Parametrized Xslt from javascript, using prototype

Here's the final product; the original page has 'a' links in a tag with id="displayableModules". The links have the form href="BadChannelsFile.xml#12345.0" where the module id is indicated after the file. This is a kind of xpointer syntax, but I remould it so the id gives the module part and then listen for 'click' events on those ids; this causes an XSLT to be run with the id as a parameter and a new window contains the SVG which results. Along the way, I experimented with various file loading mechanisms (so I made a separate loading class) but stuck with a synchronous Ajax request, although discovered that Safari requires the method to explicitly stated as 'get' in lower case. Enjoy...

var Loader = Class.create({

  initialize: function(){

    this.result="";

  },

  

  loadXml: function(docPath){

    this.ajaxLoad(docPath);

  },

  

  ajaxLoad: function(docPath){

  //bind the passed function to the original class

  //the method (get) needs to be explicitly written in lowercase for the Safari browser!

    new Ajax.Request(docPath, {asynchronous: false, onSuccess: this._callback.bind(this), method: "get",

    onFailure: function(r){alert("load failed");}})

  },

  

  _callback: function(r){

    this.result=r.responseXML;

  },

  

  doc: function(){

    if (this.result==""){

      alert("no doc");

    }

    return this.result;

  }

});

var Transformer = Class.create({

initialize: function(){

  this.processor = new XSLTProcessor();

  this.paramNames=[];

  this.paramValues=[];

  this.xslPath="";

  this.xmlPath="";

  this.fileLoader = new Loader();

},

setXslt: function(xslPath){

  this.xslPath = xslPath;

  this.fileLoader.loadXml(xslPath);

  this.stylesheet = this.fileLoader.doc();

},

setXml: function(docPath){

  this.xmlPath = docPath;

  this.fileLoader.loadXml(docPath);

  this.xmlDoc = this.fileLoader.doc();

},

setParam: function(paramName, paramValue){

  this.paramNames.push(paramName);

  this.paramValues.push(paramValue);

},

exec: function(thisdoc){

   this.processor.importStylesheet(this.stylesheet);

  for (var i=0;i<this.paramValues.length;i++){

    this.processor.setParameter("",this.paramNames[i], this.paramValues[i]);

  }

  var fragment = this.processor.transformToFragment(this.xmlDoc, thisdoc);

  return fragment;

}

});

//global functions

function changeLinks(){

  //take existing links in the div 'displayableModules' and add an id, and suppress the href link

  var allLinks=$("displayableModules").getElementsByTagName("a");

  for (var i=0;i

    var thisElement=$(allLinks[i]);

    var thisElementUrl=String(thisElement.href);

    var moduleId="module_".concat(thisElementUrl.substring(thisElementUrl.lastIndexOf('#') + 1));

    thisElement.setAttribute("id", moduleId);

    thisElement.setAttribute("name", thisElementUrl.substring(0,thisElementUrl.lastIndexOf('#')));

    thisElement.setAttribute("href","");

  }

  listenToLinks();

 }

function listenToLinks(){

//take existing links in the div 'displayableModules' and listen to them...

var allLinks=$("displayableModules").getElementsByTagName("a");

  for (var i=0;i

    var thisElement=$(allLinks[i]);

    var thisModule=String(thisElement.id);

    thisElement.observe('click',transform);

  }

}

function transform(e) {

  var moduleElement=e.element();

  var thisModule=moduleElement.id;

  var sourceFile=moduleElement.name;

  var transformer = new Transformer();

  transformer.setXslt("./xsl/graph.xsl");

  transformer.setXml(sourceFile);

  transformer.setParam("id",thisModule.substring(7));

  w=window.open("",thisModule,"width=670,height=500");

  w.document.open();

  w.document.write('

Bad channels for module ' + thisModule.substring(7) + '

');

  f=transformer.exec(w.document);

  w.document.getElementById('insert').appendChild(f);

  w.document.close();

}

document.observe('dom:loaded', changeLinks);

Prototype and running XSLT from JavaScript

I had some problem marrying the usual method of running an XSLT with prototype's library. Here's my project: Given an xml file of 'bad channel identifiers' for a module (where channels run 0-767), display the bad channels as bars on a graph in SVG in response to a user clicking on another web page link somewhere. I chose to generate the SVG using a parametrised XSLT, but I need to pass the parameters...so I'll be running the XSLT 'manually' from JavaScript instead of using the stylesheet association.

