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Welcome to:
Workload Management
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What is Workload Management (WLM)?
Sharing requests across multiple Application ServersConfiguration options that improve:
Performance improve response time for requests
Scalability grow capacity as the number of users
increasesLoad balancing allocate workload proportionately among
available resources
Availability applications are still available if a server fails
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What can be Workload Managed?
EJB
Requests
Servlet
Requests
App Server
App Server
WebContainer
WebContainer
App Server
EJBContainer
App Server
EJBContainer
App Server
WebContainer
JavaClient
HTTP
Requests
HTTPServer
Plugin
LoadBalancer HTTP
Server
Plugin
HTTP
ServerPlugin
HTTP(s)
HTTP(s)
IIOP
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Clusters
Clusters are a set of application servers having the same applications
installed, and grouped logically for Workload Management
Applications installed to the cluster are automatically distributed to
the cluster members
Creation of a ClusterCan use an existing server to become the first cluster member
Additional cluster members are created from templates
Cluster members are similar to V4 'Clones' in that they:
Run the same applicationsShare workload
Can be centrally administered
Cluster members are different from V4 'Clones' in that:
Changes to the template are NOT propagated to the cluster memberChanges to cluster members do not disassociate the cluster member
Applications binaries are copied to the nodes during synchronization
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What's Different from Previous Versions?
WAS 3.5 Models and 4.0 Server Groups were ActiveTemplates
Changes to the template were propagated to the Clones
Installing applications required manual updating of
application binariesWAS 5 uses 'passive template' concept
Once a cluster member has been created, no changes to
the template are propagatedInstalling applications - binaries are copied to the nodes
during synchronization
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Configurations: Vertical Scaling
May provide better performance with multiple processors
ClusterMember1
WebContainer
EJBContainer
ClusterMember2
WebContainer
EJBContainer
Node 1
HTTP
ServerPlug-in
Cluster
Node Agent
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ClusterMember2
WebContainer
EJBContainer
Node 2 Node Agent
Configurations: Horizontal Scaling
Supports machine failover
HTTP
ServerPlug-in
ClusterMember1
WebContainer
EJBContainer
Node 1
Cluster
Node Agent
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ClusterMember1
WebContainer
EJBContainer
ClusterMember2
WebContainer
EJBContainer
Node 1 Node Agent
Configurations: Vertical & Horizontal Scaling
Performance and failover
ClusterMember3
WebContainer EJBContainer
ClusterMember4
Web
Container
EJB
Container
Node 2
HTTPServer
Plug-in
HTTPServer
Plug-in
Cluster
Node Agent
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Creating a Cluster (1 of 3)
In console, select Servers -> Clusters and click NewEnter Cluster name
Check options
Prefer Local (default)
Create ReplicationDomain (optional)
Select the first member
(optional)Click Next
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Creating a Cluster (2 of 3)
Enter NameSelect node
Set weight
Check options:
Generate UniqueHTTP ports (default)
Create replication
entry (optional)Select template:
default template, or
existing server
Click Apply
Repeat to create other
cluster members
Click Next
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Creating a Cluster (3 of 3)
Click FinishCluster is created
Save
Configuration copiedto nodes at next
synchronization
Regenerate the HTTP server plug-in
Plug-in configuration generated on deployment managerCopy to HTTP servers
Paths in file are relative to deployment manager installationEdit paths to be correct for the system
Changes will be effective at the next reload, or when you re-start the HTTP server
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Installing Applications to a Cluster
Same steps as installing to base server except:
select a Cluster as the target, rather than a server
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Controlling a Cluster
Start the cluster
Start starts all servers together
Ripplestart starts servers one at a time
Status
Started only if all servers are startedPartial Start if some servers are stopped
M difi ti f Cl t
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Modification of Clusters
Use the Administrative console or wsadmin
What can be changed in a Cluster?
