[0]);
 404               show.hits = data.hit;
 405             } else if (data.getElementsByTagName("status")[0]
 406                   .childNodes[0].nodeValue == "OK") {
 407                 // first parse the status data send along with records
 408                 // this is strictly bound to the format
 409                 activeClients =
 410                   Number(data.getElementsByTagName("activeclients")[0]
 411                       .childNodes[0].nodeValue);
 412                 show = {
 413                   "activeclients": activeClients,
 414                   "merged":
 415                     Number( data.getElementsByTagName("merged")[0]
 416                         .childNodes[0].nodeValue ),
 417                   "total":
 418                     Number( data.getElementsByTagName("total")[0]
 419                         .childNodes[0].nodeValue ),
 420                   "start":
 421                     Number( data.getElementsByTagName("start")[0]
 422                         .childNodes[0].nodeValue ),
 423                   "num":
 424                     Number( data.getElementsByTagName("num")[0]
 425                         .childNodes[0].nodeValue ),
 426                   "hits": []
 427                 };
 428                 // parse all the first-level nodes for all <hit> tags
 429                 var hits = data.getElementsByTagName("hit");
 430                 for (i = 0; i < hits.length; i++)
 431                   show.hits[i] = Element_parseChildNodes(hits[i]);
 432             } else {
 433               context.throwError('Show failed. Malformed WS resonse.',
 434                   114);
 435             }
 436             context.activeClients = activeClients;
 437             context.showCounter++;
 438             var delay = context.showTime;
 439             if (context.showCounter > context.showFastCount)
 440               delay += context.showCounter * context.dumpFactor;
 441             if ( activeClients > 0 )
 442               context.showTimer = setTimeout(
 443                 function () {
 444                   context.show();
 445                 },
 446                 delay);
 447             context.showCallback(show);
 448           }
 449         );
 450     },
 451     record: function(id, offset, syntax, handler)
 452     {
 453         // we may call record with no previous search if in proxy mode
 454         if(!this.searchStatusOK && this.useSessions)
 455            throw new Error(
 456             'Pz2.js: record command has to be preceded with a search command.'
 457             );
 458
 459         if( id !== undefined )
 460             this.currRecID = id;
 461
 462         var recordParams = {
 463             "command": "record",
 464             "session": this.sessionID,
 465             "id": this.currRecID,
 466             "windowid" : window.name
 467         };
 468
 469         this.currRecOffset = null;
 470         if (offset != undefined) {
 471             recordParams["offset"] = offset;
 472             this.currRecOffset = offset;
 473         }
 474
 475         if (syntax != undefined)
 476             recordParams['syntax'] = syntax;
 477
 478         //overwrite default callback id needed
 479         var callback = this.recordCallback;
 480         var args = undefined;
 481         if (handler != undefined) {
 482             callback = handler['callback'];
 483             args = handler['args'];
 484         }
 485
 486         var context = this;
 487         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 488
 489         request.safeGet(
 490             recordParams,
 491             function(data) {
 492                 var recordNode;
 493                 var record;
 494                 //raw record
 495                 if (context.currRecOffset !== null) {
 496                     record = new Array();
 497                     record['xmlDoc'] = data;
 498                     record['offset'] = context.currRecOffset;
 499                     callback(record, args);
 500                 //pz2 record
 501                 } else if ( recordNode =
 502                     data.getElementsByTagName("record")[0] ) {
 503                     // if stylesheet was fetched do not parse the response
 504                     if ( context.xslDoc ) {
 505                         record = new Array();
 506                         record['xmlDoc'] = data;
 507                         record['xslDoc'] = context.xslDoc;
 508                         record['recid'] =
 509                             recordNode.getElementsByTagName("recid")[0]
 510                                 .firstChild.nodeValue;
 511                     //parse record
 512                     } else {
 513                         record = Element_parseChildNodes(recordNode);
 514                     }
 515                     var activeClients =
 516                        Number( data.getElementsByTagName("activeclients")[0]
 517                                 .childNodes[0].nodeValue );
 518                     context.activeClients = activeClients;
 519                     context.recordCounter++;
 520                     var delay = context.recordTime + context.recordCounter * context.dumpFactor;
 521                     if ( activeClients > 0 )
 522                         context.recordTimer =
 523                            setTimeout (
 524                                function() {
 525                                   context.record(id, offset, syntax, handler);
 526                                   },
 527                                   delay
 528                                );
 529                     callback(record, args);
 530                 }
 531                 else
 532                     context.throwError('Record failed. Malformed WS resonse.',
 533                                         115);
 534             }
 535         );
 536     },
 537
 538     termlist: function()
 539     {
 540         if( !this.searchStatusOK && this.useSessions )
 541             throw new Error(
 542             'Pz2.js: termlist command has to be preceded with a search command.'
