We are a group of 6 students in the last year of our studies.
We have to add new features on an existing web application. One of the most important feature and in our opinion the hardest one to implement is the following : the web application has to be functional even when offline.
As for, you must be able to consult data, make changes to the data, and when your device will be able to connect again, the app must try and synchronize with the online database. The current application use the following technologies : apache tomcat / mySQL / Hibernate / JavaEE / JavaScript / Ajax / xHTML & HTML5.
Considering that the main devices that will use the application are mainly digital tablet, smartphones (windows and android, not iOS for now), and windows PC ; my main question is the following one :
How can you do this kind of thing ?
I've done some research and it seems like you have to do a 'second' application, which will use mainly HTML5 to consult data while offline and JavaScript to control what the user is doing and what he can do. But we have no idea about the synchronization. It seems like SQLite could be of use as well
I know this is a general question but we are in the phase where we try and make sure everyone understands what the next steps will be. Thanks for your help and explanations.
Solution-1 : custom solution
There are api available to store data locally called indexDb in javascript which may help to store data.
For synchronisation i found that service workers may help.
Solution-2 : ready made tool
You can also try pouchdb but for this i think at server side you have to take apache couchdb database. I have not used it but would like to try this once.
Take a look at the Service-Worker API. Service worker is a programmable network proxy, allowing you to control how network requests from your page are handled. It's the next generation of giving users an offline experience after the App Cache.
The Service worker - in combination with local storage or even better WebSQL or a polyfill like localforage could be a way to realize that kind of application.
Downside: Service-Worker require SSL, no way around that. Second, only latest chrome and firefox support these technologies.
You might lookup PWA Progressive Web Application as a keyword, which describes / and uses exactly that kind of technologies.
Related
I am currently researching and developing an application in Java for the desktop along with a Java applet to embed inside a webpage and I am using C# to develop an Android and IOS compatible app. (I am open to using other languages, these are just what I have started with and feel the most comfortable with at the moment).
I have it so that the user can use any of the 3 environments to enter a post which is then stored in a database.
How would I make the various apps sitting on each of the platforms pull the new post down from the database so that the users can see it on all three platforms straight after it has been added to the database.
I assume that the applications would need to be looking in a specific table which is owned by the admin who is logged in and doing the posting and then as soon as it sees a new post it could send a query to retrieve it. These came concept would need to be implemented to updating and deleting posts also.
I am new to this type of cross-environment development and wanted to ask for advice. Thank you for any help. I have tried to make this question as specific as I can considering I do not have a particularly specific question in the first place.
Any advice about how to go about this task will be greatly helpful.
Thanks.
One road you could take is writing a simple web service, maybe using a high-level interpreted language, such as Python or Ruby, to provide a RESTful HTTPS backend. That way, all applications could query this web service, data would always be in sync, and you could have multiple front-end interfaces.
This seems like a trend nowadays, lots of multi-platform applications are structured as smaller micro-services on the back-end. And it really makes sense sometimes, because you get a lot of less coupling between parts.
currently we are developing a JAVA APP that runs on TOMCAT and uses POSTGREE SQL
And we have an introducting website (JOOMLA 2.5 based) that explains the app, and also have a register module, that runs on APACHE PHP, on a different server.
Our goal is that the clients enter direct to our website JOOMLA, register there and then they can go directly to the web-app.
Very like to www.tiendanube.com or shopify.
The java-app has a login as well as the joomla website.. We need to unify those process, we cannot find a form to achieve this.
The problem is also that Joomla cannot run in the same server as the web-app.
Is there any way to interconnect both the web-page and the app (which runs in differents server) to make then look as one ?
So we thinked that when the user register in the joomla it also has to be saved in the same POSTGREE SQL of the java app. Since the java app is running in a different server we cannot access postgree SQL of the java app
That can be a solution, still we are pretty sure it has to be a easy solution or a more powerful and better solution for this.
Also been the 2 services in differents servers, it seems that we are not able to mantain the same domain for both.
We will really appreciate some help
Thanks very much
Facundo
You have at least two ways to do it.
Use a LDAP, GMail authentication or equivalent. Easy, Joomla already have it
Do in a manual way with "Single Sign On across multiple domains". Will have to undestand how session cookies works and avoid avoid some problens.
Please read my recent answer on implementing SSO across subdomains in joomla
I am relatively new to web development, but I have some C++/Java experience. I have got the following conversion to do:
Current:
Desktop Application (Automation Software) developed in C# that communicates with remote PLC (Controller that overlooks different sensors in realtime) using TCP Sockets over the Web.
My Idea:
Convert the application into a server side software that will still communicate with the PLC over TCP/Socket. And use a browser to operate it, so the remote site can be monitored and controlled from any computer in our Intranet (possibly Tablets in the future).
Motive for doing it:
We had a computer fault which left the operators without control.
The new app:
I am planning on writing the server app using Java and OOP (so far no problem). And use HTML/CSS/Javascript for the WebApp and AJAX to update the page.
But I am still lost at how can I transport all this data between them in a proper and decent manner. I have read about SOAP and JSON in this Post. Although, I am not sure if I need to use them at all, is it a good solution to use either JSON or SOAP? Or is there any other solution that you may recommend?
Cheers,
Leo
If you consider skipping the development work to convert your app into a server-side software and just go for a third party solution, I suggest you take a look to Thinfinity VirtualUI.
"...offers a GUI remoting solution for in-house Windows desktop
developments, allowing them to be delivered as Windows/HTML5 dual-platform applications
simply by adding one line of code.
