Plastic Scotsman's Blog

Thinking about upgrading Oracle Forms?

2012-02-07T16:31:00.002Z

Then this OUG event is just for you: UKOUG Development SIG Meeting - Forms in the 21st Century!

There's input from Grant Ronald Oracle's authority on Forms and ADF and also from partners providing solutions for updating your Forms install base. Should be a great day for those who want to see as many of the options for modernisation in one hit.

Java7 is here! (and free t-shirt give away)

2011-07-28T20:43:00.003Z

After a long wait Java7 is finally here. Congratulations to all the team involved. I'm downloading it as I write. Thanks to Olaf and Oracle I have some lovely Java7 t-shirts to give away. If you fancy one just send me a message, first come first served of course.

2011-03-16T16:39:00.002Z

Just been asked to spread the word that the JDK7 Developer Preview is available. The details are below:

Java SE 7 Developer Preview Release - Download Now! - The JDK7 Developer Preview Release is now available for rigorous community testing. But time is running out! The latest build is feature complete, stable and ready to roll - so download, test and report bugs now.

Let us know what you think. If you report a bug in the JDK 7 developer preview before April 4th, the Java product team will sing your praises on the Java SE 7 Honor Role. PLUS... we will send you some Java swag. We’ll read, evaluate, and act on all feedback received via the usual bug-reporting channel. Bugs reported later on might not get ﬁxed in time for the initial release, so if you want to be a contributor to Java SE 7 do it before the April deadline.

Free ADF Training

2011-03-10T09:13:00.006Z

There are two upcoming ADF training events in the pipeline, one for Oracle Partners and another for UKOUG members. Both are being given by Grant Ronald of Oracle.

Details for the partner one are here and details for the UKOUG event are here.

ADF 10gR3 on WebLogic 11gR1ps3!!

2011-03-04T14:00:00.003Z

The list of certified application servers supported by JDeveloper has just been updated on OTN, you can get it here with a related footnote (H) here. Not normally ground shaking news but the implication of the combination of JDev 10gR3 being certified with WebLogic 11gR1ps3 (10.3.4) is that ADF applications written for OracleAS 10g can now be run on WebLogic. This is a great plus for customers wanting to standardise on Oracle's strategic application server without migrating in production ADF applications. Nice one ADF team!

Free Oracle Virtual Developer Days and WebLogic training

2011-01-31T09:53:00.002Z

Hi, if you're interested in the latest JEE6 and WebLogic technology then the upcoming Virtual Developer Day on 10th Feb and the following WebLogic weekly webcasts are a great chance to get up to speed. They're also free! The registration page is here.

PS3 is here!

2011-01-17T11:54:00.001Z

Sorry to disappoint gaming fans but I'm referring to Fusion Middleware 11.1.1.4 (AKA patch-set 3) is now available. Download it from here.

People's Choice - Database Development

2011-01-10T20:16:00.001Z

The JDeveloper team need your vote for their JDev + Database tooling, exercise your democratic right here by voting for "Making the Most of Logical and Physical Modeling in JDeveloper" at People's Choice - Database Development

All change

2010-09-06T16:17:00.004Z

There's been a bit of a reorganisation on OTN lately and some of the links have changed in the site's move to Oracle Universal Content Management. One of the great ADF resources, ADF Code Corner, has a new URL; you can now find it here.

There's also a great new ADF resource on OTN called ADF Insider, it's content related to more advanced ADF techniques; you'll find it here.

Enjoy!

Going Mobile

2010-05-07T10:10:00.002Z

Last week was quite a week for releases. Not only was there Ubuntu 10.04 but Oracle released patchset 2 of Fusion Middleware 11gR1. "Fusion Middleware" is an umbrella term for a family of products so overall there's a myriad of updates in there including a new version of WebLogic server 10.3.3, BPM 11g and Tuxedo, etc, etc. There's an update to JDeveloper and the Application Development Framework (ADF) which while being an incremental step includes a significant new feature that my colleagues and customers have been interested in for some time: ADF Mobile Client.

ADF Mobile Client provides a full on client Java client that can be developed using the same tools and techniques as a "standard" ADF web application. It leverages Oracle Lite to ensure the application works irrespective of connectivity e.g. on the Tube. The supported mobile platforms are currently Blackberry and Windows Mobile. What no iPhone I hear you say? Well this omission may have something to do with Apple's recent changes to their iPhone developer agreement which mean that any iPhone app must be written in Objective C on Apple hardware. Hopefully we'll see some changes to that that mean the legion of ADF and/or Java developers can unleash their creativity on the iPhone. Until then there's always ADF Mobile Browser to fill the gap!

