asp介绍 外文翻译

毕业论文外文翻译

ASP from A to Z

Nancy Winnick Cluts

Developer Technology Engineer

Microsoft Corporation

October 22, 1998

Contents

Introduction

What ASP Is

How ASP Works

ASP from A to Z

Bibliography

Introduction

There's lots of helpful information about Active Server Pages (ASP) available on this site and other sites. If you have plenty of time to search for the information, you can find answers to most of your questions. But if you want to find out what tools you can use to debug ASP or how to handle errors, you need to do some digging. This article provides an easy way to find information that pertains to ASP, including a short definition of what ASP is, how ASP works, and an alphabetical list of terms and tips that relate to ASP. In the A-to-Z list, you will see a brief description as well as pertinent links to more detailed information (when that information is available). This article is meant to be a "living" document. That means that I plan on updating it with new tips and removing tips that no longer apply. If you are an ASP developer and have a "juicy" tip, send it to me. If I publish it here, you'll get credit and the everlasting gratitude of throngs of other ASP developers.

What ASP Is

Active Server Pages is a programming environment that provides the ability to combine HTML, scripting, and components to create powerful Internet applications that run on your server. If you are already creating Web sites that combine HTML, scripting, and some reusable components, you can use ASP to glue these items together. You can create an HTML interface for your application by adding script commands to your HTML pages and you can encapsulate your business logic into reusable components. These components can be called from script or other components.

How ASP Works

When you incorporate ASP into your Web site, here's what happens:

1.The user brings up a Web site (like MSDN Library) where the default page has the extension .asp.

2.The browser requests the ASP file from the Web server.

3.The server-side script begins to run with ASP.

4.ASP processes the requested file sequentially (top-down), executes any script commands contained in the

file, and produces an HTML Web page.

5.The Web page is sent to the browser.

Because your script runs on the server, the Web server does all of the processing and standard HTML pages can be generated and sent to the browser. This means that your Web pages are limited only by what your Web server supports. Another benefit of having your script reside on the server is that the user cannot "view source" on the original script and code. Instead, the user sees only the generated HTML as well as non-HTML content, such as XML, on the pages that are being viewed.

ASP from A to Z

This section contains a list of terms and tips to help you understand ASP. They are listed in alphabetical order. Scroll down to the topic that interests you or click the letter in the alphabet below to jump down to the section containing the topic. I cribbed, er, I mean, compiled these tips and definitions from a number of sources, including technical articles (listed in the bibliography below), Knowledge Base articles, and a beta version of the Microsoft? Internet Information Server (IIS) 5.0 documentation (I'm so lucky!).

A B C D E F G I J L M O P Q R S T V W X ADO

Active Data Objects (ADO) provides a programming model for an OLE-DB data source. It is the database model that ASP uses; however, ASP can use other database access mechanisms. ADO supports the following installable objects, which are often used in ASP files: Command, Connection, Recordset, Field, and Error. Refer to the ADO Web site at https://www.360docs.net/doc/5716439291.html,/data/ado/ for more information than you can shake a stick at.

Applications

ASP is not just for prototyping. When using ASP as a solution, design your solution as an application instead of designing stand-alone ASP pages. As far as objects are concerned, it's best to take a look at what you need to accomplish and decide what you need, then whether you can buy the objects or will need to create the objects yourself. Take into consideration caching, scalability, reusability, security, and consistency.

Bottlenecks

Identify your bottlenecks (that is, the database, network card, or network connection) using the tools available: WCAT, NetMon, and performance counters. To improve server performance, take a look at all parts of the system for potential bottlenecks, including hardware configuration and software settings. This way, if you are ever asked to scale the project larger, you will know where the work needs to be done.

Browser Connection

In IIS 4.0, use the Response.IsClientConnected property to determine if the browser is still connected. If the browser is not connected, you can conserve CPU cycles by ceasing the processing of the ASP page. Refer to the Knowledge Base article Use IsClientConnected to Check if Browser is Connected.

Buffering

Turn buffering ON. By default it is OFF in IIS 4.0; in IIS 5.0, buffering is ON by default. You should buffer your ASP files so that you can abort sending a Web page. This might happen if the script being processed runs into a problem or if a user does not have appropriate security credentials. If this happens, and if you are using IIS 5.0, you can transfer the user to another page using Server.Transfer, or clear the buffer (using the Clear method of the Response object) to send different content to the user.

