Web Application Architecture in Java

Creation Quick Response Code in Java Web Application Architecture
2 Web Application Architecture
Drawing QR-Code In Java
Using Barcode generation for Java Control to generate, create QR Code JIS X 0510 image in Java applications.
In a very general sense, this book is about designing efficient Web application architectures Before we can think about designing an architecture, however, we need to establish some requirements In this chapter, I propose some very general application requirements, essential to many types of applications Based on these requirements, we will be able to envision an abstract Web application architecture Later, we will ground that abstract architecture in something more realistic, in particular to various parts of the Java 2 Enterprise Edition (J2EE) solution My intention is to gradually define and describe the parts of an application in increasing levels of detail so that we can maintain an end-to-end view throughout our journey Although it is tempting, I resist the urge to center this book on a single example, such as online trading, auctions, or portal services Unfortunately, each of these examples has traits that do not lend themselves to all the performance and scalability challenges we want to cover For example, an online brokerage application has real-time features, but it is not necessarily a good example of a 24x7 application because its usage varies widely when normal trading hours are over Portal services, on the other hand, are a better 24x7 example, but they lack the real-time demands of an online brokerage For these reasons, I use a prototypical architecture and then relate examples as they become relevant throughout the text These details are established to set boundaries on solving the problems of scalability and high performance Although there are many ways to design a Web site, we will focus on the most common current trends while giving a nod to alternative and future paths
Barcode Creation In Java
Using Barcode creation for Java Control to generate, create bar code image in Java applications.
Web Application Terminology
Bar Code Recognizer In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
To start, let's introduce a few terms related to Web applications that we will be using throughout our discussion As already discussed, a Web application is provided by a server and used by a client, and it spans the network distance between those two points To use an application, clients are required to establish one or more connections with the server so that the data to be processed can be routed In conversing with the server, a client makes a request that is typically answered by a server reply
QR-Code Generation In Visual C#
Using Barcode generator for .NET Control to generate, create QR Code ISO/IEC18004 image in .NET framework applications.
A transaction at the Web application level is a request-and-reply dialogue that corresponds to a single logical application behavior That is, the request made by the client leads to the invocation of application logic on the server side and then eventually a reply to the client For example, when you use an online application to purchase a book, you click the Buy button Clicking that button starts a series of activities that refer to the general application notion of "adding a book to your shopping cart" When you are ready to purchase the books selected, clicking a Check Out button corresponds to "adding up your bill" It is important to note that by use of the word transaction, I am not equating an application-level and a database-level transaction The former occurs at a higher level than the latter; in fact, application-level transactions typically consist of a set of database transactions Despite this, however, application-level transactions and traditional database-level transactions are the same in the sense that a logical higher-level "handle" is used to group a series of related lower-level operations Let's distinguish between transactions and isolated requests that require no application logic For example, if we are browsing a list of books before purchasing, we may be simply accessing static Web pages Clicking a hyperlink does not require corresponding application logic While such scenarios are common within any application, we make a distinction between this type of behavior and transactions Obviously, the difference is that transactions are dynamic, involve more serverside resources, are more likely to affect overall resources or act as a bottleneck, and thus have greater impact on the application's scalability requirements Serving static Web pages is a less complex problem, although serving many static large objects (such as pictures) is a challenge in its own right Still, static requests are different from dynamic requests Unless otherwise specified, we will focus on the latter Finally, a session is the use of an application by a client over some time period Sessions are composed of one or more of the transactions we have defined Thus, just as transactions correspond to a series of application operations, sessions correspond to a series of transactions However, unlike transactions, this list is not necessarily logically related For example, we may want to transfer $100 from our bank savings account to make payments on two loans that we have at the bank On Saturday night, we might log in to our online bank, take care of the first transfer, update our mailing address information, and then log out On Sunday we might complete the second transfer and log out Thus, sessions are more about a series of transactions within a welldefined time frame, not necessarily a series of related transactions For our discussion, sessions are initiated by the user logging on to an application or otherwise opening a connection to the application and then terminated by the user explicitly logging off or by the expiration of a session lifetime As an example, suppose you need to make plane reservations for three trips later in the year You access some online travel application at 6 pm and spend 15 minutes configuring your options for the first trip After choosing from several options, you click Submit and receive your confirmation code Then you do the same thing for the second trip Realizing that it's 6:30 and time for dinner, you shut down the machine and head out for Chinese food A few hours later, you come back and realize that you still need to make the third plane reservation So you go back to the same online travel application and do so By the time you're finished, you've conducted two sessions; one at 6 pm and one a few hours later During the first session, you conducted at least two transactions (purchasing each ticket)
Denso QR Bar Code Generation In .NET Framework
Using Barcode creator for ASP.NET Control to generate, create QR-Code image in ASP.NET applications.
Encode QR Code In .NET Framework
Using Barcode printer for VS .NET Control to generate, create QR-Code image in .NET applications.
Encoding UCC - 12 In Java
Using Barcode creator for Java Control to generate, create EAN 128 image in Java applications.
UPC A Creator In Java
Using Barcode printer for Java Control to generate, create UPC Symbol image in Java applications.
Code 3/9 Encoder In Java
Using Barcode encoder for Java Control to generate, create Code 39 image in Java applications.
Code 39 Full ASCII Drawer In C#
Using Barcode creator for VS .NET Control to generate, create Code 39 image in VS .NET applications.
Bar Code Decoder In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
Create Barcode In Visual Basic .NET
Using Barcode generator for .NET framework Control to generate, create barcode image in Visual Studio .NET applications.
Print GTIN - 13 In .NET
Using Barcode creation for .NET Control to generate, create EAN-13 image in Visual Studio .NET applications.