I have a CLI Java application that takes a filename as an argument, and outputs its result to STDOUT.
I don't have the source code for this application, and it performs logic that needs to be executed client-side as part of a web app.
Is it possible to create an Applet wrapper around this application, and then send input and retrieve the result via JavaScript? If so, how would I go about doing this?
Yes it is possible, though note that to redirect output streams requires a trusted applet AFAIR.
Related
I have some mex files that urgently need to be called via MATLAB, there is currently no way around. However, I really despise MATLAB's GUI (in)possibilities and would like to create some e.g. JavaFX Apps.
My question: how can a Java app's communicate with a running MATLAB instance?
I know that you can include Java objects into MATLAB, however I would prefere to have a standalone Java app.
Java can execute commands via command line for example:
Process process = Runtime.getRuntime().exec(command);
process.waitFor();
So it is possible to execute a MATLAB script via command line in Java.
In MATLAB it is possible to write files with any data needed. I don't remember the exact way you may do this. http://www.mathworks.com/help/matlab/ref/fprintf.html gives an example:
x = 0:.1:1;
A = [x; exp(x)];
fileID = fopen('exp.txt','w');
fprintf(fileID,'%6s %12s\n','x','exp(x)');
fprintf(fileID,'%6.2f %12.8f\n',A);
fclose(fileID);
It is some kind of a workaround but it should work and it is not really hard to implement.
Update.
If Matlab is already running and you want to communicate with it in another application (Java), it may be done using a network connection through the localhost. Matlab may listen to some predefined port (for code example see http://www.mathworks.com/matlabcentral/fileexchange/11802-matlab-tcp-ip-code-example ) and do some action when a "start" trigger is sent via Java (or even some data along with the trigger). In Java you may use the Socket class (some code example may be found here http://www.javaworld.com/article/2077322/core-java/core-java-sockets-programming-in-java-a-tutorial.html ).
Also it may be done writing data into files. For example, Java adds some command to some file with predefined name (command.txt). Matlab scans this file in a loop and when something is found there it starts calculation (and Java application waits for results in some results.txt file).
I would suggest to start a server in Matlab that listens on a specific port to send/receive data to/from a Java client. By using the eval Matlab command you could even invoke scripts/command/etc. remotely controlled by a Java client.
You might want to have a look at this code example.
I want to access user's scanner using PHP script. I know this can be done by using PHP script on Linux based machine.
I want to put this script on the server and wanted to run it via Java Applet I don't know Java much also I am not sure if this task can be done by this way.
Please suggest if this is correct way and How to proceed on it.
Thanks for your time!
Can the scanner PHP code be operated purely via parameters in the URL? If so, then a Java applet could connect to those URLs passing parameters as necessary, and if the PHP script returns information in the HTML output stream (as if it were returning a web page), then the applet can parse the page it 'downloads' from that URL to get the information out. Not elegant, but do-able.
I have a java program that runs on a couple different computers and I want to be able to be able to access them remotely. I don't need to do anything crazy, just some very basic input output (get and set type stuff). I could write a client type application and set each program to a server with RMI and do it that way but I will not always be on the same computer and do not want to have to carry the .java file around with me.
I'd prefer to write a simple php webpage that I can access from anywhere and have some very basic buttons that could send the commands to the different Applications and receive back some output.
Problems is that it would probably impossible to get my host to load anything other then php onto the server where I'd host my webpage.
Does anyone have any ideas? I've tried googling it and found a couple things out there that sort of sound like what I need but the more I look into them they seem to not be what I wanted after all.
If you really want to do this right I'd suggest looking at a Java web framework (I use Play! myself) to create a RESTful web service and then sending requests from your PHP code that will fetch JSON data.
A framework like Play will make it very easy to get a REST web service running. Just create some wrappers that invoke your existing java code and call renderJSON to output the result.
From the PHP code you'll issue the request using curl and then read the response using json_decode which will turn it into a handy php variable.
This also has the advantage that either end can be changed without the other noticing, as long as the json data format is kept the same.
Based on the way you described your setup you'll probably run into routing issues trying to reach your Java apps from your PHP host. I'd recommend you try something else: have your Java apps frequently check with your PHP app if there are any updates. You can simply use a Java URL connection and a timer:
http://download.oracle.com/javase/6/docs/api/java/util/Timer.html
http://download.oracle.com/javase/6/docs/api/java/net/URL.html
I am newbie in wkhtmltopdf. I am wondering how to use wkhtmltopdf with my Dynamic Web Project in Eclipse? How to integrate wkhtmltopdf with my Java dynamic web application?
Is there any tutorials available for beginners of wkhtmltopdf ?
(Basically, I would like to use wkhtmltopdf in my web application so that when user click a save button , the current page will be saved to PDF file).