Behind the curve

2010-05-05T20:32:00.005Z

You may have seen that Ubuntu 10.04 (Lucid Lynx) was released last week to positive reviews. Despite being an ardent ubuntunista I've resisted upgrading my main PC until the first updates are out.

It is on my "other" laptop and despite some minor niggles the general impression is great apart from the fact that I still keep reaching for the windows buttons in the top right hand corner. Moving them to the top left is probably the most visible sign of Canonical's desire to make Ubuntu as visually appealing as Apple's OS X. This is probably essential to get Ubuntu on more desktops of ordinary (I mean that in a good way) users but I think there's another slant that, given recent events, should be able to convert a few more PCs to the penguin.

The fact is that nowadays we conduct our much of our personal and business tasks on the Internet and the Internet is a dangerous place. Both France and Germany have warned their citizens not to use Internet Explorer. Ghostnet may (or may not) be spying on governments and businesses and even Google has fallen victim to a hacking attack. So surely it's a good idea to equip computer with an OS that will be able to protect you in this hostile environment? Ubuntu remained unhacked in 2008's pwn2own contest (browsers and smartphones are now the targets) so could quite rightly claim to be the most secure desktop OS. Pairing up with what pwn2own has proved to be the most secure browser might be a smart move. Stay safe!

JDeveloper 11gR1PS1 + Ubuntu 9.10 + Ubuntu Bug #87947

2010-04-13T20:51:00.004Z

I've been doing some ADF 11g recently and found that JDev 11g running on Ubuntu 9.10 with the default JDK 1.6u14 would occasionally crash, updating to JDK 1.6u16 was no better. It seems that the issue is recorded here as Ubuntu bug #87947 (or one of it's duplicates) with the root cause being the JDK.

The fix is in JDK7 which can be had from the Sun (or is it Oracle now :-)) site here. After installing on my system I updated the $JDEV_HOME/jdev/bin/jdev.conf file to alter the line beginning "SetJavaHome" to point to the new JDK install like this:

SetJavaHome /usr/lib/jvm/jdk1.7.0

On starting JDeveloper there's a warning to say that JDK7 is not supported but so far no more crashes...

Proactive Health Checks Released on My Oracle Support

2009-11-04T18:00:00.003Z

Oracle Support have just created a Health Recommendations Catalog/Catalogue on My Oracle Support. Initially it contains 25 recommendations across all the product lines, fortunately the middleware products are fairly well represented so this is already a useful resource and one that will only increase in value. Check out document id 868955.1 on http://support.oracle.com!!

UK OUG Application Server SIG

2009-10-29T18:35:00.006Z

I recently had the pleasure of pleasure of presenting to the Application Server SIG of the UK's OUG. The talk was an introduction to tuning and scaling Oracle AS. Although Oracle AS is no longer Oracle's strategic application server it's still the runtime for many of the layered products such as E-Business Suite. The target audience is the "DBA" who finds themselves looking after an Oracle AS instance. The presentation is here for those interested...

BPEL Easter Egg: Reloading Fault Policy Files

2009-04-29T18:39:00.008Z

A little late for Easter but this is a neat trick discovered today by Sid, one of my colleagues.

We're using the BPEL fault policy framework and while we're developing them it's a bit of a pain to restart the app server every time a change is made. The 10.1.3.3.1 BPEL console now has a button to reload them linked to this URL:

http://server:port/BPELConsole/domain/doReloadFaultPolicy.jsp

For example to reload all of the fault policies in the default domain on a local install of SOA Suite use this URL:

http://localhost:8888/BPELConsole/default/doReloadFaultPolicy.jsp

Unfortunately the BPELConsole button seems to have disappeared in 10.1.3.4 so to reload the fault policies you can paste the URL diectly into your browser (you will be prompted to log in).

Video killed the podcast star

2009-04-06T20:22:00.003Z

I got a nice surprise recently when I downloaded the latest OTN Techcasts: They've gone all video. The new format opened with an overview of the new release of Enterprise Manager Grid Control. There's also a really nice white board session on Application Grid. The final surprise was how watch-able the video podcasts are on my iPod nano.

Compiz plus JDeveloper on Ubuntu 8.10 Intrepid

2009-03-09T17:42:00.009Z

Imagine my joy when on upgrading to Ubuntu 8.10 I found that Compiz was finally working on my Thinkpad!!! Transparency, wobbly windows and Win-E for a cool window switcher all looked great providing hours of endless fun.

Imagine my despair when after starting JDeveloper 10.1.3.4 for the first time after the upgrade I was faced with a blank window. It wobbled fine but had no content. The thought of returning to the boring non-wobbly windows world of plain old Gnome was too much to bear so some rapid research turned up a solution that seems worth sharing for the "JDeveloper on Linux plus Compiz" clique.

This is a bug in Sun's JDK that has been fixed in 1.6u10. If like me you are too lazy to update your JDK or can't (JDeveloper 10.1.3.4 is only certified against Java5) then the fix is to simply open the $JDEV_HOME/jdev/bin/jdev script and add the following as the first line:

export AWT_TOOLKIT=MToolkit

Save the file, run JDeveloper again and the UI goodies should be all yours....

Of course a simpler fix if you use many different versions of JDeveloper is to add the same line to your ~/.bashrc file.

Oracle or Open Source? Oracle and Open Source!

2009-01-14T16:24:00.006Z

The recent release of JDeveloper 11g reminded me that Oracle products are available under a variety of licensing models as well as the traditional "paid for" software model that most people are probably familiar with. So what are these alternative models?

Well let's start with JDeveloper itself. Back in June 2005 Oracle offered the JDeveloper licence for zero cost, there's an FAQ here. So JDeveloper is a "free" Oracle product that users can use in a production scenario, the licence is still an Oracle one and JDev is not an open source. Users can also purchase a suppport contract for JDeveloper for those critical projects.

Another example of this type of product is Oracle Database 10g Express Edition (aka XE). This has a licence that means it's free to develop, deploy, and distribute. The distribute part means that customers can bundle it as an embedded databse in their products. There are some restrictions about number of processors, size of user data and memory used but as it includes the awesome Application Express it really is a great fit for a lot of scenarios.

Moving on to the second model and we are going from gratis to libre software (to use the common terms). Oracle is very active in the open source space, active in several projects but also donating several products to kick start open source projects. A great example of this is Oracle Toplink OR framework. This formed the basis of Toplink Essentials which was the Java Persistence API (JPA) reference implementation. Toplink Essentials uses the CDDL licence.

Toplink was also donated as the basis for the EclipseLink project which will become the permanent home for the development of the JPA 2.0 reference implementation and uses the Eclipse Distribution Licence.

Another middleware example was the donation of the ADF Faces JSF components to the Apache Software Foundation. More details about Oracle's open source activities can be found here. Outside the middleware arena there's the XQilla XQuery engine and a ton of enhancements for the Linux kernel.

On a final note it's also worth pointing out that most Oracle products are downloadable from OTN under a licence that allows development and prototyping as well as personal education. So if you're looking to do some self training on the latest Oracle products then fill your boots!

Post Christmas Sobering Reading

2009-01-13T21:11:00.002Z

Just in time to add to the January blues SANS institute has published this list of the "top" (or bottom depending on your point of view) 25 coding errors.

This old gem recently brought down my favourite internet forum, a reminder that the internet is a dangerous place.

JDeveloper 11g - now with added WebLogic!

2008-10-07T20:48:00.004Z

Jdeveloper 11g is in production! It's been a long time coming but it's arrived with an extra bonus - an integrated WebLogic server. It's available for download on OTN. Remember JDeveloper is a free product so fill your boots...

Labour Saving Device

2008-09-10T12:39:00.005Z

Just found this great on-line utility that is saving me a huge amount of time in my current task of writing ant scripts for Hudson. Try www.findjar.com, it's a work of genius!

Configuring BPEL to invoke web services via SSL

2008-07-07T21:06:00.000Z

This post details how to configure the BPEL runtime to allow SOAP and/or HTTP binding calls over SSL. In this scenario the BPEL runtime acts as the client making requests to an external web service that is secured with SSL. The service provider's SSL certificate is added to the keystore of SOA Suite server as a trusted certificate.

Official Oracle documentation is located here . The process can be broken down into two steps:

Obtain the service provider's certificate.
Import the certificate to Oracle SOA Suite's default keystore.

Step 1 - Obtain the server's certificate

This is best accomplished via the web browser on a developer's PC:

Open the web service's SSL endpoint in IE e.g. https://server:443/someservice/someport
Double click the padlock icon in at the bottom of the IE window.
Select the Details tab in the Certificate dialog box.
Click the Save to File button and step through the wizard to save the certificate to your machine. Specify Base-64 encoded X.509 format and a name e.g. newcert.cer.

