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At a Glance |
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Catalog |
System |
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Category |
Application Servers |
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User volumes |
yes |
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Min. memory |
160 MB |
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OS |
Linux |
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Constraints |
no |
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Questions/Comments |
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TOMCAT is web server appliance based on the Sun Java machine and Apache Tomcat, a Java Servlet and JavaServer Pages container developed under the Apache License. The main documentation for Tomcat is at tomcat.apache.org. Tomcat provides standards-compliant support for Servlets and JSPs. Tomcat can work as standalone web server or as application server.
TOMCAT serves static web content, automatically deploys web applications, executes servlets and JavaServer Pages from a user-configurable content volume. The paths to the documents are configurable, so that the same volume can be shared between multiple web servers and other appliances serving different content.
TOMCAT serves HTTP/1.1 and HTTP/1.0 protocol for web clients and AJP 1.3 for requests from front end servers (ex. Apache with mod_proxy_ajp).
Like WEBx servers, TOMCAT has three generic output terminals intended for accessing external services from scripts on the content volume. The db terminal is used for accessing various databases; the fs terminal is used for accessing shared file storage (using NFS); and the aux terminal is created for sending e-mail messages to an SMTP server.
The log terminal should be used to connect TOMCAT to a shared file system where TOMCAT can store log files.
Configuration of the server is defined using various properties. These properties are designed to cover the most usage variants in an easy-to-configure way. In most cases only a few need to be set to a non-default
|
Name |
Latest version |
OS |
Java machine version |
Apache Tomcat version |
|
TOMCAT |
3.0.6-1 |
CentOS 6.3 |
JDK 1.6.0.22 |
6.0.29 |
|
TOMCAT64 |
3.0.6-1 |
CentOS 6.3 (64 bit) |
JDK 1.6.0.22 |
6.0.29 |
Resources for TOMCAT
|
Resource |
Minimum |
Maximum |
Default |
|
CPU |
0.1 |
16 |
0.3 |
|
Memory |
160 MB |
4G |
512 MB |
|
Bandwidth |
1 Mbps |
2 Gbps |
250 Mbps |
Resources for TOMCAT64
|
Resource |
Minimum |
Maximum |
Default |
|
CPU |
0.1 |
16 |
0.3 |
|
Memory |
192 MB |
64G |
512 MB |
|
Bandwidth |
1 Mbps |
2 Gbps |
250 Mbps |
Note:
Important! TOMCAT has restrictions inherited from the 32-bit Java machine. This Java machine cannot work with more than approximately 2.6Gb of memory and allocating more than 2.8Gb of memory for TOMCAT is inefficient.
In addition for memory for Java applications, some amount of memory must be available to store application sessions. Each empty session (with no additional data stored) uses close to 2kbytes of memory. That memory is used during the session lifetime (the default session lifetime is 30 min). Session lifetime can be configured by modifying or adding an additional section to the web.xml configuration file of an application. For example including this code below configures the session lifetime to be 1 minute:
<session-config>
<session-timeout>1</session-timeout>
</session-config>
If 10k unique visitors are expected in 30 min, an additional 20Mb of free memory is required. In general: Required amount of memory = Maximum number of simultaneous active sessions * average size of a session.
Important! If not enough memory is available, tomcat may malfunction. This depends upon the user applications that are running in tomcat and is not a limitation of the appliance itself.
