Intelligent Management: HTTP operands

Use the HTTP operands in the subexpression utility builder, an optional tool that helps you build complex rule conditions from subexpressions by using AND, OR, NOT and parenthetical grouping.

Rules
HTTP request operands
HTTP response operands
Xpath expression
Operators

Rules

Each work class contains an optional ordered list of rules that are evaluated for a particular request to determine the policy for that request. Each rule consists of a Boolean expression and a policy value. If the expression evaluates to true for a particular request, the policy associated with that rule is used.

The syntax and semantics of a Boolean expression for a rule are similar to the WHERE clause of a Structured Query Language (SQL) expression. More precisely, the syntax of an expression is defined by the Java™ Message Service (JMS) 1.1 specification. For more information, read about rule-based request classification.

In the JMS specification, identifiers refer to various attributes that can be associated with a request, for example, a specific query parameter, cookie, or HTTP header. A JMS identifier can be thought of as a request variable, or operand. These operands can be specific to a protocol. For example, the SOAP service name is an operand that is valid only in a SOAP work class.

Because the SOAP is over HTTP, the HTTP operands are also valid in a SOAP request. JMS specification uses literals to specify a specific value to use in a comparison to a request variable. For example, in the expression:

clienthost LIKE '%.ibm.com'

'%.ibm.com' is a literal that is used to compare to the client host name for a request. This expression is true for all requests that originate from a computer in the ibm.com® domain. Enclose string literals by single quotes. Do not enclose numeric literals in single quotes. Parentheses together with the AND, OR, and NOT operators can also be used to form compound Boolean expressions. See the JMS 1.1 specification for a detailed description.

HTTP request operands

Table 1. HTTP request operands
Operand	Syntax	Description
Client host	`clienthost`	The fully-qualified client host name. This is the value of the internet protocol (IP) command host name. This operand does not support numeric operators such as `>, >=, <, <=`.
Client IPV4	`clientipv4`	The IP address of the client using the Internet Protocol version 4 (IPv4) dotted quad address type `n.n.n.n`.
Client IPV6	`clientipv6`	The Internet Protocol version 6 (IPv6) 128-bit address type of `x:x:x:x:x:x:x:x` following Request for Comments 1924 (RFC 1924) of the client computer.
Cookie name	`cookie$<name>`	A cookie name. For example, the expression `cookie$My_Cookie_Name='My_Cookie_Value'` tests a request to see if it contains a cookie named `My_Cookie_Name` with a value of `My_Cookie_Value`. To test for the presence or absence of a particular cookie, use one of the following expressions: `cookie$MyCookieName IS NOT NULL cookie$MyCookieName IS NULL`
Header name	`header$<name>`	A header name and value. For example, the expression `header$Host='localhost'` tests a request to see if it contains an HTTP host header with a value of `localhost`. To test for presence or absence of the host header, use one of the following expressions: `header$Host IS NOT NULL header$Host IS NULL`
HTTP method	`HTTPMethod`	The HTTP method for the request. Possible values are POST, GET, PUT, and DELETE.
MIME type	`MIMEType`	The MIME type of the request.
Percentage	`percentage$<val>`	The percentage operand evaluates to `true`, a fixed percentage of the time. For example, `percentage$50` evaluates to `true` on average 50% of the time.
Port	`port`	The listening port on which the request was received.
Protocol	`protocol`	The communications protocol that transmits the request. Currently supported protocols are HTTP, HTTPS, SOAP, and SOAPS.
Query parameter	`queryparm$<name>`	A header name and value. For example, the expression `queryparm$timezone='EST'` tests a request to see if the request contains an HTTP query parameter named `timezone` with a value of `EST`. To test for presence or absence of a query parameter, use one of the following forms: `queryparm$timezone IS NOT NULL queryparm$timezone IS NULL`
Rampup	`rampup$<startTime>` $<completionTime>	The rampup operand evaluates to `true` a variable percentage of the time. It always evaluates to `false` before `<startTime>` and to `true` after `<completionTime>`. As time progresses from `<startTime>` to `<completionTime>`, it evaluates to `true`, a linearly increasing percentage. The format of `<startTime>` and `<completionTime>` is `day/month/year::hour:min:sec`. where day is the day of the month, month is one of the twelve months: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec, year is the 4 digit year, hour is the 2 digit hour of the 24 hour clock, and min and sec are 2 digit values for minute and second, respectively. For example, `rampup$01/Jan/2007::08:00:00$01/Jan/2007::17:00:00` begins to occasionally evaluate to `true` at 8 AM on Jan 1, 2007 and always evaluates to `true` by ramp up completion time at 5 PM of the same day. Avoid trouble: Omissions and wild cards are not supported for the rampup operand.
Scheme of URI	`request.uri.scheme`	The scheme of the URI.
Server host	`serverhost`	The fully-qualified host name of the server. This operand does not support numeric operators such as `>, >=, <, <=`.
Server IPV4	`serveripv4`	The IP address of the server computer using the IPv4 dotted quad address type `n.n.n.n`.
Server IPV6	`serveripv6`	The IPv6 128-bit address type of `x:x:x:x:x:x:x:x` following RFC 1924 of the server computer.
Service	`service`	The name of a Web service.
Time	`time`	Used to define the date and time of day that a given request must be honored. Two optional fields are StartTime and EndTime. If a request is received outside of that defined window, the request will not be processed. The Start Time and End Time fields each have the following format: `dayOfWeek/dayOfMonth/month/year::hour:minute:second`. For example, Thursday, the 11th of April, year 2007 at 1:03:45 PM is specified as: Thu/11/Apr/2007::13:03:45 The dayofWeek values are Sun, Mon, Tue, Wed, Thu, Fri, Sat, and the dayOfMonth values range from 1-31. The month value is a non-numeric value that represents the twelve months: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec. The year value is comprised of the year's four digits. For example, 2007. The hour value is the hour of day in the 24-hour clock. For example, 8am is represented as ::8. The minute and second are integers ranging from 0-59. Avoid trouble: Omissions and wild cards are not supported for the time operand. The forward slash (/) is used to separate date parameters, the double colon (::) is used to separate the date parameters, and the colon (:) is used to separate the time of day parameters. Note that it is the Boolean result of the entire rule in which the time operand is used that determines the routing action taken.
URI	`uri`	Uniform Resource Identifier
Virtual Host	`virtualhost`	Virtual host target of the request, used for configuring Web applications to a particular host name.
Virtual Port	`virtualport`	Virtual port target of the request, used for configuring Web applications to a particular port.
Virtual Portal	`virtualportal`	Virtual portals are created within WebSphere® Portal Server, and Intelligent Management supports this operand for better integration with WebSphere Portal Server. The virtual portal is the request URL minus the context root for the WebSphere Portal application's Web module. If a given request matches the virtual portal defined, then the routing action defined for that rule is taken.

