I have an embedded system using a python interface. Currently the system is using a (system-local) XML-file to persist data in case the system gets turned off. But normally the system is running the entire time. When the system starts, the XML-file is read in and information is stored in python-objects. The information then is used for processing. My aim is to edit this information remotely (over TCP/IP) even during process. I would like to use JAVA to get this done, and i have been thinking about something to share the objects. The problem is, that I'm missing some keywords to find the right technologies to get this done. What i found is SOAP, but i think it is not the right thing for this case, is that true? I'm grateful for any tips.
As I understand, you are using XML file to store start up configuration
And my assumptions on your interface between Java & Python apps
You want your Java application to retrieve objects over Python interface
And process them locally and send it back to Python interface to reload config ?
So, depending on your circumstances, you can workout something with the following
Jython
Pickle (if you have no restriction on startup config file format or can afford to do conversion)
https://pypi.python.org/pypi/Pyro4
Also you can get some ideas from here:
Sharing a complex object between Python processes?
You should ask your python application to open a XML-RPC socket which clients can connect on. This could let an outside application to execute an endpoint, which would manipulate your python object values in someway. There are several good choices for Java XML-RPC libraries, including the amazing org.apache.xmlrpc library.
Related
Update: Jun 10, 2022
I have successfully been able to create a demo application with AspectJ integration that could extract variables from the demo application. It was quite a hassle since there's a bit of trouble going on with Eclipse AJDT integration.
I was able to use CLI Java and ajc (AspectJ compiler) to achieve binary weaving into my demo application.
Original Question:
I am trying to retrieve real-time data from a running Java application and push it into an API I have on a server.|
I have no access to the source code of the running application; I only have the Jar file. I have tried decompilation into .java files; however, due to the scale of the app, I was not able to fix all of the missing access$000 function calls.
Is there a certain approach I should use when retrieving real-time data from an existing Java application? Has that been done before? Am I missing something that I am not aware of?
Any help is appreciated.
This is big challenge obviously. If you can glean enough understanding of how the program works from decompiling and reading log files to target some methods where you suspect there's data of interest to your API, then I would read up about Aspect Oriented Programming [AOP] and use those tools.
With AOP you can modify the classes in the jar file at runtime as its loaded by the JVM and access the classes.
For example: You can gather data from:
fields within the class that owns a method
parameters passed to a method
value returned from a method
Once you gather the data, you can also insert calls to your API.
Here's a place to start - https://www.baeldung.com/aspectj .
I have a shared variable in LabView and I want to read it on my Android application written in Java. Does anybody know how could I do it?
As stated by some other users, NI's Shared Variable interface is proprietary, and is only supported through using their products. However, there are a few workarounds I can think of:
If there is a LabVIEW or TestStand instance generating the values for the shared variables, you could send the data via UDP or TCP directly to the java application, instead of, or in addition to, writing to the variables.
You are able to tie Shared Variables to OPC variables within the NI software. This requires having an OPC server to write these values to (Which NI also has-it's a re-skin of Kepware), but there are many options for reading OPC variables using Java.
Basic file I/O, as also previously mentioned, could be possible depending on the system layout.
With LabVIEW you can deploy RESTful web services which will execute specific VI's upon receiving requests. You may be able to leverage these to retrieve the values of the shared variables you are targeting.
I suggest your best bet is to write the value out to a file using LabVIEW and read it in JAVA or open an network connection/RabbitMQ pipe between the two applications.
I am looking for a solution (best example code) how to implement an register a Java Program as (D)COM Server/Service. More concise I have the following issue:
Initially situation is:
(a) I have a Java Webservice (Axis) pulling in Data from the Web.
(b) I have a 3rd Party service (written in Delphi) which wants the
data from a COM-Object and is periodically calling this (the
interface, which methods of the COM Object are called, is specified).
In order to get the data from (a) to (b), I need to implement a COM-Server which provids the needed methods for (b) to retrieve its data.
The main Question I have is:
How can I make and register the Java Service as a COM-Object and provide the needed methods so that (b) get its data when calling.
I know Java, but I am no expert to (D)COM. So, forgive me possible technical error concerning COM.
Searching the Web I found several tools/frameworks (e.g. JInterop) that allow a Java Program to interact with a COM-Object, but I did not found code etc. how to make a Java Program accessible via (D)COM.
First, take a look on using Java Servers and DCOM. An example is idl server. Also, you can see services tutorial.
I want to find a library that I can use from my Java application that will allow me to access specific Javadoc in the scope of my project (I specify where Javadocs are located). Just like in Netbeans, I want to potentially access the Javadoc from html files locally and remotely, and from source.
I expect that I could use code from Netbeans to achieve this, but I don't know how, and I can't easily digest their documentation.
Today I started thinking about the same thing.
From CI point of view, I could use #author annotation to send e-mail to someone, who wrote a test that is failing with error, not with a failure.
Google didn't help me (or I didn't google deep enough), so I started wondering how to do it on my own.
First thing that came to my mind is writing a little tool that will check all *.java files specified in a directory, bound file name to annotations and allow user to perform some actions on them.
Is that reasonable?
Pals,
I have a requirement to establish a communication channel between C++ and Java layer of my application for the exchange of objects and their properties.
I have got the following options:
XML / SOAP
Postgre SQL
Can you please advice me the Pros & Cons on these. Please share your experiences on the implementation complexities.
Thanks,
Gtk
If the option is between those I would choose XML
Object <=> XML
Java side Simple, C++ side XML Objects
Reason, its simpler for what you want, i.e. pass language objects and not Data Base
Ah, could you specify the communication channel between the apps ?
UPDATE
If you can use JSON I would recommend it instead of XML, here is why.
Another option would be JMS. There are C++ clients out there.
Every time I see XML I think RESTful web service. Both platforms you mentioned have some form of tooling to marshal & unmarshal XML. There are plenty of working examples out in the wild, so a Google/Bing search is good. A nice side-effect is once you have those interfaces built, anything can connect to them.
If you really want to bother with generating a WSDL, then feel free to go the SOAP route. However, speaking with several years of web service integration experience, RESTful is so gosh darned simple compared to anything else.
I would like to suggest a third option : YAML
You have parsing library in YAML for both java and C++. In my experience, it's easier to debug exchange in YAML that in XML (especially if you got full text field or cyclic data structure).
I depends of the kind of message you transfer.
If your message are individual entity that have a short live, I would go for XML, YAML or something similar.
If your message contains information that is going to be used later on and refer to information in previous messages, I would use a database.