Sharing dynamic client and server-side content between JSP's - javascript

I've done quite a lot of searching about capabilities of JSPs and have been unable to find a concise answer to my issue.
I am currently writing a web application which uses a single jsp (with an imported CSS) to build a site with multiple functionalities. Specifically, the application has the ability to read and write data from/to an external server, as well as update user content and info.
For the sake of aesthetics and clarity, it makes the most sense to designate different areas of the site to each of these tasks, one at a time. Rather than attempt to use page divisions and conditional statements to control their visibility and execution, I want to essentially "cut up" the logic behind this dynamic content and spread it across multiple JSPs to allow for more organized editing, testing, and modification of the code by both a web developer and programmer, without either necessarily having to collaborate.
Assuming that all of the JSPs involved have the appropriate imports, are there any essential measures I need to take to allow seamless sharing of content between these JSPs? For example, if a user writes to the server and stores their data as some entity, (from a page with tools from one jsp) will the functions used to query the database work if I simply copy that code into another jsp and have the user navigate to that page in order to access that persisted data?
Thank you for your feedback!

Learn the design pattern Model–view–controller. It'll great to help you solve many of your project problems. And your architecture will more maintainable and scalable. You can see here and here for more information about the implementation of this pattern with JSP.

Related

Make javascript do stuff on external pages

Ok so im learning javascript and I just wanted to know if its possible to make it do actions on external pages. For example if I wanted to say 'onload redirect to somesite.com/page1 then once on somesite.com/page1 fill in register form with these details'
is that possible?
You cannot do this.
This would represent, for lack of a better word, an enormous security hole.
The only way to make an external page "do stuff" is to write code that is on or explicitly included in that page itself. Period.
I have however, seen external pages get loaded INTO the current page as strings, and then have the javascript that loaded those pages modify that markup directly. But that is ugly.
On the first page you could modify some variables/values in a database. Then, in the second page you could check the values in your database, and do different "stuff" depending on those values.
You would need to set up a database and use some server-side scripting along with Javascript (server-side scripting is used to interact with your server/database). In your first page, the server-side script, like PHP, would fetch info from your Javascript. In your second page, your Javascript would fetch info from your server side script and then do stuff to that page.
This is a much safer way. If you are taking user input from things like HTML fields, you need to look into cleaning the input to prevent something called "cross-site scripting (XSS)".
You could do this IF you were rendering the other page in a frame of some sort.
There are multiple ways in which you can render an entire external page as a piece of your page. Many pages take precautions to block being rendered in a frame for just this very reason though (Not to mention copyright issues).
Once you're rendering the external page inside your page you should be able to reference components nested in your frame and do the sort of thing that you're describing.
There's no way to do this with JavaScript. The developers of all the major browsers work very, very hard to prevent this sort of thing. If this were possible, it would open up pretty massive security holes.
If you really want to use something like this for testing, you can look at browser automation software like Selenium. This allows you to automate various testing scenarios in your browser, but it does not affect other clients using your site.

Single Page Application: advantages and disadvantages [closed]

