Ruminating on JDK builds and versions

Ever since Oracle changed the licensing of Java in 2019, there has been a lot of confusion in the market. Found the below blog article to be extremely useful in this regard - 

https://www.marcobehler.com/guides/a-guide-to-java-versions-and-features

As of today, the best bet for developers looking for LTS (Long Term Support) is to use Eclipse Temurin. Memebers of this consortium include IBM/Red Hat, Microsoft, Azul, New Relic, Alibaba, T-systems, etc. A list of all OpenJDK builds by Temurin is available here https://adoptium.net/temurin/releases/

Other option for LTS is Amazon Corretto: https://aws.amazon.com/corretto/?filtered-posts.sort-by=item.additionalFields.createdDate&filtered-posts.sort-order=desc. Amazon provides LTS at no extra cost. Similary Microsoft, Red Hat also provide their LTS bundles of OpenJDK. 

It is important to note that OpenJDK available at https://jdk.java.net/23/ (openjdk.org) does not have LTS. OpenJDK.org site is managed by Oracle primarily and Oracle provides TLS only if you purchase the license of Oracle Java SDK (not OpenJDK). 

So, if you are just using the latest download from Openjdk site, then as soon as a new version is available, the older versions are NOT patched! So you will not get security patches for older versions and this can be a concern for production environments. 

OpenJDK builds having LTS are typically supported with patches for 4 years...so you have time to plan your upgrades. Security is a major concern in software development. LTS versions receive regular security updates, ensuring that vulnerabilities are patched in a timely manner. Another good blog showcasing the various LTS options is here - https://www.petefreitag.com/blog/java-lts-versions/ and https://adoptium.net/support/

Maths Formula Evaluators

A team mate today introduced me to a couple of open-source libraries that can be used for evaluating mathametical functions as strings. One can set variables and evaluate the expression.

http://www.formula4j.com/
http://www.japisoft.com/formula/index.html

Ruminating on JSF

In the past, I always hated JSF, the same way I hated EJB 2.x. But of-late, I am seeing a renewed interest in JSF, especially since a lot of pain areas were resolved in the JSF 2.0 specification.

Over the last couple of days, I have been evaluating PrimeFaces - an opensource implementation of JSF 2.0 and I would say that I am pretty impressed. Going through the sample demo pages, I was mighty pleased with the neat and clean code on both the XHTML file and the POJO beans Java code.

Also PrimeFaces has a plethora of components that should suffice for 90-95% of all basic web application requirements.

In general, if you do not require heavy UI customization and can hence sacrifice absolute control over the generated HTML, CSS and JS, then I would say that using PrimeFaces would greatly increase the productivity of an average development team. IMHO, the productivity gain could be as high as 50% over doing the conventional plumbing using MVC frameworks and JQuery.

But if there is a special requirement that cannot be sufficed by the standard UI components provided by PrimeFaces, then you are in trouble. You would then need deeper expertise to write your own JSF component or customize existing ones.

Based on my study and the common challenges we faced, I am jotting down some FAQ's that should be useful for folks embarking on using PrimeFaces.

Q) How to manipulate JSF components on the client side using plain JS or JQuery? How to use JQuery JS API or any other JS library on the client side with JSF?

http://stackoverflow.com/questions/7927716/how-to-select-primefaces-ui-or-jsf-components-using-jquery

http://stackoverflow.com/questions/5457292/jquery-conflicts-with-primefaces

Q) How to include JS file or inline JS code in a JSF XHTML page?
A) There are 3 ways to handle this.

• Escape all special chars like 'greater than' or 'lesser than'
• Use <![CDATA[ ... ]]> to hold your JavaScript code
• Put the JavaScript code in a separate .js file, and use in the JSF page  

http://www.mkyong.com/jsf2/how-to-include-javascript-file-in-jsf/

Q) How do I output HTML text in JSF? Do I need to use the 'verbatim' tag?
A) <h:outputtext escape="false" value="#{daBean.markedUpString}"></h:outputtext>

Q) Can I mix HTML tags with JSF tags?
A) You can. It is not as much as a pain as in JSF 1.x, but you need to be aware of issues.
http://stackoverflow.com/questions/5474178/jsf-facelets-why-is-it-not-a-good-idea-to-mix-jsf-facelets-with-html-tags

C heap vs Java heap

Found this interesting discussion on StackOverFlow around C Heap and Java Heap.
A good read and its important to understand that the JVM is also ultimately a C program :)
 
http://stackoverflow.com/questions/78352/what-runs-in-a-c-heap-vs-a-java-heap-in-hp-ux-environment-jvms

Passing wilcard * in Runtime.exec() command

One of the projects I was consulting on approached me with a peculiar problem.
The application was executing unix commands from a Java program using RunTime.exec() APIs. But strangely for some reason, the "rm" command was not working. The user account running the Java process had the necessary rights for deletion, so the problem was somewhere else.

A quick googling around answered the problem :)
http://www.coderanch.com/t/423573/java/java/Passing-wilcard-Runtime-exec-command

Its important to remember that when we pass wildcards to the RunTime.exec() API, it will treat it as a string only. It is the Unix shell that understands the "*" syntax.
Hence something like this would work: Runtime.exec(new String[] { "sh", "-c", "rm /tmp/ABC*" });

Why no delegates in Java? And will Closures come to Java?

Having worked across Java and .NET platforms, I often compare the features of one over the other. One of the interesting features of the .NET platform is the concept of 'delegates'.