HTTP response operands

When you are using a custom log file, you can use the following operands in addition to the operands in Table 1:

Table 2. HTTP response operands
Operand	Syntax	Description
Response code	`response.code`	Filters by HTTP response codes, such as 404, 503, and so on.
Response time	`response.time`	The number of milliseconds between when the request in the ODR is received, and until the response from the ODR is sent.
Response write error	`response.write.error`	Logs errors that can occur when writing a response to a client.
Service time	`service.time`	The number of milliseconds between when the request is sent to the application server, and when a response is received from the application server.
Target server	`targetserver`	Shows the server where the request was sent, in a WebSphere Application Server format. For example, `mycell/mynode/myserver`.

Xpath expression

The syntax for the Xpath expression is xpathexpr and is supported by HTTP.

The XPath string expression has a required field that contains the XPath expression and an optional field for defining local namespaces. If all the namespaces contained in the XPath expression are standard, the second field can be optional. If there are multiple local namespaces, separate each with a comma (,).

The following example shows an xpathexpr with one local namespace definition:

xpathexpr$/http:Envelope/soap:Body/m:getTimeZone/n:clientId$n\\=http://test2.classify.ws.ibm.com 
  = \\'1000\\' or operation IS NOT NULL

In the previous expression , the XPath expression is /http:Envelope/soap:Body/n:getTimeZone/n:clientId. It contains the local namespace of n. So, the second field of the xpathexpr is defined as n\\=http://test.classify.ws.ibm.com. The dollar sign ($) is used to denote the start of a field definition. The double backslashes are the escape sequence in this example. The first equals sign (=) is escaped because it is part of the local namespace definition, whereas the second equals sign (=) is the operator in the classification expression and must not be escaped.

The following example shows an xpathexpr with two local namespaces:

xpathexpr$/http:Envelope/http:Body/m:getTimeZone/n:clientId$m\\=http://test.classify.ws.ibm.com,n\\
 =http://test2.classify.ws.ibm.com = \\'1000\\' or operation IS NOT NULL

The following table shows the standard namespaces for the xpathexpr expression:

Table 3. Namespaces
Namespace	URL
soap	http://schemas.xmlsoap.org/soap/envelope/
soap-env	http://schemas.xmlsoap.org/soap/envelope/
soapenc	http://schemas.xmlsoap.org/soap/encoding/
soapbind	http://schemas.xmlsoap.org/wsdl/soap/
xsd	https://www.w3.org/2001/XMLSchema
xsi	https://www.w3.org/2001/XMLSchema-instance
xsi	http://ws-i.org/schemas/conformanceClaim/
wsdl	http://schemas.xmlsoap.org/wsdl/

Operators

Intelligent Management supports the operators in the following table in the rules expressions. These operators are also referred to as predicates in SQL terminology because they appear inside of a WHERE or HAVING clause. Operators are case insensitive.

Equals Ignore Case (EQUALSIGNORECASE): Identical to 'String = String', except that the case of the strings is ignored. So, 'ABC' EQUALSIGNORECASE 'abc' would evaluate to true. ('ABC' = 'abc') evaluates to false.
Not Equals ( <> ): The not equal operator expresses that the operand value is not equal to the value you enter.
In (IN): This operator expresses an operand with multiple values in a single expression. For example, if, for an operand called port, you want to express that the port value can be any or all of the values such as 9080, 9090, 9091, the expression fragment is port IN (9080,9090,9091). How the values inside the brackets are expressed depends on the data type of port. If port is an integer, the correct syntax is the values without quote marks. If port is a string, the correct syntax is port IN (‘9080’,‘9090’,‘9091’).
Like (LIKE): This operator expresses pattern matching for string operand values. The value must contain the wildcard character percent sign (%) in the position where the pattern matching starts. For example, the expression, host LIKE %blanca, matches the word blanca, or any other word that ends in blanca, while the expression host LIKE blanca% matches the word blanca or any other word that starts with blanca, and the expression, host LIKE %blanca% matches the word blanca or any word that has blanca embedded in it.
Like Ignore Case (LIKEIGNORECASE): Identical to 'string like string' except that the case of the strings is ignored.
Is Not Null (IS NOT NULL): This operator expresses that a validation of the query shows that the requested parameter exists.
Concatenate (+): This operator expresses two character strings joined together: 'abc' + 'def' = 'abcdef'.
Like In (LIKEIN): This operator expresses string likein (string1, string2, string3, etc.) evaluates to true if the string before likein matches one or more of the strings (stringN)
Is Null (IS NULL): This operator expresses that a validation of the query shows that the requested parameter does not exist.
Equals ( = ): The equality operator expresses a case-sensitive match.