9
Monitoring HTTP Server, OC4J, and Web Cache

This chapter provides an introduction to monitoring application server instances and components.

It contains the following topics:

• Introduction

• Monitoring Oracle HTTP Server

• Monitoring Oracle9iAS Containers for J2EE

• Monitoring Oracle9iAS Web Cache

Introduction

This chapter provides an introduction to monitoring components using the Oracle Enterprise Manager Web site. It discusses the available metrics for three key components: Oracle HTTP Server, Oracle9iAS Containers for J2EE, and Oracle9iAS Web Cache.

See Also: Enterprise Manager Web site allows you to monitor many other Oracle9iAS components. For more information, refer to the individual component guides and use the Enterprise Manager Web site online help.

Monitoring Oracle HTTP Server

You can use the Enterprise Manager Web site to monitor the activity of Oracle HTTP Server. The following sections describe the HTTP Server Home Page and related pages, which allow you to monitor the server status, server modules, and the server load and response metrics.

Oracle HTTP Server Home Page

The HTTP Server Home Page provides you with a high-level overview of the HTTP Server. You can access the HTTP Server Home Page in the Name column of the System Components table on the Instance Home Page. Figure 9-1 displays the HTTP Server Home Page. This is where you begin your HTTP Server monitoring tasks:

• The General section shows you the current status of the server.

• The Default Server Configuration section provides read-only information on the current configuration settings.

• The Status section provides an at-a-glance view of the overall stability of your server.

• The Response and Load section provides at-a-glance details about the performance of the server.

  Note: The performance metrics collected for virtual hosts are categorized by virtual host name only. If your site deploys multiple virtual hosts that differ only in their listening port of IP address, their performance metrics will be displayed summed together.

  Figure 9-1 HTTP Server Home Page

  

  Text description of the illustration httpserv.gif

To monitor the HTTP Server from a more detailed point of view, use the Performance section of the HTTP Server Home Page to access the following metric pages:

• Status Metrics Page

• Module Metrics Page

• Monitoring Oracle9iAS Containers for J2EE

Status Metrics Page

You can view detailed status information about your HTTP Server on the Status Metrics Page on the Oracle Enterprise Manager. Table 9-1 shows you what to look for in each section of the page.

Table 9-1 Using the Status Metrics Page  

Section	Things to Look For
System Usage Metrics	Review the CPU Usage and Memory Usage charts for a snapshot of the server's overall system usage. Specifically, monitor the system for CPU bounding, which occurs when the CPU utilization is around 90%.
Error Metrics	Review the overall number of error conditions that exist in the server. For example, check the Error Rate Since Startup metric to see if there is an increase in errors over time. The Errors by Error Type table identifies the types of errors users are receiving from the server. Select Error Log in the Related Links section to review the error log file, which can help you troubleshoot problems with your server. Select Logging Properties to configure the logging properties of the server so that it can log more detailed information for analysis.
Connection Metrics	Review the number of Active Connections and the Connections Completed Since Startup to see the level of activity on this server. If you have a high number of connections, check the average time taken for each connection. For example, if you are supporting a high number of connections and have a low average connection time, consider modifying the logic of your application so it requires fewer individual connections.

To view status information:

1. Navigate to the HTTP Server Home Page on the Oracle Enterprise Manager. Scroll to the Performance section.

2. Select Status Metrics. This opens the Status Metrics Page.

3. Review the metrics as listed in Table 9-1.

4. Click Help at the top of the page for more information about the individual metrics.

Module Metrics Page

You can determine the performance of individual Oracle HTTP Server modules using the Module Metrics Page on the Oracle Enterprise Manager.

HTTP Server modules extend your system by allowing you to add features, develop and test features independently, and enable or disable features as needed.

Note: To use a module, you must first register it with Oracle HTTP Server. This is done by modifying the http.config.h file. For more information, see Oracle HTTP Server Administration Guide.

To view metrics for your Oracle HTTP Server modules:

1. Navigate to the HTTP Server Home Page on the Oracle Enterprise Manager Web site. Scroll to the Performance section.

2. Select Module Metrics. This opens the Module Metrics Page.

   The Module Metrics page displays four request metrics for each Oracle HTTP Server module. If you detect poor performance of a particular module, see the error log to determine the cause.

