Rhino is a JavaScript interpreter running on top of JVM. I guess it was useful for server-side programming in JavaScript. Now we have Node.js. So I wonder if Rhino is still relevant and what it is useful for.
It simply provides a means to run Javascript in the JVM. As such it gives you another implementation choice on top of the JVM in preference to the Java language (in a similar fashion to JRuby, Scala, Groovy etc.). You can write complete solutions in Javascript, or mix/match with Java (or any other JVM language)
Note that this isn't specific to 'server-side' or any such deployment choice.
Speaking from personal experience, I've used it to provide trivial scripting in Ant deployments, and to provide an out-of-the-box simple scripting language for customers using Java applications/toolsets I've written.
Rhino is also used by the the HttpUnit library, which can be used in unit tests to emulate a web browser, for testing web sites. It gives the library JavaScript support.
I use Javascript with Rhino as a scripting language for my MMORPG server written in Java. It allows me to implement NPC scripts, item use scripts, event triggers and other server-sided interactive functionality in Javascript without having to touch the Java part of my server.
Implementing these features in Javascript makes the syntax for them much easier to write and read. Especially because I let the Java part of the server automatically add any trivial boilerplate code to the script sourcecode before sending them to the script engine. This further simplifies the javascript syntax.
It also allows a much clearer separation of the engine and the content.
I also added a Javascript admin shell, which allows me to run any Javascript code on the running server. This has proven to be a very useful testing and debugging tool and I expect it to be a very powerful administration tool later.
I could, of course, also have used any other scripting language, like for example Lua which is frequently used as a scripting language in game development. But Rhino is supported out-of-the-box so I don't need any additional 3rd party dependencies. Also, my client is a HTML5/Javascript application, so I don't have yet another programming language in the project. Note that although both the client and the server content use JS, there is no code shared between them - they are literally on the opposite ends of the system architecture and interact with each other through several layers of indirection, so there is no reason to share code.
Related
I want to create a mod for Minecraft, and I am aware it uses Java. I am currently learning JavaScript, and was wondering if I am able to use JavaScript for the SDK.
Yes and no.
Java is not Javascript...but a Java project can interpret Javascript
Java and Javascript are two completely different languages. However, there is a javascript interpreter created in Java, that you can plug in to java, called Rhino. However, although Rhino makes it easier to embed Javascript into your Java code, its not a simple drop in solution that would allow you to simply script what ever you want with out going through the effort of makin the proper connections. Definitely achievable, but you wont likely be able to start scripting without making that time investment to connect Java and Javascript.
Background story
The relationship between Javascript and Java is a rather shallow one. The similar name comes from a marketing plan back when it was being released by Netscape (which most developers ended up moving to the non-profit Mozilla). They made a deal with Sun (bought by Oracle) to share that similar name, but purely for marketing purposes.
Yes, it is possible to run JavaScript within a Java program, using the Rhino Javascript engine (for example).
However, this would not be a good way develop a Minecraft plugin / mod. None of your knowledge of the Javascript APIs would be relevant. Everything you did to interact with Minecraft would entail using Java classes and methods in the Java or Minecraft libraries.
My advice:
If your aim is to avoid learning Java ... don't be lazy. (You'll end up having to learn the Java APIs anyway. And learning another language will be good for you ... assuming you aspire to be a professional programmer.)
If your aim is to integrate some pre-existing Javascript code-base, it might work. But you might be better off porting the Javascript code to Java.
Sorry, Java and JavaScript are totally different languages. The "Java" in both of them was a marketing decision from ancient times.
They do share some of the same syntax that many languages share, however, so if you have learned JavaScript it might be a little easier to get started with Java. They are definitely NOT interchangeable, though.
Have a look at JDK1.6's ScriptEngine, the interface whose methods provide basic scripting functionality. Using these methods you can execute javascript. Numerous examples can be found on usage of this.
script support is avail from jdk 6 onwards:
reference link
However, this is not a full implementation of Rhino.
I've been reading about Rhino as a useful way to implement JavaScript inside my Java code.
After reading for a while, searching in google and here, I couldn't find a real reason for which I would use JavaScript inside Java.
Could you point some real world advantages you find on using Rhino for a regular Java application?
Note that since Java 6, the scripting API is in the standard Java library - see the documentation of the package javax.script. The API in javax.script is an adapted version of Rhino. The scripting API supports not only JavaScript, but many other scripting languages.
See Java Scripting Programmer's Guide
The front page there mentions some reasons you might want to use scripting:
Application extension/customization: You can "externalize" parts of your application - like configuration scripts, business logic/rules and math expressions for financial applications.
"Command line" shells for applications -for debugging, runtime/deploy time configuration etc. Most applications have a web-based GUI configuaration tool these days. But sysadmins/deployers frequently prefer command line tools. Instead of inventing ad-hoc scripting language for that purpose, a "standard" scripting language can be used.
An example: You can script Oracle Weblogic using Python scripts, for example to configure your application server domain, to start or stop the server and to do other administration tasks.
Processing XML with Rhino and E4X is a joy compared to most of the Java XML APIs
You have existing JavaScript that "just works" and you don't want to re-write it. This can happen if you have some calculation or processing happening on the client side and move it to the server.