Step 1. : Perform a transform manually using a loaded stylesheet and xml. I'll load both via an Ajax request... (this is not production code, but might help someone... and note that I already loaded the prototype library)

var Transformer = Class.create({

initialize: function(){

  this.processor = new XSLTProcessor();

},

setXslt: function(xslPath){

  //need to bind, otherwise 'this' refers to the event context, not the class

  new Ajax.Request(xslPath, {asynchronous: false, onSuccess: this._setXsl.bind(this),

  onFailure: function(r){alert("failure to load xsl");}});

  

},

_setXsl: function(r){

  this.stylesheet=r.responseXML;

  if (this.stylesheet==''){

    alert("Empty stylesheet");

  }

  this.processor.importStylesheet(this.stylesheet);

},

setXml: function(docPath){

  //need to bind, otherwise 'this' refers to the event context, not the class

   new Ajax.Request(docPath, {asynchronous: false, onSuccess: this._setXml.bind(this),

  onFailure: function(r){alert("failure to load xml");}});

},

_setXml: function(r){

  this.xmlDoc = r.responseXML;

  if (this.xmlDoc==''){

    alert("Empty xml doc");

  }

 },

exec: function(){

  var fragment = this.processor.transformToFragment(this.xmlDoc, document);

  return fragment;

}

});

function transform() {

var transformer = new Transformer();

transformer.setXslt("xsl/test.xsl");

transformer.setXml("xml/hello.xml");

f = transformer.exec();

$('insert').appendChild(f);

}

Java 'PUT' for RESTful service

I was looking around for a Java example of 'PUT' for  the CherryPy/COOL server, and at least came across a 'GET' at Jose Sandovals blog... but not much on the other methods. Andrea Formica (Atlas Muons) is trying to use it to upload calibrations. Here's the solution he came up with, using Apache's library:

public String coolPutCherryPyHttpClient() throws IOException, FileNotFoundException{

String res = "none";

HttpClient client = new HttpClient();

PutMethod put = new PutMethod(this.writenodeUrl);

    try {

String payloaddata = " 999999. "

+ "";

client.getParams().setAuthenticationPreemptive(true);

Credentials defaultcreds = new UsernamePasswordCredentials(this.name, this.psswd);

client.getState().setCredentials(new AuthScope(serverUrl, portNumber, AuthScope.ANY_REALM), defaultcreds);

NameValuePair par = new NameValuePair();

par.setName("payload");

par.setValue(payloaddata);

NameValuePair[] params = new NameValuePair[1];

params[0] = par;

put.setQueryString(params);

// Execute the method.

        int statusCode = client.executeMethod(put);

        if (statusCode != HttpStatus.SC_OK) {

          System.err.println("Method failed: " + put.getStatusLine());

        }

        // Read the response body.

        byte[] responseBody = put.getResponseBody();

        // Deal with the response.

        // Use caution: ensure correct character encoding and is not binary data

        res = new String(responseBody);

        System.out.println(new String(responseBody));

      } catch (HttpException e) {

        System.err.println("Fatal protocol violation: " + e.getMessage());

        e.printStackTrace();

      } catch (IOException e) {

        System.err.println("Fatal transport error: " + e.getMessage());

        e.printStackTrace();

      } finally {

        // Release the connection.

        put.releaseConnection();

      }  

return res;

}

Saxon XSLT 2.0 format-number problem (update!)

Later: following the post below, I managed to ask on the saxon-help list about this. The reply from Michael Kay (He Should Know!)

is that this is the expected behaviour. Looking in the W3C recommendation, it refers to the JDK 1.1 DecimalFormat class, which indeed states:

Symbol Meaning  

0      a digit  

#      a digit, zero shows as absent  

.      placeholder for decimal separator  

,      placeholder for grouping separator.  

;      separates formats.  

-      default negative prefix.  

%      multiply by 100 and show as percentage  

? multiply by 1000 and show as per mille  

¤ currency sign; replaced by currency symbol; if

         doubled, replaced by international currency symbol.

         If present in a pattern, the monetary decimal separator

         is used instead of the decimal separator.  

X      any other characters can be used in the prefix or suffix  

'      used to quote special characters in a prefix or suffix.  

