ISLifecycle
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Category:Schools & Education | Tags:exam, is, lifecycle, revision, study
Created:on 2007-12-18 | Updated:on 2008-02-11
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What are the advantages of compiled versus interpreted languages?
Tags: compiled, exam, interpreted, languages, versus on 2007-12-18 -All Annotations (0) -About
more fromascherconsulting.com
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As compiled languages tend to result in marginally faster applications,
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there are many reasons for using interpreted languages rather than compiled ones. The primary reasons are that interpreted languages generally allow for faster development, easier updating and easier debugging with only a marginal increase in processing time. Interpreted languages also tend to be more portable, able to be run without being modified for different computing environments.
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compiled languages take more time for development, updates and debugging but are generally faster to run and, quite importantly, difficult to reverse engineer. Because interpreted languages require the distribution of source code, proprietary software applications prefer to use compiled languages to prevent competitors (and customers) from seeing how their software was designed and built.
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interpreted - a definition from Whatis.com
Tags: compiler, exam, interpreted on 2007-12-18 -All Annotations (0) -About
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one before a compiled program is run, it runs much more quickly.
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An interpreted program, sometimes called a script, is a program whose instructions are actually a logically sequenced series of operating system commands, handled one at a time by a command interpreter. In turn, the command interpreter requests services from the operating system
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The writer of the interpreted program need not be concerned by low-level storage management considerations.
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On the other hand, an interpreted program can not be as efficient as a compiled program, which has been processed by a language compiler. A language compiler converts source statements into something close to the
strings of 0's and 1's that a processor ultimately is given to work on. Because this work is already done before a compiled program is run, it runs much more quickly. -
An interpreted program in a language such as Perl is much easier to write than a program written for a compiler.
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What is Java best suited for?
Tags: comp_languages, exam, java on 2007-12-18 -All Annotations (0) -About
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Because the Java programming language was designed to effectively be run on any computing platform, Java has been used in every situation where a software developer has wished to write one application and have it run on a variety of different types of computing platforms, whether personal computers, servers, palm-top computers, mobile phones or the computers embedded in machines such as automobiles.
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The problem with this approach is that, in the world of computing, one size does not fit all.
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Subsequently, while Java can be used to program almost any application, it is best suited for developing applications for mobile phones and smart cards due to each having a variety of hardware types performing similar functions. Java is also well suited for client-server networked applications, given that both client and server computers are often found to be running different operating systems.
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Interpreted vs Compiled
Tags: compiled, exam, interpreted, jaca on 2007-12-18 -All Annotations (0) -About
more fromruby.about.com
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interpreted code can be run directly from the text file it is stored in, while compiled code requires an extra step of reading that text file and turning it into a file that the computer can run.
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A passable analogy might be that of working with a coworker from another country who doesn't understand your language. You need to give that person a set of tasks to perform but you need a third party to translate. In the "interpreted" scenario, you would tell the translator the first task, who then would translate it for your coworker, who would execute the task and then wait for your next command.
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In the "compiled" scenario, you would work with the translator to translate all of your tasks into your coworkers language, and then hand the whole task list off to get done.
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Interpreted Language
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The term "InterpretedLanguage" is archaic, and referred to a language that was evaluated as the programmer typed it instead of being compiled into a single monolithic "executable". Some early languages (Pascal and many early implementations of Basic, for example) could be either compiled or interpreted according to the desire of the programmer and system administrator. While the term is still used informally in some circles, most professionals agree that advances in both compiler and interpreter design and implementation have made the distinction moot in any rigorous sense.