|
Volume |
Description |
|
content |
Volume for the storage of tomcat applications, applications data, temporary and work files. This volume is only used if the content_on_fs property set to off. |
|
Property Name |
Type |
Description |
|
content_on_fs |
String |
Specifies whether the content is relative to the file system at the fs terminal or is on the content volume. Default: off (on the content volume) |
|
hostname |
String |
Host name of the website. Default: localhost |
|
tomcat_port |
Integer |
Port where Tomcat listens for incoming HTTP requests. Default: 8080 |
|
session_timeout |
Integer |
Timeout for the user session, in minutes, during which TOMCAT will keep all data, associated with the user session, in memory. Default: 30. |
|
max_connections |
Integer |
Maximum number of allowed concurrent connections. When this number is reached, new connections are still accepted, but their processing is delayed until another connection is closed. Default: 100 |
|
heap_size |
Integer |
Memory allocated for Java heap (the -Xmx Java option), in megabytes. If 0, this value is automatically calculated. Default: 0 |
|
perm_size |
Integer |
Memory allocated for Java permanent objects (the -XX:PermSize Java option), in megabytes. If 0, this value is automatically calculated. Default: 0 |
|
app_base |
String |
Root directory for the documents, work and temp files. A typical structure of Tomcat 's ${catalina.base} directory will be created in this folder: shared for libraries that are common to all java-applications; temp and work for temporary and work files; and subdirectory defined in work_dir property - analogue of ${catalina.base}/webapps. Default: empty |
|
work_dir |
String |
Directory where the documents to be served are located. Also used for auto-deployment purpose. More information is available at Tomcat's website - Automatic Application Deployment . Default: webapps |
|
timezone |
String |
Specifies the time zone used in the appliance. If this property is empty, the timezone is not modified and left as-is. A list of supported time zones is available. Default: empty |
|
Name |
Direction |
Protocol |
Description |
|
in |
in |
HTTP |
Serves HTTP requests coming from web clients. Supports the HTTP/1.1, HTTP/1.0 and AJP protocols. |
|
db |
out |
Any |
Access to a database server. Usage is defined by whatever scripts reside on the content volume (if any). This terminal may be left unconnected if not used. |
|
fs |
out |
NFS |
Access to a network file system for shared file storage, providing read/write file access over NFS. Usage is defined by whatever scripts reside on the content volume (if any). Software on the content volume 'sees' the mounted remote file system as /mnt/fs in the appliance's filesystem space. This terminal may be left unconnected if not used. The connected server must have a read/write share named /mnt/data exported over NFS. |
|
log |
out |
CIFS |
Access to a CIFS-based network file system for storing access and error logs. This terminal may be left unconnected if not used. The connected server must allow anonymous logins and have a read/write exported share named share. |
|
aux |
out |
Any |
Access to a SMTP server for sending outgoing e-mail. |
|
net |
out |
Any |
Gateway output for subnet access. |
|
mon |
out |
CCE |
Sends performance and resource usage statistics to MON appliance. |
The default interface is enabled. It is intended for diagnostics and troubleshooting (over SSH). Future versions of this appliance may disable SSH access.
|
Property Name |
Type |
Description |
|
logs_enabled |
String |
Completely enables or disables logging. Default: no |
|
logs_base_dir |
String |
Directory where log files are stored. Default: empty, logs will be placed in root of mounted NAS volume |
|
error_log_filename |
String |
Filename prefix for the error log. Default: catalina |
|
log_level |
String |
Logging level. The values are, increasing verbosity level, SEVERE, WARNING, INFO, CONFIG, FINE, FINER, FINEST, ALL. More detailed description of log levels is available in the Tomcat documentation. Default: INFO |
|
enable_access_log |
String |
Enables or disables access log. Default: no |
|
access_log_filename |
String |
Filename prefix for the access log. Default: access.log |
The TOMCAT appliance reports the following custom counters through the mon terminal. These counters belong to the TOMCAT counter group (TOMCAT64 in the case of TOMCAT64):
|
Counter Name |
Description |
|
Classes loaded |
Number of classes loaded |
|
Classes loaded bytes |
Number of Kbytes loaded |
|
Classes unloaded |
Number of classes unloaded |
|
Classes unloaded bytes |
Number of Kbytes unloaded |
|
Classes load/unload execution time |
Time spent performing class load and unload operations |
|
Compiler compiled |
Number of compilation tasks performed |
|
Compiler failed |
Number of compilation tasks that failed |
|
Compiler invalid |
Number of compilation tasks that were invalidated |
|
Compiler execution time |
Time spent performing compilation tasks |
|
Heap s0 space capacity |
Current survivor space 0 capacity |
|
Heap s1 space capacity |
Current survivor space 1 capacity |
|
Heap s0 space utilization |
Survivor space 0 utilization |
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Heap s1 space utilization |
Survivor space 1 utilization |
|
Heap eden space capacity |
Current eden space capacity |
|
Heap eden space utilization |
Eden space utilization |
|
Heap old space capacity |
Current old space capacity |
|
Heap old space utilization |
Old space utilization |
|
Heap permanent space capacity |
Current permanent space capacity |
|
Heap permanent space utilization |
Permanent space utilization |
|
Heap young generation GC events |
Number of young generation GC Events (GC - Garbage Collection) |
|
Heap young generation GC time |
Young generation garbage collection time |
|
Heap number of GC events |
Number of full GC events |
|
Heap full GC time |
Full garbage collection time |
|
Heap total GC time |
Total garbage collection time |
|
Pool current new generation |
Current new generation capacity |
|
Pool min new generation |
Minimum new generation capacity |
|
Pool max new generation |
Maximum new generation capacity |
|
Pool current old generation |
Current old generation capacity |
|
Pool min old generation |
Minimum old generation capacity |
|
Pool max old generation |
Maximum old generation capacity |
|
Pool current permanent generation |
Current permanent generation capacity |
|
Pool min permanent generation |
Minimum permanent generation capacity |
|
Pool max permanent generation |
Maximum permanent generation capacity |
|
New generation tenuring threshold |
Tenuring threshold |
|
New generation max tenuring threshold |
Maximum tenuring threshold |
|
Desired survivor size |
Desired survivor size |
|
Compiler tasks |
Number of compilation tasks performed |
In case of appliance startup failure, the following errors may be logged into the system log:
|
Error message |
Description |
|
ERROR: Logs are enabled, but log terminal is not connected. |
log terminal is not connected, but logs_enabled or enable_access_log is set to yes. |
|
ERROR: Property content_on_fs is 'off' but the local content volume is missing. |
The content_on_fs is set to off, specifying that the data volume must be mounted locally, but TOMCAT cannot mount content volume. Most probable cause is that the content volume is not formatted, or is not defined in TOMCAT properties. |
|
ERROR: Failed to mount nfs share. |
TOMCAT cannot mount nfs share. The probable cause is that fs is not connected or TOMCAT was started before NAS (or whatever appliance is connected to the fs terminal) |
|
Message |
Description |
|
Data storage has less than 5% of free disk space |
The data volume accessed through the fs terminal has less than 5% of free disk space. It is advised to increase the size of the volume. |
|
Data storage has less than 1% of free disk space |
The data volume accessed through the fs terminal has less than 1% of free disk space. Immediate attention required; possible data loss may occur. |
|
Content volume has less than 5% of free disk space |
The content volume on the appliance has less than 5% of free disk space. It is advised to increase the size of the volume. |
|
Content volume has less than 1% of free disk space |
The content volume on the appliance has less than 1% of free disk space. Immediate attention required; possible data loss may occur. |
The TOMCAT performance may be affected when logging is turned on (either error logging enabled by logs_enabled = yes or access logging - enable_access_log equals yes. The table below contains benchmark results (specified in rps units - requests per second) performed when logs are disabled with Apache Benchmark utility that ships with Apache web server version 2.0 and 2.2. More info for ab is available on Apache website. Following settings were used for benchmarking: "bw=500M mem=2G cpu=2".
|
concurrency |
rps |
|
1 client concurrency |
2800-3200 rps |
|
10 client concurrency |
7500-7900 rps |
|
100 clients concurrency |
7700-8100 rps |
Simple Java-enabled Web Site
TOMCAT will serve applications from content volume.
Appliances in use:
|
Property name |
Value |
Notes |
|
hostname |
www.mysite.org |
Hostname of site. |
|
app_base |
MyApp |
|
|
content_on_fs |
off |
TOMCAT uses user volume content for all content. |
|
timezone |
EST |
EST timezone. |
|
tomcat_port |
80 |
Standard port for the HTTP protocol. |
Client requests arrive on the IN gateway. The gateway forwards the requests to the TOMCAT server, which serves the request.
