I have the following situation.
I have my web site written in Tapestry. On one of the pages, I'm required to generate a fairly large Excel or PDF document (around 20 MB). Now, since the entire process takes time, I'm asking my user to wait a bit.
However, when I tried to test the upper limits, I noticed that my entire application (not just the web part) freezes, because the generation eats up all the resources and the rest of the website and application becomes unresponsive.
Here is the flow how I've been doing it so far.
User clicks a button to request the file on the page
Data is being fetched from database (this part is quite fast)
Data is passed to a Tapestry service which prepares it (nothing fancy, also fast)
Prepared data is sent to EJB service which creates and deploys a visitor which creates the excel/pdf file
The InputStream of the created file is passed all the way up to Tapestry which wraps it in StreamResponse and offers the download
What would be an appropriate way to handle this problem?
Could I perhaps use Tapestry's ParallelExecutor from some Tapestry service of mine in a manner like this?
Future<InputStream> future = executor.invoke(new Invokable<InputStream>() { ... });
My main objective is that the application and website keep running, that they do not freeze.
Thank you in advance.
Take a look at the progresslink demo from tapestry stitch. It might give you some inspiration to poll for a long running / asynchronous task in tapestry.
Related
I work for a big global company (100 000 employees) and we have an internal software (its a database), this service/softwareh can be accessed from all employes via their internet browsers.
I need to change about 200 names in this databas and it is a VERY repetative work which takes time due to the cloud service is sometimes very slow. It usually takes 20 minutes to change one name... and I need to do 200 names!!
I have asked if its possible to just write a script that picks up my information from an excel sheet, then open ups the internet explorer, go to the site, click on all the correct buttons and paste the correct values.
The answer I got was "It is not possible to write a script to alter the database, you would need to go via IT department and via the correct programmers". But I assume that is if I want to superbig mass-update the database? I just want to get rid of the repetative task so I dont need to sit and wait 20 minutes x 200 names.
I guess my question is: Is it possible to write a script that performs actions via internet explorer EVEN IF ITS AN INTERNAL SOFTWARE/CLOUD SERVICE we are visiting?
Please - Im very very new to coding, as you might tell.
Welcome to stack overflow! It's definitely possible to automate those sorts of tasks using scripts, but if you're going down that route I would suggest that automating via internet explorer isn't the best option. Perhaps your IT team could look into creating a tool to access and modify the database directly instead? That would likely be much faster and less convoluted to set up than automating via a web interface.
However, if you're set on using a web browser to automate tasks I would suggest that you start by looking into basic javaScript tutorials and jquery to get started with web manipulation (jquery is an addon library for javascript that lets you set up interactions with web page elements in a friendlier way)! Using javascript you can write scripts to simulate button clicks and enter text values, which sounds like what you're looking for.
I have existing RPG4 programs with green screens, i would like to be able to call the rpg programs with Java and bypass the green screens.
I have done some research on this and IBM OAR (Open Access: RPG) keeps coming up. but i have not found a working example yet.
My goal is to create a web app to collect the the same information and feed it to the back end RPG
any help would be greatly appreciated
EDIT
Delete: You can't.
Insert: A beginner will need to master several complex new concepts before tackling this.
END-EDIT
At least, not without changing the RPG program. Web requests are processed by server jobs, which run in batch - they are not connected to a 5250 terminal. Because they aren't connected to a terminal, when the RPG program tries to open the display file, it will fall over because there's no terminal to attach to.
In order for this to work you'd have to alter the RPG program to not try display file I/O if called by a batch process like a Java app (although Java isn't necessary in this web scenario).
One way to change the RPG program is to use input parameters; if you have them, then don't try to open the display file, but stuff the input parameters into the fields where the display file would have done. Since a display file also outputs from the program you'd need to reserve some parameters for the output information as well. This could get very ugly if a subfile is involved, as there would be potentially thousands of parameters.
OAR comes into the picture because one can write an OAR handler that continues to use the same display file I/O operations, but to direct the actual I/O elsewhere, like STDIN and STDOUT for an HTTP type application. Jon Paris and Susan Gantner have written an article called Getting a Handle on RPG's Open Access which you might find helpful. It's in the July 2010 e-edition of IBM Systems Magazine.
Better perhaps is to extract the business logic in the RPG program, implement it as stored procedures which can be called by the web application via traditional ODBC / JDBC. One can write stored procedures in RPG, so that's not as hard as it might seem.
