Thursday, April 30, 2009

Multiple Faces-Config.xml in your JSF application.

Modular JSF code.

Facelets are a great templating tool for JSF and can also give performance benefits when you properly structure the way you load the pages.

If you want to modularize your web application by packing the backing beans in separate jar files, the JSF specification allows you to do that. All you have to do is pack the beans in a separate jar

file and in the META-INF folder you put your faces-config.xml file. According to the JSF specification all the jar files that contain a faces-config.xml are also automatically loaded.

You can also pack the jsp files that are specific to the module in the same jar. The trick you define a custom class that implements "com.sun.facelets.impl.ResourceResolver" interface and in your web.xml file add the facelet parameter to tell your web app to use the new custom resource resolver.


The resource resolver has one single method to implement and here is a snapshot of that code.

public URL resolveUrl(String path) {
try {
if(null != path && path.contains("/CUSTOM_INCLUDE/")){
path = path.substring(path.indexOf("/CUSTOM_INCLUDE/") + 20);
URL url = THISCLASS.class.getClassLoader().getResource(path);
return url;
// Default ResourceResolver
return Resource.getResourceUrl(FacesContext.getCurrentInstance(), path);
} catch (IOException e) {
throw new FacesException(e);

Though this mechanism works for the jsp pages and the java files as separate sub modules, if the code depends on CSS or java script then that does not get included properly. A new framework is available on called "weblets" that looks much better than the above approach.

Debugging MySql queries using My-Sql proxy.

MySql introduced a cool new utility called MySql proxy which allows you to route the queries to the database via a proxy.

The proxy utility has a lot of features and one of the very basic features is to log the queries that are routed through it and log the time taken for the query execution. This helps when you want to tune the application.

Download the utility and unzip it to a location, configure the proxy port as mentioned in your datasource and configure the original database port in your proxy. It comes bundled with a few sample scripts supported by a programming language called "lua" (btw just heard about this ). Dont worry about the new programming language, the sample scripts are good enough to get you started.

Another surprise bonus was if you have hibernate /other applications in your web layer you can see how many queries that are run against the database.

Debugging Hibernate SQL queries in MY-SQL

Have you ever wondered what kind of queries that hibernate generates? Now you can with a cool new utility called mysql-proxy. This utility allows you to find out the queries that are hitting the database, debug them,