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I've read about SPA and it advantages. I find most of them unconvincing. There are 3 advantages that arouse my doubts.
Question: Can you act as advocate of SPA and prove that I am wrong about first three statements?
=== ADVANTAGES ===
1. SPA is extremely good for very responsive sites:
Server-side rendering is hard to implement for all the intermediate
states - small view states do not map well to URLs.
Single page apps are distinguished by their ability to redraw any part
of the UI without requiring a server roundtrip to retrieve HTML. This
is achieved by separating the data from the presentation of data by
having a model layer that handles data and a view layer that reads
from the models.
What is wrong with holding a model layer for non-SPA? Does SPA the only compatible architecture with MVC on client side?
2. With SPA we don't need to use extra queries to the server to download pages.
Hah, and how many pages user can download during visiting your site? Two, three? Instead there appear another security problems and you need to separate your login page, admin page etc into separate pages. In turn it conflicts with SPA architecture.
3.May be any other advantages? Don't hear about any else..
=== DISADVANTAGES ===
Client must enable javascript.
Only one entry point to the site.
Security.
P.S. I've worked on SPA and non-SPA projects. And I'm asking those questions because I need to deepen my understanding. No mean to harm SPA supporters. Don't ask me to read a bit more about SPA. I just want to hear your considerations about that.
Let's look at one of the most popular SPA sites, GMail.
1. SPA is extremely good for very responsive sites:
Server-side rendering is not as hard as it used to be with simple techniques like keeping a #hash in the URL, or more recently HTML5 pushState. With this approach the exact state of the web app is embedded in the page URL. As in GMail every time you open a mail a special hash tag is added to the URL. If copied and pasted to other browser window can open the exact same mail (provided they can authenticate). This approach maps directly to a more traditional query string, the difference is merely in the execution. With HTML5 pushState() you can eliminate the #hash and use completely classic URLs which can resolve on the server on the first request and then load via ajax on subsequent requests.
2. With SPA we don't need to use extra queries to the server to download pages.
The number of pages user downloads during visit to my web site?? really how many mails some reads when he/she opens his/her mail account. I read >50 at one go. now the structure of the mails is almost the same. if you will use a server side rendering scheme the server would then render it on every request(typical case).
- security concern - you should/ should not keep separate pages for the admins/login that entirely depends upon the structure of you site take paytm.com for example also making a web site SPA does not mean that you open all the endpoints for all the users I mean I use forms auth with my spa web site.
- in the probably most used SPA framework Angular JS the dev can load the entire html temple from the web site so that can be done depending on the users authentication level. pre loading html for all the auth types isn't SPA.
3. May be any other advantages? Don't hear about any else..
these days you can safely assume the client will have javascript enabled browsers.
only one entry point of the site. As I mentioned earlier maintenance of state is possible you can have any number of entry points as you want but you should have one for sure.
even in an SPA user only see to what he has proper rights. you don't have to inject every thing at once. loading diff html templates and javascript async is also a valid part of SPA.
Advantages that I can think of are:
rendering html obviously takes some resources now every user visiting you site is doing this. also not only rendering major logics are now done client side instead of server side.
date time issues - I just give the client UTC time is a pre set format and don't even care about the time zones I let javascript handle it. this is great advantage to where I had to guess time zones based on location derived from users IP.
to me state is more nicely maintained in an SPA because once you have set a variable you know it will be there. this gives a feel of developing an app rather than a web page. this helps a lot typically in making sites like foodpanda, flipkart, amazon. because if you are not using client side state you are using expensive sessions.
websites surely are extremely responsive - I'll take an extreme example for this try making a calculator in a non SPA website(I know its weird).
Updates from Comments
It doesn't seem like anyone mentioned about sockets and long-polling.
If you log out from another client say mobile app, then your browser
should also log out. If you don't use SPA, you have to re-create the
socket connection every time there is a redirect. This should also
work with any updates in data like notifications, profile update etc
An alternate perspective: Aside from your website, will your project
involve a native mobile app? If yes, you are most likely going to be
feeding raw data to that native app from a server (ie JSON) and doing
client-side processing to render it, correct? So with this assertion,
you're ALREADY doing a client-side rendering model. Now the question