3. Click Help at the top of the page for more information about the individual metrics.

Response and Load Metrics Page

You can view an overall snapshot of how the server is performing on the Response and Load Metrics Page on the Oracle Enterprise Manager.

1. Navigate to the HTTP Server Home Page on the Oracle Enterprise Manager Web site. Scroll to the Performance section.

2. Select Response and Load Metrics. This opens the Response and Load Metrics Page.

   Response metrics indicate (on average) how many requests were submitted and how long it took for the server to respond to a user's request. The Load metrics indicate (on average) how many bytes of data the server processed with the requests.

   You should expect response times to be slower when larger loads are being processed, but you should also account for heavy usage in your server's initial configuration. See the Oracle9i Application Server Performance Guide for more information on handling response and load time.

3. Click Help at the top of the page for more information about the specific metrics.

Monitoring Oracle9iAS Containers for J2EE

You can use the Enterprise Manager Web site to view the running status of OC4J instances and monitor the availability, usage, and overall performance of the OC4J server and its applications.

OC4J Home Page

The OC4J Home Page is the starting point for monitoring OC4J. You can access the OC4J Home Page by selecting the OC4J instance in the Name column of the System Components table on the Instance Home Page. Figure 9-2 displays the OC4J Home Page, which displays usage and performance data for OC4J applications. Using the applications table, you can determine which application is incurring the highest volume of requests or longest response time. You can examine an application further by drilling down into the application to view the performance of individual objects, such as servlets and EJBs.

Figure 9-2 OC4J Home Page

Text description of the illustration oc4jhome.gif

The OC4J Home Page displays a single view of the instance and presents a roll up of status and performance metrics, including:

• How long the instance has been up

• OC4J system resource usage, such as the percentage of CPU and memory resources being consumed

• Volume and average processing time of application requests and transactions

The OC4J Home Page is divided into several sections that cover server status and metrics, data about deployed applications, and property and default settings information.

The General section displays the current running status of the selected OC4J instance. This section includes the Status, Start Time, and number of virtual machines used to execute OC4J application code for the current OC4J instance. You can choose to stop or restart the server from this section.

The Status section displays the key metrics listed in Table 9-2 for monitoring the overall OC4J instance health. In general, these metrics focus on three factors: volumes, rates, and duration.

Table 9-2 Status Section on OC4J Home Page  

Metric	Description
CPU Usage (%)	Percentage of the CPU being used for the OC4J instance. As usage increases, the CPU utilization increases.
Memory Usage (MB)	Number of megabytes being utilized for OC4J memory.
Heap Usage (MB)	Total amount of heap space used (in megabytes) since the server was started.

The JDBC Usage section provides information about the JDBC connections and transactions and includes the metrics listed in Table 9-3.

Table 9-3 JDBC Usage Section on OC4J Home Page

Metric	Description
Open JDBC Connections	Number of open JDBC connections.
Total JDBC Connections	Number of total JDBC connections.
Active Transactions	Number of transactions that are currently open from Enterprise Java Beans in EJB modules.
Transaction Commits	Number of Transactions committed by Enterprise Java Beans in EJB modules.
Transaction Rollbacks	Number of times a transaction was rolled back by Enterprise Java Beans in EJB modules.

The Response - Servlets and JSPs section provides the transactional details about the server and includes the metrics listed in Table 9-4.

Table 9-4 Response - Servlets and JSPs section on OC4J Home Page  

Metric	Description
Active Sessions	Number of currently active sessions for the specified OC4J instance
Active Requests	Total number of active requests currently being processed
Request Processing Time (secs)	Amount of time in seconds spent processing requests during the last period
Requests per Second	Number of requests processed during the last period divided by the time interval of the period

The Response - EJBs section provides transactional details about the Enterprise Java Beans and includes the metrics seen in Table 9-5.

Table 9-5 Response - EJBs section on OC4J Home Page  

Metric	Description
Active EJB Methods	Number of EJB Methods currently active
Method Execution Rate (per sec)	Rate of completion of the EJB Client Methods

The Deployed Applications section displays a list of all OC4J applications deployed in the OC4J instance, including the status of each application measured by the number of active requests and average processing time for the application. You can perform the following tasks in this section:

• Deploy a new OC4J application

• Redeploy or undeploy an OC4J application

The Applications table displays a list of all installed applications in the OC4J instance. You can select any application to display the Application Page for that application, which includes more performance statistics for the specified application.

