I'm a student. For my Distributed Systems project, I'm expected to create a gRPC project. I'm creating the project in Eclipse.
Two service implementation are to be coded in Java and the other is to be done in another coding language.
I've tried searching for help online but the results I'm getting are related to gRPC and how gRPC works, not about the coding or using other coding.
Ideally, I would like to use Python as the other language and to create it in Eclipse if possible. Does anyone have any information, documentation or examples I could look at, so I could can reference it?
I am able to see online searches for both Java and Python, but I'm not sure how to use both in one project.
Thank you.
So I got a lot of feedback for lecturers and classmates.
The server doesn't care what programming language is used.
So Java, Python, Node.js etc, could all be sent to the server.
A generalised simplistic idea of how I was able to understand is: Python converts its code to binary and sends it to the server. Same with Java and Node.js.
I don't know why, but I was digging myself deeper trying to figure out what code (i.e. the binary) that needed to be the communication between the server and code. I was trying to encapsulate Python into Java and vice versa.
Why did I think this? Your guess is as good as mine.
I couldn't find any reference that PostgreSQL db supports PMML using a search engine. I was wondering if anyone had any luck with this. I would like to deploy a Random Forest model that is built in R in PostgreSQL (I'm aware of other work arounds - but want to get an answer for this question before I go down the other route).
From my own reading, PostgreSQL doesn't directly support PMML, however if you use JPMML it integrates seamlessly with PostgreSQL. Its library is opensource and extensive.
https://github.com/jpmml/jpmml-postgresql
There is no built-in support. However with the XML support, the extensible stored procedure language handlers, and such it shouldn't be too hard to implement as an add-on (or perhaps an extension).
I don't foresee PMML support coming built into PostgreSQL in the near to moderate future so you would do best to either implement it yourself or go another route.
i am using contiki-os to simulate some motes which would have semantic capabilities. As the contiki-os (erbium) is written in C but our semantic libraries are written in java.
can anyone here guide me if it is possible to exploit these libraries in erbium or contiki-os. or i have to rewrite everything from scratch ?
update
just a minor update to the question. is it possible to use java code on the cooja simulator?
Cooja is indeed written in Java.
You can extend or modify Cooja if you need.
You can find out more about Cooja on the Contiki wiki as well as in numerous papres by Fredrik Österlind. Perhaps you should also take a look at Fredrik's PhD thesis "Improving Low-Power Wireless Protocols with Timing-Accurate Simulation", which is mostly about Cooja.
You might be able to use something like this:
http://www.codemesh.com/products/junction/
It appears to have a code generator that takes a java bytecode and create C code from it... but it might also need a runtime library that's platform specific.
With all that in mind, I don't think you will be successful. Most of the platforms are nearly out of space and/or flash by the time you are working with Erbuim; I doubt you'll have resources to process java code somehow.
And if you did get some success from this approach it would probably take a lot of time and effort to do so. With that time and effort you probably could have written the C code to do what you need instead.
Is there a standard way to control an Arduino from Scala? If not I am interested in hacking one together, but am unsure of where I should start. The Firmata library seemed like the way to go but there is no Java or Scala interface. SPDE supports Processing pretty well, but I see no Arduino functionality there. I also have a few snippets of Java<->Arduino example code scoured from the Arduino playground and other sources, but nothing comprehensive.
If anyone knows of a Scala or straight Java (I can just wrap it in Scala) way to do this, or has suggestions on rolling my own interface, I would like to hear about it.
Thanks.
Any programming language can be used to communicate between the serial ports of the PC and arduino,as long as the programs running on both sides can make make sense of the data exchanged.RxTX is a java library for serial port communication.Hope this helps.
You might want to check out apache MINA, which provides some nice wrapping around the RXTX libraries and offers an API that's friendly to idiomatic Scala.
I've already had some success with this approach in driving an X10 controller for home automation.
Is there a general procedure for programming extensibility capability into your code?
