I'm implementing an application that takes a file from a developer describing a UI with data bindings using a custom language I implement. My server takes the file (from a repo or directly) and creates a webpage (which implements the specified UI) that requests a .json (which specifies the data), which are served to the client. The server is responsible for, other than serving, keeping the data updated periodically from an exeternal SQL server. The application then allows the user to manipulate the data locally (think spreadsheet, with initial data from that SQL server).
I have the node part down (creation and maintenance of data structure), but I'm not sure how to serve the application itself. It will possibly have many scripts which will need to be served together. Do I place them directly in a HTML or .jade file to be served? Another option is to keep everything server-side and just have a UI which queries the data, but updates (via said user manipulation of data) are done in the server. This may make it lighter on the client, but I don't want to clog the server.
Would appreciate any help, let me know if anything needs clarification!
Related
I have an idea to make something similar to Workflowy but with some new features.
(Workflowy is basically a note-taking app which beautifully organises all your notes as an endless tree)
At first, I implemented the logic in Python. It works in a terminal by printing notes line-by-line and then waiting for the command.
Is this a good idea to keep all the logic at the server and use JS only to render items and to send commands to the server?
For instance, if I want to move the entire folder into another folder, there are two ways of doing this:
Way 1: With Python which receives a command from JS 'move folder x to folder y', processes it and sends back a result to render.
Way 2: With JS which then has to understand all the folder structure and logic. In this case, the app will use a server only for storing data.
I have a feeling that way 2 (using JS to understand all the logic and Python only for saving data) is more appropriate, but this means that I have to rewrite everything from scratch.
Is the way 1 also reasonable?
Many thanks in advance!
It depends on the application you are making.
Like if you want to display thousands of data in html file, and data are stored in a json file. If you send html file and json file to the client from the server, then on the client side, you run a script that reads json file and displays it in html, then it will be slower, because client device may not be that powerful as the server is.
So for performance, use heavy tasks on server side, this may cause little more internet usage because as the client has no data in formatted manner, whenever new task on data is to be performed, you have to request the server again.
But for opposite case, you can save internet and little low performance. Here you can do some heavy tasks on client side.
It also depends on which device is used at client side.
I am concerned with the feasibility of this:
On a pre-configured machine I will have a Web-Application pre-installed, next to an Apache-Suite. So client and server are the same!
In this Web-Application Users can drag and drop PDF-Files to an USB-Icon.
Then the Web-App should write the dropped PDF to an attached USB-Stick.
I have never done something like this (writing to USB), so I am fairly insecure.
And I am well aware of the browser-restrictions concerning JavaScript and Filesystem-Access, but...
after researching a bit I found out, that there might be some possible and
relevant (I'm a Web-Platform-Guy) solutions to this:
Make a "Chrome App" with USB-Permission (does this really work?)
Use PHP to find the USB and then write to it (how would that work under Windows?)
Use some Flash as middle man (not preferred)
Now I'd like to know:
Has anyone some good experience with before mentioned possibilities?
Has anybody ever done something similar? Did it work? Which path did you choose?
How would I know which drive the USB is mounted, and how would I get sure?
What other possible solutions to this problem are there?
You have a website ('client-side' user interface) and a back-end server ('server-side') running on the same machine. This gives you 2 options:
Client-side: Download a file through the browser via HTTP GET and let the user choose where they save it.
Server-side: Build your USB interactions into the back-end (Node.js) code, as #mcgraphix suggests.
Interacting with the USB on the server-side provides the most flexibility. Furthermore, there are a number of libraries that you can leverage. Head to npmjs.org and consider, among others, the following Node.js server-side packages:
usb-detection
usb
With the server-side approach, initiate a Webservice request when the user completes the drag & drop action on the client, and implement the USB interaction within the server (Express.js or similar) method which services the request.
If the letter of the stick is known then writing a file from PHP will be simple
file_put_contents( 'E:\\folder\\file.pdf', $data );
Update
You can read a list of drives into a dropdown and allow a user to select a default drive to write to
https://stackoverflow.com/a/8210132/696535
Your question is more an architecture question than a code specific question.