C++

If you are creating page-level components, you can use server scriptlets, Visual Basic?, V isual J++?, and Visual

C++?. If you are writing components that will be in application or session state, we recommend that you write them in C++ or Java so you can create them as both-threaded. Visual Basic is apartment-threaded. See the section below on threading for more details.

Caching

If your application sends pages to the client via a proxy server, the proxy server may cache pages to return them more quickly to the client. This reduces the load on the network and the Web server. To prevent a browser from caching ASP pages, set Response.Expires to some negative number. This will force the cached pages to expire immediately. If you set Response.Expires to 0, and if your browser clock is behind by a few minutes, the page won't expire immediately. If your Web site contains objects that do not expire often, such as images, set the expiration to some time in the future. This will greatly increase the speed at which a page is refreshed or downloaded. Proxy caching via pragma:nocache is already done for you by IIS, so you don't have to set this in your headers. More information about caching can be found in Got Any Cache?

Client-Side Scripts

Distribute the work on your Web site by providing script on both the client and the server. See Client-Side and Server-Side Objects.

COM Object Debugging

If you create a COM object and use it through ASP with Server.CreateObject, you cannot go back into your development environment and recompile the COM DLL without restarting the IIS Admin and W3SVC (Web server) service. Otherwise, the COM DLL will be locked. To restart these services, do the following:

1.At a command prompt, type net stop iisadmin /y. Please note that this will shut down IIS' parent service,

IIS Admin. This will also shut down FTP and other services that are children of IIS Admin. If you type only net stop w3svc, inetinfo.exe will not be unloaded.

2.At a command prompt, type net start w3svc. This will restart IIS Admin and the W3SVC service (Web

server).

3.You may recompile at any point after Step 1. Once you refer to an object that loads your DLL, you must repeat

Step 1 before building the component successfully.

Components

Use components to encapsulate the business logic in your ASP applications. You can create your own components or buy them "off the shelf." Once you have a component, you can reuse it wherever you need it. Develop your components using C++ or Java. Because Visual Basic is not marked as both-threaded, you cannot use Visual Basic components within application scope. If you design your own components, be sure to design components that are stateless (that is, the methods you define take parameters, rather than having a script set properties then call the method without the parameters).

Stateless components are far more flexible and reusable. In addition, if you have areas in your script where you have more than 100 lines of contiguous script, consider turning that script into a server scriptlet. More information about creating components can be found in the Active Server Components section of the Server area of the MSDN Library.

A comprehensive list of third-party components available for ASP can be found in the ASP Component Catalog. Connections

Pool your connections for optimal performance. By pooling your connections, your resources are allocated more efficiently. For support of multiple logons, provide one connection for read-only access and one connection for

read/write access. In general, avoid putting ADO connections in session state. ODBC (version 3.0 and later) automatically does connection pooling for you, and OLE-DB provides session pooling.

Cookie Munger

ASP uses cookies to store the session identifier (ASP SessionID). For machines that have cookies turned off, the Cookie Munger tool can be used to strip out cookies and put the information in a URL. This enables the use of "cookies" without actually sending out cookies. For more information, see Simulating Cookies with the Cookie Munger.

CPU

Design for scalability. Stress your ASP applications at 100% CPU to determine how to best allocate your resources. Use WCAT or a third-party tool such as Mercury's LoadRunner to tune your performance.

Data Access Components

Read Improving the Performance of Data Access Components in IIS 4.0 for a detailed explanation of the techniques that you can use to improve performance.

Database

Use ADO for adding database access to your Web pages via components. ADO can be used to create small components that connect to any OLE-DB compliant data source, whether it's relational or non-relational. This includes spreadsheets, databases, or e-mail directories.

Debugging

There are many tools available for debugging, including the Microsoft Script Debugger. The Script Debugger lets you run your server-side scripts one line at a time, monitor the value of variables, properties, or array elements during execution, and trace procedures.

Important:Once you have finished debugging your Web site, don't forget to turn off debugging

on your live servers. This will increase performance.

Dictionary Object

The Dictionary object enables you to look up and store arbitrary key-data pairs rapidly. The Dictionary object gives you access to items in the array by key, so it is faster to find things that aren't stored contiguously in memory. Instead, you use a key rather than having to know where in the array the object is stored.

Disconnected Recordsets