At first, a Java guy may take some time to understand the concept of delegates, but once you are hooked on to it, you tend to use it everywhere...because it is so convienient. The .NET framework uses delegates extensively throughtout its event framework.Java folks have traditionally used the 'Listener' interface pattern for eventing. Even concurrent/parallel libraries in .NET heavily use delegates, whereas Java folks have to still stick with interfaces :(  The closest equivalent to delegates in Java is the anonymous inner class - which IMHO is messy to read and write.

StackOverFlow has a series of interesting discussion threads on this topic:
http://stackoverflow.com/questions/44912/java-delegates
http://stackoverflow.com/questions/2635013/why-not-net-style-delegates-rather-than-closures-in-java
http://stackoverflow.com/questions/1340231/is-there-an-equivilent-of-c-sharp-anonymous-delegates-in-java
http://stackoverflow.com/questions/1973579/why-doesnt-java-have-method-delegates


Another interesting feature that many dynamic languages have is 'closures'. A closure is similar to the concept of delegate, but they are not quite the same. Martin Fowler has a good bliki post explaining the concept of Closures and the difference compared to delegates.

.NET supports both closures and delegates. Found this good article explaning closures in .NET.

Good whitepaper on WSRP Portlets

A friend of mine was confused on the concept of remote portlets and the WSRP protocol. I forwarded him this cool whitepaper that explains the concept of remote portlets in a simple and lucid language.

Some snippets from the whitepaper:

Remote portlets enable dynamic integration of business applications and information sources into portals.
This approach only works if all portlets are physically installed at the employee portal; the process of making new portlets available is tedious and expensive.
 
Instead of just providing raw data or single business functions that still require special rendering on the portal side, Web Services for Remote Portlets (WSRP) are presentation-oriented, interactive web services.
They are easy to aggregate and can be invoked through a common interface using generic portlet-independent code that is built into the portal. In addition, re-implementation of the presentation layer on each portal is avoided. The use of generic portlet proxies consuming all WSRP services conforming to the common interface eliminates the need to develop service-specific portlets to run on the portal.

The big difference between WSRP services and data-oriented web services is that they are presentation-oriented, interactive services that all have one common interface. This means that they simple plug into portal servers and do not require any service-specific code on the consuming portal.

Another point to consider is the comparison of remote portlets with mashups? Are they the same? Remote portlets and WSRP standards can be used to create mashups, but portlets also bring in the advantage of personalization and customization. Mashup's also need not just refer to aggregation of content. Wikipedia describes mashup as "A mashup is a website or Web 2.0 application that uses content from more than one source to create a completely new service. This is akin to transclusion." For e.g. tons of new applications built on top of Google Maps.

What is Micro-Architecture in software design?

Recently I came across the term 'Micro-Architecture' on a number of pages on Sun's site. Sun's engineers have an interesting definition for this term. They refer to Micro-Architecture as a composition of a set of patterns that can be used to realize a subsystem.

In the book - "Core J2EE patterns", Micro-Architecture is described as below.

We define micro-architecture as a set of patterns used together to realize parts of a system or subsystem. We view a micro-architecture as a building block for piecing together well-known, cohesive portions of an overall architecture. A micro-architecture is used to solve a coarser-grained, higher-level problem that cannot be solved by a single pattern. Thus, a micro-architecture represents a higher level of abstraction than the individual patterns.

Migrating applications across platforms

We often require to migrate applications from one platform (OS/hardware) to an other platform - either as part of a portfolio rationalization program or because the current platform is reaching its EOL. For e.g. migrating Java apps from Solaris/SPARC to Linux/IBM Power, etc.
During such migrations, it is essential to have a well documented plan covering all the aspects, so that we do not miss anything. Listed below is a brief set of points that must be included in the brainstorming discussions during the planning phase.

1. Migration of the Runtime environment: For e.g. miration of the Java runtime from Solaris to Linux. There are many JRE's available on Linux and we need to select the appropriate one.
2. Migration of the Application Infrastructure: The application may require a webserver, application server, a Message queue, etc. These infrastructure components would need to be ported to the target platform or other alternatives selected.
3. Migration of application code: Does the code need to be recompiled/linked on the target platform? Was the application using any platform specific API for performance?
4. Migration of application configuration: What configuration needs to change on the target platform? e.g. file paths, endian-ness, max-memory settings, thread pool settings, etc.
5. Migration of development environment: Would it be required to migrate the development environment? Will the same IDE work? IDE-Runtime integration issues, etc.
6. Migration of Build and Deployment process: Need to change build scripts - ANT, Maven, Shell scripts, etc.

Also it makes sense to leverage the expertise of the target platform vendor during the migration exercise. For e.g. IBM, HP, SUN, RedHat, Novell, etc. all have guidelines, recommendations and migration kits for migrating from a target platform to their platform.

Mapping UI controls to entitlements/operations

In RBAC, we often need to enable/disable a UI control based on the users role and entitlements. Most programmers write code for mapping a UI control with the operation name, i.e. if 'submitRecord' is not allowed for the user, then disable or hide the button.

Recently I came across a neat way to handle this using attributes in C#.NET. This article describes the use of attributes to specify the 'operationName' and the 'property-value' to be set on the control when we check for entitlements.
Example code snippet:
[YourCompany.Authorization("EditSalary", "ReadOnly", true)]
private System.Windows.Forms.TextBox Salary;

Though the example is that of a .NET program, the same concept can easily be applied in Java 5, which supports annotations. Annotations in Java are roughly equivalent to Attributes in .NET.