All kinds of neat caching and code loading tricks.
Your problem is better solved by a more dynamic language then Java.
List comprehensions ;)
The benefit of embedding a script language like javascript into your software is that you can offer others a way to write plugins for your software without giving the source code away.
A reason to write the whole app in another language is that you are able to write an app for a company which deploys it in their Java EE environment without having to learn Java.
We use JS (via Rhino) for a DSL in one of our products. It isn't a great DSL, but that is a fault of how we use JS, rather than Rhino.
If you considering to .Net also, I suggests to get along with Rhino.
Besides Java enviroments, rhino is one of the best performance interpreter on .NET environment (using IKVM). On the other hands, nashorn is very slow on .net.
Porting your own Rhino project to .NET is not so difficult.
I have three types of get requests that are delivered to a class file on web application from a mobile device. Because the mobile device provides no cookies, the log file hit only has
in.ter.nal.ip ser.ver.i.p:port 2009-06-05 09:14:44 GET /applicationname/mobiledevicexml reqtype=login&userid=xx### 200 87 - MercuryMobile/1.0 CFNetwork/342.1 Darwin/9.4.1 cookieArrayLength=0;
If I can instantiate javascript in my class file, and generate a javascript function call to urchinTracker() from inside the class file, I can replace that useless cookieArrayLength=0; with some useful data urchin can read from the log file into analytics reports.
We have been looking at scripting in Java with Rhino; Safari Bookshelf has:
Scripting in JavaTM: Languages,
Frameworks, and Patterns
which helped us immediately demo that we can run javascript in class files --this works out-of-the-box on Java 6.
Anyone know any resources for scripting with Rhino on Java 1.5 or 1.4?
Alternately, any suggestions for running javascript from java 1.5 would be appreciated.
The Java Scripting API (javax.scripting) package was introduced in Java 6, so that will not be available in Java 1.4 or 5. As the default installation, Java SE 6 comes with a stripped down version of Mozilla Rhino which is interfaced through javax.scripting.
However, Mozilla Rhino itself does not require Java 6. From the requirements page:
Recent versions of Rhino have only
been tested with JDK 1.4 and greater.
Older versions support JDKs as early
as 1.1.
Therefore, to use Rhino, it appears that Java 1.4 is actually sufficient.
As for resources, the documentation for Rhino seems to have a lot of information. In particular, the Embedding Rhino section might be useful to see how the scripting will work.
Of course, the lack of the javax.scripting package means that interfacing to Rhino itself is going to require the use of the Rhino API rather than the Java 6 native scripting API, but I would guess that the functionality is going to be fairly similar. The only downside I can see is, if in the future, Java 6 is going to be supported on the target platform and/or using another language, it may necessitate a rewrite to use the Java Scripting API rather than directly supporting Rhino.
[I'm posting in an answer, because I don't have enough points to post a comment on the question itself.]
Are you sure that the urchinTracker() function will operate outside of a web browser? Running the Rhino JavaScript interpreter (which isn't too difficult) won't be enough if the function relies on various browser objects, like the Document Object Model (DOM) or XmlHttpRequest.
I suggest that you at least scan the internals of the urchinTracker() function to see if this is the case.
See Server-side JavaScript for list of projects that runs JavaScript at the server-side.
For your usage, using Rhino seems like the way to go.
I've tried asp.net and jsp...and the programming language was powerful enough to create both desktop and Windows apps.
Butwhat can I possibly do with php other than creating web applications? Does it have some kind of runtime or framework?
Thanks
Powerful is an unfortunate word. It's about focus, not power. PHP is not very well suited for desktop applications. In part because of weak library support (Though some exists), and in part because of its memory management model. It can be used for jobs outside the web world though; It's often used as a general scripting language, as well as various background tasks.
PHP is not "limited" per se. PHP is primarily only used to develop Web applications. However, there are products like WinBinder that promise to allow you to use PHP to build a desktop application; I wouldn't exactly recommend that though. Also, you probably have not built Windows applications with ASP.NET and JSP but rather more likely .NET WinForms and Java (perhaps Swing). PHP is used by thousands of developers building many different Web applications. It is possible to build other kinds of applications with it but again I wouldn't recommend going down that path.
PHP was intended as a web development language, but you can write console scripts with it, and if you're feeling brave, use something like PHP-GTK to write GUI apps.
PHP makes a surprisingly good shell scripting tool. It has a wealth of simple functions built in.
File IO
String manipulation
Array manipulation
While you can do the same thing in JSP and C# you will spend a lot more time vs. any scripting langauge.
The biggest advantage PHP has over other scripting languages is PHP.net Documentation. Out of any language I have ever used this single resource defines what good documentation and organization of a langauge reference should be.
PHP can be run via an interpreter on the command line, so any computation task can be done in PHP. I don't know about desktop apps and GUI.
PHP has a runtime but it's not fully interpreted like some languages. For example, you can't redefine a method. As far as desktop apps, PHP has bindings for creating desktop apps but it's not very good. It's great for command line tools. Zend and CakePHP are two frameworks for web apps. PHP is like a very-easy to use version of C with a very good community of extensions (look at the extensions on php.net docs). PHP is well supported on windows (even by Msft).