Your web app (if you insist on a web app) should have two major components, a server side component that can be given arbitrary commands, and a client side component (javascript using XMLHttpRequest) that can make requests to the server side component to execute said arbitrary commands.
So your server side component, the component that serves your web page should have some server side code that can write your pdf to the file system, it should probably generate the pdf file as well rather than doing that on the web browser.
Which technology you use is up to you, whether that's PHP, .Net, Node.js etc...
The general gist is you want a server side framework that deals with HTTP requests, in your case probably a post request from the client side containing the encoded pdf, and responds accordingly. Bind a particular http route to trigger your save logic.
Your http post request to the server will contain your payload which is the pdf file to a particular path, e.g. http://localhost/savepdf that whichever technology stack http listens to (you'll need to configure that)
Your server side component should read the incoming data, decode it as appropriate then make a file system request to write the received payload to disk.
Suppose you were to build a highly functional single-page client-side application that listens to URL changes in order to navigate around the application.
Suppose then, that when a user (or search engine bot) loads a page by its url, instead of delivering the static javascript file and hits the api as normal, we'd like to precompute everything server-side and delivery the DOM along with the js state.
I am wondering if there are existing tools or techniques for persisting such an execution of state to the client.
I know that I could execute the script in something like phantom JS and output the DOM elements, but then event handlers, controllers and the js memory state would not be attached properly. I could sniff our user agent and only send the precomputed content to bots, but I am afraid google would punish for this, and we also lose the speed benefits of having sent everything precomputed in the first place.
So you want to compile, server-side and send to the client the results of requesting a resource at a specific URL? What is your backend written in?
We have an API running on GAE in Java. Our app is a single-page app, and we use the HTML5 history object so we have to have "real responses" for actual URLs on the front-end.
To handle this we use JSP to pre-cache the data in the page as it's loaded from the server and sent to the client.
On the front end we use Backbone, so we modified Backbone.sync to look for a copy of the data it's looking for locally on the page and if it's not there, only then to request it from the server as an AJAX call.
So, yes, this is pretty much what every site did before you had ajax. The trick is writing your app so that the data can be local in the page (or in localStorage even) and if not only then to request the data. Then make sure your page is "built" on the server end (so we actually populate the data in the HTML elements on the server end so the page doesn't require JS on the client end).
If you go somewhere else the data is dynamic and the page doesn't reload.
I'm building a single page website that will display dynamic data (updating once a second) via a graph to its users. I'm expecting this page to receive a large amount of traffic.
My data is stored in REDIS and I'm displaying the graph using Highcharts. I'm using ruby / Sinatra as my application layer.
My question is how best should I architecture the link between the data store and the JavaScript graph solution?
I've considered directly connecting to REDIS but that seems the least efficient . I'm wondering whether a XML solution where ruby builds an XML file every second and then Highcharts pulls data from there is the best as therefore the stress is only on hitting that XML file.
But I wanted to see whether anyone on here might have solved this previously or had any better ideas?
If the data is not user-specific, you should cache it into a representation that is easily read by the client. With web browsers, JSON might be a better choice.
You can cache it using Redis itself. (Memcached, Varnish are other options) You should cache it every time the data arrives and must avoid transforming the data on each request. The requests must simply serve pre-computed information from the cache (like you do with static information)
For a better experience on the client side, you should minimize the amount of data you are downloading from the server. JSON serves this purpose better than XML.
At the moment I am working on an XForms application to mutate XML data. This data comes from a local XML file. The file is exported from another application in a static way and read into the application. The problem is that every time the data changes (the XML structure remains the same). How can I fix this in XForms? I use XSLTForms in my application.
XSLTForms cannot directly access local data files because Javascript is never allowed to do that for security reasons.
For a local only treatment, it's always possible to run a local HTTP server which can be minimal.
If the data file is changing independantly, there is another problem: according to the client-server architecture, XForms can only periodically try to check the file contents.
-Alain