js/pz2.js

   1 /*
   2 ** $Id: pz2.js,v 1.63 2007-10-30 13:41:05 jakub Exp $
   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
  52     // function callbacks
  53     this.statCallback = paramArray.onstat || null;
  54     this.showCallback = paramArray.onshow || null;
  55     this.termlistCallback = paramArray.onterm || null;
  56     this.recordCallback = paramArray.onrecord || null;
  57     this.bytargetCallback = paramArray.onbytarget || null;
  58     this.resetCallback = paramArray.onreset || null;
  59
  60     // termlist keys
  61     this.termKeys = paramArray.termlist || "subject";
  62
  63     // some configurational stuff
  64     this.keepAlive = 50000;
  65
  66     if ( paramArray.keepAlive < this.keepAlive )
  67         this.keepAlive = paramArray.keepAlive;
  68
  69     this.sessionID = null;
  70     this.initStatusOK = false;
  71     this.pingStatusOK = false;
  72     this.searchStatusOK = false;
  73
  74     // for sorting
  75     this.currentSort = "relevance";
  76
  77     // where are we?
  78     this.currentStart = 0;
  79     this.currentNum = 20;
  80
  81     // last full record retrieved
  82     this.currRecID = null;
  83
  84     // current query
  85     this.currQuery = null;
  86
  87     //timers
  88     this.statTime = paramArray.stattime || 1000;
  89     this.statTimer = null;
  90     this.termTime = paramArray.termtime || 1000;
  91     this.termTimer = null;
  92     this.showTime = paramArray.showtime || 1000;
  93     this.showTimer = null;
  94     this.showFastCount = 4;
  95     this.bytargetTime = paramArray.bytargettime || 1000;
  96     this.bytargetTimer = null;
  97
  98     // counters for each command and applied delay
  99     this.dumpFactor = 500;
 100     this.showCounter = 0;
 101     this.termCounter = 0;
 102     this.statCounter = 0;
 103     this.bytargetCounter = 0;
 104
 105     // active clients, updated by stat and show
 106     // might be an issue since bytarget will poll accordingly
 107     this.activeClients = 1;
 108
 109     // if in proxy mode no need to init
 110     if (paramArray.usesessions != undefined) {
 111          this.useSessions = paramArray.usesessions;
 112         this.initStatusOK = true;
 113     }
 114     // else, auto init session or wait for a user init?
 115     if (this.useSessions && paramArray.autoInit !== false) {
 116         this.init();
 117     }
 118 };
 119
 120 pz2.prototype =
 121 {
 122     //error handler for async error throws
 123    throwError: function (errMsg, errCode)
 124    {
 125         var err = new Error(errMsg);
 126         if (errCode) err.code = errCode;
 127
 128         if (this.errorHandler) {
 129             this.errorHandler(err);
 130         }
 131         else {
 132             throw err;
 133         }
 134    },
 135
 136     // stop activity by clearing tiemouts
 137    stop: function ()
 138    {
 139        clearTimeout(this.statTimer);
 140        clearTimeout(this.showTimer);
 141        clearTimeout(this.termTimer);
 142        clearTimeout(this.bytargetTimer);
 143     },
 144
 145     // reset status variables
 146     reset: function ()
 147     {
 148         if ( this.useSessions ) {
 149             this.sessionID = null;
 150             this.initStatusOK = false;
 151             this.pingStatusOK = false;
 152         }
 153         this.searchStatusOK = false;
 154         this.stop();
 155
 156         if ( this.resetCallback )
 157                 this.resetCallback();
 158     },
 159
 160     init: function ( sessionId )
 161     {
 162         this.reset();
 163
 164         // session id as a param
 165         if ( sessionId != undefined && this.useSessions ) {
 166             this.initStatusOK = true;
 167             this.sessionID = sessionId;
 168             this.ping();
 169         // old school direct pazpar2 init
 170         } else if (this.useSessions) {
 171             var context = this;
 172             var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 173             request.get(
 174                 { "command": "init" },
 175                 function(data) {
 176                     if ( data.getElementsByTagName("status")[0]
 177                             .childNodes[0].nodeValue == "OK" ) {
 178                         if ( data.getElementsByTagName("protocol")[0]
 179                                 .childNodes[0].nodeValue
 180                             != context.suppProtoVer )
 181                             throw new Error(
 182                                 "Server's protocol not supported by the client"
 183                             );
 184                         context.initStatusOK = true;
 185                         context.sessionID =
 186                             data.getElementsByTagName("session")[0]
 187                                 .childNodes[0].nodeValue;
 188                         setTimeout(
 189                             function () {
 190                                 context.ping();
 191                             },
 192                             context.keepAlive
 193                         );
 194                     }
 195                     else
 196                         context.throwError('Init failed. Malformed WS resonse.',
