3 FORMS OF Web Application Architecture

Such terms as ”web app”, ”front-end architecture”, ”Web 2.0”, and ”HTML5 apps” have recently become trendy. Unfortunately these terms tend to be found in a misleading context which doesn’t consider the full specificity of implementation and using web app architecture. Today we’ll look for out more about the forms of web application architecture in the light of the latest web trends and key issues that matter to software owners.

We’ll outline 3 main types of web architecture and discuss their advantages and disadvantages for three points of view: software owner, software contractor (developer) and person. There can be other styles but they basically drop to these three as their subtypes.

First we’ll define a web application: it’s a client-server application – there exists a browser (the client) and a web server. The logic of a web application is distributed on the list of server and the client, there is a channel for information exchange, and the info is stored mainly on the server. Further details be determined by the architecture: different ones distribute the logic in different ways. It can be placed on the server in addition to on the client side.

It’s near to impossible to judge these very different architectures impartially. But we’ll make an effort to, using several criteria of evaluation:

Responsiveness/Usability. Updates of data on pages, switching between pages (response time). Such qualities of interface as richness and intuitiveness in use.
Linkability. Capability to save bookmarks and links to various parts of the website.
Offline work. Speaks for itself.

Speed of development. Addition of new functional features, refactoring, parallelizing the development process between developers, layout designers, etc.
Performance. Maximum speed of response from the server with minimum consumption of computation power.
Scalability. Ability to increase computation power or disc space under increases in amounts of information and/or amount of users. In case the allocated scalable system can be used, one must provide data consistence, availability and partition tolerance (CAP theorem). It is also worth noting that the case, when the number of features/screens of the client app is increased at the program owner’s request, depends upon the framework and implementation rather than the type of web architecture.
Testability. Possibility and easiness of automated unit testing.

Software owner:
Functional extendability. Adding functionality within minimal time and budget.
SEO. Users must be able to discover the application through any search engine.
Support. Expenses on app infrastructure – hardware, network infrastructure, maintenance staff.
Security. The software owner should be sure both business data and information about users are kept secure. Because the main security criterion we’ll think about the chance for changes in functionality of app behavior on your client side, and all associated risks. Standard dangers will be the same for the compared architectures. We usually do not consider security on the ‘server-client’ channel, because all these architectures are equally subjected to break-ins – this channel could possibly be the same.
Conversion: site – mobile or desktop application. Possibility to create the application form on mobile markets or even to make a desktop application from it with minimal additional costs.

Some of these criteria might seem inaccurate, but the purpose of the article is not to show what’s good and what’s bad. It’s more of an in depth review that shows the possible options of preference.

Let’s outline three main types of web applications in line with the roles performed by the server and the client browser.

Type 1: Server-side HTML

The most widespread architecture. The server generates HTML-content and sends it to the client as a full-fledged HTML-page. Sometimes this architecture is named ”Web 1.0”, because it was the first to appear and currently dominates the web.

Responsiveness/Usability: 1/5. The least optimal value among these architectures. It’s so since there is a great amount of data transferred between your server and the client. An individual has to wait before whole page reloads, giving an answer to trivial actions, for instance, when only a section of the page needs to be reloaded. UI templates on the client depend on the frameworks applied on the server. Due to the limitations of mobile internet and huge amounts of transferred data, this architecture is hardly applicable in the mobile segment. You can find no method of sending instant data updates or changes instantly. If we consider the possibility of real-time updates via generation of ready chunks of content on the server side and updates of the client (through AJAX, WebSockets), plus design with partial changes of a full page, we’ll exceed this architecture.

Linkability: 5/5. The highest of the three, since it is the easiest implementable. It’s due to the fact that automagically one URL receives particular HTML-content on the server.

SEO: 5/5. Rather easily implemented, similarly to the previous criterion – the content is known beforehand.
Speed of development: 5/5. This can be the oldest architecture, so it’s possible to choose any server language and framework for particular needs.

Scalability: 4/5. If we take a look at the generation of HTML, under the increasing load comes the moment when load balance will be needed. There’s a much more complicated situation with scaling databases, but this task may be the same for these three architectures.

Performance: 3/5. Tightly bound to responsiveness and scalability with regard to traffic, speed etc. Performance is relatively low just because a big amount of data should be transferred, containing HTML, design, and business data. Therefore it’s necessary to generate data for your page (not only for the changed business data), and all of the accompanying information (such as for example design).

Testability: 4/5. The positive thing is that there surely is no need in special tools, which support JavaScript interpretation, to test the front-end, and this content is static.

Security: 4/5. The application form behavior logic is on the server side. However, data are transferred overtly, so a protected channel may be needed (which is basically a tale of any architecture that concerns the server). All of the security functionality is on the server side.

Conversion: site – mobile or desktop application: 0/5. Normally it’s simply impossible. Rarely there’s an exception (more of exotics): for instance, if the server is realized upon node.js, and there are no large databases; or if one utilizes third-party web services for data acquisition (however, it’s a more sophisticated variant of architecture). Thus fontaneria Valencia can wrap the application form in node-webkit or analogous means.