88 Configuring a Coordinated Cache

This chapter describes how to configure a TopLink coordinated cache.

Table 88-1 Configuring TopLink Coordinated Caches

If you are configuring a...	See...
JMS Coordinated Cache	Chapter 89, "Configuring a JMS Coordinated Cache"
RMI Coordinated Cache	Chapter 90, "Configuring an RMI Coordinated Cache"
CORBA Coordinated Cache	Chapter 91, "Configuring a CORBA Coordinated Cache"
Custom Coordinated Cache	Chapter 92, "Configuring a Custom Coordinated Cache"

Table 88-1 lists the configurable options shared by two or more TopLink coordinated cache types.

For more information, see "Understanding Cache Coordination".

Configuring Common Coordinated Cache Options

Table 88-1 lists the configurable options shared by two or more TopLink coordinated cache types. In addition to the configurable options described here, you must also configure the options described for the specific Coordinated Cache Types, as shown in Table 88-2.

Table 88-2 Common Coordinated Cache Options

Option	Type	TopLink Workbench	Java
"Configuring Cache Coordination Change Propagation at the Descriptor Level"	Basic
"Configuring the Synchronous Change Propagation Mode"	Basic
"Configuring a Service Channel"	Basic
"Configuring a Multicast Group Address"	Basic
"Configuring a Multicast Port"	Basic
"Configuring a Naming Service Type"	Basic
"Configuring an Announcement Delay"	Basic
"Configuring Connection Handling"	Advanced
"Configuring Context Properties"	Advanced
"Configuring a Packet Time-to-Live"	Advanced

Configuring the Synchronous Change Propagation Mode

You can configure whether the coordinated cache should propagate object changes asynchronously or synchronously.

Table 88-3 summarizes which coordinated caches support propagation mode configuration.

Table 88-3 Coordinated Cache Support for Propagation Mode Configuration

Coordinated Cache	Using TopLink Workbench	Using Java
JMS Coordinated Cache (asynchronous only)
RMI Coordinated Cache
CORBA Coordinated Cache
Custom Coordinated Cache

Synchronous propagation mode forces the session to wait for an acknowledgement before sending the next object change notification: this reduces the likelihood of stale data at the expense of performance.

Asynchronous propagation mode allows the session to create separate threads to propagate changes to remote servers. TopLink returns control to the client immediately after the local commit operation, whether or not the changes merge successfully on the remote servers. This offers superior performance for applications that are somewhat tolerant of stale data.

For more information, "Handling Stale Data".

Using TopLink Workbench

To specify the change propagation mode, use this procedure:

1. Select a session or session broker in the Navigator. Its properties appear in the Editor.

2. Click the Cache Coordination tab. The Cache Coordination tab appears.

3. Ensure the Enable Cache Coordination option is selected, then select the appropriate coordinated cache Type (see Table 88-3). The cache coordination options appear on the tab.

   Figure 88-1 Cache Coordination Tab, Synchronous Field

   
   Description of "Figure 88-1 Cache Coordination Tab, Synchronous Field"
   
   

4. Select the Synchronous option to use synchronous change propagation. Do not select this option to use asynchronous change propagation.

Configuring a Service Channel

The service channel is the name of the TopLink coordinated cache channel to which sessions subscribe in order to participate in the same coordinated cache. Such sessions use the service channel to exchange messages with each other. Messages sent on other service channels will not be exchanged with this coordinated cache.

Table 88-4 summarizes which coordinated caches support service channel configuration.

Table 88-4 Coordinated Cache Support for Service Channel Configuration

Coordinated Cache	Using TopLink Workbench	Using Java
JMS Coordinated Cache
RMI Coordinated Cache
CORBA Coordinated Cache
Custom Coordinated Cache

Using TopLink Workbench

To specify the service channel, use this procedure:

1. Select a session or session broker in the Navigator. Its properties appear in the Editor.

2. Click the Cache Coordination tab. The Cache Coordination tab appears.

3. Ensure the Enable Cache Coordination option is selected, then select the appropriate coordinated cache Type (see Table 88-4). The cache coordination options appear on the tab.

   Figure 88-2 Cache Coordination Tab, Channel Field

   
   Description of "Figure 88-2 Cache Coordination Tab, Channel Field"
   
   

4. In the Channel field, enter the name of the service channel for this coordinated cache.

Configuring a Multicast Group Address

A multicast group address is an Internet Protocol (IP) address in the range 224.0.0.0 to 239.255.255.255 that identifies the members of an IP multicast group. To efficiently broadcast the same message to all members of an IP multicast group, you configure each recipient with the same multicast group address and send the message to that address.