The Administration section enables you to set instance properties, such as server and Web site properties, and application defaults, such as data sources and principals. The Administration section also includes related links to the UDDI registry and JAAS Policy Management.

Application Pages

The OC4J Application Page displays information and metrics about the specified application. You can access the Application Page by selecting the name of the application in the Name column of the Application table on the OC4J Home Page.

Figure 9-3 OC4J Application Page

Text description of the illustration oc4japp.gif

The Application Page provides application status information along with response metrics for Servlets, JSPs, and EJBs. There are two tables in the center of the page that list Web Modules and EJB Modules.

The General section shows the current status of the selected OC4J application and includes a Response section for Servlets, JSPs, and EJBs. You can redeploy or undeploy an OC4J application from the General section.

The Response - Servlets and JSPs section provides transactional details about the server and includes the metrics seen in Table 9-6.

Table 9-6 Response - Servlets and JSPs Section on OC4J Applications Page  

Metric	Description
Active Sessions	Number of currently active sessions for the specified OC4J application
Active Requests	Total number of active requests currently being processed
Request Processing Time (secs)	Amount of time in seconds spent processing requests during the last period
Requests per Second	Number of requests processed during the last period divided by the time interval of the period

The Response - EJBs section provides transactional details about the Enterprise Java Beans and includes the metrics seen in Table 9-7.

Table 9-7 Response - EJBs section on OC4J Application Page  

Metric	Description
Active EJB Methods	Number of EJB Methods currently active
Method Execution Rate (per sec)	Rate of completion of the EJB Client Methods

The Web Modules table displays a list of all Web modules used in the OC4J application. You can select a Web module in the Name column to drill down to the Overview Page for the Web module. The Web Module table includes the Web module name, the path, the number of active requests, the request processing time, and the number of active sessions.

The EJB Modules table displays a list of all Enterprise Java Beans modules used in the OC4J application. You can select an EJB module in the Name column to drill down to the Overview Page for that specific EJB module. The EJB Modules table lists the EJB Module name, the path, the number of EJBs deployed, the number of active EJB methods, and the method execution rate per second for each EJB module.

The Administration section provides access to basic and advanced configuration functions, data sources and their settings, and security principals and roles.

You can use the Application Page to diagnose and isolate problems involving specific servlets or JSPs. For example, if your Web application is experiencing user delays, you can use the OC4J Application Page to diagnose and isolate the servlets or JSPs responsible for the longest response times. You can use the Overview for Web Module Page or the EJB Module Page to break down further the performance of servlets, JSPs, or EJBs, looking at load times, service times, and overhead.

Monitoring Oracle9iAS Web Cache

Oracle9iAS Web Cache is a content-aware server accelerator, or reverse proxy server, that improves the performance, scalability, and availability of Web sites that run on Oracle9i Application Server.

By storing frequently accessed URLs in memory, Oracle9iAS Web Cache eliminates the need to repeatedly process requests for those URLs on the application Web server.

Unlike legacy proxy servers that handle only static documents, Oracle9iAS Web Cache caches both static and dynamically generated content from one or more application Web servers. Because Oracle9iAS Web Cache can cache more content than legacy proxies, it provides optimal performance by greatly reducing the load on application Web servers.

Oracle9iAS Web Cache sits in front of application Web servers, caching their content and providing that content to Web browsers that request it. When Web browsers access the Web site, they send HTTP protocol or HTTPS protocol requests to Oracle9iAS Web Cache. Oracle9iAS Web Cache, in turn, acts as a virtual server to the application Web servers. If the requested content has changed, Oracle9iAS Web Cache retrieves the new content from the application Web servers. The application Web servers may retrieve their content from an Oracle database.

Oracle9iAS Web Cache Home Page

The Web Cache Home Page enables you to monitor the running status of Oracle9iAS Web Cache, as well as the overall performance statistics for Oracle9iAS Web Cache. You can access the Web Cache Home Page by selecting an Oracle9iAS Web Cache server in the Name column of the System Configuration table on the Oracle9iAS Instance Home Page. Figure 9-4 displays the Web Cache Home Page.

Figure 9-4 Web Cache Home Page

Text description of the illustration wc_home.gif

The General section displays the current running status of Oracle9iAS Web Cache. It also displays the key metrics listed in Table 9-8 for monitoring overall Oracle9iAS Web Cache health.

