Configuring and Managing WebLogic Server
In addition to its ability to host dynamic Java-based distributed applications, WebLogic Server is also a fully functional Web server that can handle high volume Web sites, serving static files such as HTML files and image files as well as servlets and JavaServer Pages (JSP). WebLogic Server supports the HTTP 1.1 standard.
This attribute sets the timeout (in seconds) that WebLogic Server waits between receiving chunks of data in an HTTP POST data. Used to prevent denial-of-service attacks that attempt to overload the server with POST data.
Beginning with the WebLogic Sever 8.1 release inclusion of the contextPath in the virtualPath to the context.getRealPath() will not be allowed as it breaks the case when the subdirectories have the same name as contextPath. In order to support applications which might have been developed according to the old behaviour BEA is providing a compatibility switch. This switch will be deprecated in future releases.
Maximum HTTP message size allowable in a message header. This attribute attempts to prevent a denial of service attack whereby a caller attempts to force the server to allocate more memory than is available, thereby keeping the server from responding quickly to other requests. This setting only applies to connections that are initiated using one of the default ports (ServerMBean setListenPort and setAdministrationPort or SSLMBean setListenPort). Connections on additional ports are tuned via the NetworkChannelMBean.
Maximum number of seconds spent waiting for a complete HTTP message to be received. This attribute helps guard against denial of service attacks in which a caller indicates that they will be sending a message of a certain size which they never finish sending. This setting only applies to connections that are initiated using one of the default ports (ServerMBean setListenPort and setAdministrationPort or SSLMBean setListenPort). Connections on additional ports are tuned via the NetworkChannelMBean.
You can specify the port that each WebLogic Server listens on for HTTP requests. Although you can specify any valid port number, if you specify port
80, you can omit the port number from the HTTP request used to access resources over HTTP. For example, if you define port
80 as the listen port, you can use the form
http://hostname/myfile.html instead of
On UNIX systems, binding a process to a port less than 1025 must be done from the account of a privileged user, usually root. Consequently, if you want WebLogic Server to listen on port 80, you must start WebLogic Server as a privileged user; yet it is generally considered undesirable from a security standpoint to allow long-running processes like WebLogic Server to run with more privileges than necessary. WebLogic needs root privileges only until the port is bound.
By setting the weblogic.system.enableSetUID property (and, if desired, the weblogic.system.enableSetGID property) to true, you enable an internal process by which WebLogic Server switches its UNIX user ID (UID) after it binds to port 80. The companion properties, weblogic.system.nonPrivUser and weblogic.system.nonPrivGroup, identifies a non-privileged UNIX user account (and optionally a groupname) under which WebLogic will run after startup.
You may choose to switch to the UNIX account "nobody," which is the least privileged user on most UNIX systems. If desired, you may create a UNIX user account expressly for running WebLogic Server. Make sure that files needed by WebLogic Server, such as log files and the WebLogic classes, are accessible by the non-privileged user. Once ownership of the WebLogic process has switched to the non-privileged user, WebLogic will have the same read, write, and execute permissions as the non-privileged user.
You define a separate listen port for regular and secure (using SSL) requests. You define the regular listen port on the Servers node in the Administration Console, under the Configuration/General tab, and you define the SSL listen port under the Connections/SSL tab.
HTTP and Web Applications are deployed according to the Servlet 2.3 specification from Sun Microsystems, which describes the use of Web Applications as a standardized way of grouping together the components of a Web-based application. These components include JSP pages, HTTP servlets, and static resources such as HTML pages or image files. In addition, a Web Application can access external resources such as EJBs and JSP tag libraries. Each server can host any number of Web Applications. You normally use the name of the Web Application as part of the URI you use to request resources from the Web Application.
By default JSPs are compiled into the servers' temporary directory the location for which is (for a server: "myserver" and for a webapp: "mywebapp"): <domain_dir>\myserver\.wlnotdelete\appname_mywebapp_4344862
For more information, see Assembling and Configuring Web Applications.
Web Applications can be deployed in a cluster of WebLogic Servers. When a user requests a resource from a Web Application, the request is routed to one of the servers of the cluster that host the Web Application. If an application uses a session object, then sessions must be replicated across the nodes of the cluster. Several methods of replicating sessions are provided.
For more information, see Using WebLogic Server Clusters.
Every server instance and virtual host in your domain can declare a default Web Application. The default Web Application responds to any HTTP request that cannot be resolved to another deployed Web Application. In contrast to all other Web Applications, the default Web Application does not use the Web Application name as part of the URI. Any Web Application targeted to a server or virtual host can be declared as the default Web Application. (Targeting a Web Application is discussed later in this section. For more information about virtual hosts, see Configuring Virtual Hosting).
