Red Hat JBoss Web Server 2.1 HTTP Connectors Load Balancing Guide

Transcription

1 Red Hat JBoss Web Server 2.1 HTTP Connectors Load Balancing Guide HTTP load balancing for JBoss Enterprise Application Platform and Red Hat JBoss Web Server Misha Husnain Ali Mandar Joshi Gemma Sheldon

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3 Red Hat JBoss Web Server 2.1 HTTP Connectors Load Balancing Guide HTTP load balancing for JBoss Enterprise Application Platform and Red Hat JBoss Web Server Misha Husnain Ali Red Hat Engineering Co ntent Services m Mandar Joshi Red Hat Engineering Co ntent Services majo m Gemma Sheldo n Red Hat Engineering Co ntent Services gsheldo n@redhat.co m

4 Legal Notice Copyright 2015 RedHat, Inc. This do cument is licensed by Red Hat under the Creative Co mmo ns Attributio n- ShareAlike 3.0 Unported License. If you distribute this document, or a modified version of it, you must provide attribution to Red Hat, Inc. and provide a link to the original. If the document is modified, all Red Hat trademarks must be remo ved. Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law. Red Hat, Red Hat Enterprise Linux, the Shadowman logo, JBoss, MetaMatrix, Fedora, the Infinity Logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other co untries. Linux is the registered trademark of Linus Torvalds in the United States and other countries. Java is a registered trademark o f Oracle and/o r its affiliates. XFS is a trademark of Silicon Graphics International Corp. or its subsidiaries in the United States and/o r o ther co untries. MySQL is a registered trademark of MySQL AB in the United States, the European Union and o ther co untries. Node.js is an official trademark of Joyent. Red Hat Software Collections is not formally related to or endorsed by the official Joyent Node.js open source or commercial project. The OpenStack Wo rd Mark and OpenStack Lo go are either registered trademarks/service marks or trademarks/service marks of the OpenStack Foundation, in the United States and other countries and are used with the OpenStack Foundation's permission. We are not affiliated with, endo rsed o r spo nso red by the OpenStack Fo undatio n, o r the OpenStack co mmunity. All o ther trademarks are the pro perty o f their respective o wners. Abstract Read this guide to install and configure JBoss Enterprise Application Platform and Red Hat JBo ss Web Server HTTP co nnecto rs: mo d_jk, mo d_cluster, ISAPI, and NSAPI. This guide also discusses clustering and lo ad- balancing using these co nnecto rs.

5 T able of Cont ent s Table of Contents. Preface Do cument Co nventio ns Typ o g rap hic Co nventio ns Pull-q uo te Co nventio ns No tes and Warning s 5 2. G etting Help and G iving Feed b ack Do Yo u Need Help? We Need Feed b ack! 6. Part.... I.. Apache T.. omcat Connect or Chapt..... er O.. verview O verview Do wnlo ad and Install 8. Chapt..... er Configure Load..... Balancing Using..... Apache and.... mod_jk Co nfig ure Lo ad Balancing Using Ap ache and mo d _jk Co nfig uring Wo rker No d es in mo d _jk Co nfig uring Wo rker No d es in mo d _jk Co nfig uring Ap ache To mcat to Wo rk with mo d _jk 12. Chapt..... er WebSocket on... T. omcat Ab o ut Web So cket Imp lementing Web So cket o n To mcat 13. Part.... II... JBoss HT.. T.. P. Connect or Chapt..... er O.. verview O verview Key Features Co mp o nents Limitatio ns 19. Chapt..... er Proxy Server Component s Ap ache Mo d ules Ap ache Mo d ules mo d _manag er.so mo d _p ro xy_cluster.so mo d _ad vertise.so mo d _p ro xy.so mo d _p ro xy_ajp.so mo d _slo tmem.so Pro xy Server Co mp o nents Installatio n and Default Co nfig uratio n Pro xy Server Co mp o nents Installatio n and Default Co nfig uratio n 24. Chapt..... er Configure Basic Proxy..... Server Basic Pro xy Co nfig uratio n O verview Co nfig ure a Lo ad -b alancing Pro xy Using the HTTP Co nnecto r 25. Chapt..... er Inst.... all.. Node..... wit... h.. Basic..... Configurat ion Wo rker No d e Req uirements Install and Co nfig ure a Wo rker No d e Co nfig ure a To mcat Wo rker No d e 27. Chapt..... er Advanced Configurat ion

