We deployed a Java App on Bluemix with the JRebel agent enabled once and thereafter we can make changes to the application and test it without having to push the app each time a change is made. You can make more non-trivial changes and test it out. If you reload the URL, you will see that the word Veterinarians has been replaced by Vets without having to push the application. You should see a window with a message that the project was synchronized: Right click on the project and select JRebel > Synchronize as shown below:.Let’s make a simple change in the file src/main/webapp/WEB-INF/jsp/fragments/bodyHeader.jsp.Modify the app and deploy changes without a cf push You should see that the project is enabled for remote server support:.Provide the URL of the deployed app (substituting NAME with the unique name you used earlier) as shown below:.Click on JRebel Configuration > Remote Servers > Add Server as shown below:.Provide the remote server URL with the following steps: > Downloading JRebel Agent 6.4.1 from (1.6s)Įxpanding JRebel Agent to. Memory Settings: -Xss1M -Xmx768M -Xms768M -XX:MetaspaceSize=104857K -XX:MaxMetaspaceSize=104857K > Downloading Open JDK Like Memory Calculator 2.0.1_RELEASE from (found in cache) Now, push this app with the JRebel agent enabled with the command below:Ī partial reproduction of the output shows that the JRebel agent was uploaded as follows:.This should build the war file and end with a success message that looks something like the following: Build the war file using the following command:.JAVA_OPTS: =file:///dev/urandom -Drebel.remoting_plugin=true Create a manifest file manifest.yml in the root directory with the following contents, substituting NAME with an unique name.Push the application with remote server support enabled You should see an acknowledgement as below:.Next enable Remote Server Support as shown below:.Enable JRebel by right clicking on the project and JRebel > Enable JRebel Nature as shown below:.The final step of the import is shown below: We will use Import as an existing Maven project in Eclipse. We will use the petclinic project at spring-projects/spring-petclinic on GitHub as an example.Setup the application as an Eclipse project Install the the JRebel plugin for Eclipse.Modify the app and deploy changes without a cf push.Push the application with remote server support enabled.Setup the application as an Eclipse project.Ready to jump in? How to enable JVM HotSwap Thanks to JRebel that uses the JVM HotSwap technology to load classes without dynamic class loaders, there is no need to push the app to test every change, small or sizable. Public static void main(String.Although Cloud Foundry and Bluemix significantly ease deployment in general, you can do even more rapid prototyping of Java applications on Cloud Foundry/Bluemix without having to push each and every change. In fact, I urge you to try compiling the following code snippet, start it up with JRebel enabled, and change the “Hello World” part to something else while the program is running. When the IDE builds classes automatically, the process is as fast as using a scripting language or testing your latest HTML changes. With JRebel, you get to see the your changes immediately after compiling them. Remove bad code before it goes to QA and they make fun of you. Advantage #1: See all changes immediatelyĭoes your code smell? Find out really quickly and run your own mini-tests throughout the day. Response headers: Server: Apache-Coyote/1.1, x-rebel-response: ERRUNKNOWNREBELHASH, x-rebel-responseMessage: Remoting module. A change is made in the Java file and Synchronize is clicked. This post reviews some of the great advantages of using JRebel in Java development, and how eradicating the daily, time-consuming process of redeploying your application to see your changes has long-lasting effects on the way that you will write code in the future. Hi this is the Eclipse Console Log, after the JRebel setup has been successfully completed. And since we have JRebel, gone are the days of reading through the whole series of Harry Potter novels in one week while waiting for the application to redeploy itself after fixing that spelling typo, only to discover there's one more. We also have a huge ecosystem that provides us with amazing OSS libraries and application servers. If all you had for writing code was Notepad and a command line compiler, I would have gladly considered a worthwhile career in street-cleansing, fruit-picking, or subway-guitar playing industries.īut we have a handful of modern IDEs. Java's bane has always been a reliance on tools. With JRebel, developers get to see their code changes immediately, fine-tune their code with incremental changes, debug, explore and deploy their code with ease (both locally and remotely), and ultimately spend more time learning and communicating with colleagues instead of waiting for the dreaded application redeploy to finish. For those with only few minutes to spare, this post addresses the ways in which JRebel, Java’s famed redeploy killer, has made an impact on how developers spend their day coding.
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