I have two java applications:
a server starting with spring boot
a client using it (through REST api)
For the time, I start both applications in differents processes.
How could I start the server from the client to obtain a "standalone" application? The use of ProcessBuilder to call java.exe is a solution, but it has drawbacks: it will be OS dependant and cannot assure the server process will be shutdown / killed as the client leaves.
From the architecture point of view leave them separate is the best option, as you have a server and a client separate, it will be the behavior in a productive environment.
If you need it only during the development phase, and your reason to run both together is to save time, you can build both in containers using Docker. Basically create two applications, building from two different folders, and then you will start both together.
I found a solution in https://www.toptal.com/spring-boot/spring-boot-application-programmatic-launch . Igor Delac
opens the jar file containing the server to find the class ...loader.archive.JarFileArchive (and some other)
instanciates it and uses it to start the application on the jar itself.
The jar file is not extracted nor modified. Only a few classes are read.
Related
In our Linux environment applications are restarted periodically (the reasons aren't important here). It would be convenient for us to deploy new versions of an application by copying the application Spring Boot jar on top of the existing (old) jar thereby overwriting it and then simply wait for the application to restart (that is, the JVM running the application to restart).
However, this seems to not work. We get different kinds of errors - sometimes the app just hangs, sometimes we get a ClassNotFoundException. It's as if Spring Boot (or something inside Spring Boot) reopens the jar and expects it to be the same one it was when the application was originally started.
We had a look through Spring's common application properties, but didn't see anything appropriate. Is there a way to make this work? When we were using WAR files we configured the servlet container to unpack the WAR file and run from the unpacked version. Can we do something similar with Spring Boot?
First of all the errors you are experiencing can come from multiple sources. Usually replacing the file from a process is not a big problem as the whole file is loaded into memory before execution. Java is a little bit different, because the actual process that is running is the JVM and it only loads the jar file from disk. The JVM loads classes only on demand, this means if there was any class that was not loaded before it will try to load it and most likely fail, if the jar file is different. In the case of spring boot there are also other resources (such as HTML files) inside the jar file that are dynamically loaded.
You mentioned you are using a linux environment. If you can just replace your startup with a script you can just copy the jar and start it from the copied location:
#!/bin/bash
JAR_NAME="spring-boot.jar"
NEW_JAR_NAME=".$JAR_NAME" # Use an appropriate name here
cp $JAR_NAME $NEW_JAR_NAME
java -jar $NEW_JAR_NAME
rm $NEW_JAR_NAME
Now every time you start the application a copy is being made and started from there. You can replace the original jar and on the next restart the new application will load.
You coud also use rsync instead of cp to avoid copying the same jar twice, if the application is restarted multiple times without changing the jar.
It would be convenient for us to deploy new versions of an application
by copying the Spring Boot jar on top of the existing (old) jar and
then simply wait for the application to restart
Why would you do such a thing to yourself? You are trying solve a usecase that's against best practices, sound like asking for trouble just to avoid an app restart. When you are doing a deployment, you need to make sure the deployment went through, otherwise how will you troubleshoot if something goes wrong in your application, you will have one more variable in hand when you troubleshoot, i,e the uncertainty of current version of the code.
If you are having downtime while deploying (I am assuming thats why you want to limit the restarts), why don't you bring up another instance with the newer version of code and once its healthy shutdown the old one
In IBM Websphere Application Server (WAS) what are the purpose of com.ibm.wsspi.bootstrap.WSPreLauncher and com.ibm.ws.bootstrap.WSLauncher? Every morning we are restarting the Websphere Application Server. So on the stat of WAS it will always be called to load applications war file? Or there are certain action on which these two are used by WAS?
WSPreLauncher and WSLauncher are main entry points in the starting the OSGi framework and server processes. If you look at startServer script, you'll see it invokes the WSLauncher class with a number of additional arguments that are essential to proper server startup. To your question, when using the serverStart script, WSLauncher will be called and as a part of starting all the components of the server, applications, including war files, may be started depending on your specific configuration. You should not invoke either the WSPreLauncher or WSLauncher entry points yourself and instead should use the provided scripts like startServer, startNode, etc.
Our application are built on Spring boot, the app will be packaged to a war file and ran with java -jar xx.war -Dspring.profile=xxx. Generally the latest war package will served by a static web server like nginx.
Now we want to know if we can add auto-update for the application.
I have googled, and people suggested to use the Application server which support hot deployment, however we use spring boot as shown above.
I have thought to start a new thread once my application started, then check update and download the latest package. But I have to terminate the current application to start the new one since they use the same port, and if close the current app, the update thread will be terminated too.
So how to you handle this problem?
In my opinion that should be managed by some higher order dev-ops level orchestration system not by either the app nor its container. The decision to replace an app should not be at the dev-ops level and not the app level
One major advantage of spring-boot is the inversion of the traditional application-web-container to web-app model. As such the web container is usually (and best practice with Spring boot) built within the app itself. Hence it is fully self contained and crucially immutable. It therefore should not be the role of the app-web-container/web-app to replace either part-of or all-of itself.
Of course you can do whatever you like but you might find that the solution is not easy because it is not convention to do it in this way.
Is it possible in Jboss deploying a ear and war file in the same server instance? If so any good source to get started? Any suggestion.
I have two applications deployed under my default deploy folder of jboss. I am running one application from which i have to call the other application to get some data. Is this possible? If so how to get started??
It is actually recommended that you only put 1 application in a server instance as a time. That said, I have had multiple ears and wars running in the same instance while I am developing. But for production it is better to separate them out. Since there is no extra cost involved this makes it easier to observe and debug apps.
Do you have a specific reason for wanting them to run side by side?
What version of JBoss are you running.
We are developing a open source trading platform based on Springframework and Hibernate http://code.google.com/p/algo-trader/ and http://www.algotrader.ch. The application consists of a trading framework and several strategies that can be started independently. So far, these different parts have been running in separate JVM's communicating through RMI and JMS.
To avoid unnecessary serialization and network overhead we would like to run the entire application within some sort of container (potentially an application server). We do however have the requirement, that the individual parts of the application can be deployed, started and stopped independently.
We have looked into OSGi, but a lot of the libraries that we use are not OSGi ready yet, so this is not currently an option. Also please note, there is no web-GUI in our application.
Any suggestions on this?
Thanks
Andy
If OSGI is not an option then functionality can be broken into smaller units and then deploy them as utility jar, if deployed as utility jar they can be managed independently.
For application server I feel either glassfish or Jboss will be a good option considering they are open source and free.
Though at a later point in time you can check with Weblogic (Dev free).
So in your case you would like to break the static data configuration(Counterparty, Currencies), Dealing(Pricing, Quoting, Booking) as two separate feature.
For your choose of an application server i advise you Jboss and specially in his version 7.1 which is faster and more stable!