6 Red Hat JBoss Web Server 2.1 HT T P Connect ors Load Balancing G uide. Chapt..... er Advanced Configurat ion Static Pro xy Co nfig uratio n 30. Chapt..... er Configuring ht.. t. pd... for... SSL.... connect ions Co nfig uring http d fo r SSL co nnectio ns 31. Part.... III... O.. nline..... Cert... ificat..... e. St.. at.. us... Prot.... ocol Chapt..... er O.. nline..... Cert... ificat..... e. St.. at.. us... Prot.... ocol Ab o ut O nline Certificate Status Pro to co l Using O nline Certificate Status Pro to co l fo r http d Co nfig ure http d to valid ate O CSP certificates Verify the co nfig uratio n 34. Part.... IV... Using Jsvc.... wit... h.. JBoss Ent... erprise Web.... Server Chapt..... er Jsvc Ab o ut Jsvc Use Jsvc with To mcat 6 and Run Jsvc with To mcat 6 and Co nfig ure Jsvc with To mcat 6 and Chapt..... er Working Examples Co mp lete Wo rking Examp le mo d _auth_kerb Examp le Ab o ut the mo d _auth_kerb Examp le mo d _auth_kerb Examp le Prereq uisites Co nfig ure the Kerb ero s Client Co nfig ure mo d _auth_kerb Test the Kerb ero s Authenticatio n 43. Reference A.1. wo rkers.p ro p erties 45. Java.... Propert ies... Reference B.1. Pro xy Co nfig uratio n 48 B.2. mo d _cluster Pro xy and Pro xy Disco very Co nfig uratio n Attrib utes 49 B.3. Lo ad Co nfig uratio n 50. Revision Hist... ory

7 Preface Preface 1. Document Convent ions This manual uses several conventions to highlight certain words and phrases and draw attention to specific pieces of information T ypographic Convent ions Four typographic conventions are used to call attention to specific words and phrases. These conventions, and the circumstances they apply to, are as follows. Mo no -spaced Bo l d Used to highlight system input, including shell commands, file names and paths. Also used to highlight keys and key combinations. For example: To see the contents of the file my_next_bestsel l i ng _no vel in your current working directory, enter the cat my_next_bestsel l i ng _no vel command at the shell prompt and press Enter to execute the command. The above includes a file name, a shell command and a key, all presented in mono-spaced bold and all distinguishable thanks to context. Key combinations can be distinguished from an individual key by the plus sign that connects each part of a key combination. For example: Press Enter to execute the command. Press C trl +Al t+f2 to switch to a virtual terminal. The first example highlights a particular key to press. The second example highlights a key combination: a set of three keys pressed simultaneously. If source code is discussed, class names, methods, functions, variable names and returned values mentioned within a paragraph will be presented as above, in mo no -spaced bo l d. For example: File-related classes include fi l esystem for file systems, fi l e for files, and d i r for directories. Each class has its own associated set of permissions. Proportional Bold This denotes words or phrases encountered on a system, including application names; dialog-box text; labeled buttons; check-box and radio-button labels; menu titles and submenu titles. For example: Choose System Preferences Mouse from the main menu bar to launch Mouse Preferences. In the Butto ns tab, select the Left-hand ed mo use check box and click C l o se to switch the primary mouse button from the left to the right (making the mouse suitable for use in the left hand). To insert a special character into a gedit file, choose Applications Accessories Character Map from the main menu bar. Next, choose Search Find from the Character Map menu bar, type the name of the character in the Search field and click Next. The character you sought will be highlighted in the 3