The examples domain that is shipped with Weblogic Server has a default Web Application already configured. The default Web Application in this domain is named
DefaultWebApp and is located in the
applications directory of the domain.
Using the virtual directory mapping feature, you can create one directory to serve static files such as images for multiple Web Applications. For example, you would create a mapping similar to the folowing:
Virtual hosting allows you to define host names that servers or clusters respond to. When you use virtual hosting you use DNS to specify one or more host names that map to the IP address of a WebLogic Server instance or cluster, and you specify which Web Applications are served by the virtual host. When used in a cluster, load balancing allows the most efficient use of your hardware, even if one of the DNS host names processes more requests than the others.
For example, you can specify that a Web Application called
books responds to requests for the virtual host name
www.books.com, and that these requests are targeted to WebLogic Servers A,B and C, while a Web Application called
cars responds to the virtual host name
www.autos.com and these requests are targeted to WebLogic Servers D and E. You can configure a variety of combinations of virtual host, WebLogic Servers, clusters and Web Applications, depending on your application and Web server requirements.
For each virtual host that you define you can also separately define HTTP parameters and HTTP access logs. The HTTP parameters and access logs set for a virtual host override those set for a server. You may specify any number of virtual hosts.
You can also designate a default Web Application for each virtual host. The default Web Application for a virtual host responds to all requests that cannot be resolved to other Web Applications deployed on the same server or cluster as the virtual host.
Unlike other Web Applications, a default Web Application does not use the Web Application name (also called the context path) as part of the URI used to access resources in the default Web Application.
For example, if you defined virtual host name
www.mystore.com and targeted it to a server on which you deployed a Web Application called
shopping, you would access a JSP called
cart.jsp from the
shopping Web Application with the following URI:
For more information, see How WebLogic Server Resolves HTTP Requests.
When using multiple Virtual HOsts with diferent default web applications, you can not use single sign-on, as each web application will overwrite the JSESSIONID cookies set by the previous web application. This will occur even if the CookieName, CookiePath, and CookieDomain are identical in each of the default web applications.
Virtual host resolution for a given HTTP request is performed base on the incoming HOST header. If the HOST header is incorrect or absent, the Web application resolves to the default virtual host (default Web server).
When WebLogic Server receives an HTTP request, it resolves the request by parsing the various parts of the URL and using that information to determine which Web Application and/or server should handle the request. The examples below demonstrate various combinations of requests for Web Applications, virtual hosts, servlets, JSPs, and static files and the resulting response.
Note: If you package your Web Application as part of an Enterprise Application, you can provide an alternate name for a Web Application that is used to resolve requests to the Web Application. For more information, see Deploying Web Applications as Part of an Enterprise Application.
There are additional considerations for servlet mappings. For more information, see Configuring Servlets.
For more information, see Configuring Servlets.
For more information, see Customizing HTTP Error Responses.
* For more information, see Configuring Welcome Pages.
WebLogic Server can keep a log of all HTTP transactions in a text file, in either common log format or extended log format. Common log format is the default, and follows a standard convention. Extended log format allows you to customize the information that is recorded. You can set the attributes that define the behavior of HTTP access logs for each server or for each virtual host that you define.
You can also choose to rotate the log file based on either the size of the file or after a specified amount of time has passed. When either one of these two criteria are met, the current access log file is closed and a new access log file is started. If you do not configure log rotation, the HTTP access log file grows indefinitely. You can configure the name of the access log file to include a time and date stamp that indicates when the file was rotated. If you do not configure a time stamp, each rotated file name inlcudes a numeric portion that is incremented upon each rotation. Separate HTTP Access logs are kept for each Web Server you have defined.
The default format for logged HTTP information is the common log format. This standard format follows the pattern:
WebLogic Server also supports extended log file format, version 1.0, as defined by the W3C. This is an emerging standard, and WebLogic Server follows the draft specification from W3C. The current definitive reference may be found from the W3C Technical Reports and Publications page
The extended log format allows you to specify the type and order of information recorded about each HTTP communication. To enable the extended log format, set the Format attribute on the HTTP tab in the Administration Console to
Extended. (See Creating Custom Field Identifiers).
You specify what information should be recorded in the log file with directives, included in the actual log file itself. A directive begins on a new line and starts with a # sign. If the log file does not exist, a new log file is created with default directives. However, if the log file already exists when the server starts, it must contain legal directives at the head of the file.
xxxx describes the data fields to be recorded. Field types are specified as either simple identifiers, or may take a prefix-identifier format, as defined in the W3C specification. Here is an example:
This identifier instructs the server to record the date and time of the transaction, the request method that the client used, and the URI of the request for each HTTP access. Each field is separated by white space, and each record is written to a new line, appended to the log file.
