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Web Server Plug-in

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Web Server Plug-in

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    1. Web Server Plug-in Communication between Web server and Application server Web server plug-in Web server or HTTP server plug-in is the component that enables communication between the HTTP server and application server. It has a new transport protocol in WebSphere V4.0. It now uses the industry-standard HTTP transport protocol for non-secure transports and HTTPS for secure transports. The plug-in can be configured via the administrative console. The plug-in can also be configured in three additional ways: automatically during the WebSphere installation process, set up as a custom service each time the application server is started, or using the GenPluginCfg command.Web server plug-in Web server or HTTP server plug-in is the component that enables communication between the HTTP server and application server. It has a new transport protocol in WebSphere V4.0. It now uses the industry-standard HTTP transport protocol for non-secure transports and HTTPS for secure transports. The plug-in can be configured via the administrative console. The plug-in can also be configured in three additional ways: automatically during the WebSphere installation process, set up as a custom service each time the application server is started, or using the GenPluginCfg command.

    2. Web server plug-in Web server or HTTP server plug-in is the component that enables communication between the HTTP server and application server. uses the industry-standard HTTP transport protocol for non-secure transports and HTTPS for secure transports.

    3. Plug-in Communication

    4. Plug-in Communication The WebSphere application server works with a HTTP server or a Web server, to handle requests for dynamic content such as servlets from Web applications. The HTTP server communicates with the WebSphere application server using the WebSphere HTTP plug-in. The HTTP plug-in uses an easy-to-read XML configuration file to determine whether a request should be handled by the Web server or the application server. the standard HTTP protocol to communicate with the application server. secure HTTPS protocol, if required. The HTTP plug-in is available for popular Web servers, including IBM HTTP Server, Apache, Microsoft IIS, and Netscape iPlanet.

    5. Sample Plug-in XML File LoadModule was_ap20_module /usr/WebSphere/AppServer/bin/mod_was_ap20_http.so WebSpherePluginConfig /usr/WebSphere/AppServer/config/plugin-cfg.xml Sample /usr/WebSphere/AppServer/config/plugin-cfg.xml file:- <?xml version="1.0"?> <Config> <Log LogLevel="Error" Name="/usr/WebSphere/AppServer/logs/native.log"/> <VirtualHostGroup Name="default_host"> <VirtualHost Name="*:443"/> <VirtualHost Name="*:80"/> <VirtualHost Name="*:xxxx"/> <VirtualHost Name="domainname"/> <VirtualHost Name="hostname1"/> <VirtualHost Name="hostname2"/> <VirtualHost Name="ipaddressofserver1"/> <VirtualHost Name="ipaddressofserver2"/> <VirtualHost Name="ipaddressofcluster"/> <VirtualHost Name="clustername"/> </VirtualHostGroup>

    6. Sample Plug-in XML File <UriGroup Name="xxxxxx/xxxxxx_URIs"> <Uri AffinityCookie="XXSESSIONID" Name="/xxxxxx/*.wss"/> <Uri AffinityCookie="xxSESSIONID" Name="/xxxxxx/*.jsp"/> <Uri AffinityCookie="xxSESSIONID" Name="/xxxxxx/*.jsv"/> <Uri AffinityCookie="xxSESSIONID" Name="/xxxxxx/*.jsw"/> <Uri AffinityCookie="xxSESSIONID" Name="/xxxxxx/yyyyy"/> </UriGroup> <Route ServerGroup="xxxxxxSG" UriGroup="xxxxxx/xxxxxx_URIs" VirtualHostGroup="default_host"/> <ServerGroup Name="xxxxxxSG"> <Server CloneID="number" Name="xxxxxxAS"> <Transport Hostname="hostname1" Port="90xx" Protocol="http"/> </Server> <Server CloneID="number" Name="xxxxxxAS"> <Transport Hostname="hostname2" Port="90xx/yy" Protocol="http"/> </Server> </ServerGroup> </Config>

    7. Plug-in Configuration The plug-in can be configured via the administrative console automatically during the WebSphere installation process by setting up as a custom service each time the application server is started by using the GenPluginCfg command.

