The new Apache 2.2.0 What are the major changes? Must be very concerned about open-source enthusiasts, while certainly do not want to know immediately whether the need to upgrade to new version. Issue Forum on the answers to these questions for you.
Apache 2.2.0 is the Apache httpd server is a major release, it contains a number of significant changes. Many changes are made to improve the existing modules, but there have been many new modules and features many aspects of the operation was improved. The new 2.2.0 version is not just an updated version of existing software. Many of the code is new, or made significant improvements and expansion to provide additional functionality, or extend or simplify existing properties.
Apache2.2.0 changes
Profile
Apache's configuration file so that the user has been a love-hate relationship. Some users like the whole, all the configuration information in a file approach. Others prefer to split into multiple files configuration file, use the import system to insert specific configuration information. Although this does not affect the configuration, but the use of multiple files easier to understand this approach, but also more convenient because it allows you to put a single virtual host configuration information into a single file.
Apache version of the default configuration file is a whole type, often contain many users do not use or do not understand the instructions, and will not change some of the instructions. Some Linux versions (such as Gentoo) has been split in this default configuration file. Now this is the standard version of a standard feature.
Retains the main httpd.conf file. In addition, the configuration file to selectively include the following elements of the standard configuration file: server pool management (multi-processing module (MPM) configuration), multi-language error messages, detailed directory listing, language settings, the user local directory, the user requests / configuration real-time information (/ server-info and / server-status), the virtual host configuration, the use of the Apache manual, Distributed Authoring and Versioning (WebDAV), a variety of default settings, SSL configuration.
Authorization / authentication module
Although the authorization and verification itself has not changed, but offers this feature of the module is rebuilt, and in some cases been re-under the name of the specific requirements in order to load Zu Jian Jian Hua. Also added a new module, through LDAP (mod_authnz_ldap) to provide authorization.
Standard authorization modules have been changed so that the module name and the authorization of these modules to provide some consistency between the type. For example, the original mod_auth module has been split into mod_auth_basic (now earmarked for HTTP authentication) and the mod_authn_file module (provided through the file in order to verify the back-end interface). Module prefix is now recognized that these modules in the authorization / verification process role.
mod_auth_ * indicates that the module for HTTP authentication mechanisms (such as mod_auth_basic and mod_auth_digest so); mod_authn_ * indicates that the module back-end authentication mechanisms (such as the mod_authn_file and mod_authn_dbm); mod_authz_ * indicates that the module authorization mechanisms (such as mod_authz_dbm and mod_authz_host); mod_authnz_ * indicates that the module for authentication and authorization are two mechanisms (including the new mod_authnz_ldap module).
Proxy / cache module
Additional load balancing module: mod_proxy_balancer mod_proxy proxy for the main module provides load balancing services. Load balancer through two ways: the number of requests count and weighted flow meter, so that requests to work process (worker) distributed between. Count count only the number of requests for the request and then distributed to all the work request process, until each process is handling the same amount of work requests.
The number of weighted meter works with a simple count of the same request, but the process can be single weighted, so some of the work process of the implementation process the request more than the other. Can follow the byte, rather than follow the simple request to be configured, so the user can configure a work process to handle the number of bytes that the process of twice the other, despite coming from a more likely number of Shao's actual request.
Cache modules (mod_cache, mod_disk_cache and mod_mem_cache) has never been considered to be a complete module, but there are many organizations already use these modules without any problems. However, these modules are now considered to have a quality of the environment can be used in production. There is also a new procedure called htcacheclean, it can clear the cache of the document database of documents. The program can run independently, can also be run as a daemon, it can provide statistical data on the size of the cache directory.
Filter Module
mod_filter module function has been expanded to allow the criteria to run under conditional filters. This changes the original model: According to the configuration instructions AddOutputFilter, or slightly more flexibility under the AddOutputFilterByType configuration command only to filter the document unconditionally.
Now, we have created a suitable filter chain (filter chain) - the output from the filter chain to deal with each filter, rather than for specific file types to add a specific filter. This requires a statement of available filter types, if necessary, should declare the source needs (file type) and the applicable filters.