I am wondering what the general procedure is for adding extension-type capability to a system you are writing so that functionality can be extended through some kind of plugin API rather than having to modify the core code of a system.
Do such things tend to be dependent on the language the system was written in, or is there a general method for allowing for this?
I've used event-based APIs for plugins in the past. You can insert hooks for plugins by dispatching events and providing access to the application state.
For example, if you were writing a blogging application, you might want to raise an event just before a new post is saved to the database, and provide the post HTML to the plugin to alter as needed.
This is generally something that you'll have to expose yourself, so yes, it will be dependent on the language your system is written in (though often it's possible to write wrappers for other languages as well).
If, for example, you had a program written in C, for Windows, plugins would be written for your program as DLLs. At runtime, you would manually load these DLLs, and expose some interface to them. For example, the DLLs might expose a gimme_the_interface() function which could accept a structure filled with function pointers. These function pointers would allow the DLL to make calls, register callbacks, etc.
If you were in C++, you would use the DLL system, except you would probably pass an object pointer instead of a struct, and the object would implement an interface which provided functionality (accomplishing the same thing as the struct, but less ugly). For Java, you would load class files on-demand instead of DLLs, but the basic idea would be the same.
In all cases, you'll need to define a standard interface between your code and the plugins, so that you can initialize the plugins, and so the plugins can interact with you.
P.S. If you'd like to see a good example of a C++ plugin system, check out the foobar2000 SDK. I haven't used it in quite a while, but it used to be really well done. I assume it still is.
I'm tempted to point you to the Design Patterns book for this generic question :p
Seriously, I think the answer is no. You can't write extensible code by default, it will be both hard to write/extend and awfully inefficient (Mozilla started with the idea of being very extensible, used XPCOM everywhere, and now they realized it was a mistake and started to remove it where it doesn't make sense).
what makes sense to do is to identify the pieces of your system that can be meaningfully extended and support a proper API for these cases (e.g. language support plug-ins in an editor). You'd use the relevant patterns, but the specific implementation depends on your platform/language choice.
IMO, it also helps to use a dynamic language - makes it possible to tweak the core code at run time (when absolutely necessary). I appreciated that Mozilla's extensibility works that way when writing Firefox extensions.
I think there are two aspects to your question:
The design of the system to be extendable (the design patterns, inversion of control and other architectural aspects) (http://www.martinfowler.com/articles/injection.html). And, at least to me, yes these patterns/techniques are platform/language independent and can be seen as a "general procedure".
Now, their implementation is language and platform dependend (for example in C/C++ you have the dynamic library stuff, etc.)
Several 'frameworks' have been developed to give you a programming environment that provides you pluggability/extensibility but as some other people mention, don't get too crazy making everything pluggable.
In the Java world a good specification to look is OSGi (http://en.wikipedia.org/wiki/OSGi) with several implementations the best one IMHO being Equinox (http://www.eclipse.org/equinox/)
Find out what minimum requrements you want to put on a plugin writer. Then make one or more Interfaces that the writer must implement for your code to know when and where to execute the code.
Make an API the writer can use to access some of the functionality in your code.
You could also make a base class the writer must inherit. This will make wiring up the API easier. Then use some kind of reflection to scan a directory, and load the classes you find that matches your requirements.
Some people also make a scripting language for their system, or implements an interpreter for a subset of an existing language. This is also a possible route to go.
Bottom line is: When you get the code to load, only your imagination should be able to stop you.
Good luck.
If you are using a compiled language such as C or C++, it may be a good idea to look at plugin support via scripting languages. Both Python and Lua are excellent languages that are used to script a large number of applications (Civ4 and blender use Python, Supreme Commander uses Lua, etc).
If you are using C++, check out the boost python library. Otherwise, python ships with headers that can be used in C, and does a fairly good job documenting the C/python API. The documentation seemed less complete for Lua, but I may not have been looking hard enough. Either way, you can offer a fairly solid scripting platform without a terrible amount of work. It still isn't trivial, but it provides you with a very good base to work from.