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Lesson 3 Scheduling Cache Content Downloads
The scheduled cache content download service of ISA Server enables you to schedule Web content downloads from the Internet directly to the ISA Server cache. To support this feature, a background process downloads the content according to a predefined schedule.
After this lesson, you will be able to
Create and configure scheduled content download jobs in ISA Server
Estimated lesson time: 25 minutes
Scheduled Cache Content Downloads
Scheduled cache content downloads allow you to update the ISA Server cache with HTTP content that may be requested by Web Proxy clients sometime in the near future. When used wisely, scheduled cache content downloads save valuable network bandwidth and improve the overall cache performance without affecting throughput.
Figure 5.8 shows how you can create a new scheduled content download job in ISA Management.
Figure 5.8 Creating a content download job
Updating Cache Content Automatically
By monitoring and analyzing Internet access, you can determine which HTTP content is needed and when. You can then use the scheduled cache content download feature to download the HTTP content directly to the ISA Server cache, upon request or as scheduled. This enables you to update the ISA Server cache with HTTP content that you anticipate will be requested by clients in your organization. This content will be available for access directly from the ISA Server cache, rather than from the Internet.
You can download a single URL, multiple URLs, or an entire Web site. When you create a scheduled cache content download job, you can limit which content should be downloaded. For example, you can limit the download to a single domain. Similarly, you can limit how many links should be followed.
Scheduled content download jobs are created through the New Scheduled Content Download Job wizard. This wizard is shown in Figure 5.9.
Figure 5.9 The New Scheduled Content Download Job wizard
Follow these steps to create a scheduled cache content download job:
In the console tree of ISA Management, right-click the Scheduled Content Download Jobs folder.
Point to New, and then click Job.
Follow the on-screen instructions.
Configuring Properties for Existing Download Jobs
You can also configure properties for existing scheduled download jobs. To do this, select the Scheduled Content Download Jobs folder under the Cache Configuration node in ISA Management, right-click a scheduled download job in the details pane, and then click Properties. This procedure is illustrated in Figure 5.10.
Figure 5.10 Accessing the properties of a scheduled download job
Follow these steps to configure a location from which to download cache content:
In the console tree of ISA Management, click the Scheduled Content Download Jobs folder.
In the details pane, right-click the applicable scheduled content download job, and then click Properties.
On the Parameters tab, in the Begin Downloading From URL text box, type the URL from which to download the content.
To download only content from the domain specified in the Begin Downloading From URL text box, click the Keep Download Process Inside URL Domain Only check box.
To limit the number of links to follow from a single page when downloading content, click the Cache Up To Maximum Links Depth Of check box, and type the number of links.
To limit the total number of objects to cache, in the Maximum Number Of Cached Objects text box, type the number of objects.
Click OK.
Follow these steps to configure TTL for downloaded cache content:
In the console tree of ISA Management, click the Scheduled Content Download Jobs folder.
In the details pane, right-click the applicable scheduled content download job, click Properties and click the Parameters tab.
To override the TTL for an object, click the Always Override Object's TTL check box.
To override the TTL for an object, if the TTL is not defined, click the Override TTL If Not Defined check box.
To configure a specific TTL for the downloaded objects, type a TTL in Mark Downloaded Objects With A New TTL Of <number> Minutes text box.
Click OK.
If you click Always Override Object's TTL, the TTL is determined either by the TTL specified here or by the TTL specified in cache configuration properties.
Downloading Dynamic Content
When you schedule a cache content download, you can configure dynamic content to be cached by configuring the ISA Server cache to store the objects, even if the HTTP cache control headers indicate that they are not necessarily cacheable.
If the Web server from which the object is being downloaded requires client authentication, the scheduled content download job will fail.
Follow these steps to cache dynamic content for scheduled cache content download jobs:
In the console tree of ISA Management, click the Scheduled Content Download Jobs folder.
In the details pane, right-click the applicable scheduled content download job, and then click Properties.
On the Parameters tab, select the Cache Dynamic Content check box.
Click OK.
Configuring the Schedule for Content Download Jobs
The download occurs according to a preconfigured schedule. (You can also specify whether the schedule should recur periodically.) Scheduled content download jobs can be configured for outgoing Web requests and for incoming Web requests.
For outgoing Web requests, you determine which objects on the Internet are most often requested by users. You can then schedule jobs that retrieve the objects from the Internet and load them into the cache.
For incoming Web requests, you can schedule jobs that retrieve content from your internal Web servers.
Follow these steps to configure a cache content download job schedule:
In the console tree of ISA Management, click the Scheduled Content Download Jobs folder.
In the details pane, right-click the applicable scheduled cache content download job, and then click Properties.
On the Frequency tab, in the Date calendar box and Time spin box, select the date and time when the content should be downloaded from the Internet.
In the Frequency section, do one of the following:
To download the content only once at the specified time, click the Once radio button.
To download the content every day at the specified time, click the Daily radio button.
To download the content on a specified day at a specified time, click the Weekly On radio button and select the check boxes for the days on which to download content.
Click OK.
Practice: Creating a Scheduled Content Download Job
In this exercise, you schedule a content download for training materials at the Microsoft Web site. The scheduled content download includes dynamic content and a maximum of 5,000 objects.
To schedule a content download
In ISA Management, navigate to Servers And Arrays, MyArray, Cache Configuration.
Expand the Cache Configuration node.
Right-click the Scheduled Content Download Jobs folder, point to New and then click Job.The New Scheduled Content Download Job wizard appears.
In the Job Name text box, type Microsoft Online Seminars, and then click Next.The Start Time screen appears.
Leave the default date as it appears, and change the time to 11:59:59 p.m.
Click Next.The Frequency screen appears.
Click the Weekly On radio button, and then click the Sunday check box.
Click Next.The Content screen appears.
In the Download Content From This URL text box, type http://www.microsoft.com/seminar/1033/.
Click the Cache Dynamic Content check box.
Click Next.The Links And Downloaded Objects screen appears.
In the Maximum Number Of Cached Objects text box, type 5000 and then click Next.The Completing The Scheduled Content Download Job Wizard screen appears.
Click Finish.
Click on the Scheduled Content Download Jobs folder.The Microsoft Online Seminars job appears in the details pane.
Lesson Summary
Scheduled cache content downloads allow you to update the ISA Server cache with content that may soon be requested by Web Proxy clients. By monitoring and analyzing Internet access, you can determine which Web content is needed and when. You can then use the New Scheduled Content Download Job wizard to configure Web content downloads directly to the ISA Server cache. Content download jobs can be configured to occur either once or as scheduled. When you create a download job, you can configure a download for a single URL, multiple URLs, or an entire Web site.