In order to give detailed examples of standard documents, the server side include (SSI) directive Yuanyou style filter method from "AddOutputFilter INCLUDES. Shtml" to read:
FilterDeclare SSI
FilterProvider SSI INCLUDES resp = Content-Type $ text / html
FilterChain SSI
Filter chain enabled us in a specific point in the chain to increase the filter can even specify: According to a particular condition, remove a filter. For example, you may want to increase the output for all SSI, unless such output is Common Gateway Interface (CGI). You can be achieved through the following means: for this chain increase the SSI filter, but the request CGI script, remove the filter.
Database Support
Apache module in the database support function previously required to prepare the code to build a wrapper for the code to gain access to the database. For example, if you want to increase by MySQL or PostgreSQL SQL-based authentication mechanism, then the module must provide their own SQL database interface. Programming and performance issues make it into a solution is not ideal.
Apache now provides mod_dbd module, it uses standard interfaces to provide the database connection. The module uses apr_dbd interfaces, which also means that the database connection can be used by providing connection pooling, thread environment. This should help to improve the flexibility of the database environment, and improve the database connection of the modules need to have performance.
Note: This is not applicable to dynamic website database accessible solution, but in the future, we may provide connectivity through the block-based interfaces (such as mod_perl and mod_php) to provide this feature.
Module Development
Used in conjunction with the Apache build custom modules, you need to back-end aspects of the interface some changes in order to develop certain characteristics. Release Notes provide more detailed information, but the basic changes include the following: Connection error log feature simplifies the recording and have access to the error message; be configured test, the test configuration hook provides test results; for thread-based MPM, can change the stack size; protocol processing on the output filter. Order and filter system changes have maintained the same, the filter can now be the correct type of output to 璁剧疆 the responsibility to mod_filter; monitor linked to the module to automatically request periodic 鎵ц or press the implementation of the plan tasks; regular expression interfaces has changed , Perl-compatible regular expressions (PCRE) library has been upgraded to version 5.0, support for regular expression functions header file and regular expression functions have been changed; new DBD framework of the simplified interface, with SQL databases, but should be use their own custom systems to modify the module.
Any use of these features of the modules should be upgraded accordingly.
Procedural changes
Support the Apache httpd server process has added some small improvements. First, an additional httpd command line option should be to simplify the debugging module availability. Now you can always use the-l command line option list httpd run-time code in the built-in modules.
If the module is added to the configuration file directives, usually by using the-L command lists the supported command line option to determine whether the module has been loaded, but this method is not foolproof.
The new-M command line option lists all the modules, static link to httpd server module and configured to share the LAC set according to the module. Module type (static or shared) will be displayed.
Upgrade or wait?
Today, users still face a common problem: an upgrade to the new version? Or continue to use the current version and install the software?
On the one hand, Apache 2.2.0 only performance is very stable, fully tested patch version of the Apache httpd project. Apache 2.0 branch of the first official version: v2.0.35 is released in April 2002. Despite the many flaws and patches, Apache 2.0 series, and no major problems. So, in theory, version 2.2.0 is actually stable, fully tested version of an updated version.
However, the changes authorized by the module will get some for use without further testing of the 2.2.0 version of the disturbed. Of course, the configuration change means in a production environment before using Apache 2.2.0, its first in the test server (staging server) on the test - if your site relies heavily on Apache authentication and authorization functions driven, but also to test .
If the development and installation of custom modules for use with Apache software, and immediately moved to the new version should also be careful. Regular expression engine and API changes will require some re-development work. If the module uses the SQL interface to connect to MySQL or other database, then the priority should be to use the new mod_dvd interface, rather than their own customized solutions. However, to stress once again: this is only affecting the use of the technology module, will not affect the dynamic driven applications.
Therefore, the current selection is: Apache 2.0.55 is the latest stable 2.2.0 version before, Apache 2.2.0 is the latest official version, Apache 1.3.34 is the latest Apache 1.x version.
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