Step 2 - Import the certificate to Oracle AS's default keystore

This is done using the keytool utility of the JDK on the OracleAS server:

Copy the certificate fie (e.g. newcert.cer) to the server e.g. to the user's home directory.
Locate the default keystore. This is usually $ORACLE_HOME/jdk/jre/lib/security/cacerts.
Change directory to the location of the keystore. In this example $ORACLE_HOME/jdk/jre/lib/security/.
Import the certificate to the keystore using the command: $ORACLE_HOME/jdk/jre/bin/keytool -import -v -file ~/newcert.cer -keystore ./cacerts -alias someAlias . You will be prompted to enter a keystore password, the default password is changeit. The alias SomeAlias is a new alias for the certificate in the keystore, this is not mandatory but it's best to specify your own alias.
Restart the SOA Suite server.

Radio Ga Ga

2008-07-07T19:18:00.006Z

Last week a podast feed that had been quiet for a while leapt back into life in Spectacular fashion. Oracle Fusion Middleware Radio dumped fourteen (yes 14) pearls of wisdom about the new strategic direction of Fusion Middleware now that BEA are part of the team. There's some great stuff there about how the BEA products are going to become part of the #1 middleware portfolio. The feed is here if you want to subscribe or download the mp3's from here.

In a strange coincidence another of my podcast feeds also came back from the dead in the same week. The ITV Tour de France feed dumped a retrospective of last year's tour on my PC, a nice reminder that the greatest race on earth is back for three weeks of sprints, crashes, alps and pharmacy. Maybe the FMW guys wanted to get their podcasts out of the way early so they could enjoy Le Tour?

Schema based XML editing in JDeveloper

2008-05-03T08:04:00.011Z

Recently I've been using Oracle SOA Suite a lot and one of its interesting features in 10.1.3.3 is the policy driven fault handling framework where business faults and errors in the BPEL process manager can be handled by declarative policies. Nice I hear you think but the point is that these policies are defined in XML files that are defined by an XML schema. Writing these files is a lot easier when you've got an editor that provides some insight into the syntax and JDeveloper can be configured to do just that.

The XML schemas in question are shipped with SOA Suite and are made available over HTTP. You can copy the files to the developers machine or you can use the URL, in this example I'm using the latter. They could be any schema that you need to base XML files on.

First off you need to register the schemas in JDev so go to Tools > Preferences. In the Preferences window click on XML Schemas in the menu pane.

The schema I'm interested in is at http://localhost:8888/orabpel/xmllib/fault-policy.xsd on my SOA Suite install. Next click Add and paste the schema URL into the new window like this.
If the XML instance files you're going to create have a special extension (*.wsdl or *.xhtml) enter the extension here. Click OK and OK again. So to actually create a new XML document based on this schema open the new gallery and pick XML document from XML Schema from the General > XML category.

On clicking OK you'll be greeted with a wizard, on page 1 give your new file a name and click Use Registered Schema. On page 2 you'll see a drop down with the target namespaces declared in your registered schemas, in my case the one I want is http://schemas.oracle.com/bpel/faultpolicy. Select the desired root element (faultPolicy) the desired depth of elements to be created and the encoding.

Click Next then OK and the new file will open in an editor window. Because the structure is driven off the schema any errors will be underlined in red and prssing Ctrl-Space will give yo code insight for elements, attributes and attribute values.

As well as the insight you can right click on the editor and use the Validate XML context menu to check whether it's valid.

As I've mentioned before JDeveloper is a lot more than a Java IDE. Another related feature is a really nice graphical XML Schema editor. HTH!

ORABPEL-12101 ERRJMS_TRX_COMMIT using AQ + JMS Adapter!!??!!##&&**!!

2008-04-21T09:32:00.007Z

On our current SOA Suite project one of the teams has just swapped out OracleAS JMS provider for the Oracle AQ JMS provider. They're using the SOA Suite JMS Adapter to talk to the JMS Queue but found that using AQ they get a ORABPEL-12101 ERRJMS_TRX_COMMIT error on enqueuing a message. This seems to be an error that others have experienced but there are a couple of ways to fix this depending on your situation.

This section of our project is in development so we're coding, deploying, coding, deploying, etc. We haven't set up a JCA connection factory in OracleAS for AQ yet so we don't have an entry in our oc4j-ra.xml to edit. So how do we fix the issue?

Well if the JMS adapter can't find a connection factory at the specified JNDI location ("eis/Jms/SampleAq" in our example) it falls back to the development time values given in the WSDL. In the WSDL for our enqueue operation we changed the mcf.IsTransacted attribute of the jca:address element from true to false. It now looks like:

<jca:address location="eis/Jms/SampleAq" UIConnectionName="SampleAq" ManagedConnectionFactory="oracle.tip.adapter.jms.JmsManagedConnectionFactory" mcf.ConnectionFactoryLocation="java:comp/resource/OEMSAQProvider/QueueConnectionFactories/QCF" mcf.IsTopic="false" mcf.IsTransacted="false" mcf.FactoryProperties="" mcf.Username="common" mcf.Password="46969068B219FCC282915821ED80F355D62D1A19DF561D1E" UIJmsProvider="OJMS"/>

On redeployment the error was gone and the JMS enqueue operation was working as expected.