 543             );
 544
 545         // if called explicitly takes precedence
 546         clearTimeout(this.termTimer);
 547
 548         var context = this;
 549         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 550         request.safeGet(
 551             {
 552                 "command": "termlist",
 553                 "session": this.sessionID,
 554                 "name": this.termKeys,
 555                 "windowid" : window.name
 556             },
 557             function(data) {
 558                 if ( data.getElementsByTagName("termlist") ) {
 559                     var activeClients =
 560                         Number( data.getElementsByTagName("activeclients")[0]
 561                                     .childNodes[0].nodeValue );
 562                     context.activeClients = activeClients;
 563                     var termList = { "activeclients":  activeClients };
 564                     var termLists = data.getElementsByTagName("list");
 565                     //for each termlist
 566                     for (i = 0; i < termLists.length; i++) {
 567                         var listName = termLists[i].getAttribute('name');
 568                         termList[listName] = new Array();
 569                         var terms = termLists[i].getElementsByTagName('term');
 570                         //for each term in the list
 571                         for (j = 0; j < terms.length; j++) {
 572                             var term = {
 573                                 "name":
 574                                     (terms[j].getElementsByTagName("name")[0]
 575                                         .childNodes.length
 576                                     ? terms[j].getElementsByTagName("name")[0]
 577                                         .childNodes[0].nodeValue
 578                                     : 'ERROR'),
 579                                 "freq":
 580                                     terms[j]
 581                                     .getElementsByTagName("frequency")[0]
 582                                     .childNodes[0].nodeValue || 'ERROR'
 583                             };
 584
 585                             var termIdNode =
 586                                 terms[j].getElementsByTagName("id");
 587                             if(terms[j].getElementsByTagName("id").length)
 588                                 term["id"] =
 589                                     termIdNode[0].childNodes[0].nodeValue;
 590                             termList[listName][j] = term;
 591                         }
 592                     }
 593
 594                     context.termCounter++;
 595                     var delay = context.termTime
 596                         + context.termCounter * context.dumpFactor;
 597                     if ( activeClients > 0 )
 598                         context.termTimer =
 599                             setTimeout(
 600                                 function () {
 601                                     context.termlist();
 602                                 },
 603                                 delay
 604                             );
 605
 606                    context.termlistCallback(termList);
 607                 }
 608                 else
 609                     context.throwError('Termlist failed. Malformed WS resonse.',
 610                                         116);
 611             }
 612         );
 613
 614     },
 615     bytarget: function()
 616     {
 617         if( !this.initStatusOK && this.useSessions )
 618             throw new Error(
 619             'Pz2.js: bytarget command has to be preceded with a search command.'
 620             );
 621
 622         // no need to continue
 623         if( !this.searchStatusOK )
 624             return;
 625
 626         // if called explicitly takes precedence
 627         clearTimeout(this.bytargetTimer);
 628
 629         var context = this;
 630         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 631         request.safeGet(
 632             { "command": "bytarget", "session": this.sessionID, "windowid" : window.name},
 633             function(data) {
 634                 if ( data.getElementsByTagName("status")[0]
 635                         .childNodes[0].nodeValue == "OK" ) {
 636                     var targetNodes = data.getElementsByTagName("target");
 637                     var bytarget = new Array();
 638                     for ( i = 0; i < targetNodes.length; i++) {
 639                         bytarget[i] = new Array();
 640                         for( j = 0; j < targetNodes[i].childNodes.length; j++ ) {
 641                             if ( targetNodes[i].childNodes[j].nodeType
 642                                 == Node.ELEMENT_NODE ) {
 643                                 var nodeName =
 644                                     targetNodes[i].childNodes[j].nodeName;
 645                                 var nodeText =
 646                                     targetNodes[i].childNodes[j]
 647                                         .firstChild.nodeValue;
