Tuesday, January 23, 2007

GWT POST request doesn't include parameters

GWT POST request parameters HTTP HTML RequestBuilder AJAX

Following the GWT documentation for making a http-post but it's not clear what the post data should look like if you want it to include form parameters. The newer documentation for com.google.gwt.http.client has a bit more detail but the server side code processing the request (a java servlet) says there's no parameters in the request.

It's not in the documentation, but if you want to post form data you must set the "Content-type" header value in the request to "application/x-www-form-urlencoded"

For Example:
StringBuffer postData = new StringBuffer();
// note param pairs are separated by a '&' 
// and each key-value pair is separated by a '='

RequestBuilder builder = new RequestBuilder(RequestBuilder.POST, "/yourserver/formprocessor"));
builder.setHeader("Content-type", "application/x-www-form-urlencoded");
try {
  builder.sendRequest(postData.toString(), this /* or other RequestCallback impl*/);
} catch (RequestException e) {
  // handle this

This sample chapter from the JavaScript™ Phrasebook is useful: Sending a POST Request

Monday, January 15, 2007

How to give initialisation parameters to a GWT component

GWT init initialisation parameter dynamic config

Where you have a servlet, JSP or other technology dynamically producing the HTML "host page" for a GWT component, it makes sense that you may want to parameterise the way the GWT component renders/behaves based on certain initialisation/input parameters.

How do pass parameters into the Module?

There is a useful Dictionary facility in the Internationalisation (I18N) module ... it doesn't really have anything to do with Internationalisation but it's in this module because you could get the host page to provide key-to-locale-specific-message mappings to save the Module using any hard coded message text in a specific language.

It's generic enough that you could use it for any mapping of values.

The GWT documentation for Dictionary shows how to import the I18N module to your own module and then load the key-value mappings defined in the host page from your GWT code.

Friday, January 05, 2007

GWT shell resource not found *.nocache.html

GWT AJAX shell resource not found nocache.html cache.html

Following the Developer guide for making a GWT UI module. The code compiles fine with the GWT compiler and I now what to test and run using the GWT shell.

It starts up fine but I get the following error in the tree log of the shell when it opens up the HTML test page:
The development shell servlet received a request for
in module 'com.example.gwt.mypackage.MyModuleName'

My examplisation of the error message highlights what the problem was ...

The HTML "host page" must reference the module name in the meta tag, not the EntryPoint class or the ".client" package (it should be called .client if you want to use the GWT expectations for where things are). The module name is typically the package name parent of the ".client" package plus the name of the *.gwt.xml config file minus the extension.

<meta name='gwt:module' content='com.example.gwt.MyModuleName'/>

Thursday, January 04, 2007

JSTL TransformerFactoryImpl ClassCastException on WAS

JSTL TransformerFactoryImpl ClassCastException WAS xalan JAXP core xerces

A web application that has the following properties:
  1. includes the JAXP api jar files (in WEB-INF\lib)
  2. deploys with the class loader properties of "Parent Last"
  3. uses JSTL core
Will encounter the following stack trace from WAS when ever a JSP is loaded that contains JSTL (core reference):

JSP Processing Error
HTTP Error Code: 500
java.lang.ClassCastException: org.apache.xalan.processor.TransformerFactoryImpl
at javax.xml.transform.TransformerFactory.newInstance(Unknown Source)
at com.ibm.ws.jsp.translator.visitor.validator.PageDataImpl._getInputStream(PageDataImpl.java:125)
at com.ibm.ws.jsp.translator.visitor.validator.PageDataImpl.getInputStream(PageDataImpl.java:117)
at org.apache.taglibs.standard.tlv.JstlBaseTLV.validate(JstlBaseTLV.java:156)
at org.apache.taglibs.standard.tlv.JstlCoreTLV.validate(JstlCoreTLV.java:96)
at com.ibm.ws.jsp.translator.visitor.validator.ValidateVisitor.validateTagLib(ValidateVisitor.java:939)
at com.ibm.ws.jsp.translator.visitor.validator.ValidateVisitor.visitJspRootStart(ValidateVisitor.java:453)
at com.ibm.ws.jsp.translator.visitor.JspVisitor.processJspElement(JspVisitor.java:124)
at com.ibm.ws.jsp.translator.visitor.JspVisitor.visit(JspVisitor.java:110)
at com.ibm.ws.jsp.translator.JspTranslator.processVisitors(JspTranslator.java:121)
at com.ibm.ws.jsp.translator.utils.JspTranslatorUtil.translateJsp(JspTranslatorUtil.java:168)
at com.ibm.ws.jsp.translator.utils.JspTranslatorUtil.translateJspAndCompile(JspTranslatorUtil.java:81)
at com.ibm.ws.jsp.webcontainerext.JSPExtensionServletWrapper.translateJsp(JSPExtensionServletWrapper.java:360)
at com.ibm.ws.jsp.webcontainerext.JSPExtensionServletWrapper._checkForTranslation(JSPExtensionServletWrapper.java:329)
at com.ibm.ws.jsp.webcontainerext.JSPExtensionServletWrapper.checkForTranslation(JSPExtensionServletWrapper.java:237)
at com.ibm.ws.jsp.webcontainerext.JSPExtensionServletWrapper.handleRequest(JSPExtensionServletWrapper.java:144)
at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:3003)
at com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:221)
at com.ibm.ws.webcontainer.VirtualHost.handleRequest(VirtualHost.java:210)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:1958)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:88)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:472)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:411)
at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:101)
at com.ibm.ws.tcp.channel.impl.WorkQueueManager.requestComplete(WorkQueueManager.java:566)
at com.ibm.ws.tcp.channel.impl.WorkQueueManager.attemptIO(WorkQueueManager.java:619)
at com.ibm.ws.tcp.channel.impl.WorkQueueManager.workerRun(WorkQueueManager.java:952)
at com.ibm.ws.tcp.channel.impl.WorkQueueManager$Worker.run(WorkQueueManager.java:1039)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1470)

In short, make sure the JSPs, JSTL refs and the web app are 2.4 compliant (see past post: What Spec?) and install the latest fix pack for WAS from IBM.

In detail, the following Problem ID is a different issue but underlying problem is the same - incorrect handling of loading XML & XSLT API classes for Parent Last apps - IBM - PK26233. The comment says it is resolved in the fix pack for WebSphere Application Server, but I used seeing it was newer - V6.0.2 Fix Pack 17.