8 Red Hat JBoss Web Server 2.1 HT T P Connect ors Load Balancing G uide C haracter T abl e. Double-click this highlighted character to place it in the T ext to co py field and then click the C o py button. Now switch back to your document and choose Edit Paste from the gedit menu bar. The above text includes application names; system-wide menu names and items; application-specific menu names; and buttons and text found within a GUI interface, all presented in proportional bold and all distinguishable by context. Mono-spaced Bold Italic or Proportional Bold Italic Whether mono-spaced bold or proportional bold, the addition of italics indicates replaceable or variable text. Italics denotes text you do not input literally or displayed text that changes depending on circumstance. For example: To connect to a remote machine using ssh, type ssh username@ domain.name at a shell prompt. If the remote machine is exampl e. co m and your username on that machine is john, type ssh jo hn@ exampl e. co m. The mo unt -o remo unt file-system command remounts the named file system. For example, to remount the /ho me file system, the command is mo unt -o remo unt /ho me. To see the version of a currently installed package, use the rpm -q package command. It will return a result as follows: package-version-release. Note the words in bold italics above: username, domain.name, file-system, package, version and release. Each word is a placeholder, either for text you enter when issuing a command or for text displayed by the system. Aside from standard usage for presenting the title of a work, italics denotes the first use of a new and important term. For example: Publican is a DocBook publishing system Pull-quot e Convent ions Terminal output and source code listings are set off visually from the surrounding text. Output sent to a terminal is set in mo no -spaced ro man and presented thus: books Desktop documentation drafts mss photos stuff svn books_tests Desktop1 downloads images notes scripts svgs Source-code listings are also set in mo no -spaced ro man but add syntax highlighting as follows: static int kvm_vm_ioctl_deassign_device(struct kvm *kvm, struct kvm_assigned_pci_dev *assigned_dev) { int r = 0; struct kvm_assigned_dev_kernel *match; mutex_lock(& kvm->lock); match = kvm_find_assigned_dev(& kvm->arch.assigned_dev_head, assigned_dev->assigned_dev_id); if (!match) { printk(kern_info "%s: device hasn't been assigned 4

9 Preface before, " } "so cannot be deassigned\n", func ); r = -EINVAL; goto out; kvm_deassign_device(kvm, match); kvm_free_assigned_device(kvm, match); out: mutex_unlock(& kvm->lock); return r; } 1.3. Not es and Warnings Finally, we use three visual styles to draw attention to information that might otherwise be overlooked. Note Notes are tips, shortcuts or alternative approaches to the task at hand. Ignoring a note should have no negative consequences, but you might miss out on a trick that makes your life easier. Important Important boxes detail things that are easily missed: configuration changes that only apply to the current session, or services that need restarting before an update will apply. Ignoring a box labeled Important will not cause data loss but may cause irritation and frustration. Warning Warnings should not be ignored. Ignoring warnings will most likely cause data loss. 2. Get t ing Help and Giving Feedback 2.1. Do You Need Help? If you experience difficulty with a procedure described in this documentation, visit the Red Hat Customer Portal at Through the customer portal, you can: search or browse through a knowledgebase of technical support articles about Red Hat products. submit a support case to Red Hat Global Support Services (GSS). access other product documentation. 5

10 Red Hat JBoss Web Server 2.1 HT T P Connect ors Load Balancing G uide Red Hat also hosts a large number of electronic mailing lists for discussion of Red Hat software and technology. You can find a list of publicly available mailing lists at Click on the name of any mailing list to subscribe to that list or to access the list archives We Need Feedback! If you find a typographical error in this manual, or if you have thought of a way to make this manual better, we would love to hear from you! Please submit a report in Bugzilla: against the product Red Hat JBoss Web Server. When submitting a bug report, be sure to mention the manual' s identifier: HTTP_Connectors_Load_Balancing_Guide If you have a suggestion for improving the documentation, try to be as specific as possible when describing it. If you have found an error, please include the section number and some of the surrounding text so we can find it easily. 6

