第11章Webアプリケーション開発

By the end of this section, you will be able to:

• Understand the use of server-side rendering and MVC patterns

• Relate to the technology used to create responsive Web 2.0 applications

• Become familiar with the technology used to create native mobile applications

• Understand how to create Web 3.0 applications as well as hybrid Web 2.0/3.0 applications

The World Wide Web, or the Web as it is known today, started as a way to link content (primarily text and images) stored on different servers or machines. It was invented by Tim Berners-Lee in 1989 while he worked as a researcher at the European Organization for Nuclear Research (CERN), home to the European Particle Physics Laboratory. Sir Tim Berners-Lee was knighted by Queen Elizabeth II in 2004 for his pioneering work. He created the Hypertext Transfer Protocol (HTTP) that operates on top of Transmission Control Protocol/Internet Protocol (TCP/IP), the principal protocols used on the Internet. Clients (web browsers) transmit HTTP requests to a web server, which is a software application that runs at a Uniform Resource Locator (URL) that specifies a location on the Web to access it, and responds by providing pages rendered in the hypertext markup language (HTML). This simple request and response paradigm, a client-server model, was easy to implement and allowed for the rapid growth of the Web. This phase of the Web, which began after 1989 and ended around 2004, would become known as Web 1.0, a period where the user’s interaction was limited primarily to reading and selecting web pages. A web page is a document commonly written in HTML and viewed in a browser. Figure 11.2 shows a simple Web 1.0 architecture and common usage. An encryption layer was later added to the HTTP protocol, which resulted in creating the HTTPS protocol. This made it possible to protect the sharing of sensitive information over the Web from eavesdropping attacks. While web servers only served web pages initially, a Common Gateway Interface (CGI) was subsequently added after the initial implementation of web servers to make it possible to link to applications via URLs on the Web.

As the Web evolved from this basic architecture, the need for more dynamic and interactive experiences became apparent. Users were no longer content with simply viewing static pages; they wanted to contribute content and engage with other users. Also called online publishing, web publishing publishes content on the Web while applying traditional publishing models. It was akin to digitizing an encyclopedia (images and text) and putting it online with hyperlinks. Today, simple websites with limited functionality, such as early blogs or static sites, still follow this model. A more interactive model that could scale to meet user demand was needed to support users’ desire to provide content and interact with other users. A design pattern is a reusable solution to a common software design problem. Figure 11.3 illustrates the Model-View-Controller (MVC) design pattern that was employed to separate a traditional web application’s data model, presentation, and business logic layers into its components.

The original implementation of the MVC pattern on the Web was such that the View would send requests to the Controller and the Controller obtained data from the Model and rendered it within HTML pages that were passed to browsers for presentation purposes. AJAX technology was later introduced to enable a more complete implementation of MVC on the Web that allowed asynchronous updates to page components and did not require refreshing pages in the browser to fetch data.

Following Moore’s law, which states that the number of transistors on an integrated circuit doubles roughly every two years, the processing power of smaller devices like laptops, tablets, and mobile phones became the preferred way users interacted on the Web. As Internet data transfer speeds and bandwidth increased through better hardware, fiber-optic cables, and mobile wireless technology, the rendering of web applications’ interactive interfaces moved from the server side to the client side. This led to being able to run native applications (apps) on mobile wireless phones that could take advantage of specific device rendering features. In a paradigm shift that was opposite to web apps, the data model moved off the phone and onto remote servers. These solutions led to a richer user experience known as Web 2.0, which is a phase of the Web focused on social interactions. This phase started in 2004, and social media websites using Web 2.0, such as Facebook (now Meta) and Twitter (now X), are well-known examples of this web phase of social interactivity.

The next phase of the web, Web 3.0, which is a phase of the Web where user activities may focus on decentralized access to solutions and data, is seeing a shift from the more traditional client-server model to a peer-to-peer networking model. A peer-to-peer (P2P) network is one in which devices connect and can share data and processing without needing a centralized server. Peers in this scheme can perform the role of a traditional client, server, or both. This shift fosters a trusted, decentralized, and open web, where large companies do not own the data, but rather where data is collectively owned by users. The use of other technologies like generative artificial intelligence (GenAI), which is powered by machine learning, aims to improve information access by mediating end-user searches to generate corresponding meaningful information out of the content available on the Web. While the benefits of artificial intelligence and machine learning are vast, enabling enhanced data processing and decision-making, it is equally important to consider the risks. These technologies can pose ethical concerns, such as data privacy issues, biased algorithms, and the potential for misuse, thus highlighting the importance of responsible development and implementation. In particular, while GenAI technology is appealing and can be successful in some cases, GenAI is also known to hallucinate and generate unpredictable and often inaccurate responses to web searches. The exemplar apps of the Web 3.0 and later phases are still to be determined. Still, if the previous phases of the Web are any indication, it will fundamentally change how we operate in an ever-evolving technological world.

Throughout this section, we will discover how the application architectures found in Web 2.0 apps, native mobile apps, and Web 3.0 apps are designed.