These Windows applications can keep their standard desktop environment behavior and,
alternatively, be accessed remotely from any modern web browser in a multi-user,
multi-instance fashion when hosted on a Thinfinity VirtualUI Server environment."
https://www.cybelesoft.com/docs/thinfinity_virtualui_whitepaper.pdf
SOAP is for defining public APIs that are published on the internet for other people to use, which does not seem like your use case. It is not particularly awesome to have to deal with it from inside a browser either, although there are javascript SOAP-client libraries. There is also going to be a fair bit more overhead on the server side parsing and validating XML than de/serializing between JSON and POJOs.
JSON is much easier to deal with in a browser, being natively understood and all that. Everything you need is built into the core of jQuery, no dependence on plugins that may have unknown levels of future support.
I want to create a websocket Java API for these requirements:
"When the user logs into my application, if he enters a page which has constant updates from the server, then the Java API should identify the user and keep pushing the contents on a regular interval"
So for this I want to get started in creating a generic Java API so that for other pages, which requires push from server, I can use the APIs instead of reinventing the wheel everytime
What are the things I should take into consideration and how should I approach this problem
Please key in your thoughts
Thanks in advance
GitHub has a number of libraries which deal with Java and WebSocket. You can build your application on top of one of them. Examples are vert.x, SockJS, Atmosphere etc.
At the SockJS page you can see a list of clients/servers for working with it.
IMHO It is better to re-use one of the existing libraries/frameworks than building your own, because yours is a common usecase and working with web sockets, providing corss browser compatibility etc are not trivial as of now.
We currently have a 2-tier Java Swing application sitting on top of MS SQL Server 2005. All the business logic is in the database. The client is quite old (and not very friendly), and for reasons of performance and scalability, we've already started porting some services to a middle tier in Java.
However, we still have a number of short and long term goals:
Pick a technology stack for a new front-end
This isn't easy - I can see everything from a web app at one end of the continuum to a traditional desktop app at the other being viable choices. The current front-end isn't really complex (mostly form-based), so I can see web/AJAX fitting, but it's an area where we don't know what we don't know.
Stacks on my list are:
Eclipse RCP, Netbeans RCP
Flex/Flash, Silverlight, JavaFX
Pure Javascript frontends (Sprout Core, Javascript MVC, ...)
Java-based Web frameworks (Wicket, JSF, ...)
Find a way of making the current application perform acceptably in a remote situation
We have some clients who resale our app to smaller clients and need to be able to remotely deploy it. Due to the 2-tier nature of the current architecture this leads to terrible performance (for example, calling a stored procedure that returns 18 result sets). We've used a Citrix solution in the past, but no-one likes that approach. Tunneling JDBC through port 80 also sounds like a bad idea. I was starting to wonder if there's anything that could use a X-Windows like approach to remote just the GUI part.
To simplify development and leverage your experience in Swing consider using Vaadin for your frontend. It is a Java framework for building modern web applications that look great, and perform well. All the code is written in Java and looks very similar to Swing.
As far as overall application architecture I would advise multi-tier, service oriented architecture. The best way to do it is by using Spring framework with Hibernate for database access.
If you want to easily redeploy your application, for an update, security reasons, etc. and if you want your application to be it to be accessed remotely, you should really consider a web based front end.
Plus, this way, only one app, your web app, will handle connection to the database, so no JDBC tunneling or whatever.
Concerning the best framework, it depends on your team knowledge, the way your application will be used (more or less javascript), etc.
We've just gone through a very similar evaluation process as we're migrating a legacy application.
For us the biggest deciding factor in what front-end framework to use was the prior knowledge of the development team. We wanted something that everybody would be comfortable with immediately. We had a couple of the senior developers that have worked with X or Y, but the framework that everybody knew was Swing.
In the end we decided on the NetBeans platform using RESTful webservice to communicate with an EE server.
As a bonus you can get your NetBeans platform application to deploy as a Java WebStart application, which means you get the benefit of not having to worry about individual installations.
If the frontend is mostly form-based, I would stay away from Flex. Flex is great for some applications (I'm using it for a canvas based application), but the form components of Flex has some usability issues. They just don't work like you expect from todays web. (like missing support for mousewheel, typing in dropdownlist only take first character into account etc.)
Assuming that you are going to force all your clients to install a new middle tier, I can't think of an argument against making it a Java web app. As already mentioned you have the benefit of controlling all access into your platform over HTTP, which allows easy resale, just with firewall configuration. There's no reason you can't make use of Javascript within a web front end, you may be interested in DWR, which allows you to interact directly with Java objects via Javascript. I've used this before to add some simple Ajax interaction to a Spring MVC webapp.
The reasons I like this approach, you're already migrating code into Java middle tier, so
Already imposing Java server hardware cost on clients, hosting app server / web server is comparable
Already have Java expertise, can be leveraged with DWR
Can use as much/little Javascript as appropriate (I've used DWR with IE6, Firefox 3, Chrome)
I think you're right to be wary of pushing too much functionality to the client, I'd go for as thin a client as possible. The only reason I'd look at the first two stack choices would be if you have some developer expertise in a particular area, and not Java webapp/Javascript.
I'd suggest to create a short list of candidate frameworks and create a small test application with all of them. This way you will get a sense of good and bad aspects from all of them and also get a picture what the community activity and documentation is like for each project (there is a lot of variance on those).If you end up doing this I hope you'll include Vaadin in your short list, I think it would fit you very well. If you have any questions just come over to our forums and we'll help you to get started.