11 Part I. Apache T omcat Connect or Part I. Apache Tomcat Connector 7

12 Red Hat JBoss Web Server 2.1 HT T P Connect ors Load Balancing G uide Chapter 1. Overview 1.1. Overview Apache is a well-known web server which can be extended using plug-ins. The Apache Tomcat Connector mod_jk is a plug-in designed to allow request forwarding from Apache httpd Server to a Servlet container. The module also supports load-balancing HTTP calls to a set of Servlet containers while maintaining sticky sessions Download and Inst all Apache httpd is included in the JBoss Enterprise Web Server binary you download from mo d _jk is included in the native installation binaries for JBoss Enterprise Application Platform and JBoss Enterprise Web Server. Follow the procedures in the JBoss Enterprise Application Platform or JBoss Enterprise Web Server Installation Guide to download and install the correct platform and native binaries. For supported configurations, see the JBoss Enterprise Web Server Supported Configurations page. 8

13 Chapt er 2. Configure Load Balancing Using Apache and mod_jk Chapter 2. Configure Load Balancing Using Apache and mod_jk 2.1. Configure Load Balancing Using Apache and mod_jk Follow the tasks in this chapter to correctly configure load balancing using Apache and the mod_jk connector. Procedure 2.1. Configure Apache to Load mod_jk Ensure that Apache and mod_jk are installed (see Section 1.2, Download and Install ). To configure Apache to Load mod_jk: 1. Open HTTPD_DIST/co nf/httpd. co nf and add a single line at the end of the file. # Include mod_jk's specific configuration file Include conf/mod-jk.conf 2. Create a new file named HTTPD_DIST/co nf/mo d -jk. co nf 3. Add the following configuration to the mo d -jk. co nf file. Important The Lo ad Mo d ul e directive must reference the mod_jk library directory location applicable to the native binary you installed. Note The JkMo unt directive specifies which URLs Apache should forward to the mod_jk module. Based on the directive' s configuration, mo d_jk forwards the received URL onto the correct Servlet containers. To enable Apache to serve static content (or PHP content) directly, and only use the load balancer for Java applications, the suggested configuration specifies all requests with URL path /appl i cati o n/* are sent to the mod_jk load-balancer. Only mod_jk is used as a load balancer, forward all URLs to mod_jk by specifying /* in the directive. # Load mod_jk module # Specify the filename of the mod_jk lib LoadModule jk_module modules/mod_jk.so # Where to find workers.properties JkWorkersFile conf/workers.properties # Where to put jk logs JkLogFile logs/mod_jk.log 9

14 Red Hat JBoss Web Server 2.1 HT T P Connect ors Load Balancing G uide # Set the jk log level [debug/error/info] JkLogLevel info # Select the log format JkLogStampFormat "[%a %b %d %H:%M:%S %Y]" # JkOptions indicates to send SSK KEY SIZE JkOptions +ForwardKeySize +ForwardURICompat -ForwardDirectories # JkRequestLogFormat JkRequestLogFormat "%w %V %T" # Mount your applications JkMount /application/* loadbalancer # Add shared memory. # This directive is present with and # later versions of mod_jk, and is needed for # for load balancing to work properly JkShmFile logs/jk.shm # Add jkstatus for managing runtime data <Location /jkstatus/> JkMount status Order deny,allow Deny from all Allow from </Location> 4. O ptional: JKMountFile Directive In addition to the JkMo unt directive, use the JkMo untfi l e directive to specify a mount points configuration file. The configuration file contains multiple Tomcat forwarding URL mappings. a. Navigate to HTTPD_DIST/co nf. b. Create a file named uri wo rkermap. pro perti es. c. Specify the URL to forward and the worker name using the following syntax example as a guide. The example block will configure mod_jk to forward requests to /jmx-co nso l e and /web-co nso l e to Apache. The syntax required takes the form /url = wo rker_name. # Simple worker configuration file # Mount the Servlet context to the ajp13 worker /jmx-console=loadbalancer /jmx-console/*=loadbalancer /web-console=loadbalancer /web-console/*=loadbalancer d. In HTTPD_DIST/co nf/mo d -jk. co nf, append the following directive. 10