becomes, why shouldn't you use the same model for the website-version
of your project? Kind of a no-brainer. Then the question becomes
whether you want to render server-side pages only for SEO benefits and
convenience of shareable/bookmarkable URLs
I am a pragmatist, so I will try to look at this in terms of costs and benefits.
Note that for any disadvantage I give, I recognize that they are solvable. That's why I don't look at anything as black and white, but rather, costs and benefits.
Advantages
Easier state tracking - no need to use cookies, form submission, local storage, session storage, etc. to remember state between 2 page loads.
Boiler plate content that is on every page (header, footer, logo, copyright banner, etc.) only loads once per typical browser session.
No overhead latency on switching "pages".
Disadvantages
Performance monitoring - hands tied: Most browser-level performance monitoring solutions I have seen focus exclusively on page load time only, like time to first byte, time to build DOM, network round trip for the HTML, onload event, etc. Updating the page post-load via AJAX would not be measured. There are solutions which let you instrument your code to record explicit measures, like when clicking a link, start a timer, then end a timer after rendering the AJAX results, and send that feedback. New Relic, for example, supports this functionality. By using a SPA, you have tied yourself to only a few possible tools.
Security / penetration testing - hands tied: Automated security scans can have difficulty discovering links when your entire page is built dynamically by a SPA framework. There are probably solutions to this, but again, you've limited yourself.
Bundling: It is easy to get into a situation when you are downloading all of the code needed for the entire web site on the initial page load, which can perform terribly for low-bandwidth connections. You can bundle your JavaScript and CSS files to try to load in more natural chunks as you go, but now you need to maintain that mapping and watch for unintended files to get pulled in via unrealized dependencies (just happened to me). Again, solvable, but with a cost.
Big bang refactoring: If you want to make a major architectural change, like say, switch from one framework to another, to minimize risk, it's desirable to make incremental changes. That is, start using the new, migrate on some basis, like per-page, per-feature, etc., then drop the old after. With traditional multi-page app, you could switch one page from Angular to React, then switch another page in the next sprint. With a SPA, it's all or nothing. If you want to change, you have to change the entire application in one go.
Complexity of navigation: Tooling exists to help maintain navigational context in SPA's, like history.js, Angular 2, most of which rely on either the URL framework (#) or the newer history API. If every page was a separate page, you don't need any of that.
Complexity of figuring out code: We naturally think of web sites as pages. A multi-page app usually partitions code by page, which aids maintainability.
Again, I recognize that every one of these problems is solvable, at some cost.
But there comes a point where you are spending all your time solving problems which you could have just avoided in the first place. It comes back to the benefits and how important they are to you.
Disadvantages
1. Client must enable javascript. Yes, this is a clear disadvantage of SPA. In my case I know that I can expect my users to have JavaScript enabled. If you can't then you can't do a SPA, period. That's like trying to deploy a .NET app to a machine without the .NET Framework installed.
2. Only one entry point to the site. I solve this problem using SammyJS. 2-3 days of work to get your routing properly set up, and people will be able to create deep-link bookmarks into your app that work correctly. Your server will only need to expose one endpoint - the "give me the HTML + CSS + JS for this app" endpoint (think of it as a download/update location for a precompiled application) - and the client-side JavaScript you write will handle the actual entry into the application.
3. Security. This issue is not unique to SPAs, you have to deal with security in exactly the same way when you have an "old-school" client-server app (the HATEOAS model of using Hypertext to link between pages). It's just that the user is making the requests rather than your JavaScript, and that the results are in HTML rather than JSON or some data format. In a non-SPA app you have to secure the individual pages on the server, whereas in a SPA app you have to secure the data endpoints. (And, if you don't want your client to have access to all the code, then you have to split apart the downloadable JavaScript into separate areas as well. I simply tie that into my SammyJS-based routing system so the browser only requests things that the client knows it should have access to, based on an initial load of the user's roles, and then that becomes a non-issue.)
Advantages
A major architectural advantage of a SPA (that rarely gets mentioned) in many cases is the huge reduction in the "chattiness" of your app. If you design it properly to handle most processing on the client (the whole point, after all), then the number of requests to the server (read "possibilities for 503 errors that wreck your user experience") is dramatically reduced. In fact, a SPA makes it possible to do entirely offline processing, which is huge in some situations.
