Custom web applications are some of the most popular web applications among professionals worldwide. By using customized web applications, website developers and programmers can incorporate the preferred features, being able to serve various industries (health care, finances, IT, communications, etc.).
IT solutions may not be identical for more business. These software solutions can not be universal and can not meet the requirements of each client. It’s wise to use from the start custom web applications in order to receive solutions according to your particular needs and requirements.
What exactly means a web application?
Starting from the surface, a “web application” is the first term that should be defined. In principle, a web application is similar to a website whose pages are dynamically generated. From the outside, this fact is transparent, as the client receives only HTML pages. However, the fact that URLs don’t indicate files with an “html” extension shows that the pages are dynamically generated. Also, a high degree of interactivity based on web forms is a sure sign that we’re dealing with an application and not with a static website.
To access information on the Internet, a computer accesses a Web server. In general, there are HTTP servers, Do not confuse the notion of web server (which is a computer connected to the Internet) with a HTTP server (web application running on a Web server, which provides the transfer of information between the server and Web browser users). The standard transfer protocol that describes the requests and answers allowed is HTTP- HyperText Transfer Protocol.
Here are the main reasons to choose custom web applications:
- They help in offering to the customer exactly what he wants;
- The webmasters can combine new and old technologies, in order to achieve the desired results;
- This kind of application doesn’t require any maintenance;
- Most custom web applications can be developed by using different open source technologies like PHP, and MySQL, resulting in a user friendly and functional website;
- By using custom web application, even the most complex websites can be designed in short time.
A custom website is usually built and maintained by web professionals; therefore, you just have to wait and to choose carefully the website’s features. It is required a constant evaluation regarding the website navigational fluidity amp; innovation, quality, user functionality and security.
1. Standards, protocols and basic web programming languages
- URL (Uniform Resource Locators)
- A URL contains the Internet address of a resource. It consists of 3 parts: protocol, host name (plus any port number, separated by the sign “:”) and file name (with a directory path).
- HTTP protocol
HTTP protocol consists of 2 types of messages: a request and an answer.
HTTP Requests-A HTTP request consists of: the method of application, the URL of the application fields of a header and the body.
HTTP 1.1 defines the following methods of application:
- GET – requests a resource identified by a URL.
- HEAD – returns the header identified by the URL request;
- POST – sends unlimited data to a web server;
- PUT – storing a resource to the given URL address;
- DELETE – deleting a resource identified by request URL;
- OPTIONS- return the HTTP methods supported by server.
TRACE – returns the header fields sent with the request TRACE.
HTTP 1.0 includes only the methods GET, HEAD, and POST.
HTTP Answers- HTTP answer contains: the result code, header fields and a body (body).
Status codes:
- 404 – The resource requested is not available.
- 401 – The request requires HTTP authentication.
- 500 – Indicates an error in HTTP server that prevents solving the application.
- 503 – Indicates that the HTTP server is overload and can not answer.
2. Interactivity in Web – HTML Forms
To ensure the web content interactivity (communication with the user), it is used a web form, introduced in the HTM page by a element which, in turn, may include various elements of communication with users (controls).
Interactivity in Web applications can be obtained through “client slide” and “server- slide”.
Generating dynamic HTML pages is done through various methods of programming to the server (server-side), of which the best known are: common gate interface (CGI – Common Gateway Interface), PHP scripts (Personal Hypertext Preprocessor), servlet components, JSP servers (JavaServer Pages).
JSP pages (JavaServer Pages) present several advantages because they allow the separation of static HTML page content from the content generated dynamically; writing the HTML content directly (not through print operations) is more simple and intuitive. However, it must be considered that a JSP document is always converted into a servlet and the HTML content is written (printed) in the output stream of the generated servlet.
HTML text of a JSP page (which is called template text) is passed directly from the JSP document to the page returned to the client, with two small exceptions: to get the sequence JSP pages are compiled automatically (at the first access) by the compiler of the server (container) Tomcat.
Unlike the standard HTML language, there can be used three types of constructions in JSP pages:
- JSP scripts- which specify parts of Java code that will become part of the generated servlet.
- JSP Directives- which control the overall structure of the servlet.
JSP scripting elements
Expressions: . The expression is evaluated during execution (run-time), converted into a series of characters (string) and inserted into the document output.
Scripts: . The code is inserted into the servlet service method.
Declarations: . The code is inserted into the servlet class, outside any method.
The standard package of applications doesn’t meet everyone’s criteria. Thus, customized software solutions remain the best IT solutions among companies. With these solutions and technological innovation, the customer sets the differences and competitive advantage.