Table 88-5 summarizes which coordinated caches support multicast group address configuration.

Table 88-5 Coordinated Cache Support for Multicast Group Address Configuration

Coordinated Cache	Using TopLink Workbench	Using Java
JMS Coordinated Cache
RMI Coordinated Cache
CORBA Coordinated Cache
Custom Coordinated Cache

Note: Ensure your host and network are configured to support multicast operation before configuring this option.

In addition to configuring the multicast group address, you must also configure the multicast port (see "Configuring a Multicast Port") for the coordinated cache types shown in Table 88-5.

Using TopLink Workbench

To specify the multicast group address, use this procedure:

1. Select a session or session broker in the Navigator. Its properties appear in the Editor.

2. Click the Cache Coordination tab. The Cache Coordination tab appears.

3. Ensure the Enable Cache Coordination option is selected, then select the appropriate coordinated cache Type (see Table 88-5). The cache coordination options appear on the tab.

   Figure 88-3 Cache Coordination Tab, Multicast Group Address Field

   
   Description of "Figure 88-3 Cache Coordination Tab, Multicast Group Address Field"
   
   

4. Enter the multicast group address in the range 224.0.0.0 to 239.255.255.255 to subscribe this session to a given coordinated cache.

Configuring a Multicast Port

The multicast port is the port on which multicast messages are received. Members of a multicast group (see "Configuring a Multicast Group Address") rely on messages broadcast to their multicast group address to communicate with one another.

Table 88-6 summarizes which coordinated caches support multicast port configuration.

Table 88-6 Coordinated Cache Support for Multicast Port Configuration

Coordinated Cache	Using TopLink Workbench	Using Java
JMS Coordinated Cache
RMI Coordinated Cache
CORBA Coordinated Cache
Custom Coordinated Cache

Note: Ensure your host and network are configured to support multicast operation before configuring this option

Using TopLink Workbench

To specify the multicast port, use this procedure:

1. Select a session or session broker in the Navigator. Its properties appear in the Editor.

2. Click the Cache Coordination tab. The Cache Coordination tab appears.

3. Ensure the Enable Cache Coordination option is selected, then select the appropriate coordinated cache Type (see Table 88-6). The cache coordination options appear on the tab.

   Figure 88-4 Cache Coordination Tab, Multicast Port Field

   
   Description of "Figure 88-4 Cache Coordination Tab, Multicast Port Field"
   
   

4. Enter the multicast port on which messages broadcast to the multicast group address are received.

Configuring a Naming Service Type

The session's message transport service uses a naming service when it looks up connections to other sessions in the coordinated cache. You can configure the message transport service to look up remote objects using an RMI registry or Java Naming and Directory Interface (JNDI). By default, JNDI is used.

Table 88-7 summarizes which coordinated caches support naming service configuration.

Table 88-7 Coordinated Cache Support for Naming Service Configuration

Coordinated Cache	JNDI Naming Service	RMI Registry Naming Service
JMS Coordinated Cache
RMI Coordinated Cache
CORBA Coordinated Cache
Custom Coordinated Cache

For information, see:

• "Configuring RMI Registry Naming Service Information"

• "Configuring JNDI Naming Service Information"

Configuring JNDI Naming Service Information

The session's message transport service uses a naming service when it looks up connections to other sessions in the coordinated cache. If you choose to use a JNDI naming service, you must configure JNDI naming service information.

Table 88-8 summarizes which coordinated caches support JNDI naming service configuration.

Table 88-8 Coordinated Cache Support for JNDI Naming Service Configuration

Coordinated Cache	Using TopLink Workbench	Using Java
JMS Coordinated Cache
RMI Coordinated Cache
CORBA Coordinated Cache
Custom Coordinated Cache

TopLink uses JNDI naming service information differently, depending on the type of coordinated cache.

For a JMS coordinated cache, when a particular session's coordinated cache starts up, it uses its JNDI naming service information to locate and create a connection to the JMS server. The coordinated cache is ready when all participating sessions are connected to the JMS server. At this point, sessions can start sending and receiving object change messages. You can then configure all sessions that are participating in the same coordinated cache with the same JNDI naming service information.

For an RMI or CORBA coordinated cache, when a particular session's coordinated cache starts up, the session binds its connection in JNDI, creates an announcement message (that includes its own JNDI naming service information), and broadcasts the announcement to its multicast group (see "Configuring a Multicast Group Address" and "Configuring a Multicast Port"). When a session that belongs to the same multicast group receives this announcement, it uses the JNDI naming service information in the announcement message to establish bidirectional connections with the newly announced session's coordinated cache. The coordinated cache is ready when all participating sessions are interconnected in this way, at which point, sessions can start sending and receiving object change messages. You can then configure each session with JNDI naming information that identifies the host on which the session is deployed.