 648                                 bytarget[i][nodeName] = nodeText;
 649                             }
 650                         }
 651                         if (bytarget[i]["state"]=="Client_Disconnected") {
 652                           bytarget[i]["hits"] = "Error";
 653                         } else if (bytarget[i]["state"]=="Client_Error") {
 654                           bytarget[i]["hits"] = "Error";
 655                         } else if (bytarget[i]["state"]=="Client_Working") {
 656                           bytarget[i]["hits"] = "...";
 657                         }
 658                         if (bytarget[i].diagnostic == "1") {
 659                           bytarget[i].diagnostic = "Permanent system error";
 660                         } else if (bytarget[i].diagnostic == "2") {
 661                           bytarget[i].diagnostic = "Temporary system error";
 662                         }
 663                         var targetsSuggestions = targetNodes[i].getElementsByTagName("suggestions");
 664                         if (targetsSuggestions != undefined && targetsSuggestions.length>0) {
 665                           var suggestions = targetsSuggestions[0];
 666                           bytarget[i]["suggestions"] = Element_parseChildNodes(suggestions);
 667                         }
 668                     }
 669
 670                     context.bytargetCounter++;
 671                     var delay = context.bytargetTime
 672                         + context.bytargetCounter * context.dumpFactor;
 673                     if ( context.activeClients > 0 )
 674                         context.bytargetTimer =
 675                             setTimeout(
 676                                 function () {
 677                                     context.bytarget();
 678                                 },
 679                                 delay
 680                             );
 681
 682                     context.bytargetCallback(bytarget);
 683                 }
 684                 else
 685                     context.throwError('Bytarget failed. Malformed WS resonse.',
 686                                         117);
 687             }
 688         );
 689     },
 690
 691     // just for testing, probably shouldn't be here
 692     showNext: function(page)
 693     {
 694         var step = page || 1;
 695         this.show( ( step * this.currentNum ) + this.currentStart );
 696     },
 697
 698     showPrev: function(page)
 699     {
 700         if (this.currentStart == 0 )
 701             return false;
 702         var step = page || 1;
 703         var newStart = this.currentStart - (step * this.currentNum );
 704         this.show( newStart > 0 ? newStart : 0 );
 705     },
 706
 707     showPage: function(pageNum)
 708     {
 709         //var page = pageNum || 1;
 710         this.show(pageNum * this.currentNum);
 711     }
 712 };
 713
 714 /*
 715 ********************************************************************************
 716 ** AJAX HELPER CLASS ***********************************************************
 717 ********************************************************************************
 718 */
 719 var pzHttpRequest = function ( url, errorHandler ) {
 720         this.maxUrlLength = 2048;
 721         this.request = null;
 722         this.url = url;
 723         this.errorHandler = errorHandler || null;
 724         this.async = true;
 725         this.requestHeaders = {};
 726
 727         if ( window.XMLHttpRequest ) {
 728             this.request = new XMLHttpRequest();
 729         } else if ( window.ActiveXObject ) {
 730             try {
 731                 this.request = new ActiveXObject( 'Msxml2.XMLHTTP' );
 732             } catch (err) {
 733                 this.request = new ActiveXObject( 'Microsoft.XMLHTTP' );
 734             }
 735         }
 736 };
 737
 738
 739 pzHttpRequest.prototype =
 740 {
 741     safeGet: function ( params, callback )
 742     {
 743         var encodedParams =  this.encodeParams(params);
 744         var url = this._urlAppendParams(encodedParams);
 745         if (url.length >= this.maxUrlLength) {
 746             this.requestHeaders["Content-Type"]
 747                 = "application/x-www-form-urlencoded";
 748             this._send( 'POST', this.url, encodedParams, callback );
 749         } else {
 750             this._send( 'GET', url, '', callback );
 751         }
 752     },
 753
 754     get: function ( params, callback )
 755     {
 756         this._send( 'GET', this._urlAppendParams(this.encodeParams(params)),
 757             '', callback );
 758     },
 759
 760     post: function ( params, data, callback )
 761     {
 762         this._send( 'POST', this._urlAppendParams(this.encodeParams(params)),
 763             data, callback );
 764     },
 765
 766     load: function ()
 767     {
 768         this.async = false;
 769         this.request.open( 'GET', this.url, this.async );
 770         this.request.send('');
 771         if ( this.request.status == 200 )
 772             return this.request.responseXML;
 773     },