Performance is certainly better with client-side rendering if you do it right, but this is not the most compelling reason to build a SPA. (Network speeds are improving, after all.) Don't make the case for SPA on this basis alone.
Flexibility in your UI design is perhaps the other major advantage that I have found. Once I defined my API (with an SDK in JavaScript), I was able to completely rewrite my front-end with zero impact on the server aside from some static resource files. Try doing that with a traditional MVC app! :) (This becomes valuable when you have live deployments and version consistency of your API to worry about.)
So, bottom line: If you need offline processing (or at least want your clients to be able to survive occasional server outages) - dramatically reducing your own hardware costs - and you can assume JavaScript & modern browsers, then you need a SPA. In other cases it's more of a tradeoff.
One major disadvantage of SPA - SEO. Only recently Google and Bing started indexing Ajax-based pages by executing JavaScript during crawling, and still in many cases pages are being indexed incorrectly.
While developing SPA, you will be forced to handle SEO issues, probably by post-rendering all your site and creating static html snapshots for crawler's use. This will require a solid investment in a proper infrastructures.
Update 19.06.16:
Since writing this answer a while ago, I gain much more experience with Single Page Apps (namely, AngularJS 1.x) - so I have more info to share.
In my opinion, the main disadvantage of SPA applications is SEO, making them limited to kind of "dashboard" apps only. In addition, you are going to have a much harder times with caching, compared to classic solutions. For example, in ASP.NET caching is extreamly easy - just turn on OutputCaching and you are good: the whole HTML page will be cached according to URL (or any other parameters). However, in SPA you will need to handle caching yourself (by using some solutions like second level cache, template caching, etc..).
I would like to make the case for SPA being best for Data Driven Applications. gmail, of course is all about data and thus a good candidate for a SPA.
But if your page is mostly for display, for example, a terms of service page, then a SPA is completely overkill.
I think the sweet spot is having a site with a mixture of both SPA and static/MVC style pages, depending on the particular page.
For example, on one site I am building, the user lands on a standard MVC index page. But then when they go to the actual application, then it calls up the SPA. Another advantage to this is that the load-time of the SPA is not on the home page, but on the app page. The load time being on the home page could be a distraction to first time site users.
This scenario is a little bit like using Flash. After a few years of experience, the number of Flash only sites dropped to near zero due to the load factor. But as a page component, it is still in use.
For such companies as google, amazon etc, whose servers are running at max capacity in 24/7-mode, reducing traffic means real money - less hardware, less energy, less maintenance. Shifting CPU-usage from server to client pays off, and SPAs shine. The advantages overweight disadvantages by far.
So, SPA or not SPA depends much on the use case.
Just for mentioning another, probably not so obvious (for Web-developers) use case for SPAs:
I'm currently looking for a way to implement GUIs in embedded systems and browser-based architecture seems appealing to me. Traditionally there were not many possibilities for UIs in embedded systems - Java, Qt, wx, etc or propriety commercial frameworks. Some years ago Adobe tried to enter the market with flash but seems to be not so successful.
Nowadays, as "embedded systems" are as powerful as mainframes some years ago, a browser-based UI connected to the control unit via REST is a possible solution. The advantage is, the huge palette of tools for UI for no cost. (e.g. Qt require 20-30$ per sold unit on royalty fees plus 3000-4000$ per developer)
For such architecture SPA offers many advantages - e.g. more familiar development-approach for desktop-app developers, reduced server access (often in car-industry the UI and system muddles are separate hardware, where the system-part has an RT OS).
As the only client is the built-in browser, the mentioned disadvantages like JS-availability, server-side logging, security don't count any more.
2. With SPA we don't need to use extra queries to the server to download pages.
I still have to learn a lot but since I started learn about SPA, I love them.
This particular point may make a huge difference.
In many web apps that are not SPA, you will see that they will still retrieve and add content to the pages making ajax requests. So I think that SPA goes beyond by considering: what if the content that is going to be retrieved and displayed using ajax is the whole page? and not just a small portion of a page?
Let me present an scenario. Consider that you have 2 pages:
a page with list of products
a page to view the details of a specific product
Consider that you are at the list page. Then you click on a product to view the details. The client side app will trigger 2 ajax requests:
a request to get a json object with the product details