First, a technical note: Because you want to use wkhtmltopdf in a web project, if and when you deploy to a Linux server machine that you access via ssh (i.e. over the network), you will need to either use the patched Qt version, or run an X server, e.g. the dummy X server xvfb. (I don't know what happens if you deploy to a server running an operating system other than Linux.)
Second, it should be really quite simple to use wkhtmltopdf from any language in a web project.
If you just want to save the server-generated version of the current page, i.e. without any changes which might have been made like the user filling on forms, or Javascript adding new DOM elements, you just need to have an extra optional argument like ?generate=pdf on the end of your URL, which will cause that page to be generated as a PDF, and then the PDF button will link to that URL. This may be a lot of work to add to each page manually if you are just using simple JSP or something, but depending on which web framework you are using, the web framework may offer some help to implement the same action on every page, if you need to implement that.
To implement this approach, you would probably want to capture the response by wrapping the response object and overridding its getWriter() and getOutputStream() methods.
Another approach is to have a button "submit and generate PDF" which will generate the next page as a PDF. This might make more sense if you have a form the user needs to fill in - I don't know. It's a design decision really.
A third approach is to use Javascript to upload the current state of the page back to the server, and process that using wkhtmltopdf. This will work on any page. (This can even be used on any site, not just yours, if you make it a bookmarklet. Just an idea that occurred to me - it may not be a good idea.)
A fourth approach is, because wkhtmltopdf can fetch URLs, to pass the URL of your page instead of the contents of the page (which will only work if the request was a HTTP GET, or if it's equivalent to a HTTP GET on the same URL). This has some small amount of overhead over capturing your own response output, but it will probably be negligible. You will also very likely need to copy the cookie(s) into a cookie jar with this approach, since presumably your user might be logged in or have an implicit session.
So as you can see there are quite a lot of choices!
Now, the question remains: when your server has the necessary HTML, from any of the above approaches, how to feed it into wkhtmltopdf? This is pretty simple. You will need to spawn an external process using either Runtime.getRuntime().exec(), or the newer API called ProcessBuilder - see http://www.java-tips.org/java-se-tips/java.util/from-runtime.exec-to-processbuilder.html for a comparison. If you are smart about it you should be able to do this without needing to create any temporary files.
One of the wkhtmltopdf websites is currently down, but the main README is available here, which explains the command line arguments.
This is merely an outline answer which gives some pointers. If you need more details, let us know what specifically you need to know.
Additional info:
If you do end up trying to call wkhtmltopdf in an external process from java (or for that matter, any language), please note that the "normal" output that you see when using wkhtmltopdf from the command line (i.e. what you would expect to see in STDOUT) is not not in STDOUT but in STDERR. I raised this issue in the project page
http://code.google.com/p/wkhtmltopdf/issues/detail?id=825
and was replied that this is by design because wkhtmltopdf supports giving the actual pdf output in STDOUT. Please see the link for more details and java code.
java-wkhtmltopdf-wrapper provides an easy API for using wkhtmltopdf in Java.
It also works out-of-the-box on a headless server with xvfb.
E.g., on a Ubuntu or Debian server:
aptitude install wkhtmltopdf xvfb
Then in Java:
Pdf pdf = new Pdf();
pdf.addPage("http://www.google.com", PageType.url);
pdf.saveAs("output.pdf");
See the examples on their Github page for more options.
I would like to open a webpage and run a javascript code from within a java app.
For example I would like to open the page www.mytestpage.com and run the following javascript code:
document.getElementById("txtEmail").value="test#hotmail.com";
submit();
void(0);
This works in a browser...how can I do it programatically within a java app?
Thanks!
You can use Rhino to execute JavaScript but you won't have a DOM available - i.e. document.getElementById() would work.
You can use HTML Unit (headless) or WebDriver/Selenium (Driving a browser) to execute JavaScript in an environment that has a DOM available.
I'm not sure what you are looking for but I assume that you want to write automated POST request. This can be done in with Http Client library. Only you have to set appropriate request (POST or GET) parameters.
Look at examples - with this library you can do basic authentication or post files too.
Your question is a bit ambiguous, as we don't know the position of the Java program.
If that's a Java applet inside your page, you should look at Java<->JavaScript interaction, it works well.
If you need a separate Java program to control a browser, like sending a bookmarklet in the address bar (as one of your tags suggests), it is a bit harder (depends on target browser), perhaps look at the Robot class.
There's Rhino JS engine written in Java that you can run on app server such as Tomcat and feed JS to, however - it's not clear what are you trying to do with this?
There's also Envjs simulated browser environment which is based on Rhino but complete enough to run jQuery and/or Prototype
DWR (and other frameworks) now support "reverse ajax." The general idea is that you use one of three methods to communicate back to the client:
Comet (long-lived https session)
Polling
opportunistic / piggy-back (i.e. next time a request comes from the client, append your js call)
Regardless of method (which is typically a configuration-time decision and not a coding issue), you will have full access to any/all js calls you want to make.
Check out the reference page from DWR to get a pretty good explanation.