 197                                             110);
 198                 }
 199             );
 200         // when through proxy no need to init
 201         } else {
 202             this.initStatusOK = true;
 203         }
 204     },
 205     // no need to ping explicitly
 206     ping: function ()
 207     {
 208         // pinging only makes sense when using pazpar2 directly
 209         if( !this.initStatusOK || !this.useSessions )
 210             throw new Error(
 211             'Pz2.js: Ping not allowed (proxy mode) or session not initialized.'
 212             );
 213         var context = this;
 214         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 215         request.get(
 216             { "command": "ping", "session": this.sessionID },
 217             function(data) {
 218                 if ( data.getElementsByTagName("status")[0]
 219                         .childNodes[0].nodeValue == "OK" ) {
 220                     context.pingStatusOK = true;
 221                     setTimeout(
 222                         function () {
 223                             context.ping();
 224                         },
 225                         context.keepAlive
 226                     );
 227                 }
 228                 else
 229                     context.throwError('Ping failed. Malformed WS resonse.',
 230                                         111);
 231             }
 232         );
 233     },
 234     search: function (query, num, sort, filter, showfrom)
 235     {
 236         clearTimeout(this.statTimer);
 237         clearTimeout(this.showTimer);
 238         clearTimeout(this.termTimer);
 239         clearTimeout(this.bytargetTimer);
 240
 241         this.showCounter = 0;
 242         this.termCounter = 0;
 243         this.bytargetCounter = 0;
 244         this.statCounter = 0;
 245
 246         // no proxy mode
 247         if( !this.initStatusOK )
 248             throw new Error('Pz2.js: session not initialized.');
 249
 250         if( query !== undefined )
 251             this.currQuery = query;
 252         else
 253             throw new Error("Pz2.js: no query supplied to the search command.");
 254
 255         if ( showfrom !== undefined )
 256             var start = showfrom;
 257         else
 258             var start = 0;
 259
 260         var searchParams = {
 261             "command": "search",
 262             "query": this.currQuery,
 263             "session": this.sessionID
 264         };
 265
 266         if (filter !== undefined)
 267             searchParams["filter"] = filter;
 268
 269         var context = this;
 270         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 271         request.get(
 272             searchParams,
 273             function(data) {
 274                 if ( data.getElementsByTagName("status")[0]
 275                         .childNodes[0].nodeValue == "OK" ) {
 276                     context.searchStatusOK = true;
 277                     //piggyback search
 278                     context.show(start, num, sort);
 279                     if ( context.statCallback )
 280                         context.stat();
 281                     if ( context.termlistCallback )
 282                         context.termlist();
 283                     if ( context.bytargetCallback )
 284                         context.bytarget();
 285                 }
 286                 else
 287                     context.throwError('Search failed. Malformed WS resonse.',
 288                                         112);
 289             }
 290         );
 291     },
 292     stat: function()
 293     {
 294         if( !this.initStatusOK )
 295             throw new Error('Pz2.js: session not initialized.');
 296
 297         // if called explicitly takes precedence
 298         clearTimeout(this.statTimer);
 299
 300         var context = this;
 301         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 302         request.get(
 303             { "command": "stat", "session": this.sessionID },
 304             function(data) {
 305                 if ( data.getElementsByTagName("stat") ) {
 306                     var activeClients =
 307                         Number( data.getElementsByTagName("activeclients")[0]
 308                                     .childNodes[0].nodeValue );
 309                     context.activeClients = activeClients;
 310                     var stat = {
 311                         "activeclients": activeClients,
 312                         "hits":
 313                             Number( data.getElementsByTagName("hits")[0]
 314                                         .childNodes[0].nodeValue ),
 315                         "records":
 316                             Number( data.getElementsByTagName("records")[0]
 317                                         .childNodes[0].nodeValue ),
 318                         "clients":
 319                             Number( data.getElementsByTagName("clients")[0]
 320                                         .childNodes[0].nodeValue ),
 321                         "initializing":
 322                             Number( data.getElementsByTagName("initializing")[0]