a request to get an html template where the product details will be inserted
Then, the client side app will insert the data into the html template and display it.
Then you go back to the list (no request is done for this!) and you open another product. This time, there will be only an ajax request to get the details of the product. The html template is going to be the same so you don't need to download again.
You may say that in a non SPA, when you open the product details, you make only 1 request and in this scenario we did 2. Yes. But you get the gain from an overall perspective, when you navigate across of many pages, the number of requests is going to be lower. And the data that is transferred between the client side and the server is going to be lower too because the html templates are going to be reused. Also, you don't need to download in every requests all those css, images, javascript files that are present in all the pages.
Also, let's consider that you server side language is Java. If you analyze the 2 requests that I mentioned, 1 downloads data (you don't need to load any view file and call the view rendering engine) and the other downloads and static html template so you can have an HTTP web server that can retrieve it directly without having to call the Java application server, no computation is done!
Finally, the big companies are using SPA: Facebook, GMail, Amazon. They don't play, they have the greatest engineers studying all this. So if you don't see the advantages you can initially trust them and hope to discover them down the road.
But is important to use good SPA design patterns. You may use a framework like AngularJS. Don't try to implement an SPA without using good design patterns because you may end up having a mess.
Disadvantages:
Technically, design and initial development of SPA is complex and can be avoided. Other reasons for not using this SPA can be:
a) Security: Single Page Application is less secure as compared to traditional pages due to cross site scripting(XSS).
b) Memory Leak: Memory leak in JavaScript can even cause powerful Computer to slow down. As traditional websites encourage to navigate among pages, thus any memory leak caused by previous page is almost cleansed leaving less residue behind.
c) Client must enable JavaScript to run SPA, but in multi-page application JavaScript can be completely avoided.
d) SPA grows to optimal size, cause long waiting time. Eg: Working on Gmail with slower connection.
Apart from above, other architectural limitations are Navigational Data loss, No log of Navigational History in browser and difficulty in Automated Functional Testing with selenium.
This link explain Single Page Application's Advantages and Disadvantages.
Try not to consider using a SPA without first defining how you will address security and API stability on the server side. Then you will see some of the true advantages to using a SPA. Specifically, if you use a RESTful server that implements OAUTH 2.0 for security, you will achieve two fundamental separation of concerns that can lower your development and maintenance costs.
This will move the session (and it's security) onto the SPA and relieve your server from all of that overhead.
Your API's become both stable and easily extensible.
Hinted to earlier, but not made explicit; If your goal is to deploy Android & Apple applications, writing a JavaScript SPA that is wrapped by a native call to host the screen in a browser (Android or Apple) eliminates the need to maintain both an Apple code base and an Android code base.
I understand this is an older question, but I would like to add another disadvantage of Single Page Applications:
If you build an API that returns results in a data language (such as XML or JSON) rather than a formatting language (like HTML), you are enabling greater application interoperability, for example, in business-to-business (B2B) applications. Such interoperability has great benefits but does allow people to write software to "mine" (or steal) your data. This particular disadvantage is common to all APIs that use a data language, and not to SPAs in general (indeed, an SPA that asks the server for pre-rendered HTML avoids this, but at the expense of poor model/view separation). This risk exposed by this disadvantage can be mitigated by various means, such as request limiting and connection blocking, etc.
In my development I found two distinct advantages for using an SPA. That is not to say that the following can not be achieved in a traditional web app just that I see incremental benefit without introducing additional disadvantages.
Potential for less server request as rendering new content isn’t always or even ever an http server request for a new html page. But I say potential because new content could easily require an Ajax call to pull in data but that data could be incrementally lighter than the itself plus markup providing a net benefit.
The ability to maintain “State”. In its simplest terms, set a variable on entry to the app and it will be available to other components throughout the user’s experience without passing it around or setting it to a local storage pattern. Intelligently managing this ability however is key to keep the top level scope uncluttered.
Other than requiring JS (which is not a crazy thing to require of web apps) other noted disadvantages are in my opinion either not specific to SPA or can be mitigated through good habits and development patterns.