The mcf.* properties are intended for development time only and once you've set up a connection factory in OracleAS at the required JNDI location they can be deleted (see this diagram in the docs for a clear explanation of where connection info is sourced). Don't forget to set the isTransacted property to false in the connection factory set up or you will be back to square one!

Hope this helps someone out!

JDocs - Javadoc goes web 2.0

2008-04-14T18:34:00.004Z

If you can't configure JDeveloper to view javadocs over the web then you're probably always searching for whatever javadoc you need in your browser. JDocs acts as a one-stop shop for almost all the (open source) javadoc you need, all served up in a slick ajax style.

Things you find down the back of the sofa #3

2008-03-10T13:55:00.010Z

The focus of this post was going to be forms in ADF Faces applications and how to make them "user friendly". It's still sitting in my drafts waiting to be finished because one morning last week my netvibes feed aggregator delivered a blog post by Duncan Mills, Oracle ADF guru, on exactly the same subject. I'd like to say it's a case of great minds thinking alike but as Duncan is one of the brains behind the whole Application Development Framework he's always going to be a few miles ahead of me!

Duncan's post covers two techniques to make your ADF forms a little "smarter", setting the initial cursor position in an input component ready for the user to start typing (a new feature in 11g) and also to enable form submission with the enter key removing the need to move the mouse to the submit button.

So is there anything to add or should I just pack in now? Well fortunately for me there are a couple of extra tweaks you can add to your application's forms. It's worth the extra effort because in a typical web application the users may be filling in the same form several times an hour, think of a login or a query page, so they're going to thank you (maybe not literally) for making your forms a joy to use.

One neat feature of the ADF command button and command link eliminates the possibility of double form submissions. You will have probably seen the dire javascript warnings on some websites that warn against clicking the mouse, touching the keyboard or breathing while a form is being submitted. Using a component based framework like ADF-Faces allows you to solve this issue in a simpler, more elegant fashion by altering the behaviour of the button, in this case by disabling the button after it has been clicked. To do this with a simple submit button you simply set the blocking attribute to true like this:

<af:commandButton text="Submit" blocking="true"/>

Another tip is to make your forms easier to navigate by adding keyboard shortcuts like Alt-R for a form reset. Again this is nice and easy to do with a component based framework. For the reset button example above you'd add this:

<af:resetButton text="Reset Form" accessKey="R"/>

Add an access key to every input and command component and your power users will soon forget they have a mouse!

NB In writing this post I discovered that the default behaviour of the command button is to be blocking in Firefox and also that the accessKey doesn't work in Firefox. They're still features worth adding though as for some reason 80% of web users still use Internet Explorer?!?!?

Things you find down the back of the sofa #2

2008-01-15T20:28:00.001Z

One item that often gets overlooked in a Java EE web application is the http session time out. If a value is not explicitly set in the web.xml deployment descriptor then the target application server's default is used. In OC4J, Oracle's Java EE server, that default is 20 minutes. Although it's a sensible default it's unlikely to suit all applications, for a webmail application a longer period would make sense, for an internet banking app a shorter one would be nice!

Http sessions also come at a cost. Often the session ends up storing a lot of objects, some that should really be on shorter scopes, and this can cause memory starvation. All those sessions holding onto loads of objects preventing them from being garbage collected for 20 minutes after the user stops using your web app. It's for this reason that I usually setting the time out to something less than the default.

So how do you set the time out? Well the documentation is here but JDeveloper has a few tricks to help you get the web.xml right:

Select the web.xml in your application navigator and then move to the structure pane (usually in the bottom left corner). Right click on the web-app element and in the menu select Insert inside web-app > Browse.In the resulting dialog box select the session-config element.

Back in the structure pane select the newly added session-config and double click it. You'll get the following dialog box:Add your desired time out in minutes and press OK. This will add the following snippet to your web.xml:

<session-config>
<session-timeout>5</session-timeout>
</session-config>

That's it!

Are you a good programmer or a terrible one?

2008-01-15T19:42:00.000Z

I'm definitely not a good programmer, I'd like to be a terrible programmer really. So what are you, good or terrible? I'll put a poll on the blog, have a look at the links and let me know what you are.

Amazon and you're done....

2007-12-10T20:35:00.000Z

... or not of you're rafting the Amazon (the big river in Brazil).