 323                                         .childNodes[0].nodeValue ),
 324                         "searching":
 325                             Number( data.getElementsByTagName("searching")[0]
 326                                         .childNodes[0].nodeValue ),
 327                         "presenting":
 328                             Number( data.getElementsByTagName("presenting")[0]
 329                                         .childNodes[0].nodeValue ),
 330                         "idle":
 331                             Number( data.getElementsByTagName("idle")[0]
 332                                         .childNodes[0].nodeValue ),
 333                         "failed":
 334                             Number( data.getElementsByTagName("failed")[0]
 335                                         .childNodes[0].nodeValue ),
 336                         "error":
 337                             Number( data.getElementsByTagName("error")[0]
 338                                         .childNodes[0].nodeValue )
 339                     };
 340
 341                     context.statCounter++;
 342                     var delay = context.statTime
 343                         + context.statCounter * context.dumpFactor;
 344
 345                     if ( activeClients > 0 )
 346                         context.statTimer =
 347                             setTimeout(
 348                                 function () {
 349                                     context.stat();
 350                                 },
 351                                 delay
 352                             );
 353                     context.statCallback(stat);
 354                 }
 355                 else
 356                     context.throwError('Stat failed. Malformed WS resonse.',
 357                                         113);
 358             }
 359         );
 360     },
 361     show: function(start, num, sort)
 362     {
 363         if( !this.searchStatusOK && this.useSessions )
 364             throw new Error(
 365                 'Pz2.js: show command has to be preceded with a search command.'
 366             );
 367
 368         // if called explicitly takes precedence
 369         clearTimeout(this.showTimer);
 370
 371         if( sort !== undefined )
 372             this.currentSort = sort;
 373         if( start !== undefined )
 374             this.currentStart = Number( start );
 375         if( num !== undefined )
 376             this.currentNum = Number( num );
 377
 378         var context = this;
 379         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 380         request.get(
 381             {
 382                 "command": "show",
 383                 "session": this.sessionID,
 384                 "start": this.currentStart,
 385                 "num": this.currentNum,
 386                 "sort": this.currentSort,
 387                 "block": 1
 388             },
 389             function(data) {
 390                 if ( data.getElementsByTagName("status")[0]
 391                         .childNodes[0].nodeValue == "OK" ) {
 392                     // first parse the status data send along with records
 393                     // this is strictly bound to the format
 394                     var activeClients =
 395                         Number( data.getElementsByTagName("activeclients")[0]
 396                                     .childNodes[0].nodeValue );
 397                     context.activeClients = activeClients;
 398                     var show = {
 399                         "activeclients": activeClients,
 400                         "merged":
 401                             Number( data.getElementsByTagName("merged")[0]
 402                                         .childNodes[0].nodeValue ),
 403                         "total":
 404                             Number( data.getElementsByTagName("total")[0]
 405                                         .childNodes[0].nodeValue ),
 406                         "start":
 407                             Number( data.getElementsByTagName("start")[0]
 408                                         .childNodes[0].nodeValue ),
 409                         "num":
 410                             Number( data.getElementsByTagName("num")[0]
 411                                         .childNodes[0].nodeValue ),
 412                         "hits": []
 413                     };
 414                     // parse all the first-level nodes for all <hit> tags
 415                     var hits = data.getElementsByTagName("hit");
 416                     var hit = new Array();
 417                     for (i = 0; i < hits.length; i++) {
 418                         show.hits[i] = new Array();
 419                         show.hits[i]['location'] = new Array();
 420                         var locCount = 0;
 421                         for ( j = 0; j < hits[i].childNodes.length; j++) {
 422                             if ( hits[i].childNodes[j].nodeType
 423                                 == Node.ELEMENT_NODE ) {
 424                                 if (hits[i].childNodes[j].nodeName
 425                                     == 'location') {
 426                                     var locNode = hits[i].childNodes[j];
