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An introduction to the performance enhancement fastcgi api

Introduction The surge in the use of the Web by business has created a tremendous need for server extension applications that create dynamic an introduction to the performance enhancement fastcgi api. These are the applications that will allow businesses to deliver products, services, and messages whose shape and content are in part determined by the interaction with, and knowledge of, the customers to which they are delivered.

This important movement away from static Web content is pushing the limits and exposing the weaknesses of the environment in which these applications are currently bound: Most importantly it does not offer the performance these applications require.

A new communication infrastructure is needed to connect Web servers with these new applications. This paper assumes that the reader has basic familiarity with Web technology and developing Web applications.

CGI has many benefits: It is easy to understand. CGI applications can be written in nearly any language. Since applications run in separate processes, buggy applications cannot crash the Web server or access the server's private internal state.

Some form of CGI has been implemented on every Web server. CGI is not tied to any particular server architecture single threaded, multi-threaded, etc. CGI also has some significant drawbacks. The leading problem is performance: Since a new process is created for each request and thrown away when the request is done, efficiency is poor.

CGI also has limited functionality: It only supports a simple "responder" role, where the application generates the response that is returned to the client. CGI programs can't link into other stages of Web server request processing, such as authorization and logging. The freely available Apache server also has an API. Vendor APIs have the following problems: Vendor APIs introduce a steep learning curve, with increased implementation and maintenance costs.

Since the applications run in the server's address space, buggy applications can corrupt the core server or each other. A malicious or buggy application can compromise server security, and bugs in the an introduction to the performance enhancement fastcgi api server can corrupt applications. Coding your application to a particular API locks you into a particular vendor's server.

Tie-in to server architecture. API applications have to share the same architecture as the server: If the Web an introduction to the performance enhancement fastcgi api is multi-threaded, the application has to be thread-safe.

If the Web server has single-threaded processes, multi-threaded applications an introduction to the performance enhancement fastcgi api gain any performance advantage. Also, when the vendor changes the server's architecture, the API will usually have to change, and applications will have to be adapted or rewritten.

FastCGI processes are persistent-they are reused to handle multiple requests. This solves the CGI performance problem of creating new processes for an introduction to the performance enhancement fastcgi api request.

Simplicity, with easy migration from CGI. Applications built with the application library can also run as CGI programs, for backward compatibility with old Web servers. A buggy FastCGI application cannot crash or corrupt the core server or other applications.

A malicious FastCGI application cannot steal any secrets such as session keys for encryption from the Web server. The FastCGI interface is not tied to a particular server architecture. Also, FastCGI does not impose any architecture on the application: Support for distributed computing. FastCGI provides the ability to run applications remotely, which is useful for distributing load and managing external Web sites. Basic CGI request processing proceeds as follows: For each request, the server creates a new process and the process initializes itself.

The CGI program writes any output to be returned to the client on standard output. Error information written to standard error is logged by the Web server. When the CGI process exits, the request is complete. FastCGI processes are persistent: Instead of using operating system environment variables and pipes, the FastCGI protocol multiplexes the environment information, standard input, output and error over a single full-duplex connection.

Request processing in a single-threaded FastCGI application proceeds as follows: The processes may be created at startup, or created on demand. The server sends the CGI environment variable information and standard input over the connection.

The FastCGI process sends the standard output and error information back to the server over the same connection.

2. FastCGI Interface

When the FastCGI process closes the connection, the request is complete. FastCGI applications can run locally on the an introduction to the performance enhancement fastcgi api machine as the Web server or remotely.

For local applications, the server uses a full-duplex pipe to connect to the FastCGI application process. For remote applications, the server uses a TCP connection. FastCGI applications can be single-threaded or multi-threaded. For single threaded applications, the Web server maintains a pool of processes if the application is running locally to handle client requests. The size of the pool is user configurable.

Multi-threaded FastCGI applications may accept multiple connections from the Web server and handle them simultaneously in a single process.

For example, Java's built-in multi-threading, garbage collection, synchronization primitives, and platform independence make it a natural implementation language for multi-threaded FastCGI applications. These benefits are described in this section, along with some of the security issues that affect remote FastCGI applications.

FastCGI with Firewalls Applications that run on organizational external Web servers and depend on internal databases can be a challenge to administer. Figure 1 shows a typical organization, with an external Web server, a firewall restricting access to the internal network, and internal databases and applications. This means the server administrator has to replicate the necessary database information onto the system hosting the Web server which may be difficult to do in an automated way without compromising firewall security.

Or, the an introduction to the performance enhancement fastcgi api may build a "bridge" that allows access through the Web server to internal databases and applications which is effectively re-inventing remote FastCGI. With remote FastCGI, the applications an introduction to the performance enhancement fastcgi api run on the internal network, simplifying the administrator's job. When used with appropriate firewall configuration and auditing, this approach provides a secure, high-performance, scalable way to bring internal applications and data to the external network.

The usual way to solve this performance problem is to buy a bigger, faster Web server machine, or to partition the Web site across several Web servers.

FastCGI Process Manager (FPM)

With remote FastCGI, the resource-intensive applications can be moved off the Web an introduction to the performance enhancement fastcgi api machine, giving the server administrator additional flexibility in configuring the Web server. The administrator can configure FastCGI applications "behind the scenes" without having to change any content links or the external view of the Web site. The administrator can use several smaller, inexpensive server machines for applications, and can tailor each machine to the application it is hosting.

FastCGI applications should only accept connections from Web servers that they trust the application library includes support for IP address validation. Future versions of the protocol will include support for applications authenticating Web servers, as well as support for running remote connections over secure transport protocols such as SSL or PCT. Most application developers will use the FastCGI application library and won't have to worry about the protocol details.

However, specialized applications are free to an introduction to the performance enhancement fastcgi api the FastCGI protocol directly.

FastCGI uses a simple packet record format on the connection between the application and the Web server. The same record format is used in both directions and is outlined in Figure 2. The type field specifies the type of the record described in the following section. The request ID identifies this record to a particular request, allowing multiple requests to be multiplexed over a single connection. The data length field specifies the number of data bytes that follow.

The different FastCGI packet types are: CGI programs can only provide an introduction to the performance enhancement fastcgi api responses to requests. FastCGI provides expanded functionality with support for three different application "roles": Other roles will be defined in the future. For instance, a "logger" role would be useful, where the FastCGI program would receive the server's log entries for real-time processing and analysis. The roles are described in more detail in the following sections.

Let's assume that the Web server is configured so that all files with the. The process is outlined in Figure 3. Filter applications can significantly improve performance by caching filter results the server provides the modification time in the request information so that applications can flush the cache when the server file has been modified. The Filter role is useful for: On-the-fly format conversions Dynamic documents such as documents with embedded SQL queries, or dynamic advertisement insertion Applying a standard template: The FastCGI application an introduction to the performance enhancement fastcgi api invoked with all of the request information, just as in the Responder role.

If the authorizer application generates a "200 OK" HTTP result, the Web server assumes that access is allowed and proceeds with the request.

The Web server may process other access checks, including other FastCGI authorizers, before access is ultimately allowed. If the application generates any other response, that response is returned to the client and the request is ended. The Authorizer role is useful for: Access control based on username and password, where the user information is looked up in an external database.

Complex access policies, such as time-of-day based access. The library converts references to standard input, standard output, and standard error to the FastCGI protocol. This approach has several benefits: