[Version 5.0.2 and later]plugin-cfg.xml file

The plugin-cfg.xml file includes the following elements and attributes. Unless indicated otherwise, each element and attribute can only be specified once within the plugin-cfg.xml file.

Config (required)

This element starts the WebSphere HTTP plug-in configuration file. It can include one or more of the following elements and attributes.

IgnoreDNSFailures
Specifies whether the plug-in ignores DNS failures within a configuration when starting. When set to true, the plug-in ignores DNS failures within a configuration and starts successfully if at least one server in each ServerCluster is able to resolve the host name. Any server for which the host name can not be resolved is marked unavailable for the life of the configuration. No attempts to resolve the host name are made later on during the routing of requests. If a DNS failure occurs, a log message is written to the plug-in log file and the plug-in initialization continues rather than causing the Web server not to start. The default value is false, meaning DNS failures cause the Web server not to start.
RefreshInterval
The time interval (in seconds) at which the plug-in should check the configuration file to see if updates or changes have occurred. The plug-in checks the file for any modifications that have occurred since the last time the plug-in configuration was loaded.

In a development environment in which changes are frequent, a lower setting than the default setting of 60 is preferable. In production, a higher value than the default is preferable because updates to the configuration will not occur so often. If the plug-in reload fails for some reason, a message is written to the plug-in log file and the previous configuration is used until the plug-in configuration file successfully reloads. If you are not seeing the changes you made to your plug-in configuration, check the plug-in log file for indications of the problem.

ASDisableNagle
Specifies whether the user wants to disable nagle algorithm for the connection between the plug-in and the application server. By default, nagle algorithm is enabled.

The value can be true or false.

IISDisableNagle
Specifies whether the user wants to disable nagle algorithm on Microsoft Internet Informations Services (IIS). By default, nagle algorithm is enabled.

The value can be true or false.

ResponseChunkSize
The plug-in reads the response body in 64k chunks until all of the response data is read. This approach causes a performance problem for requests whose response body contains large amounts of data.

The ResponseChunkSize attribute allows the users to specify the maximum chunk size to use when reading the response body. For example, <Config ResponseChunkSize="N">, where N equals the chunk size in kilobytes.

If the content length of the response body is unknown, a buffer size of N kilobytes is allocated and the body is read in N kilobyte size chunks, until the entire body is read. If the content length is known, then a buffer size of either content length or N (whichever is less) is used to read the response body.

The default chunk size is 64k.

Log
The log describes the location and level of log messages that are written by the plug-in. If a log is not specified within the configuration file, then, in some cases, log messages are written to the Web server error log.

For example, you might specify the following:

<Log LogLevel="Error" Name="/log_directory/filename"/>
Name (exactly one attribute for each Log)
The fully qualified path to the log file to which the plug-in will write error messages.

Note: The time the information was written to the log file and the process ID will be appended to the file name specified on this element.

LogLevel (zero or one attribute for each Log)
The level of detail of the log messages that the plug-in should write to the log. You can specify one of the following values for this attribute:
  • Trace. All of the steps in the request process are logged in detail.
  • Warn. All warning and error messages resulting from abnormal request processing are logged.
  • Error. Only error messages resulting from abnormal request processing are logged.

If a LogLevel is not specified for the Log element, the default value Error is used.

Be careful when setting the level to Trace. A lot of messages are logged at this level which can cause the file system to fill up very quickly. A Trace setting should never be used in a normally functioning environment as it adversely affects performance.

Property Name="ESIInvalidationMonitor" Value="true/false"
Used to indicate whether or not the ESI processor should receive invalidations from the Application Server.

Value can be set to true or false. By default, this property is set to false). This property must be set to false for WebSphere Application Server for z/OS.

ServerCluster (one or more elements for each Config)
A group of servers that are generally configured to service the same types of requests.

In the simplest case, the cluster contains only one server definition. In the case in which more than one server is defined, the plug-in will load balance across the defined servers using either a Round Robin or a Random algorithm. The default is Round Robin.

Following is an example of a ServerCluster element

<ServerCluster CloneSeparatorChange="false"
        LoadBalance="Round Robin" Name="Cluster1"
        PostSizeLimit="10000000" RemoveSpecialHeaders="true" 
        RetryInterval="60">
<Server
CloneID="BA36BEC1EB243D8B000000E4000000030926301B"
            ConnectTimeout="0" ExtendedHandshake="false"
            LoadBalanceWeight="2" MaxConnections="0"
            Name="SY1_ClusterMember1" WaitForContinue="false">
<Transport Hostname="BOSSXXXX.PLEX1.L2.IBM.COM" Port="9084" Protocol="http"/>
<Transport Hostname="BOSSXXXX.PLEX1.L2.IBM.COM" Port="0" Protocol="https">
<Property Name="Keyring" value="/WebSphere/V5R0M0/DeploymentManager/etc/
            plugin-key.kdb"/>
<Property Name="Stashfile" value=""/WebSphere/V5R0M0/DeploymentManager/etc/
            plugin-key.sth"/>
<Property Name="certLabel" Value="selfsigned"/>
</Transport>
</Server>
<Server CloneID="BA36BED017FDF40E000000E4000000030926301B"
            ConnectTimeout="0" ExtendedHandshake="false"
            LoadBalanceWeight="2" MaxConnections="0"
            Name="SY1_ClusterMember2" WaitForContinue="false">
<Transport Hostname="BOSSXXXX.PLEX1.L2.IBM.COM" Port="9085" Protocol="http"/>
<Transport Hostname="BOSSXXXX.PLEX1.L2.IBM.COM" Port="0" Protocol="https">
<Property Name="Keyring" value="/WebSphere/V5R0M0/DeploymentManager/etc/
            plugin-key.kdb"/
<Property Name="Stashfile" value="/WebSphere/V5R0M0/DeploymentManager/etc/
            plugin-key.sth"/>
<Property Name="certLabel" Value="selfsigned"/>
</Transport>
</Server>
<PrimaryServers>
<Server Name="Server Name="SY1_ClusterMember1"/>
<Server Name="Server Name="SY1_ClusterMember2"/>
</PrimaryServers>
</ServerCluster>

Note: If you are using the WebSphere HTTP Plug-in for z/OS, the Property Name=keyring and the Property Name=stashfile elements included here will be ignored if they are included in the plugin-cfg.xml file for that plug-in. The WebSphere HTTP Plug-in for z/OS uses the SSL setup specified in the hosting HTTP Server's httpd.conf file and does not look for these elements in the plugin-cfg.xml file.

Name (exactly one attribute for each ServerCluster)
The logical or administrative name to be used for this group of servers.
LoadBalance (zero or one attribute for each ServerCluster)
The default load balancing type is Round Robin.

The Round Robin implementation has a random starting point. The first server will be picked randomly. Round Robin will be used to pick servers from that point forward. This implementation ensures that in multiple process based Web servers, all of the processes don't start up by sending the first request to the same Application Server.

RetryInterval (zero or one attribute for each ServerCluster)
An integer specifying the length of time that should elapse from the time that a server is marked down to the time that the plug-in will retry a connection. The default is 60 seconds.
RemoveSpecialHeaders (zero or one attribute for each ServerCluster)
The plug-in adds special headers to the request before it is forwarded to the application server. These headers store information about the request that will need to be used by the application. By default the plug-in will remove these headers from incoming requests before adding the headers it is supposed to add.

The value can be true or false. Setting the attribute to false introduces a potential security exposure by not removing headers from incoming requests.

CloneSeparatorChange (zero or one attribute for each ServerCluster)
Some pervasive devices cannot handle the colon character (:) used to separate clone IDs in conjunction with session affinity. This attribute for the server group tells the plug-in to expect the plus character (+) as the clone separator. You must change application server configurations so that an application server separates clone IDs with the plus character as well.

The value can be true or false.

PostSizeLimit (zero or one attribute for each ServerCluster)
The maximum number of bytes of request content allowed in order for the plug-in to attempt to send the request to an application server. If a request is received that is greater than this size, the plug-in fails the request. The default value is -1 bytes, which indicates that there is no limit for the post size.
Server (one or more elements for each ServerCluster)
A WebSphere Application Server instance that is configured to handle requests routed to it given the routing rules of the plug-in configuration. The Server should correspond to an application server running on either the local machine or a remote machine.
Name (exactly one attribute for each Server)
The administrative or logical name for the server.
CloneID (zero or one attribute for each Server)
If this unique ID is present in the HTTP cookie header of a request (or the URL if using URL rewriting), the plug-in routes the request to this particular server, provided all other routing rules are met. If a CloneID is not specified in the Server, then session affinity is not enabled for this server.

This attribute is used in conjunction with session affinity. When this attribute is set, the plug-in checks the incoming cookie header or URL for JSESSIONID. If JSESSIONID is found then the plug-in looks for one or more clone IDs. If clone IDs are found, and a match is made to the value specified for this attribute, then the request is sent to this server rather than load balanced across the cluster.

If you are not using session affinity then it is best to remove these clone IDs from the configuration because there is added request processing in the plug-in when these are set. If clone IDs are not in the plug-in then it is assumed that session affinity is not on and the request is load balanced across the cluster.

WaitForContinue (zero or one attribute for each Server)
Specifies whether to use the HTTP 1.1 100 Continue support before sending the request content to the application server. Possible attribute values are true or false. The default value is false; the plug-in does not wait for the 100 Continue response from the application server before sending the request content because it is a performance hit.

This property will be ignored for POST requests in order to prevent a failure from occurring if the Application server closes a connection because of a keep alive time-out.

Enable this function (set to true) when configuring the plug-in to work with certain types of proxy firewalls.

LoadBalanceWeight (zero or one attribute for each Server)
The weight associated with this server when the plug-in does weighted Round Robin load balancing. The algorithm for this attribute decrements all weights within the server cluster until all weights reach zero. Once a particular server's weight reaches zero, no more requests are routed to that server until all servers in the cluster have a weight of zero. After all servers reach zero, the weights for all servers in the cluster are reset and the algorithm starts over.
ConnectTimeout (zero or one attribute for each Server)
The ConnectTimeout attribute of a Server element enables the plug-in to perform non-blocking connections with the application server. Non-blocking connections are beneficial when the plug-in is unable to contact the destination to determine if the port is available or unavailable.

If no ConnectTimeout value is specified, the plug-in performs a blocking connect in which the plug-in sits until an operating system times out (as long as 2 minutes depending on the platform) and allows the plug-in to mark the server unavailable. A value of 0 causes the plug-in to perform a blocking connect. A value greater than 0 specifies the number of seconds you want the plug-in to wait for a successful connection. If a connection does not occur after that time interval, the plug-in marks the server unavailable and fails over to one of the other servers defined in the cluster.

ExtendedHandshake (zero or one attribute for each Server)
The ExtendedHandshake attribute is used when a proxy firewall is between the plug-in and the application server. In such a case, the plug-in is not failing over, as expected.

The plug-in marks a server as down when the connect() fails. However, when a proxy firewall is in between the plug-in and the application server, the connect() will succeed, even though the back end application server is down. This causes the plug-in to not failover correctly to other application servers.

The plug-in performs some handshaking with the application server to ensure that it is started before sending the request. This enables the plug-in to failover in the event the application server is down.

The value can be true or false.

Transport (one or more elements for each Server)
The transport for reading and writing requests to a particular WebSphere application server instance. The transport provides the information needed to determine the location of the application server to which the request will be sent. If the Server has multiple transports defined to use the same protocol, the first one will be used.

It is possible to configure the Server to have one non-secure transport and one that uses SSL. In this configuration, a match of the incoming request protocol will be performed to determine the appropriate transport to use to send the request to the application server.