 427                                     var id = locNode.getAttribute('id');
 428                                     show.hits[i]['location'][locCount] = {
 429                                         "id": locNode.getAttribute("id"),
 430                                         "name": locNode.getAttribute("name")
 431                                     };
 432                                     locCount++;
 433                                 }
 434                                 else {
 435                                     var nodeName =
 436                                         hits[i].childNodes[j].nodeName;
 437                                     var nodeText = 'ERROR'
 438                                     if ( hits[i].childNodes[j].firstChild )
 439                                         nodeText =
 440                                             hits[i].childNodes[j]
 441                                                 .firstChild.nodeValue;
 442                                     show.hits[i][nodeName] = nodeText;
 443                                 }
 444                             }
 445                         }
 446                     }
 447                     context.showCounter++;
 448                     var delay = context.showTime;
 449                     if (context.showCounter > context.showFastCount)
 450                             delay += context.showCounter * context.dumpFactor;
 451                     if ( activeClients > 0 )
 452                         context.showTimer = setTimeout(
 453                             function () {
 454                                 context.show();
 455                             },
 456                             delay);
 457
 458                     context.showCallback(show);
 459                 }
 460                 else
 461                     context.throwError('Show failed. Malformed WS resonse.',
 462                                         114);
 463             }
 464         );
 465     },
 466     record: function(id, offset, params)
 467     {
 468         // we may call record with no previous search if in proxy mode
 469         if( !this.searchStatusOK && this.useSessions)
 470            throw new Error(
 471             'Pz2.js: record command has to be preceded with a search command.'
 472             );
 473         if ( params == undefined )
 474             params = {};
 475
 476         if ( params.callback != undefined ) {
 477             callback = params.callback;
 478         } else {
 479             callback = this.recordCallback;
 480         }
 481
 482         // what is that?
 483         if ( params['handle'] == undefined )
 484             handle = {};
 485         else
 486             handle = params['handle'];
 487
 488         if( id !== undefined )
 489             this.currRecID = id;
 490
 491         var context = this;
 492         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 493
 494         var recordParams = { "command": "record",
 495                             "session": this.sessionID,
 496                             "id": this.currRecID };
 497
 498         if (offset !== undefined) {
 499             recordParams["offset"] = offset;
 500         }
 501
 502         if (params.syntax != undefined) {
 503             recordParams['syntax'] = params.syntax;
 504         }
 505
 506         this.currRecOffset = offset;
 507
 508         request.get(
 509             recordParams,
 510             function(data) {
 511                 var recordNode;
 512                 var record = new Array();
 513                 record['xmlDoc'] = data;
 514                 if (context.currRecOffset !== undefined) {
 515                     record['offset'] = context.currRecOffset;
 516                     callback(record, handle);
 517                 } else if ( recordNode =
 518                     data.getElementsByTagName("record")[0] ) {
 519                     // if stylesheet was fetched do not parse the response
 520                     if ( context.xslDoc ) {
 521                         record['recid'] =
 522                             recordNode.getElementsByTagName("recid")[0]
 523                                 .firstChild.nodeValue;
 524                         record['xslDoc'] =
 525                             context.xslDoc;
 526                     } else {
 527                         for ( i = 0; i < recordNode.childNodes.length; i++) {
 528                             if ( recordNode.childNodes[i].nodeType
 529                                 == Node.ELEMENT_NODE
 530                                 && recordNode.childNodes[i].nodeName
 531                                 != 'location' ) {
 532                                 var nodeName =
 533                                     recordNode.childNodes[i].nodeName;
 534                                 var nodeText =
 535                                     recordNode.childNodes[i]
 536                                         .firstChild.nodeValue;
 537                                 record[nodeName] = nodeText;
 538                             }
 539                         }
 540                         // the location might be empty!!