My pal Bruce Low has decided to raft the Rio Amazon from source to sea to raise money for charity. It will be a tough trip so if you have any spare cash you can sponsor him here and read about his exploits here.

Things you find down the back of the sofa #1

2007-12-01T21:43:00.000Z

It's been a while since I've posted on this blog mainly due to the release of Mini Myles v3.0. We missed the drop date by 15 days but so far things seem to be going well. There are some minor issues related to vomiting and waking in the middle of the night but generally v3.0 is pretty bug free. I'm hoping the TCO of this version will be lower due to reuse from v2.0. Now back to business...

In this post I wanted to talk about the things I don't see when I work on Java EE projects, some of the niceties that make an application easier to use, easier to maintain and easier to debug. Sure the application will work fine without them but in my opinion it will be better with them.

Presuming the application requires a login one thing that's often omitted is a logout button. Encouraging users to logout makes sense on a couple of levels. There's the obvious security advantage of course but also the advantage of getting rid of all those session plus all the objects that have been stored on those sessions. Normally these will hang around consuming the resources of your app server until the session times out, encouraging the users to logout can save some valuable heap memory.

A logout button is pretty simple to implement in Oracle ADF. First you need a command button, drop it wherever makes sense on your page layout, an ideal place being one of the new page templates in 11g. In the JSP source it will look like this:

<af:commandButton text="#{msgs[\'label.logout\']}" action="#{Login.logout}" immediate="true"/>

Note that the immediate attribute has been set to true, this will bypass any validation on input components on the page and go straight to the navigation method logout in the Login managed bean.

The logout method in the session scoped managed bean would look like this:

public String logout()
{
// Logout/invalidate the existing session...
FacesContext fc = FacesContext.getCurrentInstance();
ExternalContext ec = fc.getExternalContext();
HttpSession session = (HttpSession)ec.getSession(false);
if(session != null) session.invalidate();

// Execute the global navigation rule "logout"
return "logout";
}

Rather than repeat the logout navigation rule for each page the logout rule is a global one, defined in faces-config.xml like this:

<navigation-rule>
<navigation-case>
<from-outcome>logout
<to-view-id>/login.jsp
<redirect/>
</navigation-case>
</navigation-rule>

Note that we have added the redirect element to the navigation case so that the browser is sent a HTTP 302 redirect. This helps to solve the issues caused if the user reloads the page or clicks the back button.

More bits of fluff to follow.

Ubuntu 7.10 is ready

2007-10-18T12:15:00.001Z

Just a quick not to say that Ubuntu 7.10 is out! Get it here while it's fresh.

How to warn there are unsaved changes in an ADF web app

2007-09-11T09:13:00.001Z

A customer recently asked me how, in an ADF web application, the user can be warned that there are unsaved changes, much like in a desktop application. A bit of research showed that John Stegeman had already blogged about a solution on his blog. It's a nice solution but as my client was using a JSF menu component from the Tomahawk library would have been hard to implement in our case.

So we took John's discovery that the expression "#{bindings.Commit.enabled}" evaluates to true when there are "unsaved" changes and set about creating an alternative solution. We also wanted to exploit as many use standard features of JSF wherever possible. The core of our solution was to use a custom JSF NavigationHandler. A default navigation handler is provided by the JSF implementation but it's easy to define a custom class that extends javax.faces.application.NavigationHandler in the faces-config.xml. In our custom class we can intercept all navigation requests and if unsaved changes are found add a warning message to the user and redisplay the same view. If no changes are found the custom class delegates decisions about the navigation to the default handler i.e. navigation proceeds as expected.

Our custom NavigationHandler is defined like this in the faces-config.xml:

....
<application>
....

<navigation-handler>CommitNavigationHandler</navigation-handler>
....
</application>
....

The new navigation handler uses the decorator pattern and looks like this:

public class CommitNavigationHandler
extends NavigationHandler
{
private NavigationHandler handler = null;

public static final String COMMIT_ENABLED =
"#{bindings.Commit.enabled}";

public CommitNavigationHandler(NavigationHandler handler)
{
super();
this.handler = handler;
}

@Override
public void handleNavigation(FacesContext facesContext,
String fromAction, String outcome)
{
Boolean outstandingChangesWrapper =
resolveExpressionAsBoolean(CommitNavigationHandler.COMMIT_ENABLED, facesContext);
if (outcome != null && outstandingChangesWrapper != null &&
outstandingChangesWrapper.booleanValue())
{
// The outcome is not null (so we are navigating away from the current page)
// and the page has some unsaved changes so display the same page with a
// message to tell user to either save the changes or reset the form.
FacesMessage message =
new FacesMessage("You have uncommitted changes! Please either save or reset.");
facesContext.addMessage(null, message);
this.handler.handleNavigation(facesContext, fromAction, null);
}
else
{
// No changes or it's a postback, do navigation as intended
this.handler.handleNavigation(facesContext, fromAction, outcome);
}
}

private Boolean resolveExpressionAsBoolean(String el, FacesContext fc)
{
ValueBinding valueBinding =
fc.getApplication().createValueBinding(el);
return (Boolean) valueBinding.getValue(fc);
}
}