15 Chapt er 2. Configure Load Balancing Using Apache and mod_jk # Use external file for mount points. # It will be checked for updates each 60 seconds. # The format of the file is: /url=worker # /examples/*=loadbalancer JkMountFile conf/uriworkermap.properties 2.2. Configuring Worker Nodes in mod_jk Configuring Worker Nodes in mod_jk Configure two mod_jk Worker node definitions in a weighted round robin configuration with sticky sessions active between two servlet containers. Procedure 2.2. Configure mod_jk Worker Nodes As a prerequisite, understand the format of the wo rkers. pro perti es directives, as specified in Section A.1, workers.properties and configure mod_jk (see Section 2.1, Configure Load Balancing Using Apache and mod_jk ). To configure mod_jk worker nodes: 1. Navigate to HTTPD_DIST/co nf/. 2. Create a file named wo rkers. pro perti es. 3. Append the following information into the wo rkers. pro perti es file. # Define list of workers that will be used # for mapping requests worker.list=loadbalancer,status # Define Node1 # modify the host as your host IP or DNS name. worker.node1.port=8009 worker.node1.host=node1.mydomain.com worker.node1.type=ajp13 worker.node1.ping_mode=a worker.node1.lbfactor=1 # Define Node2 # modify the host as your host IP or DNS name. worker.node2.port=8009 worker.node2.host=node2.mydomain.com worker.node2.type=ajp13 worker.node2.ping_mode=a worker.node2.lbfactor=1 # Load-balancing behavior worker.loadbalancer.type=lb worker.loadbalancer.balance_workers=node1,node2 11

16 Red Hat JBoss Web Server 2.1 HT T P Connect ors Load Balancing G uide worker.loadbalancer.sticky_session=1 # Status worker for managing load balancer worker.status.type=status 2.3. Configuring Apache T omcat t o Work wit h mod_jk Tomcat is configured to use mod_jk by default. Specifically, see the co nf/server. xml file, which contains the following code for this purpose: <connector port="8009" protocol="ajp/1.3" redirectport="8443" /> Set the jvmroute attribute at your engine as follows: <Engine name="catalina" jvmroute="node1" > The jvmroute attribute value must match the worker name set in wo rkers. pro perti es. This default Tomcat configuration is ready for immediate use with mod_jk. 12

17 Chapt er 3. WebSocket on T omcat Chapter 3. WebSocket on Tomcat 3.1. About WebSocket WebSocket is a web technology that provides bi-directional, full duplex, messages to be instantly distributed between the client and server over a single TCP socket connection. A full duplex communication allows two-way communication simultaneously. The container provides an implementations of the WebSockets 1.0 JSR 356 API. To use the API, you must run Java 7+ and configure the APR or NIO2 HTTP/1.1 connectors of the web container. JSR 356 is a standard for WebSocket API for Java. Developers can use JSR 356 API for creating WebSocket applications independent of the implementation. The WebSocket API is purely event driven. D evelopers can use JSR 356 Java API for WebSocket to integrate WebSockets in applications on the server side as well as on the java client side. Tomcat 7 and 8 implement WebSocket protocol that adheres to JSR-356 standard. A Java client uses JSR 356 compliant client implementation to connect to a WebSocket server. For web clients, WebSocket JavaScript API can be used to communicate with WebSocket server. The only difference between a WebSocket client and a WebSocket server is the method in which they are connected. A WebSocket client is a WebSocket point from which the connection to a peer originates. While a WebSocket server is WebSocket endpoint which is already published and awaits connections from peers. Some of the examples where WebSocket can be used are banking applications, chat applications, multiplayer applications, and social networking applications Implement ing WebSocket on T omcat The WebSocket on Tomcat configuration requires individual configuration of the following: Configuring write timeout Configuring incoming binary messages Configuring incoming text messages Configuring additional programmatic deployment Configuring callbacks for asynchronous writes Configuring timeout for IO operations while establishing the connections Configuring write timeout You can change the write timeout in blocking mode by using the o rg. apache. to mcat. webso cket. BLO C KING _SEND _T IMEO UT property. The property accepts values in milliseconds. The default value is milliseconds (20 seconds). Configuring incoming binary messages 13