 774
 775     encodeParams: function (params)
 776     {
 777         var sep = "";
 778         var encoded = "";
 779         for (var key in params) {
 780             if (params[key] != null) {
 781                 encoded += sep + key + '=' + encodeURIComponent(params[key]);
 782                 sep = '&';
 783             }
 784         }
 785         return encoded;
 786     },
 787
 788     _send: function ( type, url, data, callback)
 789     {
 790         var context = this;
 791         this.callback = callback;
 792         this.async = true;
 793         this.request.open( type, url, this.async );
 794         for (var key in this.requestHeaders)
 795             this.request.setRequestHeader(key, this.requestHeaders[key]);
 796         this.request.onreadystatechange = function () {
 797             context._handleResponse(url); /// url used ONLY for error reporting
 798         }
 799         this.request.send(data);
 800     },
 801
 802     _urlAppendParams: function (encodedParams)
 803     {
 804         if (encodedParams)
 805             return this.url + "?" + encodedParams;
 806         else
 807             return this.url;
 808     },
 809
 810     _handleResponse: function (savedUrlForErrorReporting)
 811     {
 812         if ( this.request.readyState == 4 ) {
 813             // pick up appplication errors first
 814             var errNode = null;
 815             if (this.request.responseXML &&
 816                 (errNode = this.request.responseXML.documentElement)
 817                 && errNode.nodeName == 'error') {
 818                 var errMsg = errNode.getAttribute("msg");
 819                 var errCode = errNode.getAttribute("code");
 820                 var errAddInfo = '';
 821                 if (errNode.childNodes.length)
 822                     errAddInfo = ': ' + errNode.childNodes[0].nodeValue;
 823
 824                 var err = new Error(errMsg + errAddInfo);
 825                 err.code = errCode;
 826
 827                 if (this.errorHandler) {
 828                     this.errorHandler(err);
 829                 }
 830                 else {
 831                     throw err;
 832                 }
 833             } else if (this.request.status == 200 &&
 834                        this.request.responseXML == null) {
 835               if (this.request.responseText != null) {
 836                 //assume JSON
 837
 838                 var json = null;
 839                 var text = this.request.responseText;
 840                 if (typeof window.JSON == "undefined")
 841                     json = eval("(" + text + ")");
 842                 else {
 843                     try {
 844                         json = JSON.parse(text);
 845                     }
 846                     catch (e) {
 847                         // Safari: eval will fail as well. Considering trying JSON2 (non-native implementation) instead
 848                         /* DEBUG only works in mk2-mobile
 849                         if (document.getElementById("log"))
 850                             document.getElementById("log").innerHTML = "" + e + " " + length + ": " + text;
 851                         */
 852                         try {
 853                             json = eval("(" + text + ")");
 854                         }
 855                         catch (e) {
 856                             /* DEBUG only works in mk2-mobile
 857                             if (document.getElementById("log"))
 858                                 document.getElementById("log").innerHTML = "" + e + " " + length + ": " + text;
 859                             */
 860                         }
 861                     }
 862                 }
 863                 this.callback(json, "json");
 864               } else {
 865                 var err = new Error("XML response is empty but no error " +
 866                                     "for " + savedUrlForErrorReporting);
 867                 err.code = -1;
 868                 if (this.errorHandler) {
 869                     this.errorHandler(err);
 870                 } else {
 871                     throw err;
 872                 }
 873               }
 874             } else if (this.request.status == 200) {
 875                 this.callback(this.request.responseXML);
 876             } else {
 877                 var err = new Error("HTTP response not OK: "
 878                             + this.request.status + " - "
 879                             + this.request.statusText );
 880                 err.code = '00' + this.request.status;
 881                 if (this.errorHandler) {
 882                     this.errorHandler(err);
 883                 }
 884                 else {
 885                     throw err;
 886                 }
 887             }
 888         }
 889     }
 890 };
 891
 892 /*
 893 ********************************************************************************
 894 ** XML HELPER FUNCTIONS ********************************************************
 895 ********************************************************************************
