What Are Cache Rules?
In some cases, you may have different caching requirements for specific Web content.You can use cache rules to define the types of Web content that is stored in the cache and how Web content is stored and returned to users from the cache.
Why Use Cache Rules?
The default caching configuration, including the cache settings and the default cache rule, is sufficient for many organizations. If these settings are not modified, the default settings apply to all Web content cached in the ISA Server cache for both forward and reverse caching scenarios.
However, in some cases, you may need to configure a more specific caching configuration.For example, users in your organization may frequently access a Web site, so you may want to configure the cache so that all content from that Web site is cached on the computer running ISA Server. If the Web site contains critical information that changes frequently, you may need to implement the opposite solution, that is, configure the Web site to never be cached.
Cache Rule Settings
When you enable caching on ISA Server, a default cache rule is enabled. You can also configure a wide variety of settings that enable you to fine-tune caching performance on ISA Server. Table 6-3 describes how you can change options to fine-tune caching performance and how the default cache rule is configured.
Managing Cache Rules
After you configure caching rules, you may need to modify the cache rule settings or manage the cache rules. There are several actions that you may need to perform to manage cache rules. These include the following:
1- Modifying settings You may need to modify a cache rule after creating it. To modify the cache rule settings, open ISA Server Management, expand the Cache container, and click the cache rule on the Cache Rules tab. Then click Edit Selected Rule, as shown in Figure 6-12. The configuration options when modifying the rule are the same as the options when creating the rule, with one additional option. When you modify the cache rule properties, you can use destination sets to configure exceptions to the network entities that the rule applies to. For example, if you need to configure a rule that applies to all Web sites except one, you can configure a destination set for the Web site’s URL and add it to the Exceptions list.
2- Managing rule order Just like firewall access rules, you may need to modify the cache rule order to achieve a desired result. When ISA Server receives a Web request, it evaluates the cache rules in order. The first cache rule that matches the client request is applied. For example, you may have a cache rule that specifies the caching criteria for all Internet Web sites and another rule that specifies different caching requirements for a specific Web site. If the caching rule controlling caching for all Web sites is listed before the more specific rule, the more specific rule will never be applied. In general, you should configure the more specific rules so that they are evaluated first. The default caching rule will always be the last rule to be applied. To modify the rule order, click the rule you want to reorder and click either Move Selected Rules Up or Move Selected Rules Down.
3- Disabling or deleting cache rules If a cache rule is no longer required, you can disable or delete the rule. To do this, click the rule you want to modify and then click Disable Selected Rules or Delete Selected Rules.
4- Export and import cache rules Just as with any other ISA Server configuration setting, you can export the cache rule configuration to an .xml file and import cache rule settings. Use this option to create a backup copy of your cache rules before modifying the configuration.
In some cases, you may have different caching requirements for specific Web content.You can use cache rules to define the types of Web content that is stored in the cache and how Web content is stored and returned to users from the cache.
Why Use Cache Rules?
The default caching configuration, including the cache settings and the default cache rule, is sufficient for many organizations. If these settings are not modified, the default settings apply to all Web content cached in the ISA Server cache for both forward and reverse caching scenarios.
However, in some cases, you may need to configure a more specific caching configuration.For example, users in your organization may frequently access a Web site, so you may want to configure the cache so that all content from that Web site is cached on the computer running ISA Server. If the Web site contains critical information that changes frequently, you may need to implement the opposite solution, that is, configure the Web site to never be cached.
Cache Rule Settings
When you enable caching on ISA Server, a default cache rule is enabled. You can also configure a wide variety of settings that enable you to fine-tune caching performance on ISA Server. Table 6-3 describes how you can change options to fine-tune caching performance and how the default cache rule is configured.
Managing Cache Rules
After you configure caching rules, you may need to modify the cache rule settings or manage the cache rules. There are several actions that you may need to perform to manage cache rules. These include the following:
1- Modifying settings You may need to modify a cache rule after creating it. To modify the cache rule settings, open ISA Server Management, expand the Cache container, and click the cache rule on the Cache Rules tab. Then click Edit Selected Rule, as shown in Figure 6-12. The configuration options when modifying the rule are the same as the options when creating the rule, with one additional option. When you modify the cache rule properties, you can use destination sets to configure exceptions to the network entities that the rule applies to. For example, if you need to configure a rule that applies to all Web sites except one, you can configure a destination set for the Web site’s URL and add it to the Exceptions list.
2- Managing rule order Just like firewall access rules, you may need to modify the cache rule order to achieve a desired result. When ISA Server receives a Web request, it evaluates the cache rules in order. The first cache rule that matches the client request is applied. For example, you may have a cache rule that specifies the caching criteria for all Internet Web sites and another rule that specifies different caching requirements for a specific Web site. If the caching rule controlling caching for all Web sites is listed before the more specific rule, the more specific rule will never be applied. In general, you should configure the more specific rules so that they are evaluated first. The default caching rule will always be the last rule to be applied. To modify the rule order, click the rule you want to reorder and click either Move Selected Rules Up or Move Selected Rules Down.
3- Disabling or deleting cache rules If a cache rule is no longer required, you can disable or delete the rule. To do this, click the rule you want to modify and then click Disable Selected Rules or Delete Selected Rules.
4- Export and import cache rules Just as with any other ISA Server configuration setting, you can export the cache rule configuration to an .xml file and import cache rule settings. Use this option to create a backup copy of your cache rules before modifying the configuration.