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Multi-tier Architecture: Know-how
Tags: architecture, exam, multi, tier on 2007-12-18 -All Annotations (0) -About
more fromwww.infocopter.com
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High-level Analysis of the
Architecture -
emerged in the 1990s to
overcome the limitations of the two-tier architecture the third tier (middle
tier server) is between the user interface (client) and the data management
(server) components. This middle tier provides process management where business
logic and rules are executed and can accommodate hundreds of users (as compared
to only 100 users with the two tier architecture) by providing functions
such as queuing, application execution, and database staging. -
The three tier
architecture is used
when an effective distributed client/server design is needed that provides (when
compared to the two tier) increased performance, flexibility, maintainability,
reusability, and scalability, while hiding the complexity of distributed
processing from the user. -
1.1.1
<!--[endif]-->
3-Tier
ArchitectureThe 3-tier architecture overcomes the weaknesses
of the 2-tier and
client/server architectures. It contains a client workstation, a component
server, and a database server. The user interface is on the client side while
business logic and data management are in dedicated tiers. Business logic resides
on one machine where it can be easily managed. Successful implementation of a
3-tier architecture requires considerable
applied
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Multitiered Architectures (Linktionary term)
Tags: architecture, exam, mult, tier on 2007-12-18 -All Annotations (0) -About
more fromwww.linktionary.com
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Multitiered architectures are software models (and hardware models, as discussed later) that extend the basic two-tiered client/server model to three tiers. In the basic two-tiered client/server model, the client requests services and the server provides services. There are software interfaces on the client and the server side that connect with one another to handle these interactions.
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However, the two-tiered model has some drawbacks. Both clients and servers run a portion of the application logic, with the servers handling the loads of back-end data management. This requires that client software be installed, managed, and updated on a potentially large number of systems. The two-tier model tends to move large numbers of records across the network to clients that may not always be optimized to handle them. The model is not efficient in distributed wide area network environments like the Internet. For example, a Web client may be a hand-held system with limited memory and processing power. It cannot be relied on to handle front-end processing tasks.
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QL became popular as a form of client/server middleware because it was efficient at selecting and moving just the records that were needed. In addition, it could run stored procedures directly at the database server, rather than moving data to the client and then running procedures on the client. The three-tiered model extends this approach by moving application logic (the equivalent of SQL stored procedures) to a middle server called the application server. This server performs processing for the client and other tasks as necessary.
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- Presentation services tier Responsible for gathering information from the user, sending the user information to the business services for processing, receiving the results of the business services processing, and presenting those results to the user.
- Business services tier Responsible for receiving input from the presentation tier, interacting with the data services to perform the business operations that the application was designed to automate (for example, income tax preparation, order processing, and so on), and sending the processed results to the presentation tier.
- Data services tier Responsible for storage, retrieval, maintenance, and integrity of data.
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The Web is a good example of where to apply the three-tier model. Application developers know little about the potential clients except that they have a near-universal interface: the Web browser. The middle tier accepts requests from clients, retrieves information from the back-end systems, processes the data, and forwards the results to the client. The client is relieved of a lot of work. Thin clients are a good fit in this model.
The middle tier may provide the following services:
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- The code for the middle tier can exist on multiple application servers, all accepting requests from multiple users (via load-balancing switches) and all connecting with the back-end systems.
- Message queuing allows clients to interact asynchronously with the back-end servers. In other words, transactions don't need to follow a precisely timed flow. The client may need to wait for a message from the server.
- The middle-tier server can provide transaction monitoring, which tracks the order and events of an online exchange to ensure that everything is complete and handled correctly. If not, the transaction is backed out.
- Distributed object computing services in which application logic and/or data resides in objects that are made available through an ORB (object request broker). An ORB provides a sort of software bus through which objects on one system can make requests of objects on another system. See "Distributed Object Computing."
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The thin client model represents another aspect of multitier architectures. A thin client is a Web browser device that relies on an external server to run its applications and store its data. It displays information and accepts keyboard inputs. Some systems have small drives to cache objects from Web sites. A typical thin client is the inexpensive Internet appliance you've seen pictured on kitchen counters with TV-like knobs for accessing the interface. Users store data on a server located at a service provider or an online service. Electronic mail is accessed through a Web browser interface on a remote e-mail server. In this model, the service provider is the middle tier. In fact, giant Internet data centers are emerging to support this model. In some cases, the data center caches so much information via content distribution techniques that users are likely to find what they need at the data center rather than out on the bigger Internet. The Internet data center could be referred to as "Internet in a building."
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Multitier architecture - Wikipedia, the free encyclopedia
Tags: architecture, exam, multi, tier on 2007-12-18 -All Annotations (0) -About
more fromen.wikipedia.org
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Web Development usage
In the Web development field, three-tier is often used to refer to Websites, commonly Electronic commerce websites, which are built using three tiers:
- A front end Web server serving static content
- A middle dynamic content processing and generation level Application server, for example Java EE platform.
- A back end Database, comprising both data sets and the Database management system or RDBMS software that manages and provides access to the data.
Three Tier Architecture (Linux journal) [1]
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