18 Red Hat JBoss Web Server 2.1 HT T P Connect ors Load Balancing G uide To configure incoming binary messages, Messag ehand l er. P arti al must be defined. If Messag ehand l er. P arti al is not defined then incoming binary messages must be buffered so that the entire message is delivered in a single call to Messag ehand l er. Who l e. The default buffer size for binary messages is 8192 bytes. You can change the buffer size for a web application by changing the value of the servlet context initializing parameter o rg. apache. to mcat. webso cket. bi narybuffersi ze. Configuring incoming text messages To configure incoming text messages, Messag ehand l er. P arti al must be defined. If Messag ehand l er. P arti al is not defined then incoming text messages must be buffered so that the entire message is delivered in a single call to Messag ehand l er. Who l e. The default buffer size for text messages is 8192 bytes. You can change the buffer size for a web application by changing the value of the servlet context initializing parameter o rg. apache. to mcat. webso cket. textbuffersi ze. Configuring additional programmatic deployment Java WebSocket specification 1.0 does not allow programmatic deployment after the first endpoint has started a WebSocket handshake. However, Tomcat by default allows additional programmatic deployment. Additional programmatic deployment can be done by using the servlet context initialization parameter o rg. apache. to mcat. webso cket. no Ad d AfterHand shake. Set the system property o rg. apache. to mcat. webso cket. ST R IC T _SP EC _C O MP LIANC E to true to change the default setting. Configuring callbacks for asynchronous writes Callbacks for asynchronous writes need to be performed on a different thread to the thread that initiated the write. The container thread pool is not exposed via the Servlet API. Hence the WebSocket implementation has to provide its own thread pool. The following servlet context initialization parameters control the thread pool: o rg. apache. to mcat. webso cket. executo rc o resi ze The core size of the executor thread pool. If not set, the default of 0 (zero) is used. o rg. apache. to mcat. webso cket. executo rmaxsi ze The maximum permitted size of the executor thread pool. If not set, the default of 10 is used. o rg. apache. to mcat. webso cket. executo rkeepal i vet i meseco nd s The maximum time an idle thread will remain in the executor thread pool until it is terminated. If not specified, the default of 60 seconds is used. Configuring timeout for IO operations while establishing the connections The timeout for IO operations while establishing the connections is controlled by userp ro perti es of the provided javax. webso cket. C l i entend po i ntc o nfi g. You can change timeout by changing the o rg. apache. to mcat. webso cket. IO _T IMEO UT _MS property. The property accepts the values in milliseconds. The default value is 5000 (5 seconds). To connect WebSocket client to secure server endpoints, the client SSL configuration is controlled by userp ro perti es of the provided javax. webso cket. C l i entend po i ntc o nfi g. 14