Like the original solution there are a few caveats:

Pages where you want this to warning to work will need a button bound to the default Commit operation.
There should be a JSF messages component in the page to show the warning message.
Pages will also need a binding to the Rollback operation so the user can cancel all changes and then navigate off the page. A rollback button would look a bit like this:
<af:commandButton actionListener="#{bindings.Rollback.execute}"
text="Rollback" disabled="#{!bindings.Rollback.enabled}"
immediate="true">
<af:resetActionListener/>
</af:commandButton>

That's about it. Setting up the navigation listener is once per application and then just make sure every page where you want this feature follows the rules above.

Feed me. Feed me now.

2007-08-23T17:58:00.000Z

It's a hard task to stay up to date with the latest advances in technology. A client recenly asked me how I keep up and this is what I said:
RSS feeds are a godsend for staying current. At last something useful from web 2.0 rather than social networking! Pick a nice reader and you can review new articles quickly and easily from multiple sources. Some suggestions for readers:

I use NetVibes, a web based RSS reader. I'm really impressed with it.
Google has Google Reader which has just added off-line capabilities using Google Gears. Great for catching up when you're on a flight.

So on to the content for your shiny new reader:

There's no doubt the main source for ADF material is the Oracle Technology Network. As this covers all Oracle technologies you'll need to dig a little deeper to get to the ADF stuff.

The Learn ADF centre is here. ADF teams should become very familiar with all the items in the 4GL developers track, that's the sample application, the developers guide and the tutorial.

The main technology page for ADF is here. Two useful links for your team members are the To-Dos and the Tutorials.
It's also worth subscribing to the JDeveloper newsletter and also subscribing to the JDev RSS feed.
The OTN forums are very useful, each product/area has an RSS feed.

Oracle Metalink is also a great resource and the whole team should get themselves an account. It's probably the first place to look is you are getting a strange error or something is not working as expected. A lot of "issues" can be fixed by a visit to Metalink!!
The holy trinity of Oracle ADF product managers all have excellent blogs all with an RSS feed:

Some other great Oracle staff blogs are:

JDev product manager Shay Shmeltzer.
OC4J product manager Tugdual Grall.
OracleAS product manager Debu Panda.

Some non Oracle ADF blogs worth monitoring are:

IT Eye, a Dutch IT company with a lot of ADF posts.
Real World ADF with John Stegeman.
JSF news site JSF Central is great.

Sun JavaEE 5 tutorial has a lot af material about JSF - see chapter 9 -14 .

Hope you enjoy! I'm also addicted to podcasts and will post a list of my favourites soon...

Ctrl-Alt-F9-Shift-ShortcutNinja

2007-07-30T15:27:00.000Z

Hi

Following on from the posts below if you're a developer that hates the mouse and loves shortcuts then you will love this treasure trove of shortcuts from JDeveloper product manager Shay Shmeltzer. Happy finger twister!

Angus

PS I'm writing this in Vilnius and Blogger has internationalized itself to Lithuanian. I could be consigning this post to junk rather than successfully posting it. On the plus side the free wifi in the hotel is very fast and reminds me that I must order faster broadband at home to feed my podcast addiction.

Cheap and cheerful shortcut

2007-07-27T12:57:00.000Z

Quickly... here's another useful shortcut/feature in JDev that was added in 10.1.3 (I think). It's extended paste. If you use Ctrl-v a lot try Ctrl-Shift-v and you'll get a window showing you the last few contents of the clipboard. Click one to insert. Just like a popular office program but without the dancing paper clip!

New JDeveloper version

2007-07-11T14:26:00.000Z

A bit late this as I've just been on holiday but there's a new version of JDeveloper on OTN. 10.1.3.3 is the current production version with many bug fixes. The downloads for JDev are here.

I also want to start highlighting some simple features of JDev that make life a little easier. Today it's "Copy Path" or Ctrl + Shift + C that copies the full path of the highlighted file to the clipboard. This is a boon for clumsy typists like me as it is certainly less error prone than doing it by hand! You can then paste the path into an open dialog, documentation or command prompt. Lovely! More to come....