Table 9-8 General Section in Web Cache Home Page  

Metric	Description
CPU Usage (%)	Percentage of the CPU being used for Oracle9iAS Web Cache (As traffic increases, the CPU utilization increases.)
Memory Usage (MB)	Number of megabytes being utilized for cache memory
Number of Cached Documents	Number of documents currently cached
Size of Cached Documents (MB)	Number of megabytes utilized by documents in the cache

The Activity section displays the cache resource and performance information listed in Table 9-9.

Table 9-9 Activity Section in Web Cache Home Page  

Metric	Description
Requests Per Second	Number of requests that Oracle9iAS Web Cache is currently serving each second
Data Served (MB/sec)	Number of megabytes that Oracle9iAS Web Cache is currently serving each second
Apologies Pages Served (% of requests)	Percentage of apology pages that Oracle9iAS Web Cache is serving to Web browsers, due to a network or busy Web site error
Cache Cluster	Name of the cache cluster. This field displays only if a cache cluster is configured.
Open Connections	Current number of incoming open connections to the Oracle9iAS Web Cache server and outgoing open connections to the application Web servers

The Performance section provides access to the following pages:

• Activity Page

• Application Web Servers Page

• Popular Cached Documents Page

Activity Page

The Web Cache Activity Page enables you to monitor the efficiency of the cache. It displays metrics for cache hit requests, compression requests, and apology page requests.

To access the Activity Page:

1. Navigate to the Web Cache Home Page on the Oracle Enterprise Manager Web Site.

2. Scroll to the Performance section.

3. Select Activity. This opens the Web Cache Activity Page.

Figure 9-5 displays the Web Cache Activity Page.

Figure 9-5 Web Cache Activity Page

Text description of the illustration wc_activ.gif

For cache hit rates, compression, and apology pages, the page provides the following information:

• Documents currently being served by Oracle9iAS Web Cache each second in the Current (per second) columns

• Percentage of documents currently being served by Oracle9iAS Web Cache each second in the Current Requests (%) columns

• Total documents served since Oracle9iAS Web Cache was started or restarted in the Total columns

Application Web Servers Page

The Web Cache Application Web Servers Page enables you to view the status of the application Web servers to which Oracle9iAS Web Cache forwards requests.

To access the Web Cache Activity Page:

1. Navigate to the Web Cache Home Page on the Oracle Enterprise Manager Web Site.

2. Scroll to the Performance section.

3. Select Application Web Servers. This opens the Application Web Servers Page.

Figure 9-6 displays the Web Cache Application Web Servers Page.

Figure 9-6 Web Cache Application Web Servers Page

Text description of the illustration wc_wbsrs.gif

View the Up/Down column. An Up status specifies that the last communication with the server was successful. A Down status specifies that the server is down. If this is the last server in a single or multiple server configuration, Oracle9iAS Web Cache continues to forward requests to the server. If this is not the last server, then no new requests are sent to server. However, Oracle9iAS Web Cache polls the inactive server until it is back online.

To view detailed metrics for a specific application Web server:

1. Select an application Web server host name to view. This opens the Application Web Server Page.

2. View the metrics in which you are interested:
   • The Active Requests metric in the Requests Throughput section shows the current load

   • The metrics in the Request Processing Time section shows processing latency

   • The Concurrent Bound Sessions metric in the Connections section shows the number of open connections

Figure 9-7 displays the Web Cache Application Web Server Page for myserver.mycompany.com:4444.

Figure 9-7 Web Cache Application Web Server Page

Text description of the illustration wc_wbsrv.gif

Popular Cached Documents Page

The Web Cache Popular Cached Documents Page enables you to view the URLs of the most popular documents in the cache and to generate a list of the URLs of all the objects currently in the cache. This information helps you verify that the cacheability rules are configured correctly: that the objects that you want cached are being cached. Figure 9-8 displays the Web Cache Popular Cached Documents Page.

Figure 9-8 Web Cache Popular Cached Documents Page

Text description of the illustration wc_pop.gif

Note: The Popular Cached Documents Page lists only those documents that are valid. Although the cache may contain documents that are expired or that have been invalidated, those documents are not included in the list of popular documents.

To access the Popular Cached Documents Page:

1. Navigate to the Web Cache Home Page on the Oracle Enterprise Manager Web Site.

2. Scroll to the Performance section.

3. Select Popular Cached Documents. This opens the Popular Cached Documents Page.