 541                         var locationNodes =
 542                             recordNode.getElementsByTagName("location");
 543                         record["location"] = new Array();
 544                         for ( i = 0; i < locationNodes.length; i++ ) {
 545                             record["location"][i] = {
 546                                 "id": locationNodes[i].getAttribute("id"),
 547                                 "name": locationNodes[i].getAttribute("name")
 548                             };
 549
 550                             for (j = 0;
 551                                 j < locationNodes[i].childNodes.length;
 552                                 j++) {
 553                                 if ( locationNodes[i].childNodes[j].nodeType
 554                                     == Node.ELEMENT_NODE ) {
 555                                     var nodeName =
 556                                         locationNodes[i].childNodes[j].nodeName;
 557                                     var nodeText = '';
 558                                     if (locationNodes[i].childNodes[j]
 559                                             .firstChild)
 560                                         nodeText =
 561                                             locationNodes[i].childNodes[j]
 562                                                 .firstChild.nodeValue;
 563                                     record["location"][i][nodeName] = nodeText;
 564                                 }
 565                             }
 566                         }
 567                     }
 568
 569                     callback(record, handle);
 570                 }
 571                 else
 572                     context.throwError('Record failed. Malformed WS resonse.',
 573                                         115);
 574             }
 575         );
 576     },
 577
 578     termlist: function()
 579     {
 580         if( !this.searchStatusOK && this.useSessions )
 581             throw new Error(
 582             'Pz2.js: termlist command has to be preceded with a search command.'
 583             );
 584
 585         // if called explicitly takes precedence
 586         clearTimeout(this.termTimer);
 587
 588         var context = this;
 589         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 590         request.get(
 591             {
 592                 "command": "termlist",
 593                 "session": this.sessionID,
 594                 "name": this.termKeys
 595             },
 596             function(data) {
 597                 if ( data.getElementsByTagName("termlist") ) {
 598                     var activeClients =
 599                         Number( data.getElementsByTagName("activeclients")[0]
 600                                     .childNodes[0].nodeValue );
 601                     context.activeClients = activeClients;
 602                     var termList = { "activeclients":  activeClients };
 603                     var termLists = data.getElementsByTagName("list");
 604                     //for each termlist
 605                     for (i = 0; i < termLists.length; i++) {
 606                         var listName = termLists[i].getAttribute('name');
 607                         termList[listName] = new Array();
 608                         var terms = termLists[i].getElementsByTagName('term');
 609                         //for each term in the list
 610                         for (j = 0; j < terms.length; j++) {
 611                             var term = {
 612                                 "name":
 613                                     (terms[j].getElementsByTagName("name")[0]
 614                                         .childNodes.length
 615                                     ? terms[j].getElementsByTagName("name")[0]
 616                                         .childNodes[0].nodeValue
 617                                     : 'ERROR'),
 618                                 "freq":
 619                                     terms[j]
 620                                     .getElementsByTagName("frequency")[0]
 621                                     .childNodes[0].nodeValue || 'ERROR'
 622                             };
 623
 624                             var termIdNode =
 625                                 terms[j].getElementsByTagName("id");
 626                             if(terms[j].getElementsByTagName("id").length)
 627                                 term["id"] =
 628                                     termIdNode[0].childNodes[0].nodeValue;
 629                             termList[listName][j] = term;
 630                         }
 631                     }
 632
 633                     context.termCounter++;
 634                     var delay = context.termTime
 635                         + context.termCounter * context.dumpFactor;
 636                     if ( activeClients > 0 )
 637                         context.termTimer =
 638                             setTimeout(
 639                                 function () {
 640                                     context.termlist();
 641                                 },
 642                                 delay
 643                             );
 644
 645                    context.termlistCallback(termList);
 646                 }
 647                 else
 648                     context.throwError('Termlist failed. Malformed WS resonse.',
 649                                         116);
 650             }
 651         );
 652
 653     },
 654     bytarget: function()
 655     {
 656         if( !this.initStatusOK && this.useSessions )
 657             throw new Error(
 658             'Pz2.js: bytarget command has to be preceded with a search command.'