    8. Log Files WebSphere Application Server provides a comprehensive range of logs to help you diagnose problems: Installation logs Administrative server logs Application server logs WebSphere activity logs Web server and Web server plug-in logs

    9. Installation Log files Installation logs can be found in the <WAS_HOME>/logs directory: wssetup.log (NT) install.log (UNIX) wasdb2.log (NT) The wssetup.log and install.log files are created during the install process. The install process consists of: Verifying prerequisites Copying files Updating the configuration files for both WebSphere Application Server and the Web server.

    10. Administrative Log Files Administrative server logs can be found in the <WAS_HOME>/logs directory by default- tracefile nanny.trace adminserver_stderr.log The tracefile describes the startup and shutdown of the administrative server and the application servers. It also shows interactions of different WebSphere Application Server components with the administrative server. Attempts to start the administrative server are logged in the nanny.trace file. A separate process called “nanny” launches the administrative server and attempts to relaunch it if it fails. The com.ibm.ejs.sm.util.process.Nanny.maxtries property in the admin.config file tells the nanny process how many times it should attempt to restart the administrative server. Administrative server startup errors are usually placed in adminserver_stderr.log file. If this file is not empty, it usually means an error condition occurred.

    11. Application Log Files Application server logs WebSphere Application Server creates standard output and standard error logs for each application server. They contain application server communication. The location and name of the standard output and standard error files are defined by the application server administrator.

    12. Activity Log Files Activity log captures events that show a history of WebSphere Application Server’s activities. The activity.log file is a binary file located in the <WAS_HOME>/logs directory and cannot be viewed with an ASCII editor. Use either the showlog command or the Log Analyzer (GUI) to view the file. Follow these instructions to view the activity file using showlog Change directory to <WAS_HOME>/bin. Run the showlog tool with no parameters, to display the usage instructions. To direct the activity log contents to standard output, use the invocation: showlog ../logs/activity.log To dump the activity.log to a text file that can be viewed using a text editor, use the invocation: showlog ../logs/activity.log > text_file_name Log Analyzer. To view the activity.log file with the Log Analyzer, use waslogbr from <WAS_HOME>/bin.

    13. Plug-in Log Files The plug-in log file is created by the WebSphere plug-in running in the Web server process. The default plug-in log file is <WAS_HOME>/logs/native.log. The plug-in log contains error and informational messages generated from the Web server plug-in. This information reflects Web server startup and server status change requests (start/stop/restart).

    14. Workload Management Network Dispatcher, which is part of WebSphere Edge Server, can also be used for workload management. Placed in front of Web servers, client requests come into the Network Dispatcher machine, which then forwards the requests to the HTTP servers using one of several routing algorithms. To the client, Network Dispatcher looks like a Web server. Network Dispatcher can be configured for high availability.

    15. Workload Management

    16. Workload Management Workload management with server groups, clones server groups and clones provide necessary support for workload management, failover, and scalability. When you modify a server group the change is propagated to all its clones. makes it easy to administer several servers as one logical server. keeps the servers identical so that requests can be routed to any of them with the same results.

    17. WebSphere Load Balancing

    18. Troubleshooting WebSphere installation problems Successful installation means that no errors occur during the install process and, more importantly, that the product runs correctly the first time you start it. In this section we look at problems where the Installation hangs Installation displays an error message or Installation finishes but components are missing.

    19. Troubleshooting Installation hangs Check <WAS_HOME>\logs\wssetup.log on Windows, or <WAS_HOME>/logs/install.log on UNIX. If wssetup.log does not display errors, look at the command session from which the installation was launched. In a Windows NT environment, this means executing setup.exe from a command window instead of double-clicking it from within Windows Explorer. When the installation hangs, look at the window: does it display an operating system error or Java exception ?