OAR is probably going to be your best bet....
However, every example I can think of that I've seen has resolved around building a handler to replace a printer file (PRTF) or physical file (PF).
Replacing a display file (DSPF) is a whole other ball game. Primarily because the 5250 protocol is an "intelligent" protocol; unlike dumb character type protocols such as used by ANSI/VT100.
It certainly can and had been done. If you have a single basic screen, you might be able to do it. But for a complex application with multiple screens and subfiles you'll probably have a tough time. Especially if you don't have a in depth understanding of the 5250 protocol.
I'd recommend you take a look at one of the vendor toolset designed to use OAR to replace a 5250 screen with a web page. Those vendors have put years of time and effort into developing the handler needed.
http://www.profoundlogic.com/solutions/rpg-application-modernization.html
https://asna.com/us/products/wings
You might find the following publication useful:
Modernizing IBM i Applications
Lastly note that ROA isn't the only option. There's an older technique, "screen scraping" in which your application basically emulates a 5250 terminal. It's simpler than a full ROA handler, but the end result is simpler also. IBM has it's own tool, HATS. And for instance Profound logic also has a tool, GENIE. But you could conceivably build your own screen scraper, the opensource TN5250J would probably be a place to start. But even this would be non-trivial.
You should use a mix of parsin json on the iseries(this eliminates the subfile problems), one good javascript framework( I've used Extjs) and The Apache server for I.
I've developed a HTTP services framework based on json parameters send directly from the browser using Ajax, processing each request with any ILE language program(mostly rpgle) and returning the result in pure json created inside the program. With this approach, you just send/receive business data, leaving the front-end to the Javascript framework.
Hope this helps. Contact me if you need more help.
I searched a lot regarding this topic but did not get any good answer.
Scenario:
We have Rest web service bases implementation in our project. Ideally frontEnd (Flex) call web service and backend send huge data point to frontEnd. Then frontEnd create chart of these data points and display to end user.
Our requirement is that user can export these charts and save as pdf file on the server. We are able to create JPG file from flex server and save as pdf file.
Problem occurs when end user has scheduled that chart report. Now that report can run at any time and may be browser is not opened at that time. So how backEnd will interact with frontEnd (flex) functions. Problems are:
browser is not opened so swf file is not loaded.
java/jsp need to interact with frontEnd(flex) as a reverseAjax so that frontEnd send JPG file back to server.
Does anybody face this issue before?
Is it somehow possible??
Asnwers/any leads are highly appreciated.
Please provide comments on this
Probably the only way to do this is to run a version of your Flex application (at least the charting part) on your server, and have your Java server interact with it.
I have faced a similar problem and have asked a similar question before. It is not very elegant, but what I mentioned before seems to be the only way to go.
I am using GWT 2.0.3 with ext version.When I run the application its take some time to load.As much as I know It take time to load some JS file (Not sure about it).For slow internet connection it wiil take more time.
I want to know what exactly GWT application do while loading.If it is loading some JS file the is there ant way to reudce loading time by dividing JS file or by nay other way?
Thanks in advance
When a GWT application loads, it loads all js files contained in your html host page, what means everything client side related is loaded.
To optimize this GWT introduced code splitting some time ago. You can check it here. The basic idea is to divide your application in logical parts, when a user wants to access to another part, its loaded on demand.
To speed up web app loading time, indeed split points are a first step.
But check as well this tool:
http://pagespeed.googlelabs.com
Slowness can also come from uncompressed pictures for instance.
Also, when you compile your GWT app, ensure you use "OBFUSCATED" mode for your compiled javascript, which makes it significantly smaller.
http://code.google.com/webtoolkit/doc/1.6/FAQ_DebuggingAndCompiling.html#Why_is_my_GWT-generated_JavaScript_gibberish?
Now if you are using Apache HTTPD as web server, Google has released a wonderful Apache module that implements web app best practices out of the box:
http://code.google.com/p/modpagespeed/
I'm working on a web application. There is one place where the user can upload files with the HTTP protocol. There is a choice between the classic HTML file upload control and a Java applet to upload the files.
The classic HTML file upload isn't great because you can only select one file at a time, and it's quite hard to get any progress indication during the actual upload (I finally got it using a timer refreshing a progress indicator with data fetched from the server via an AJAX call). The advantage: it's always working.
With the Java applet I can do more things: select multiple files at once (even a folder), compress the files, get a real progress bar, drag'n'drop files on the applet, etc...