You can also create user-defined fields for inclusion in an HTTP access log file that uses the extended log format. To create a custom field you identify the field in the ELF log file using the
Fields directive and then you create a matching Java class that generates the desired output. You can create a separate Java class for each field, or the Java class can output multiple fields. A sample of the Java source for such a class is included in this document. See Java Class for Creating a Custom ELF Field.
For more information on the
Fields directive, see Creating the Fields Directive.
Fieldsdirective (for example
myCustomField). This class defines the information you want logged in your custom field. The Java class must implement the following interface:
HttpAccountingInfoobject to access HTTP request and response data that you can output in your custom field. Getter methods are provided to access this information. For a complete listing of these get methods, see Get Methods of the HttpAccountingInfo Object.
CLASSPATHstatement used to start WebLogic Server. You will probably need to modify the
CLASSPATHstatements in the scripts that you use to start WebLogic Server.
Note: When writing the Java class that defines your custom field, you should not execute any code that is likely to slow down the system (For instance, accessing a DBMS or executing significant I/O or networking calls.) Remember, an HTTP access log file entry is created for every HTTP request.
Note: If you want to output more than one field, delimit the fields with a tab character. For more information on delimiting fields and other ELF formatting issues, see Extended Log Format.
The following methods return various data regarding the HTTP request. These methods are similar to various methods of
A Denial-of-Service attack is a malicious attempt to overload a server with phony requests. One common type of attack is to send huge amounts of data in an HTTP
POST method. You can set three attributes in WebLogic Server that help prevent this type of attack. These attributes are set in the console, under Servers or virtual hosts. If you define these attributes for a virtual host, the values set for the virtual host override those set under Servers.
HTTP tunneling provides a way to simulate a stateful socket connection between WebLogic Server and a Java client when your only option is to use the HTTP protocol. It is generally used to tunnel through an HTTP port in a security firewall. HTTP is a stateless protocol, but WebLogic Server provides tunneling functionality to make the connection appear to be a regular T3Connection. However, you can expect some performance loss in comparison to a normal socket connection.
Under the HTTP protocol, a client may only make a request, and then accept a reply from a server. The server may not voluntarily communicate with the client, and the protocol is stateless, meaning that a continuous two-way connection is not possible.
WebLogic HTTP tunneling simulates a T3Connection via the HTTP protocol, overcoming these limitations. There are two attributes that you can configure in the Administration Console to tune a tunneled connection for performance. You access these attributes in the Servers section, under the Connections and Protocols tabs. It is advised that you leave them at their default settings unless you experience connection problems. These properties are used by the server to determine whether the client connection is still valid, or whether the client is still alive.
When an HTTP tunnel connection is set up, the client automatically sends a request to the server, so that the server may volunteer a response to the client. The client may also include instructions in a request, but this behavior happens regardless of whether the client application needs to communicate with the server. If the server does not respond (as part of the application code) to the client request within the number of
If the number of
On the client side, a special tag is appended to the
http protocol, so that WebLogic Server knows this is a tunneling connection, instead of a regular HTTP request. Your application code does not need to do any extra work to make this happen.
The client must specify the port in the URL, even if the port is 80. You can set up your WebLogic Server to listen for HTTP requests on any port, although the most common choice is port 80 since requests to port 80 are customarily allowed through a firewall.
When running WebLogic Server on Windows NT/2000 you can specify that WebLogic Server use the native operating system call TransmitFile instead of using Java methods to serve static files such as HTML files, text files, and image files. Using native I/O can provide performance improvements when serving larger static files.
To use native I/O, add two parameters to the web.xml deployment descriptor of a Web Application containing the files to be served using native I/O. The first parameter, weblogic.http.nativeIOEnabled should be set to TRUE to enable native I/O file serving. The second parameter, weblogic.http.minimumNativeFileSize sets the minimum file size for using native I/O. If the file being served is larger than this value, native I/O is used. If you do not specify this parameter, a value of 4K is used.
Generally, native I/O provides greater performance gains when serving larger files; however, as the load on the machine running WebLogic Server increases, these gains diminish. You may need to experiment to find the correct value for weblogic.http.minimumNativeFileSize.
The following example shows the complete entries that should be added to the web.xml deployment descriptor. These entries must be placed in the web.xml file after the <distributable> element and before <servlet> element.