Cluster Member settings:Weights
Prefer LocalInstall or update applications
Application Server settingsCluster members are application servers and the normal application
server settings can be modified
After making changes:
Save the configuration and resynchronizeRegenerate the HTTP Server plug-in and redistribute it
B i WLM R t R ti
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Basic WLM Request Routing
Routing Decision Points
Load BalancerRouting decision table stored
internally
Configured using NDAdmin toolMultiple intelligent routing options
HTTP Server Plug-inRouting table part of plugin-cfg.xml
Configured using Administrative Consoleor wsadmin scripting tool
WLM-aware ClientIncludes Web Container, Java client, EJB
Routing table supplied by name serverConfigured using Administrative Console
or wsadmin scripting tool
Options:Prefer Local - yes or no
LoadBalancer
HTTPServer
Plugin
HTTP(s)
App Server
WebContainer
App Server
EJB
Container
HTTP(s)
IIOP
W i ht d R ti E l
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Weighted Routing Example
Routing Table*
14
Server 1 Server 2Server 2
Weight = 2
Server 1
Weight = 8EJBClient
ORB
WLMPlug-in
HTTPServer
Plug-in
* HTTP Plug-in reduces to lowest common denominator.
EJB WLM uses two tables for Prefer Local & Remote
After: Server 1 Server 2
0 requests 4 1
1 request 3 1
2 requests 3 0
3 requests 2 04 requests 1 0
5 requests 0 0
Reset: 4 1
No NEW Requests to App Server 2
Ed C t F il
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Edge Components Failover
Load Balancer can be paired with a backup machine
Topology is 'Active/Standby'
One machine does all the work
The other waits for a failure to begin handling routing
LoadBalancer
LoadBalancer
HTTPServer
Plugin
HTTP(s)
HTTP Server Failover
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HTTP Server Failover
Multiple HTTP servers provide coverage
Load Balancer can route around a failed HTTP server
HTTP Plug-in
Every plug-in knows about all Web containers
Session key contains address of serverSessions get properly routed
Topology is 'Active/Active',
with all HTTP servershandling load before failover
HTTPServer
Plugin
LoadBalancer
HTTPServer
Plugin
HTTP(s)
App Server
WebContainer
HTTP(s)
HTTPServer
Plugin
App Server
WebContainer
App Server
WebContainer
Web Container Failover
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Web Container Failover
HTTP Server Plug-in
Detects Failure
Marks Container as unavailable
Tries next Cluster member in the Cluster
What about in-flight sessions?Sessions may be persisted
to database
Sessions may be replicatedin memory
HTTPServer
Plugin
App Server
Web
Container
App Server
EJB
Container
HTTP(s)
IIOP
App Server
WebContainer
App Server
Web
Container
EJB Container Failover
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EJB Container Failover
Client code and ORB plug-in can route to next available
cluster member
Failure occurs before any work was initiated on the cluster
member:
ORB automatically re-routes EJB requestIf no other cluster member available, throws
"NO_IMPLEMENT" exception
Failure occurs after EJB method call initiated work:System exceptions are thrown
Client needs to determine
appropriate recovery actionRe-issue request, rollback transaction, etc.
If "NO_IMPLEMENT" exception
thrown, no recovery is possible
App Server
WebContainer
App Server
EJBContainer
IIOP
App Server
EJBContainer
App Server
EJBContainer
JavaClient
Node Agent Failover
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Node Agent Failover
V5 clients need one Node Agent up for first call to name
server
These clients can use a list of name servers if multiple
nodes are available in the topology
The IOR contains the list of name server host and portsInteroperability
V3 and V4 clients will work only when the specific Node
Agent they connect to is aliveWebSphere-aware clients get "special treatment"
WebSphere private information in the WLM
TaggedComponentIncludes a complete description of the cluster's topology
Secure and non-secure transport ports for all cluster members are
included and can be used directly by the client ORB
Support for Third-party Client ORB
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Support for Third-party Client ORB
WebSphere Application Server supplies "indirect IOR" to
client ORB for EJB WLM
According to the specs defined by CORBA's GIOP 1.4
Indirect IOR points to the Node Agent
Node Agent used to get "direct IOR" pointing to actualcluster member
Failover Support
Third-party ORB compliant with GIOP 1.4Request fails, ORB gets new IOR via indirect IOROther ORBs
Less transparent recovery
Likely to need to regain access to the object via create() or findBy...()
Deployment Manager Failover
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Deployment Manager Failover
Deployment Manager failover not implemented
Node Agents have copies of all configuration information
Consequence of Deployment Manager failure:
Unable to broadcast configuration changes to Node Agents
Administrative Console unavailablewsadmin unavailable (unless directed to specific server)
In short, you cannot change the master configuration
Deployment Manager handles routing table 'masters'If the Deployment Manager is down, failed or stopped
servers will still have routed requests
Performance degradation is possible if Deployment
Manager stays down
HTTP Session Management
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HTTP Session Management
HTTP is a stateless protocol
Sessions allow you to maintain state information across a
series of HTTP requests from the same client.