 896 */
 897
 898 // DOMDocument
 899
 900 if ( window.ActiveXObject) {
 901     var DOMDoc = document;
 902 } else {
 903     var DOMDoc = Document.prototype;
 904 }
 905
 906 DOMDoc.newXmlDoc = function ( root )
 907 {
 908     var doc;
 909
 910     if (document.implementation && document.implementation.createDocument) {
 911         doc = document.implementation.createDocument('', root, null);
 912     } else if ( window.ActiveXObject ) {
 913         doc = new ActiveXObject("MSXML2.DOMDocument");
 914         doc.loadXML('<' + root + '/>');
 915     } else {
 916         throw new Error ('No XML support in this browser');
 917     }
 918
 919     return doc;
 920 }
 921
 922
 923 DOMDoc.parseXmlFromString = function ( xmlString )
 924 {
 925     var doc;
 926
 927     if ( window.DOMParser ) {
 928         var parser = new DOMParser();
 929         doc = parser.parseFromString( xmlString, "text/xml");
 930     } else if ( window.ActiveXObject ) {
 931         doc = new ActiveXObject("MSXML2.DOMDocument");
 932         doc.loadXML( xmlString );
 933     } else {
 934         throw new Error ("No XML parsing support in this browser.");
 935     }
 936
 937     return doc;
 938 }
 939
 940 DOMDoc.transformToDoc = function (xmlDoc, xslDoc)
 941 {
 942     if ( window.XSLTProcessor ) {
 943         var proc = new XSLTProcessor();
 944         proc.importStylesheet( xslDoc );
 945         return proc.transformToDocument(xmlDoc);
 946     } else if ( window.ActiveXObject ) {
 947         return document.parseXmlFromString(xmlDoc.transformNode(xslDoc));
 948     } else {
 949         alert( 'Unable to perform XSLT transformation in this browser' );
 950     }
 951 }
 952
 953 // DOMElement
 954
 955 Element_removeFromDoc = function (DOM_Element)
 956 {
 957     DOM_Element.parentNode.removeChild(DOM_Element);
 958 }
 959
 960 Element_emptyChildren = function (DOM_Element)
 961 {
 962     while( DOM_Element.firstChild ) {
 963         DOM_Element.removeChild( DOM_Element.firstChild )
 964     }
 965 }
 966
 967 Element_appendTransformResult = function ( DOM_Element, xmlDoc, xslDoc )
 968 {
 969     if ( window.XSLTProcessor ) {
 970         var proc = new XSLTProcessor();
 971         proc.importStylesheet( xslDoc );
 972         var docFrag = false;
 973         docFrag = proc.transformToFragment( xmlDoc, DOM_Element.ownerDocument );
 974         DOM_Element.appendChild(docFrag);
 975     } else if ( window.ActiveXObject ) {
 976         DOM_Element.innerHTML = xmlDoc.transformNode( xslDoc );
 977     } else {
 978         alert( 'Unable to perform XSLT transformation in this browser' );
 979     }
 980 }
 981
 982 Element_appendTextNode = function (DOM_Element, tagName, textContent )
 983 {
 984     var node = DOM_Element.ownerDocument.createElement(tagName);
 985     var text = DOM_Element.ownerDocument.createTextNode(textContent);
 986
 987     DOM_Element.appendChild(node);
 988     node.appendChild(text);
 989
 990     return node;
 991 }
 992
 993 Element_setTextContent = function ( DOM_Element, textContent )
 994 {
 995     if (typeof DOM_Element.textContent !== "undefined") {
 996         DOM_Element.textContent = textContent;
 997     } else if (typeof DOM_Element.innerText !== "undefined" ) {
 998         DOM_Element.innerText = textContent;
 999     } else {
1000         throw new Error("Cannot set text content of the node, no such method.");
1001     }
1002 }
1003
1004 Element_getTextContent = function (DOM_Element)
1005 {
1006     if ( typeof DOM_Element.textContent != 'undefined' ) {
1007         return DOM_Element.textContent;
1008     } else if (typeof DOM_Element.text != 'undefined') {
1009         return DOM_Element.text;
1010     } else {
1011         throw new Error("Cannot get text content of the node, no such method.");
1012     }
1013 }
1014
1015 Element_parseChildNodes = function (node)
1016 {
1017     var parsed = {};
1018     var hasChildElems = false;
1019
1020     if (node.hasChildNodes()) {
1021         var children = node.childNodes;
1022         for (var i = 0; i < children.length; i++) {
1023             var child = children[i];
1024             if (child.nodeType == Node.ELEMENT_NODE) {
1025                 hasChildElems = true;
1026                 var nodeName = child.nodeName;
1027                 if (!(nodeName in parsed))
1028                     parsed[nodeName] = [];
1029                 parsed[nodeName].push(Element_parseChildNodes(child));
1030             }
1031         }
1032     }
1033
1034     var attrs = node.attributes;
1035     for (var i = 0; i < attrs.length; i++) {
1036         var attrName = '@' + attrs[i].nodeName;
1037         var attrValue = attrs[i].nodeValue;
1038         parsed[attrName] = attrValue;
1039     }
1040
1041     // if no nested elements, get text content
1042     if (node.hasChildNodes() && !hasChildElems) {
1043         if (node.attributes.length)
1044             parsed['#text'] = node.firstChild.nodeValue;
1045         else
1046             parsed = node.firstChild.nodeValue;
1047     }
1048
1049     return parsed;
1050 }
1051
1052 /* do not remove trailing bracket */
1053 }