...so , perverse as it seems, the behaviour is as advertised.

Original post:

One of the (many) advantages of using XSLT 2.0 is its supposed ability to understand scientific notation, e.g. 1E-2 is correctly interpreted as 0.01. However the only implementation I know of for XSLT 2.0 is Saxon, so the XSLT 2.0 standard basically defines this one application. Here's a nasty I discovered while trying to format exponential numbers using Saxon 9.1.0.6: Formatting zero with

format-number(xs:double($myNumber),'#.#######')

causes an empty string to be output.

Heres a sample xml:

<numbers>
<test> id="1">1.3</test>
<test> id="2">8E-4</test>
<test> id="3">8E-8</test>
<test> id="4">0.0</test>
<test> id="5">0</test>
</numbers>

and an xslt:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
exclude-result-prefixes="xs"
version="2.0">
<xsl:output method="text"/>
<xsl:template match="numbers">
<xsl:apply-templates/>
</xsl:template>
<xsl:template match="test">
<xsl:value-of select="concat('Original: ',text())"/>
Format with #.#####
'<xsl:value-of select="format-number(xs:double(.), '#.#####')"/>'
Format with #.#########
'<xsl:value-of select="format-number(xs:double(.), '#.#########')"/>'
</xsl:template>
</xsl:stylesheet>

But the output is not what one would expect:

Original: 1.3
Format with #.#####
'1.3'
Format with #.#########
'1.3'

Original: 8E-4
Format with #.#####
'.0008'
Format with #.#########
'.0008'

Original: 8E-8
Format with #.#####
''
Format with #.#########
'.00000008'

Original: 0.0
Format with #.#####
''
Format with #.#########
''

Original: 0
Format with #.#####
''
Format with #.#########
''

CherryPy Caching: reprise

Finally I had to turn off caching, even with my fix in place. Users reported a malformed xml being returned for certain queries, and it turned out that anything longer than the maxobjectsize was being cached and returned truncated. I'm sure there's an easy way around this, but not sure I want to spend more time on it just now.

CherryPy Caching

I just tried turning on CherryPy web caching, this is one of the few things which receives only very cursory treatment in Sylvain Hellegouarch's  excellent book, 'CherryPy Essentials'. I managed by incorporating the 

conf = {'/':{'tools.caching.on':True}}

line in my code, however I was dismayed to discover that once on, I couldn't form a request would not get the cached result. Neither 'Cache-Control:max-age=0' nor 'Pragma: no-cache' would do it. Looking into the code (I'm using v. 3.1.1), I found the caching.py tool and indeed saw it pays pretty much no attention to the http request headers except (bizarrely, I think) the 'Vary' header. I've inserted a few lines into caching.py to fix this and submitted a trac bug, so we'll see whether this changes. The code lines are reproduced here:

#some people still use Pragma : no-cache to demand a fresh resource

        pragma_no_cache=False

        pragma_header=request.headers.get('Pragma')

        if pragma_header:

            pragma_values=[header.strip() for header in pragma_header.split(',')]

            for this_value in pragma_values:

                if 'no-cache' in this_value:

                    pragma_no_cache=True

                    break

        #added by shaun, look at cache-control

        max_acceptable_age=MemoryCache.delay

        age_seconds=int(response.time - create_time)

        cache_control_header=request.headers.get('Cache-Control')

        if cache_control_header:

            #split string on commas to get the multiple words

            cache_control_values=[header.strip() for header in cache_control_header.split(',')]

            #look for max-age

            for this_value in cache_control_values:

                if ('max-age' in this_value) and ('=' in this_value):

                    age_pair=[age.strip() for age in this_value.split('=')]

                    if age_pair[1].isdigit():

                      max_acceptable_age=int(age_pair[1])

                    break

                  

        #return if the cache is older than the acceptable age

        if (age_seconds > max_acceptable_age) or pragma_no_cache:

            request.cached = False

            request.cacheable = True

            return False

            

        # Add the required Age header

        response.headers["Age"] = str(age_seconds)

Reviews and DB

I've been reviewing the InDetGlobalMonitoring code for Heidi, and trying to get more info into my 'run summary' page for the FDR. This second has not been easy, I need to understand the Tier0 database a lot better!

On the bright side, I had my SEDUX paper accepted for the SVG conference in Nuremberg in August.