For example, maintain shopping cart until checkout.
Java Servlet specification defines session managementprocess for Web applications
Session Manager stores Session information, and sends
client a unique Session ID through:Cookie in HTTP header, or
URL rewriting in parameter on links or forms
SessionID: 123:AWeb
Client
HTTP
ServerPlug-in
App Server A
Web
ContainerSessionID: 123:A
Session Object
SessionID: 123
ServerID: ACustName: BobProductID: xyz
Session Affinity
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Session Affinity
An application may retain state information for a users
session in memory.
Other servers in the cluster do not have this information.
HTTP Server Plug-in routes subsequent Servlet requests
consistently to same Application Server after Session createdUsing Server ID passed with Session ID in cookie or URL
SessionID: 123:A
HTTPServer
Plug-in
App Server A
Web
Container
SessionID: 123
ServerID: ACustName: Bob
ProductID: xyz
App Server B
WebContainer
WebClient
Web
Client
SessionID: 456:B
SessionID: 456
ServerID: B
CustName: Joe
ProductID: abc
Session Persistence
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Session Persistence
Session object cached in memory by server
Session object will be lost if server fails
Two methods to enable persistence
Database
Session objects persisted using JDBC data sourceDB2 included in WAS package for session persistence
Memory-to-Memory replicationSessions copied to another server using WebSphere Internal
MessagingMultiple topology models possible:
Single Replica ('Buddy') N-way peer-to-peer
Client/server (Dedicated replication server)Can specify when replication performed
Data transfer between JVMs can be encrypted
Better performance than database persistence
WebSphere Internal Messaging
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WebSphere Internal Messaging
N-way Peer-to-Peer
Client/server
WebContainer
WAS
(Store)
WebContainer
WAS
(Store)
WebContainer
WAS
(Store)
WebContainer
WAS
WebContainer
WAS
WAS
(Store)
WAS
(Store)
Session Configuration
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Session Configuration
Three levels:
Web Container
Application
Web Module
Database Persistence Configuration
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Database Persistence Configuration
Create database in DBMS
Create data source: Resources > JDBC Providers
Select Database in Distributed Environment Settings page
Configure database settings
Internal Messaging Configuration
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g g g
Create replication domain
Can be created when creating clusterOr use: Environment > Internal Replication Domains
Select Memory to Memory Replication in Distributed
Environment Settings pageConfigure InternalMessaging settings
Partitions allow serversto listen only onconfigured channelsNumber of partitions is
configurableRecommendation:Use at least 10 partitionchannels per cluster
Unit Summary
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y
Workload Management possible for:
HTTP requests (using Load Balancer)
Servlet requests (using plug-in)
EJB requests (using plug-in to Object Request Broker)
WAS V5 supports clusters of serversCluster members created from templates
Server weights control distribution of requests
Cluster can be started/stopped as a unitMany configurations (topologies) possible
Vertical scaling to increase utilization of large machine
Horizontal scaling for scalability and failover
Session management enabled at Web Container, Applicationor Web module level
Session affinity routes sessions requests to same server
Session persistence via database or messaging