 659             );
 660
 661         // no need to continue
 662         if( !this.searchStatusOK )
 663             return;
 664
 665         // if called explicitly takes precedence
 666         clearTimeout(this.bytargetTimer);
 667
 668         var context = this;
 669         var request = new pzHttpRequest(this.pz2String, this.errorHandler);
 670         request.get(
 671             { "command": "bytarget", "session": this.sessionID },
 672             function(data) {
 673                 if ( data.getElementsByTagName("status")[0]
 674                         .childNodes[0].nodeValue == "OK" ) {
 675                     var targetNodes = data.getElementsByTagName("target");
 676                     var bytarget = new Array();
 677                     for ( i = 0; i < targetNodes.length; i++) {
 678                         bytarget[i] = new Array();
 679                         for( j = 0; j < targetNodes[i].childNodes.length; j++ ) {
 680                             if ( targetNodes[i].childNodes[j].nodeType
 681                                 == Node.ELEMENT_NODE ) {
 682                                 var nodeName =
 683                                     targetNodes[i].childNodes[j].nodeName;
 684                                 var nodeText =
 685                                     targetNodes[i].childNodes[j]
 686                                         .firstChild.nodeValue;
 687                                 bytarget[i][nodeName] = nodeText;
 688                             }
 689                         }
 690                     }
 691
 692                     context.bytargetCounter++;
 693                     var delay = context.bytargetTime
 694                         + context.bytargetCounter * context.dumpFactor;
 695                     if ( context.activeClients > 0 )
 696                         context.bytargetTimer =
 697                             setTimeout(
 698                                 function () {
 699                                     context.bytarget();
 700                                 },
 701                                 delay
 702                             );
 703
 704                     context.bytargetCallback(bytarget);
 705                 }
 706                 else
 707                     context.throwError('Bytarget failed. Malformed WS resonse.',
 708                                         117);
 709             }
 710         );
 711     },
 712
 713     // just for testing, probably shouldn't be here
 714     showNext: function(page)
 715     {
 716         var step = page || 1;
 717         this.show( ( step * this.currentNum ) + this.currentStart );
 718     },
 719
 720     showPrev: function(page)
 721     {
 722         if (this.currentStart == 0 )
 723             return false;
 724         var step = page || 1;
 725         var newStart = this.currentStart - (step * this.currentNum );
 726         this.show( newStart > 0 ? newStart : 0 );
 727     },
 728
 729     showPage: function(pageNum)
 730     {
 731         //var page = pageNum || 1;
 732         this.show(pageNum * this.currentNum);
 733     }
 734 };
 735
 736 /*
 737 ********************************************************************************
 738 ** AJAX HELPER CLASS ***********************************************************
 739 ********************************************************************************
 740 */
 741 var pzHttpRequest = function ( url, errorHandler ) {
 742         this.request = null;
 743         this.url = url;
 744         this.errorHandler = errorHandler || null;
 745         this.async = true;
 746
 747         if ( window.XMLHttpRequest ) {
 748             this.request = new XMLHttpRequest();
 749         } else if ( window.ActiveXObject ) {
 750             try {
 751                 this.request = new ActiveXObject( 'Msxml2.XMLHTTP' );
 752             } catch (err) {