Hostname (exactly one attribute for each Transport)
The host name or IP address of the machine on which the WebSphere application server instance is running.
Port (exactly one attribute for each Transport)
The port on which the WebSphere application server instance is listening.
Protocol (exactly one attribute for each Transport)
The protocol to use when communicating over this transport -- either HTTP or HTTPS.
Property (zero, one, or more elements for each Transport)
When the Protocol of the Transport is set to HTTPS, use this element to supply the various initialization parameters, such as password, keyring and stashfile. for example, the portion of the plugin_cfg.xml file containing these elements might look like the following:
<Transport Hostname="192.168.1.2" Port="9443" Protocol="HTTPS">
<Property Name="keyring" value="c:/WebSphere/AppServer/keys/keyring.kdb"/>
<Property Name="stashfile" value="c:/WebSphere/AppServer/keys/keyring.sth"/>
<Property Name="password" value="WebAS"/>

Note: The default password for viewing the plugin-key.kdb file using iKeyMan is WebAS.

Name (exactly one attribute for each Property)
The name of the Property being defined. Supported names recognized by the transport are keyring, stashfile, and password.

Note: password is the only name that can be specified for the WebSphere HTTP Plug-in for z/OS. keyring, and stashfile, if specified, will be ignored.

Value (exactly one attribute for each Property)
The value of the Property being defined.
ServerIOTimeout
The ServerIOTimeout attribute of a server element enables the plug-in to set a time out value, in seconds, for sending requests to and reading responses from the application server. If a value is not set for the ServerIOTimeout attribute, the plug-in, by default, uses blocked I/O to write request to and read response from the application server until the TCP connection times out. For example, if you specify:
<Server Name="server1" ServerIOTimeout=300>

In this case, if an application server stops responding to requests, the plug-in waits 300 seconds (50 minutes) before timing out the TCP connection. Setting the ServerIOTimeout attribute to a reasonable value enables the plug-in to time out the connection sooner, and transfer requests to another application server when possible.

When selecting a value for this attribute, remember that sometimes it might take a couple of minutes for an application server to process a request. Setting the value of the ServerIOTimeout attribute too low could cause the plug-in to send a false server error response to the client.

ClusterAddress (zero or one element for each server cluster)
A cluster address is like a Server element in that you can specify the same attributes and elements as for a Server element. The difference is that you can only define one of them within a server cluster. Use a cluster address when you do not want the plug-in to perform any type of load balancing because you already have some type of load balancer in between the plug-in and the application server.

Note: If you include a ClusterAddress tag, you must include the Name attribute on that tag. The plug-in uses the Name attribute to associate the cluster address with the correct host and port. If you do not specify the Name attribute, the plug-in assigns the cluster address the name that is specified for the server that is using the same host and port.

<ClusterAddress Name="MyClusterAddr">
<Transport Hostname="192.168.1.2" Port="9080" Protocol="HTTP"/>
<Transport Hostname="192.168.1.2" Port="9443" Protocol="HTTPS">
</ClusterAddress>

If a request comes in that does not have affinity established, the plug-in routes it to the cluster address, if defined. If affinity has been established, then the plug-in routes the request directly to the clone, bypassing the cluster address entirely. If no cluster address is defined for the server cluster, then the plug-in load balances across the servers in the primary servers list.

PrimaryServers (zero or one element for each server cluster)
Specifies a list of servers to which the plug-in routes requests for this cluster. If a list of primary servers is not specified, the plug-in routes requests to servers defined for the server cluster.
BackupServers (zero or one element for each server cluster)
Specifies a list of servers to which requests should be sent to if all servers specified in the primary servers list are unavailable. The plug-in does not load balance across the backup servers, but traverses the list in order until no servers are left in the list or until a request is successfully sent and a response received from an application server.
VirtualHostGroup
A group of virtual host names that will be specified in the HTTP Host header. Enables you to group virtual host definitions together that are configured to handle similar types of requests.

Following is an example of a VirtualHost Group element and associated elements and attributes

<VirtualHostGroup Name="Hosts">
<VirtualHost Name="www.x.com"/>
<VirtualHost Name="www.x.com:443"/>
<VirtualHost Name="*:8080"/>
<VirtualHost Name="www.x.com:*"/>
<VirtualHost Name="*:*"/>
</VirtualHostGroup>
Name (exactly one attribute for each VirtualHostGroup)
The logical or administrative name to be used for this group of virtual hosts.
VirtualHost (one or more elements for each VirtualHostGroup)
The name used for a virtual or real machine used to determine if incoming requests should be handled by WebSphere Application Server or not. Use this element to specify host names that will be in the HTTP Host header which should be seen for requests that need to be handled by the application server. You can specify specific host names and ports that incoming requests will have or specify an * for either the host name, port, or both.
Name (exactly one attribute for each VirtualHost)
The actual name that should be specified in the HTTP Host header in order to match successfully with this VirtualHost.