Two-tier Application with Database, Log, and Monitoring
Appliances in use:
Example property configuration:
|
Property Name |
Value |
Notes |
|
hostname |
www.mysite.org |
Hostname of site |
|
app_base |
MyApp |
|
|
content_on_fs |
on |
TOMCAT uses remote storage through the fs terminal for all content |
|
timezone |
EST |
EST timezone |
|
tomcat_port |
80 |
Standard port for HTTP protocol |
|
max_connections |
200 |
Max of 200 concurrent users |
|
logs_enabled |
yes |
Enables error logs |
|
logs_base_dir |
MyApp_Log_Dir |
|
|
log_level |
INFO |
|
|
error_log_filename |
error_log |
Error log name |
|
enable_access_log |
yes |
Enables access log |
|
access_log_filename |
myapp_access |
Access log name |
Client request arrive on the IN gateway. The gateway forwards the requests to the TOMCAT server, which serves the request. Content and logs are on storage appliance. Counters are reported to mon appliance.
Note: Java applications can use many types of databases. It depends only of presence of appropriate JDBC driver in application. TOMCAT allow to connect any database appliance to its db terminal.
WEB6 as a front end for TOMCAT
The following diagram shows a usage of the TOMCAT appliance as application server and WEB6 as frontend. WEB6 serves static content and redirects all requests that require server-side processing to the TOMCAT using AJP protocol.
Note: It is necessary to enable AJP support (enable mod_proxy and mod_proxy_ajp) in WEB6 for this mode.
Appliances in use:
Example property configuration:
|
Property Name |
Value |
Notes |
|
content_on_fs |
off |
TOMCAT uses the user volume content for all content |
|
timezone |
EST |
EST timezone |
Others settings have their default values.
WEB6 must be properly configured to work as frontend and communicate with TOMCAT using AJP protocol.
mod_proxy and mod_proxy_ajp must be enabled by including next lines in apache config
LoadModule proxy_module modules/mod_proxy.so LoadModule proxy_ajp_module modules/mod_proxy_ajp.so
some path of url space must be specified to serve by TOMCAT , for example
ProxyPass /path-that-served-by-tomcat ajp://aux:8009/some-servlet ProxyPassReverse /path-that-served-by-tomcat ajp://aux:8009/some-servlet
For example:
|
path |
content |
served by |
|
/index.html |
static html document |
served by WEB6 |
|
/images/* |
static graphical files |
served by WEB6 |
|
/scripts/*.php |
dynamic content generated by php scripts |
served by WEB6 |
|
/path-that-served-by-tomcat |
dynamic content generated by jsp |
served by TOMCAT |
Client request arrive on the IN gateway. The gateway forwards the requests to the frontend web server, which servers requests for static html pages, graphical files and php scripts. Requests for jsp pages or servlet pages are forwarded to AppServer and served by it.
Scalable Java-enabled Web Site
Appliances in use:
Example property configuration for both AppServer1 and AppServer2:
|
Property Name |
Value |
Notes |
|
content_on_fs |
off |
TOMCAT uses the user volume content for all content |
|
timezone |
EST |
EST timezone |
Others settings have their's default values.
Client request arrive on the IN gateway. The gateway forwards the requests to the lb load balancer, which directs the request to one of the servers AppServer1 and AppServer2.
TOMCAT and TOMCAT64 use the following third party open source packages as well as the third party open source packages used by their base class LUX6 and LUX64 respectively.
TOMCAT
|
Software |
Version |
Modified |
License |
Notes |
|
Apache Tomcat |
6.0.29 |
Yes |
Apache License v2.0 |
homepage |
|
JDK |
1.6.0.22 |
No |
Sun-BCL |
available on Sun website |
|
samba-client |
3.5.10-125.el6 |
No |
GPLv2 |
N/A |
|
samba-common |
3.5.10-125.el6 |
No |
GPLv2 |
N/A |
TOMCAT64
|
Software |
Version |
Modified |
License |
Notes |
|
Apache Tomcat |
6.0.29 |
Yes |
Apache License v2.0 |
homepage |
|
JDK |
1.6.0.22 |
No |
Sun-BCL |
available on Sun website |
|
samba-client |
3.5.10-125.el6 |
No |
GPLv2 |
N/A |
|
samba-common |
3.5.10-125.el6 |
No |
GPLv2 |
N/A |
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Copyright © 2013 CA Technologies.
All rights reserved.
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