 753                 this.request = new ActiveXObject( 'Microsoft.XMLHTTP' );
 754             }
 755         }
 756 };
 757
 758 pzHttpRequest.prototype =
 759 {
 760     get: function ( params, callback )
 761     {
 762         this._send( 'GET', params, '', callback );
 763     },
 764
 765     post: function ( params, data, callback )
 766     {
 767         this._send( 'POST', params, data, callback );
 768     },
 769
 770     load: function ()
 771     {
 772         this.async = false;
 773         this.request.open( 'GET', this.url, this.async );
 774         this.request.send('');
 775         if ( this.request.status == 200 )
 776             return this.request.responseXML;
 777     },
 778
 779     _send: function ( type, params, data, callback )
 780     {
 781         this.callback = callback;
 782         var context = this;
 783         this.async = true;
 784         this.request.open( type, this._urlAppendParams(params), this.async );
 785         this.request.onreadystatechange = function () {
 786             context._handleResponse();
 787         }
 788         this.request.send(data);
 789     },
 790
 791     _urlAppendParams: function (params)
 792     {
 793         var getUrl = this.url;
 794
 795         var sep = '?';
 796         var el = params;
 797         for (var key in el) {
 798             if (el[key] != null) {
 799                 getUrl += sep + key + '=' + encodeURIComponent(el[key]);
 800                 sep = '&';
 801             }
 802         }
 803         return getUrl;
 804     },
 805
 806     _handleResponse: function ()
 807     {
 808         if ( this.request.readyState == 4 ) {
 809             // pick up pazpr2 errors first
 810             if ( this.request.responseXML
 811                 && this.request.responseXML.documentElement.nodeName == 'error'
 812                 && this.request.responseXML.getElementsByTagName("error")
 813                     .length ) {
 814                 var errAddInfo = '';
 815                 if ( this.request.responseXML.getElementsByTagName("error")[0]
 816                         .childNodes.length )
 817                     errAddInfo = ': ' +
 818                         this.request.responseXML
 819                             .getElementsByTagName("error")[0]
 820                             .childNodes[0].nodeValue;
 821                 var errMsg =
 822                     this.request.responseXML.getElementsByTagName("error")[0]
 823                         .getAttribute("msg");
 824                 var errCode =
 825                     this.request.responseXML.getElementsByTagName("error")[0]
 826                         .getAttribute("code");
 827
 828                 var err = new Error(errMsg + errAddInfo);
 829                 err.code = errCode;
 830
 831                 if (this.errorHandler) {
 832                     this.errorHandler(err);
 833                 }
 834                 else {
 835                     throw err;
 836                 }
 837             } else if ( this.request.status == 200 ) {
 838                 this.callback( this.request.responseXML );
 839             } else {
 840                 var err = new Error("Pz2.js: HTTP request error (AJAX). Code: "
 841                             + this.request.status + " Info: "
 842                             + this.request.statusText );
 843                 err.code = 'HTTP';
 844
 845                 if (this.errorHandler) {
 846                     this.errorHandler(err);
 847                 }
 848                 else {
 849                     throw err;
 850                 }
 851             }
 852         }
 853     }
 854 };
 855
 856 /*
 857 ********************************************************************************
 858 ** XML HELPER FUNCTIONS ********************************************************
 859 ********************************************************************************
