I am quite new to working with jars and from reading online I think what I am describing is possible but I am not sure about it. If anyone has an alternative pipeline, I welcome that as well. Thanks for your time.
I would like to do the following:
I have a java program running on my machine and I would like to accept requests jars during runtime from a remote user. The users submits the jar and I would like to add the classes in the jar (which implement some predefined interfaces) to my classpath and call functions that are implemented in the submitted jar. I am using thrift as my communication platform.
How can I receive the jar file in thrift?
Once I have the jar, how do I load it? (There is no path etc because it was received from elsewhere?)
Related
I've been handed a JAR file, told it contains a web application, and instructed to deploy it. I'm familiar with java as a language, but I have next to no experience with its web ecosystem. Trying to run it as an executable, I find out it has no main class, so I take a look at the contents, and find that it has a META-INF/web-fragment.xml file, along with a couple of Servlet classes and some config files referenced in the xml. It looks like there is basically everything here for a complete application, but I have no idea how to actually deploy it, and google only yields tutorials on how to build these things from scratch with IDEs and deploy using maven plugins and goals.
Assuming that building from source is out of the question and I only have standard unix and java CLI tools available, based on the information provided (And I can provide more if necessary), what is the simplest way to get this up and running?
A web applicaton should be in a WAR file, not a JAR file, and you should only need to just drop it into the webapp directory of your Tomcat, or follow the instructions for whatever other container you're using.
If it's only a fragment, as appears from the XML, (a) it isn't a webapp, only part of one, and (b) you personally can't deploy it at all. You need the whole thing.
Send the assignment back for clarification.
I am developing an application on xpages, with Domino version 9.0.1 FP8. This is the first application in which I have developed a call to java classes through a one-button SSJS event. But specifically I am consuming a web service using the technique presented in the article. What I noticed is that every time I change something that has a direct relationship with java, such as the java classes created and stored in the java folder of the designer or in the call of the web service method inside the SSJS event, an error is listed below . The only way to solve the problem, at least until now is to restart the Domino server. It's no use clearing the project, rebuilding it, and restarting http.
Does anyone know how to solve this problem? Is there any command on the Domino server that reflects this change? Is there any parameter in the application that I have to configure?
As we can see from the error below, it seems that it does not find the web service client classes that are located in a jar in the application jar folder.
HTTP JVM: java.lang.NullPointerException
HTTP JVM: at com.ibm.domino.xsp.module.nsf.ModuleClassLoader.getResource(ModuleClassLoader.java:206)
To solve your specific issue, issue res task http at the console. There are other workarounds posted in the comments to the main question that may be more practical for your situation though.
As a workaround you can rename the jar file when you make changes to it, import the renamed jar file and delete the old jar file. This way Domino will see the changes in the jar file.
I am using the rename trick whenever I make changes to code assembled in a jar file.
I'm trying to convert my java software jar into a Java WebStart application. I've managed to successfully deploy it as a WebStart with a jnlp file that provides details about the software's jar.
However, my software requires certain details to be stored locally in a file on user's machine. These details can be set & the file can be generated by having the user run another java software (a very small java utility software) coded by me. I wonder if it's possible to package in this smaller software's jar as well along with the main software using the tag. As far as I know, we can use the tag to specify additional jars/ libraries that our software jar uses.
Can we package in another java jar created by us in the jnlp and would it then get downloaded alongside the main software jar and other libraries (jars) when the user launches the jnlp ?
Kindly let me know. Thanks.
P.S: I know that all jars downloaded by a WebStart application end up in the deployment cache. Is there no way to specify where they should get downloaded to ? In my case, I would prefer it if the 2nd software's jar gets downloaded in an easier-to-find location.
Yes, it would be downloaded - but it would end up in the deployment-cache with no easy way to find it (names get all mixed up) or start it.
There's no way around webstart keeping the files in the deployment-cache: if you could specify the download-location different versions of jar-files with the same names and different codebase could end up in the same location causing no end of trouble.
I see two ways to get the wanted functionality:
Add the ability to change the local configuration as an additional function in the main application. You probably can use most of the existing code but use a method-call instead of starting it as a separate application
Create a second jnlp-file to start the configuration-program. From what you write it should be pretty small and not too much effort to create.
I am currently writing a program in JAVA that examines the behavior of external executable. One of the requirements is to observe the file operations of the external executable in real time (check if the executable creates/ deletes/modifies any file). I tried to find a suitable API in java to help me do this though it was not possible to find one. I have found the Class FileAlterationObserver which is not suitable for my program since you have to specify manually all the directories you want to monitor.
I was wondering if any of you knows a good API to use?
Thanks for your time in advance.
Without java, you could use the linux lsof command to list the open files in the system. Alternatively, and with Java, you can use libnotify, but you will need to specify the folders. I can't see any other way of doing this with pure java.
EDIT #Keppil linked you to the file change notification API that looks way more suitable than libjnotify. I wasn't aware it existed!
I am trying to create executable under windows platform for Java program using JNI ,C/C++ and invocation API, I have already created jar file for my program which includes all dependencies. I want to embed it in exe file, I was successful in running simple main class(present in file system) using JNI invocation API, I am planning to add jar file as resource in C/C++ program. But I don't know how do I run that jar file , One option is create temporary jar file on file system and run it using java, But I do not want to expose my jar file to everyone for security reasons, How can I run jar file on the fly using JNI ?
Compiling Java to an executable with GCJ does not work all the time, there are limitations as far as using reflection and other items such as UI classes, Look at this page.
If you convert you Java Code to a library or simply another module then you could link to it and simply run it without the need for a JVM.
My initial reaction was that I would be shocked if you could get this to work and have it be performant. But then I started thinking about it, and maybe you could pull this off using a custom class loader. If you embed the jar in the exe as a resource, it would be exactly the same as having the jar bytes be present at a particular offset in any file (whether an exe or not).
So, here's a potential strategy: implement a custom class loader that accepts the exe path and offset of the jar resource in that file. This would use a custom version of ZipFile that uses a fixed index offset for it's reads (unfortunately, it isn't going to be possible to use ZipFile itself - but if you grab the source of ZipFile it should be pretty obvious where you'll need to add the offset).
There is a bootstrapping issue here (how do you load the custom class loader?) - but I think it might be possible to do that from the JNI side. Basically you'd store the .class file for the loader as a separate resource in the exe, load it fully into memory then construct it using JNI calls. That will be a hassle, but it's just for one class, and then you can let the Java runtime take over the rest.
Sounds like an interesting project (Although, as others are pointing out, there isn't much security in what you are doing... I suppose that you could encrypt the embedded jar and add decryption code to the classloader, but you've kinda got to decide how far you want to take this thing).