BUT there are a few drawbacks:
it's a nightmare to get it to work properly on Mac Safari and Mac Firefox (Thanks Liveconnect)
the UI isn't exactly the native UI and some people notice that
the applet isn't as responsive as it should (could be my fault, but everything looks ok to me)
there are bugs in the Java UrlConnection class with HTTPS, so I use the Apache common HTTP client to do the actual HTTP upload. It's quite big a package and slows down the download of the .jar file
the Apache common HTTP client has sometimes trouble going through proxies
the Java runtime is quite big
I've been maintaining this Java applet for a while but now I'm fed up with all the drawbacks, and considering writing/buying a completely new component to upload theses files.
Question
If you had the following requirements:
upload multiple files easily from a browser, through HTTP or HTTPS
compress the files to reduce the upload time
upload should work on any platform, with native UI
must be able to upload huge files, up to 2gb at least
you have carte blanche on the technology
What technology/compontent would you use?
Edit :
Drag'n'Drop of files on the component would be a great plus.
It looks like there are a lot of issues related to bugs with the Flash Player (swfupload known issues). Proper Mac support and upload through proxies with authentication are options I can not do without. This would probably rule out all Flash-based options :-( .
I rule out all HTML/Javascript-only options because you can't select more than one file at a time with the classic HTML control. It's a pain to click n-times the "browse" button when you want to select multiple files in a folder.
I implemented something very recently in Silverlight.
Basically uses HttpWebRequest to send a chunk of data to a GenericHandler.
On the first post, 4KB of data is sent. On the 2nd chunk, I send another 4K chunk.
When the 2nd chunk is received, I calculate the round trip it took between first and 2nd chunk and so now
the 3rd chunk when sent will know to increase speed.
Using this method I can upload files of ANY size and I can resume.
Each post I send along this info:
[PARAMETERS]
[FILEDATA]
Here, parameters contain the following:
[Chunk #]
[Filename]
[Session ID]
After each chunk is received, I send a response back to my Silverlight saying how fast it took so that it can now send a larger
chunk.
Hard to put my explaination without code but that's basically how I did it.
At some point I will put together a quick writeup on how I did this.
I've never used it with files of 2GB in size, but the YUI File Uploader worked pretty well on a previous project. You may also be interested in this jQuery Plugin.
That said, I still think the Java Applet is the way to go. I think you'll end up with less portability and UI issues than you expect and Drag/Drop works great. For the record, Box.net uses a Java Applet for their multi-file quick uploads.
OK this is my take on this
I did some testing with swfupload, and I have my previous experience with Java, and my conclusion is that whatever technology is used there is no perfect solution to do uploads on the browser : you'll always end up with bugs when uploading huge files, going through proxies, with ssl, etc...
BUT :
a flash uploader (a la swfupload) is really lightweight, doesn't need authorization from the user and has a native interface which is REALLY cool, me thinks
a java uploader needs authorization but you can do whatever you want with the files selected by the user (aka compression if needed), and drag and drop works well. Be prepared for some epic bugs debuggin' though.
I didn't get a change to play with Silverlight as long as I'd like maybe that's the real answer, though the technology is still quite young so ... I'll edit this post if I get a chance to fiddle a bit with Silverlight
Thanks for all the answers !!
There are a number of free flash components that exist with nice multiple file upload capability. They make use of ActionScripts FileReference class with a PHP (or whatever) receiver on the server side. Some have recently broken with the launch of FP10 but I know for certain that swfupload will work :)
Hope this helps!
What about these two
Jupload
http://jupload.sourceforge.net/
and
jumploader
http://jumploader.com/
Both are java applets but they are also both really easy to use and implement.
what about google gears?
There are HTTP/HTTPS upload controls that allow multi-file upload. Here is one from Telerik, which I have found to be solid and reliable. The latest version looks to have most if not all of your feature requirements.
You can upload multiple files with HTTP forms as well, as Dave already pointed out, but if you're set on using something beyond what HTTP and Javascript offers I would heavily consider Flash. There are even some pre-existing solutions for it such as MultiPowUpload and it offers many of the features you're looking for. It's also easier to obtain progress information using a Flash client than with AJAX calls from Javascript since you have a little more flexibility.
You may check the Apache Commons FileUpload package. It allows you to upload multiple files, monitor the progress of the upload, and more. You can find more information here:
http://commons.apache.org/fileupload/
http://commons.apache.org/fileupload/using.html
Good luck