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Manual Chapter: Configuring Proxying Rules
Manual Chapter
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In general, the WebAccelerator® system attempts to service all HTTP requests from its cache. However, if you have certain types of content that you do not want the WebAccelerator system to service from its cache, you can configure proxying rules. Using proxying rules, you identify HTTP request elements that prompt the WebAccelerator system to send a request to your origin web servers for content.
Proxying Options
Which consist of the following directives:
Always proxy
When you select this option, the WebAccelerator system sends all requests that match the associated node to the origin web server for content. This option overrides any configured proxying rules.
Configure and use Proxy Rules
When you select this option, the WebAccelerator system applies configured proxy rules to requests that match the associated node.

Note: When you use Configure and use Proxy Rules and disable the Enable Content Assembly on Proxies option, located on the Assembly tab, if the content in the WebAccelerator system cache is unexpired, the WebAccelerator system services from its cache and performs content assembly. If the WebAccelerator system cache is empty or the content is expired, the WebAccelerator system refreshes its cache, by sending the request to the origin web server for content, and does not perform content assembly. This response from the origin web server also includes ETags from the origin web server.
Proxy rules
For this option, you can define specific parameters for proxying rules. In general, proxy rules options are only relevant to requests that match their node, rather than to matched responses.
Proxy overrides rules
For this option, you can define parameters and associated conditions under which the WebAccelerator system should ignore proxying rules options.
1.
In the navigation pane, expand WebAccelerator and click Policies.
The Policies screen displays a list of existing acceleration policies.
4.
From the Matching Rules list, choose Acceleration Rules.
5.
Click Proxying.
7.
Click the Save button.
For a new or modified acceleration policy to be in effect for your site, you must publish it. One way to do this is to click the Publish button.
When defining parameters for proxy rules, you identify the parameter and its value that must appear in a request, for the WebAccelerator system to send it to the origin web server for content.
That is, if you create a proxy rule based on a cookie named version, the WebAccelerator system sends the request to the origin server if one of the following conditions is true:
The version cookie does not appear on the request.
The version cookie appears on the request, but has no value set for it (version is empty).
1.
In the navigation pane, expand WebAccelerator and click Policies.
The Policies screen displays a list of existing acceleration policies.
4.
From the Matching Rules list, choose Acceleration Rules.
5.
Click Proxying.
6.
Enable the Configure and use Proxy Rules for this node option.
7.
In the Proxy Rules area, select Cookie from the Add Parameter list, and click the Add button.
8.
In the Name box, type version.
9.
From the Value(s) list, select Value does not match, and select the associated check box.
11.
Select the Value is an empty string check box.
12.
Click the Save button.
For a new or modified acceleration policy to be in effect for your site, you must publish it. One way to do this is to click the Publish button.
When the WebAccelerator system matches a request to a node that has the Always proxy requests for this node setting enabled, it sends the request to the origin server, and responds to the request without caching the content. This option overrides any configured proxying rule, and is useful for specific content that is private.
1.
In the navigation pane, expand WebAccelerator and click Policies.
The Policies screen displays a list of existing acceleration policies.
3.
4.
From the Matching Rules list, choose Acceleration Rules.
The acceleration rules display on the Policy Editor menu bar.
6.
7.
Click the Save button.
For a new or modified acceleration policy to be in effect for your site, you must publish it. One way to do this is to click the Publish button.
Once you publish the acceleration policy, the WebAccelerator system sends all matched requests to the origin server for content.
One common application for proxy override rules, is for sites that receive a high volume of traffic related to web crawlers and robots clients. You can avoid having your origin web server manage this excessive traffic by configuring a proxy override rule. It is especially important to consider a proxy override rule for this application if your proxy rules are based on a set cookie, because web crawlers and robots rarely present cookies in their requests.
Before configuring the rule, you could examine the origin servers log files to see if the web crawler presents a specific a string that you can use for a proxy override rule. For example, the web crawler might present a string for the HTTP USER_AGENT request header that looks very much like the value presented for MSIE 5.0 browsers. However, the web crawler adds badcrawler to the HTTP USER_AGENT string. For this example, you use a proxy override rule for the nodes proxying rule, based on the user agent parameter to match the regular expression .*badcrawler.*
When the WebAccelerator system finds the user agent with this regular expression in an HTTP request, it services the request from its cache, even if the matched proxying rule dictates that the WebAccelerator should send the request to the origin server.
1.
In the navigation pane, expand WebAccelerator and click Policies.
The Policies screen displays a list of existing acceleration policies.
4.
From the Matching Rules list, choose Acceleration Rules.
5.
Click Proxying.
6.
In the Proxy Override Rules area, select User Agent from the Add Parameter list, and click the Add button.
7.
In the Value(s) area, select Values matches from the list and select the Values matches check box.
8.
In the Value matches box, type the regular expression that matches the user agent value. For this example, type .*badcrawler.*
9.
Click the Save button.
For a new or modified acceleration policy to be in effect for your site, you must publish it. One way to do this is to click the Publish button.
Once you publish the acceleration policy, the WebAccelerator system attempts to service, from its cache, all requests that it receives with a HTTP USER_AGENT value that matches .*badcrawler.*, regardless of any proxy rules that the request matches.
This section of the chapter provides information about how to configure an example proxying rule. For this site, you have three top-level nodes on the Policy Tree as follows:
Home
This branch node specifies the rules related to the home page.
Applications
This branch node specifies the rules related to the applications for the site, with the following leaf nodes:
Default
This leaf node specifies the rules related to non-search related applications.
Search
This leaf node specifies the rules related to your sites search application.
Images
This branch node specifies the rules related to graphics images.
For this example, you use a segment parameter to contain identifying information for your shopping cart application. Requests for your applications are all in the following form:
If the session tracking string does not appear in the segment parameter at the end of the URI, you want the WebAccelerator system to send the request to the origin web servers for special handling. Create a proxying rule for your Applications node with just one parameter based on the path segment data type. This rule should identify the subject as being:
Note: See Path segment, for information about path segments and their ordinals.
1.
In the navigation pane, expand WebAccelerator and click Policies.
The Policies screen displays a list of existing acceleration policies.
3.
4.
From the Matching Rules list, choose Acceleration Rules.
5.
Click Proxying.
6.
Click the Configure and use Proxy Rules for this node option.
7.
In the Proxy Rules area, select Path Segment from the Add Parameter list, and click the Add button.
8.
In the Alias box, type a meaningful name for the parameter.
9.
In the Segment Ordinal box, type 1, and from the list, select Numbering Right-to-Left in the Full Path.
10.
In the Parameter Ordinal box, type 1.
12.
Click the Save button.
For a new or modified acceleration policy to be in effect for your site, you must publish it. One way to do this is to click the Publish button.
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