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