19 Chapt er 3. WebSocket on T omcat The following user properties are supported: o rg. apache. to mcat. webso cket. SSL_C O NT EXT o rg. apache. to mcat. webso cket. SSL_P R O T O C O LS o rg. apache. to mcat. webso cket. SSL_T R UST ST O R E o rg. apache. to mcat. webso cket. SSL_T R UST ST O R E_P WD The default truststore password is changeit. The o rg. apache. to mcat. webso cket. SSL_T R UST ST O R E and o rg. apache. to mcat. webso cket. SSL_T R UST ST O R E_P WD properties are ignored if the o rg. apache. to mcat. webso cket. SSL_C O NT EXT property is set. 15

20 Red Hat JBoss Web Server 2.1 HT T P Connect ors Load Balancing G uide Part II. JBoss HTTP Connector 16

21 Chapt er 4. O verview Chapter 4. Overview 4.1. Overview The JBoss HTTP Connector mo d_clu st er is a reduced configuration, intelligent load-balancing solution for JBoss Enterprise Application Platform, based on technology originally developed by the JBoss mod_cluster community project. The JBoss HTTP connector load-balances HTTP requests to JBoss Enterprise Application Platform and JBoss Enterprise Web Server worker nodes, utilizing Apache as the proxy server. It serves as a load balancing solution for Tomcat in JBoss Enterprise Web Server as well as for JBoss Enterprise Application Platform Key Feat ures Table 4.1. Features Feature Apache HTTP Server-based Real-time load-balancing calculation Description The JBoss HTTP Connector mod-cluster uses Apache as the proxy server. The JBoss HTTP Connector mo d_clu st er creates a feedback network between the worker nodes and the proxy server. The mod_cluster service is deployed on each of the worker nodes. This service feeds real time load information to the proxy server. The proxy server then allocates work, based on the current load on each worker node. This real time adaptive load distribution results in increased optimization of resources. The information reported by the worker nodes and the load-balancing policy used by the proxy are customizable. Routing based on real-time application life cycle Automatic Proxy D iscovery The JBoss HTTP Connector mo d_clu st er service deployed on the worker nodes relays application lifecycle events to the proxy server. This allows the server to dynamically update its routing table. When an application is undeployed on a node, the proxy server does notroute traffic for that application to that node The proxy server is configured to announce its presence via UD P multicast. New worker nodes discover the proxy server and automatically add themselves to the load-balancing cluster. This reduces the configuration and maintenance needed. When UDP multicast is not available or is undesirable, worker nodes are configured with a static list of proxies. 17

22 Red Hat JBoss Web Server 2.1 HT T P Connect ors Load Balancing G uide Feature Multiple Protocol Support Description The JBoss HTTP Connector mo d_clu st er uses either HTTP, HTTPS, or Apache JServ Protocol (AJP) for communication between the proxy and the worker nodes Component s Proxy Server On the proxy server, the JBoss HTTP Connector mod-cluster consists of four Apache modules. Table 4.2. Components Component mo d _sl o tmem. so mo d _manag er. so mo d _pro xy_cl uster. so mo d _ad verti se. so Description The Shared Memory Manager module shares the real time worker node information with multiple Apache server processes The Cluster Manager module receives and acknowledges messages from nodes, including worker node registrations, worker node load data, and worker node application life cycle events The Proxy Balancer Module handles request routing to cluster nodes. The Proxy Balancer selects the appropriate destination node based on application location in the cluster, current state of each of the cluster nodes, and the Session ID (if a request is part of an established session). The Proxy Advertisement Module broadcasts the existence of the proxy server via UDP multicast messages. The server advertisement messages contain the IP address and port number where the proxy is listening for responses from nodes that want to join the load-balancing cluster. see Section 5.1.1, Apache Modules for detailed information about the available modules including user-configurable parameters. Worker Node Components Worker Node Service The mo d _cl uster offered as part of JBoss Enterprise Web Server is used instead of a JBoss HTTP Connector client service for the worker node service. The mod_cluster in JBoss Enterprise Web Server consists of the following two parts: Native - Apache HTTP Server module (balancer logic) Java - Tomcat6/7 Listener library (worker logic) 18