    20. Troubleshooting Installation hangs Check that the user ID, under which the installation is running, has the authority to read the installation files or to write to (or overwrite files in) the target installation directory. Installation can be unsuccessful if WebSphere Application Server and related processes have not been stopped before installation. Stop the related processes before installing WebSphere Application Server (all but for migration installs). Web servers and Web administrative servers should also be stopped.

    21. Troubleshooting Installation displays an error message If the installation fails with an error message, the message will be an indicative of the type of problem: Insufficient disk space. Check that the drive has enough available space. On UNIX, check that there is sufficient available space in the WebSphere Application Server file system as well as in the /tmp directory. Insufficient software prerequisite level. Check that the supporting software is at the right level. Visit the IBM WebSphere Application Server prerequisites site for the latest prerequisites.

    22. Troubleshooting If you plan to use a Web server or database at a level that exceeds the current version required by WebSphere Application Server, you need to disable the WebSphere Prerequisite Checker before installing WebSphere Application Server: Copy the prereq.properties file from the product CD to a temporary directory. Edit the file by changing the value of the prereq_checker parameter from 1 to 0. Pass the prereq.properties file to the installation program using the -prereqfile argument, for example on Windows 2000: setup.exe -prereqfile <tmp>/prereq.properties. File permission problems. Check that the user ID under which the installation is running has the authority to read the installation files or to write to (or overwrite files in) the target installation directory. Make sure that WebSphere Application Server and related processes are stopped before installation.

    23. Troubleshooting Installation finishes but components are missing If the installation is complete, but the product directories have not been created, there are files missing, or Windows services entries or Start menu icons have not been added: Check <WAS_HOME>\logs\wssetup.log on Windows, or <WAS_HOME>/logs/install.log on UNIX. Look for errors indicating that the installation program was unable to read from a file, write to a file, or overwrite a file (see the file permission problems).

    24. Troubleshooting Administrative server fails to start after installation After installing WebSphere Application Server for the first time, try starting the administrative server as the WebSphere administrative user (root on UNIX and wasadmin on Windows, for example). Check the following logs for more information on why the administrative server does not start: Check the entries in the log files in the <WAS_HOME>/logs directory: – tracefile – adminserver_stderr.log – activity.log – nanny.trace (UNIX) . If the loganalyzer format is in use, run the logs through the Log Analyzer to obtain more information regarding the errors. Errors such as DB2 service not started, incorrect JDBC URL (DB2), Incorrect UID (DB2) or incorrect PWD (DB2) will be easily identified in the above files. Trace the administrative server from startup if necessary. Try to diagnose the problem by launching the administrative server from the command line by executing adminservice.exe (Windows) or startupServer.sh (UNIX) and look for errors displayed in the command window.

    25. Troubleshooting An application server fails to start If the application server fails to start check the following: View any errors or exceptions thrown in the administrative console. View the <WAS_HOME>/logs/tracefile. Check the application server’s standard output and standard error files. Make sure that the path given for the standard output and standard error files while configuring the application server do actually exist. View the activity.log file.

    26. Troubleshooting Problems accessing the application The following sections outline some of the things to check if you are having problems accessing your application from a browser, whether it is static HTML, servlets, JSPs or EJBs. In the following sections we will assume that security is not enabled. Cannot access any servlet, JSP, or HTML file from a browser If you are unable to access any web resources from a browser, examine the following files for clues: The Web server error log. The plug-in log file. The default is <WAS_HOME>/logs/native.log. The plug-in configuration file, <WAS_HOME>/config/plugin-cfg.xml. Try accessing your resources using the WebSphere Application Server’s built-in HTTP server, bypassing the production Web server. If successful, the problem relates to the Web server or to its WebSphere plug-in. To access a resource through an application server’s HTTP server, specify the application server’s HTTP listener port in the URI, for example: http://localhost:9080/servlet/snoop where 9080 is the port number used by the application server under which the enterprise application that contains snoop is installed.

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