The value is a host name or IP address and port combination, separated by a colon.

You can configure the plug-in to route requests to the application server based on the incoming HTTP Host header and port for the request. The Name attribute specifies what those combinations are.

You can use a wildcard for this attribute. The only acceptable solutions are either an * for the host name, a * for the port, or a * for both. A * for both means that any request will match this rule. If no port is specified in the definition the default HTTP port of 80 is assumed.

UriGroup
A group of URIs that will be specified on the HTTP request line. The same application server must be able to handle the URIs. The route will compare the incoming URI with the URIs in the group to determine if the application server will handle the request.

Following is an example of a UriGroup element and associated elements and attributes:

<UriGroup Name="Uris">
<Uri Name="/servlet/snoop"/>
<Uri Name="/webapp/*"/>
<Uri Name="*.jsp"/>
</UriGroup>
Name (exactly one attribute for each UriGroup)
The logical or administrative name for this group of URIs.
Uri (one or more elements for each UriGroup)
The virtual path to the resource that will be serviced by WebSphere Application Server. Each URI specifies the incoming URLs that need to be handled by the application server. You can use a wildcard in these definitions.
Name (exactly one attribute for each Uri)
The actual string that should be specified in the HTTP request line in order to match successfully with this URI. You can use a wildcard within the URI definition. You can specify rules such as *.jsp or /servlet/* to be handled by WebSphere Application Server. When you assemble your application, if you specify File Serving Enabled then only a wildcard URI is generated for the Web application, regardless of any explicit servlet mappings. If you specify Serve servlets by classname then a URI having <Uri Name="Web_application_URI/servlet/*"> is generated.
AffinityCookie (zero or one attribute for each Uri)
The name of the cookie the plug-in should use when trying to determine if the inbound request has session affinity. The default value is JSESSIONID. See the description of the CloneID attribute for additional session affinity information.
Route
A request routing rule by which the plug-in will determine if an incoming request should be handled by a WebSphere application server.

The route definition is the central element of the plug-in configuration.It specifies how the plug-in will handle requests based on certain characteristics of the request. The route definition contains the other main elements: a required ServerCluster, and either a VirtualHostGroup, UriGroup, or both.

Using the information that is defined in the VirtualHostGroup and the UriGroup for the route, the plug-in determines if the incoming request to the Web server should be sent on to the ServerCluster defined in this route.

Following is an example of this element:

<Route VirtualHostGroup="Hosts" UriGroup="Uris" ServerCluster="servers/>
VirtualHostGroup (zero or one attribute for each Route)
The group of virtual hosts that should be used in route determination. The incoming host header and server port are matched to determine if this request should be handled by the application server.

It is possible to omit this from the route definition. If it is not present then every request will match during the virtual host match portion of route determination.

UriGroup (zero or one attribute for each Route)
The group of URIs to use for determining the route. The incoming URI for the request is matched to the defined URIs in this group to determine if this request should be handled by the application server.

It is possible to omit this from the route definition. If it is not present than every request will match during the URI match portion of route determination.

ServerCluster (exactly one attribute for each Route)
The cluster to which to send request that successfully match the route.

The cluster that should be used to handle this request. If both the URI and the virtual host matching is successful for this route then the request is sent to one of the servers defined within this cluster.


Related tasks
Manually editing the plug-in configuration
Configuring Web server plug-ins
Installing a distributed platform Web server plug-in
Installing the WebSphere HTTP Plug-in for z/OS



Searchable topic ID:   rrun_plugin
Last updated: Jun 21, 2007 9:56:50 PM CDT    WebSphere Application Server for z/OS, Version 5.0.2
http://publib.boulder.ibm.com/infocenter/wasinfo/index.jsp?topic=/com.ibm.websphere.zseries.doc/info/zseries/ae/rwsv_plugin.html

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