 860 */
 861
 862 // DOMDocument
 863
 864 if ( window.ActiveXObject) {
 865     var DOMDoc = document;
 866 } else {
 867     var DOMDoc = Document.prototype;
 868 }
 869
 870 DOMDoc.newXmlDoc = function ( root )
 871 {
 872     var doc;
 873
 874     if (document.implementation && document.implementation.createDocument) {
 875         doc = document.implementation.createDocument('', root, null);
 876     } else if ( window.ActiveXObject ) {
 877         doc = new ActiveXObject("MSXML2.DOMDocument");
 878         doc.loadXML('<' + root + '/>');
 879     } else {
 880         throw new Error ('No XML support in this browser');
 881     }
 882
 883     return doc;
 884 }
 885
 886
 887 DOMDoc.parseXmlFromString = function ( xmlString )
 888 {
 889     var doc;
 890
 891     if ( window.DOMParser ) {
 892         var parser = new DOMParser();
 893         doc = parser.parseFromString( xmlString, "text/xml");
 894     } else if ( window.ActiveXObject ) {
 895         doc = new ActiveXObject("MSXML2.DOMDocument");
 896         doc.loadXML( xmlString );
 897     } else {
 898         throw new Error ("No XML parsing support in this browser.");
 899     }
 900
 901     return doc;
 902 }
 903
 904 DOMDoc.transformToDoc = function (xmlDoc, xslDoc)
 905 {
 906     if ( window.XSLTProcessor ) {
 907         var proc = new XSLTProcessor();
 908         proc.importStylesheet( xslDoc );
 909         return proc.transformToDocument(xmlDoc);
 910     } else if ( window.ActiveXObject ) {
 911         return document.parseXmlFromString(xmlDoc.transformNode(xslDoc));
 912     } else {
 913         alert( 'Unable to perform XSLT transformation in this browser' );
 914     }
 915 }
 916
 917 // DOMElement
 918
 919 Element_removeFromDoc = function (DOM_Element)
 920 {
 921     DOM_Element.parentNode.removeChild(DOM_Element);
 922 }
 923
 924 Element_emptyChildren = function (DOM_Element)
 925 {
 926     while( DOM_Element.firstChild ) {
 927         DOM_Element.removeChild( DOM_Element.firstChild )
 928     }
 929 }
 930
 931 Element_appendTransformResult = function ( DOM_Element, xmlDoc, xslDoc )
 932 {
 933     if ( window.XSLTProcessor ) {
 934         var proc = new XSLTProcessor();
 935         proc.importStylesheet( xslDoc );
 936         var docFrag = false;
 937         docFrag = proc.transformToFragment( xmlDoc, DOM_Element.ownerDocument );
 938         DOM_Element.appendChild(docFrag);
 939     } else if ( window.ActiveXObject ) {
 940         DOM_Element.innerHTML = xmlDoc.transformNode( xslDoc );
 941     } else {
 942         alert( 'Unable to perform XSLT transformation in this browser' );
 943     }
 944 }
 945
 946 Element_appendTextNode = function (DOM_Element, tagName, textContent )
 947 {
 948     var node = DOM_Element.ownerDocument.createElement(tagName);
 949     var text = DOM_Element.ownerDocument.createTextNode(textContent);
 950
 951     DOM_Element.appendChild(node);
 952     node.appendChild(text);
 953
 954     return node;
 955 }
 956
 957 Element_setTextContent = function ( DOM_Element, textContent )
 958 {
 959     if (typeof DOM_Element.textContent !== "undefined") {
 960         DOM_Element.textContent = textContent;
 961     } else if (typeof DOM_Element.innerText !== "undefined" ) {
 962         DOM_Element.innerText = textContent;
 963     } else {
 964         throw new Error("Cannot set text content of the node, no such method.");
 965     }
 966 }
 967
 968 Element_getTextContent = function (DOM_Element)
 969 {
 970     if ( typeof DOM_Element.textContent != 'undefined' ) {
 971         return DOM_Element.textContent;
 972     } else if (typeof DOM_Element.text != 'undefined') {
 973         return DOM_Element.text;
 974     } else {
 975         throw new Error("Cannot get text content of the node, no such method.");
 976     }
 977 }
 978
 979 /* do not remove trailing bracket */
 980 }