UI Development - JavaScript vs Ajax

This is a design question. I find myself going back and forth between two UI design styles.
The UI on a prototype I developed recently relied heavily on loading the elements of the UI as partial views via AJAX. I did not like that approach because I had to do a lot of requests to the server while my page was loading. However, the plus of this design was that I could easily edit the partial view templates, so the code was easier to manage.
In the next iteration I decided to package all the information at once and then use JavaScript to generate partial views and plug this information into it (and only use Ajax when on-demand up-to-date information was actually needed). My page loads faster, but I find myself generating a lot of HTML snippets in JavaScript, which is getting harder to manage.
As I see it, using Ajax you get:
Easier to maintain (+)
Longer UI response times (-)
And with JavaScript only, you get
Faster UI response (+)
Easier to handle server-side errors (+)
Harder to maintain (-)
So, There are a few things on which I would like to hear your comments:
I do not like using Ajax unless I don't have a need for actual on-demand data. Am I wrong?
Are there frameworks/libraries that would make managing HTML-generating JavaScript code easier?
Are there any other pros/cons of the two approaches that I have missed?
Thanks,
There are templating libraries for JavaScript, if you want to get that involved. In general I would avoid manually sticking together HTML strings from JS unless there's a particular need to (eg in some cases for performance when dealing with very large tables).
HTML-hacking is difficult to read and prone to HTML-injection security holes when you don't get escaping right.
Start instead with the DOM methods, and use DOM-like content manipulation libraries to make it easier. For example, if using jQuery, do this:
$('<a>', {href: somelink, text: sometext})
and not this:
$(''+sometext+'') // insecure mess
There doesn't need to be a big difference between fetching data through XMLHttpRequest vs including it in the HTML document itself. You can direct a bunch of JSON data to the same function that will build page parts whether it was just fetched by XMLHttpRequest in an update operation, or included in function calls at document load time.
When including data in the page you will generally need to include a timestamp they were generated in any case, so that if the browser goes back to the page a while later without reloading it, the browser can detect that the information is now out-of-date, and cue up an XMLHttpRequest to update it.
The usual question when you're creating your page content from data with client-side JavaScript is, are you going to fill in the initial static HTML version from the server too? If so, you're going to be duplicating a lot of your content generation work in both client-side JS and the server-side language(*). If not, then you're making the content invisible to non-JS user agents which includes search engines. Whether or not that matters to you typically depends on what the app is doing (ie does it need to be searchable and accessible?)
(*: unless you can use server-side JavaScript from something like node.js and re-use your content generation code. This is still a somewhat rare approach.)
Why not look at integrating require.js into your workflow? I'm not entirely sure how it would work with templates, but included in their pipeline is the ability to package all required script files into a single .js to be served by a single server request/response.
I have no personal experience about it, but Closure looks promising. The thing about its templates being usable on both server and client side might be of interest to you. Here is what was said about using it in Google+:
The cool thing about Closure templates is they can be compiled into both Java and JavaScript. So we use Java server-side to turn the templates into HTML, but we can also do the same in JavaScript client-side for dynamic rendering. For instance, if you type in a profile page URL directly, we'll render it server-side, but if you go to the stream say and navigate to someone's profile page, we do it with AJAX and render it client-side using the same exact template.
When working with remote data after a page is loaded, for small datasets I prefer returning data only and adding to the UI with templates.
For large datasets, I recommend using your partial views to render the html on the server to reduce overhead in the client as #bobince mentioned.
For client-side state tracking, check out Knockout at http://www.knockoutjs.com. It uses an MVVM approach with data models bound to UI elements and makes it very simple to send the data back to the server via AJAX. It works with the jquery.tmpl template library out of the box or you can integrate another library of preference with a little more effort.
As far as managing templates, it's easy enough to store common templates in an object, either on the server to be retrieved with your remote data, or in a javascript object on the client.

Opinion Regarding Filtering of Content using JS

I'm working on a project and there is some battle between how some JS filtering should be implemented and I would like to ask you guys some input on this.
Today we have this site that displays a long list of repeated entries of data and some JS filtering would be nice for the users to navigate through. The usual stuff: keyword, order, date, price, etc. The question is not the use of JS, which is obvious, but the origin of the data. One person defends that the HTML itself should be used and that the JS should parse through it making the user's desired filtering. Another person defends that we should use a JSON generated in the server, and that JSON should be the data's origin.
What you guys think on this? What are the pros and cons?
As a final request, I would like you to be the most informative as possible since your answers will be used and referenced for all us in the company. (Yes, that is how we trust you!:)
The right action is matter of taste and system architecture as well as utility.
I would go with dynamically generated pages with JS and JSON -- These days I think you can safely assume that most browsers has Javascript enabled -- however you may need to make provisions for crawler (GoogleBot, Bing, Ask etc) as they may not fully execute all JS and hence may not index the page if you do figure out some kind of exception for supporting those.
Using JS+JSON also means that you make your code work so that support for mobile diveces is done client side, without the webserver having to create anything special.
Doing DOM manipulation as the alternative would not be my best friend, as the logic of the page control and layout is split-up in two places -- partly in the View controller on the webserver, and partly in the JavaScript -- it is in my opinion better to have it in one place and have the view controller only generate JSON and server the root pages etc.
However this is a matter of taste, and im not sure that I would be able to say that there is one correct and best solution.
I think it's a lot cleaner if the data is delivered in JSON and then the presentation HTML or view of that data is generated from that JSON with javascript.
This fits the more classic style of keeping core data structures separate from views. In this manner you can generate all types of views without having to constantly munge/revise the way you store, access and manipulate the data. You can even build classes and methods to develop a clean interface on your data that is entirely independent of how that data is displayed.
The only issue I see with that is if the browser doesn't support javascript and that browser is a desired viewer. In that case, you have to include a default HTML version from the server that will obviously not be manipulated and the JSON will be ignored.
The middle ground is that you include both JSON and the "default", initial HTML view of that data in rendered HTML. The view comes up quickly and non-JS browsers can see something useful. But, then any future manipulation of the view (sorting, for example) uses the JSON data and generates a new clean view from the JSON data. No data is then ever "parsed" from the HTML view.
In larger projects, this also can facilitate the separation of presentation from data manipulation so different people may work on creating HTML views vs. manipulate the data (like sorting).
I would make the multiple ajax calls to the server and have it return the sorted/filtered data. If you server backend is fast than it won't be very taxing and you could even cache the data between requests.
If you only have 50-100 items than it would be reasonable to send it all to the client and have javascript sort and filter it.
Some considerations to help make the decision
Is the information sensitive and unique? (this voids and benefit to caching in my first point)
What is the most common request that will happen and are you optimizing for that?
How much data is there? (tens of rows, hundreds, thousands, millions)?
Does you site have to work with JavaScript turned off? (supporting older browsers?)
Is your development team more comfortable doing this in the front-end or back-end?
The answer is that it depends on your situation.