Metaphor/Simile Competition

2007-06-18T12:36:00.000Z

No, this isn't a search for new smilies. :-) Olaf (font of all knowledge) has recently had a Java quiz on his blog so I thought I'd follow suit.....except that this is a little less technical and little more abstract.

You used to be able to describe a "general purpose" architecture for J2EE applications that could be described as a wedding cake with multiple tiers.....you get the idea. Now with SOA this simile doesn't work anymore but what to replace it with? Let's hear your ideas! To make things a little more interesting I'll exclude "star", "wheel & spoke" and "grid" as they're all pretty overused.

Installing OracleAS on Oracle Enterprise Linux

2007-06-05T14:21:00.001Z

Just in case you hadn't noticed Oracle has its own Linux now, see the FAQ here. Today I was installing OracleAS 10.1.3.1 on Oracle Enterprise Linux and had an issue with the prerequisite checks of the Oracle Universal Installer (OUI), it kept saying that my OS wasn't recognised??? A quick call to Olaf Heimburger got me back on track.

Olaf suggested editing two files to keep OUI happy:

/etc/issue
/etc/redhat-release

In both it's a case of replacing the first instance of "Enterprise Linux" with "Red Hat". I made the change, ran the installer again and was soon up and running. When it's all done don't forget to change the files back. Thanks Olaf!

Free tech lectures!

2007-05-25T08:56:00.001Z

The employees at Google enjoy a series of lunchtime lectures on a variety of science and engineering subjects. Google shares these with the world via Google Video. There's a very interesting lecture on their new open source dependency injection framework, Guice, at http://video.google.com/videoplay?docid=6068447410873108038&q=user%3A%22Google+engEDU%22+guice.

The framework looks great, all Java with no need for XML configuration files. Guice and the Google Web Toolkit looks like the start of a series of really cool frameworks that they've donated to the OSS movement.

There's a huge range of talks on Google Video. You can browse for something that interests you at http://video.google.com/videosearch?q=user%3A%22Google+engEDU%22.

JDeveloper 11g is here!

2007-05-08T15:26:00.000Z

Big news from the Oracle JDeveloper team today: A technology preview of JDeveloper 11g is available on OTN - http://www.oracle.com/technology/products/jdev/11/index.html.

There's so many features that the J in JDeveloper is a bit misleading. Not only is it a really productive Java & Java EE coding platform but it's also great for database development, XML, BPEL, UML and ESB design time.

I'm looking forward to test driving it over the next few days...

Roll on Java 7 :-(

2007-04-03T12:51:00.000Z

Java5 added annotations to the language and one of the nice applications of this language feature was the @Override and @Deprecated annotations.

@Override allows a developer to make their code more robust by flagging that a certain method must override a method in the superclass. That means that if any "refactoring" goes a little wrong then this dependency will be flagged up at compile time.

Great, perfect, happy days! Except if you follow Josh Bloch's recommendation that interfaces are the correct way to specify type in Java then this feature is next to useless. The clue is in the use of "superclass" above rather than "supertype". @Override in Java SE 5 only works with classes: http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Override.html.

This was due to be fixed in Java SE 6 but unfortunately a small issue means that we won't be able to exploit this feature with interfaces until Java SE 7. The details (and a great deal of discussion about the subtle differences between implements and overrides) can be found at http://blogs.sun.com/ahe/entry/override_snafu.

A tongue twister?

2007-04-02T20:45:00.000Z

Technical content is zero on this post but...........is it just me or is "JEE" harder to pronounce than good old "J2EE"?

Update: My colleague Olaf has suggested that "Java EE" is the easiest to pronounce and I think he may be right.

A STANDARD way to package libraries in Java EE

2007-04-02T20:26:00.000Z

JEE5 specified a new vendor independent way to package libraries in an EAR file, which is good news. It's also implemented in OracleAS 10.1.3.1.0 which is even better news! In brief you can bundle your JARs into a sub-directory in the EAR and add an entry pointing to it in the application.xml.

The OracleAS documentation for this feature is here http://download-uk.oracle.com/docs/cd/B31017_01/web.1013/b28952/classload.htm#BABGAABD.
Note that you need to set the version attribute of the application element to "5" in application.xml for this to work. The deployment descriptor creation wizard in Oracle JDeveloper will guide you through this.

OracleAS 10.1.3.x also has the concept of shared libraries. These two features should mean that library packaging has got a little simpler in JEE.

Welcome

2007-04-02T20:18:00.000Z

Welcome to my Blog! I'm not sure if I'm a natural blogger but I'm going to try and use my blog to talk about interesting stuff about Oracle and J2EE/JEE. I hope that that won't prove to be an oxymoron. ;-)

Stay tuned...

Angus