Quite often it is the "limitation" or for want of a better word "focus" of a language that makes it powerful rather than weak.
I'd say PHP is best suited for web application development.
It does the job, and does it well.
But that's not to say that it is not useful for anything else. It can be used as a generic scripting language.
With Qt, you can even develop desktop apps using PHP. Check out http://php-qt.org/
But the focus must be with web apps: PHP was intended for the web.
Depends on what you consider powerful?
It is designed for server-side web-development, and it does that perfectly.
I can't see myself saying one language is more powerful than the other, as it is always a matter of preference, the task at hand and whether the language was designed for what you are trying to accomplish.
I am interested to create a drag-and-drop layout designer using only JavaScript, HTML and CSS. The designer will allow the user to drag the page elements from one place to another (something like Blogger's layout designer) to create a site layout. But I don't want to hand code everything in JavaScript, I would prefer to write my application in .NET (preferably) or Java and rely on a compiler to compile it to JavaScript and HTML.
What are the .NET or Java to JavaScript compilers that you have used and can recommend? For Java to JavaScript I know GWT is available. What about .NET to JavaScript? Microsoft did come out with Volta, but the project seems to be no longer available.
Look no further, you already mentioned GWT pick that!
It has a very good API and many good applications have use them.
Even JavaScript frameworks like http://extjs.com/ have GWT support.
I use it for an small JavaScript calendar recently.
To be honest, I don't really like JavaScript that much. Most of the times the errors are hard to track (specially for a non JavaScript guy as me) and the workarounds included some plug-ins for the explorer just to get exactly what a compiler should do. Catch silly error early.
In the other hand I'm very familiar with the Java Programming language, and many of the libraries (if not the most important) such as java.lang and java.util have been ported to GWT.
Plus, the guy who wrote relevant parts of java.util is the same behind GWT (google Joshua Bloch.)
Check out Nikhil Khotari's Script# project. It allows you to write C# code and compiles it to JavaScript.
Script# has already been mentioned. It hasn't been updated since August 2008.
Milescript is another, but also has seen very little for 6 months.
Extsharp for the Ext library. Adds Ext support for Script#
Javascript compiler to Java (going the wrong way for you)
Java to script Eclipse plugin
My issues with Script# (a known issue) is it doesn't support jQuery yet. However it comes with a very lightweight library to tie in with the .NET framework, in Nikhil's sscorlib.js file and ssfx.core.js files. And also has support for lots of other Javascript APIs (mostly Microsoft, seeing as he is in the ASP.NET team).
I'd love to see a Script# extension for jQuery (I'm thinking about writing it if it's easy enough). As it stands, most don't provide full compilation yet but they're certainly getting there.
Update: I wrote a small extension to enable JQuery support Script# a few months ago. The project can be found here.
I'm going to second the use of GWT. I've used it for several projects and, when used in combination with a modern editor like Eclipse or IDEA, it really makes the mess manageable.
It's important to note that not only does it allow you to write in Java and have that transformed into optimized and obfuscated Javascript it also comes with a substantial subset of the core Java API. In addition to this they provide lots of additional classes for doing things like parsing and working with JSON and XML and communicating with a server via asynchronous HTTP. You can check out the docs to get an idea of what else they offer.
Another feature that might be of special interest to you for implementing drag and drop functionality is it's integration with javascript libraries like Ext and scriptaculous. Either through pre-built interfaces or via JSNI
Also for Java there is J2S.
Java2Script (J2S) Pacemaker provides
an Eclipse Java to JavaScript compiler
plugin and an implementation of
JavaScript version of Eclipse Standard
Widget Toolkit (SWT) with other common
utilities, such as java.lang.* and
java.util.*. You can convert your
SWT-base Rich Client Platform (RCP)
into Rich Internet Application (RIA)
by Java2Script Pacemaker.
This means that if you use the SWT IDE (drag and drop) you can then convert the generated code to JS + HTML.
I wouldn't hand write any Javascript for UI. This can lead to maintenance disaster. jQuery is what I am using but I still wouldn't use it to write full UI Javascript code. ExtJS is also another good option if you plan to write in Javascript. In general what I am saying here is that it's so much easier to main in Java/C# than Javascript. Check out cappuccino framework and Atlas. Never used GWT. Script# is similar to GWT but for ASP.NET framework. Also depends on the requirement, if your site is public facing then RIA isn't a good option. It's all about which extreme end you pursuit (hand written and web standard, or RAD or libraries like jQuery/ExtJS as the middle option).
Check out Axial, a .NET to JavaScript converter that works well in ASP.NET. It supports WebForms, jQuery and canvas. It's not very mature, but it's worth a look.
http://jsc.sourceforge.net/ is a C# to JavaScript, Java, Flash and PHP compiler.
JscriptSuite offers another free .NET to Javascript compiler. There is a big difference to Saltarelle (jsc, SharpKit# etc.). Developer write down and debug only C# code (or any other .NET langauge), like in GWT. Javascript will be generated für deployment only.