What is the best practice to decouple GUI design from server-side development when developing modern web applications?

We are currently developing a few web applications and are letting our designers convert signed off paper prototypes into static web pages. In addition to having hyperlinks between pages the designers have started adding jquery calls to update elements on the pages by fetching data from static json files. Once the designers are finished and handoff the completed web pages, CSS, and JavaScript files; the server-side developers then edit the pages and replace the references to the local static json documents with references to live json urls that return the same json data structures.
My question:
What are efficient ways to decouple GUI design from serverside dev and reduce the integration time and effort? Some examples:
Do you have the developers manually change every json reference in the designers' prototype web pages?
Do you add a global variable somewhere to enable the designers' pages to be easily switched back and forth between using static and dynamic data?
Do you make the web pages self-aware of when they are running from a web server or just being served from a folder somewhere?
It depends on how much state information does your application need to manage. The examples you have given mention only read operations from the server. Are there any writes? Both read and write operations can potentially fail. Do your designers take care of those cases, or the server-side team jumps in and patches up the GUI later on?
I think it's best to provide a mock server-side implementation of your services for the designers. The server mock could simulate real life behavior as in throw errors and exceptions beyond just the happy path. It really is much less of a hassle to install a simple web server nowadays and a single script that acts as a mock service, rather than trying to create processes for later integration.
One of the things I have seen work fairly successfully for the whole "url/path" problem (dev vs test vs production, etc) is to create a subdomain for your project of "proto" (so proto.mycoolapp.company.int) and have that be the basis for all urls used anywhere in the app.
On top of that using whatever framework you are using set up global page handlers to identify section/page/function+[url data] for all of your data files (i.e. json calls etc).
This allows you to segregate your app into sections and build up functionality as you go and allows both the UI team and the dev team to work on hints for the other team.
For example say I have an app with three sections (login, account management, preview) I would have a login url service (data, files, whatever) at proto.mycoolapp.company.int/frontend/login/securelogin?user=GrayWizardX. The UI team can add these as they identify a need for data and your app dev team can see what functions are being requested (through server logs, etc) and make sure everything is matching up.
The good part is that when you move to production, the only change is to find "proto" and replace it. If that is in your global var, then its a quick and simple change.
It's not real clear what exactly your environment is (plain html only? or something like php?), so this is a bit of a shot in the dark...
If it's plain old HTML + javascript, you could probably use a javascript include on each page to get the right set of addresses. When the include file with all this environment specific information (i.e. use local or use server) remains in the same relative place, you don't need to worry about modifying the actual page. Just tell the GUI guys to always use this same set of variables for the address information and define the address information in that include file. The variable names don't change whether your getting locally or from the server, just the values stored in the variables.
I'm low on Vitamin Coffee, so hopefully that makes sense.

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