Oracle HTTP Server Metrics
Oracle Application Server Tips by Burleson
Here we see three sections, system usage
metrics, error metrics, and connection metrics.
OHS System Usage Metrics
The system usage metrics page shows CPU and
RAM memory usage for the HTTP server. Note that the RAM is
displayed in a pie chart, with HTTP server RAM, Free RAM, and other.
On an active Application Server, there is normally little free RAM,
as many components will expand to use the available RAM.
OHS Error Metrics
This shows the error rate as a percentage of
total transactions, error rate since startup, and total errors since
startup. We also see a listing of all error types and a count
of the type. From this section we can click the Error Log and
Logging Properties links for further details.
Clicking the Error Log link displays EM?s
log page, with the HTTP_Server in the right-hand box. At the bottom
of the page is a list of error logs from the HTTP_Server.
Select the error_log link to see the details (Figure 5). To
add logs from other components simply select the component in the
left box and move it to the right box. Em will add it?s logs
to the available log list.
Figure 5: Enterprise Manager HTTP_Server
HTTP Server response and load metrics
Now we return to the HTTP server page
(Figure 2 above) and click the Response and Load Metrics link.
Figure 6: Enterprise Manager HTTP_Server
Response and Load Metrics
This page provides a snapshot of the current
load on OHS, including request throughput and processing time.
It also gives a snapshot of the number of active and idle processes
on the server.
Finding a performance problem in the
application server is difficult, due to the number of components
interacting within the server. This is a good place to look
for performance problems. Slow response time and large numbers
of active processes on OHS may indicate a need to add an additional
instance to the cluster. If one user appears to be
experiencing a problem, you can drill down and get process
information by selecting the Process Details link.
Figure 7: Enterprise Manager HTTP_Server
Process Detail Page
A processor that is gaining time may
indicate a problem within the application server and assist you in
tracking it down.
HTTP Server Module Metrics
Returning to the HTTP_Server page (Figure
2), we now select the Module Metrics link.
Figure 8: Enterprise Manager HTTP_Server
Module Metrics Page
This page lists all modules that have had at
least one request since OHS was started. This can also be
helpful in tracking down a performance issue. Request
processing time that is abnormally high could indicate a problem in
the module or in a program called by the module.
HTTP Server Virtual Host Page
Returning to the HTTP_Server page (Figure
2), we want to look at the Virtual Host section. Currently,
OHS only has one virtual host defined and it supports SSL
connections to the default server. By selecting the Virtual
Host?s Server Name we get the Virtual Host?s page.
Figure 9: Enterprise Manager HTTP_Server
Virtual Host Page
This page provides a snapshot of the load
and performance statistics for that virtual host. There is
also an Administration section that will allow you to update all the
host parameters defined in the httpd.conf file for this virtual
You can also create or delete a virtual host
using Enterprise Manager. Returning to the HTTP_Server page
(Figure 2) we see that the Virtual Host section contains Create,
Delete, and Create Like buttons. At the far left of the
Virtual Host section is a radio button that is on for our single
virtual host. That button is used with the Create Like button
to create a new virtual host like the one selected. Let?s
create a new virtual host using the wizard. Selecting the
Create button starts the wizard.
Figure 10: HTTP_Server Virtual Host Creation
Wizard Welcome Page
The Introduction lists the type of
information you will need to successfully create the new virtual
host. This information was covered in the virtual host section
of the httpd.conf file. Selecting the Next button takes us to the
Figure 11: HTTP_Server Virtual Host Creation
Wizard General Page
The General page allows you to set a
DocumentRoot directive for the new virtual host. It also
allows you to select which type of virtual host you will create, IP,
named, or default. It defaults to the default type and the
default DocumentRoot. In this example, we are creating a
name-based virtual host, which as we discussed earlier, allows hosts
with different names to use the same IP address. We left the
defaults for the remaining items. Selecting the Next button
takes us to the Addresses page.
Figure 12: HTTP_Server Virtual Host Creation
Wizard Addresses Page
Here we entered the DNS name for our new
virtual host. Since we are sharing the same IP as the default
host, we did not enter a new IP address. Selecting the Next
button takes us to the Ports page.
Figure 13: HTTP_Server Virtual Host Creation
Wizard Ports Page
For this example, we will just listen on the
default port for the main server and continue to the Error Log page.
Notice that we skipped the Protocal page. Since we are using
the default server?s IP and ports we can?t change the protocol.
Figure 14: HTTP_Server Virtual Host Creation
Wizard Error_log Page
Here we define a new error_log for our
virtual host and leave the logging level at Warning. The next
page is the summary page.
Figure 15: HTTP_Server Virtual Host Creation
Wizard Summary Page
This page lists all of our selections for
the new virtual host. Select Finish and Enterprise Manager
updates the httpd.conf file and then restarts OHS.
Figure 16: HTTP_Server Virtual Host Creation
Wizard Complete Page
Figure 17: HTTP_Server Restart Page
Once OHS has restarted, the new Virtual Host
is now up and running. You can see the additional code created
by the Wizard in the httpd.conf file.
Very little additional code was needed since
our new virtual host mainly used the default server?s settings.
When we return to the HTTP_Server page, our new virtual host is now
Figure 18: Updated HTTP_Server Page
As we have seen in this chapter, the Oracle
HTTP Server is the gateway between our clients and all other
components of the application server. By building OHS on the
Apache web server, Oracle has created a proven, reliable, and secure
communication interface with Oracle9iAS. Later chapters will
detail areas such as dynamic content and security, adding additional
capabilities to the OHS and the application server. The Oracle
HTTP Server is not the base of Oracle9i Application Server but it
definitely is the front end.
This is an excerpt from "Oracle
10g Application Server Administration Handbook" by Don Burleson
and John Garmany.