Using TopLink Workbench

To specify the sessions's JNDI naming service, use this procedure:

1. Select a session or session broker in the Navigator. Its properties appear in the Editor.

2. Click the Cache Coordination tab. The Cache Coordination tab appears.

3. Ensure the Enable Cache Coordination option is selected, then select the appropriate coordinated cache Type (see Table 88-8). The cache coordination options appear on the tab.

   Figure 88-5 Cache Coordination Tab, JNDI Naming Service Options

   
   Description of "Figure 88-5 Cache Coordination Tab, JNDI Naming Service Options"
   
   

Use the following information to enter data in the fields of the Cache Coordination tab to configure the naming service options:

Field	Description
URL	The location of the JNDI naming service. For a JMS coordinated cache: If you are using the Oracle Containers for J2EE (OC4J) JNDI naming service and all the hosts in your coordinated cache can communicate using the OC4J proprietary RMI protocol ORMI, use a URL similar to the following: ormi://<JMS-host-IP>:<JMS-host-port> where JMS-host-IP is the IP address of the host on which the JMS service provider is running and JMS-host-port is the port on which the JMS service provider is listening for JMS requests. For an RMI or CORBA coordinated cache: If you are using the OC4J JNDI naming service and all the hosts in your coordinated cache can communicate using the OC4J proprietary RMI protocol ORMI on OC4J default port 23791, use a URL similar to the following: ormi://<session-host-IP>:23791 where session-host-IP is the IP address of the host on which this session is deployed.
Username	The user name required to log in to the JNDI naming service. The value you enter defines the Context.SECURITY_PRINCIPAL environment property.
Password	The plain text (unencrypted) password required to log in to the JNDI naming service. The password appears in plain text in TopLink Workbench, but it is encrypted when written to the sessions.xml file The value you enter defines the Context.SECURITY_CREDENTIALS environment property.
Initial Context Factory	The name of the factory class, provided by your JNDI naming service provider, that implements the javax.naming.spi.InitialContextFactory interface. This factory class is used to create a javax.naming.Context instance that can access the JNDI naming service provider's context implementation. The value you enter defines the Context.INITIAL_CONTEXT_FACTORY environment property.
Properties	The JNDI context properties. Click Properties to configure custom JNDI context properties (see "Configuring Context Properties").

Configuring RMI Registry Naming Service Information

The session's message transport service uses a naming service when it looks up connections to other sessions in the coordinated cache. If you choose to use an RMI registry naming service, you can configure RMI registry naming service options.

Table 88-8 summarizes which coordinated caches support RMI registry naming service configuration.

Table 88-9 Coordinated Cache Support for RMI Registry Naming Service Configuration

Coordinated Cache	Using TopLink Workbench	Using Java
JMS Coordinated Cache
RMI Coordinated Cache
CORBA Coordinated Cache
Custom Coordinated Cache

For an RMI coordinated cache, when a particular session's coordinated cache starts up, the session binds its connection in its RMI registry, creates an announcement message (that includes its own naming service information), and broadcasts the announcement to its multicast group (see "Configuring a Multicast Group Address" and "Configuring a Multicast Port"). When a session that belongs to the same multicast group receives this announcement, it uses the JNDI naming service information in the announcement message to establish bidirectional connections with the newly announced session's coordinated cache. The coordinated cache is ready when all participating sessions are interconnected in this way, at which point, sessions can start sending and receiving object change messages. You can then configure each session with RMI registry naming information that identifies the host on which the session is deployed.

Using TopLink Workbench

To specify the sessions's registry naming service, use this procedure:

1. Select a session or session broker in the Navigator. Its properties appear in the Editor window.

2. Click the Cache Coordination tab. The Cache Coordination tab appears.

3. Ensure the Enable Cache Coordination option is selected, then select the appropriate coordinated cache Type (see Table 88-9). The cache coordination options appear on the tab.

   Figure 88-6 Cache Coordination Tab, Naming Service Options

   
   Description of "Figure 88-6 Cache Coordination Tab, Naming Service Options"
   
   

Use the following information to configure the naming service options:

Field	Description
URL	Assuming that you are using the OC4J JNDI naming service and that all the hosts in your coordinated cache can communicate using the OC4J proprietary RMI protocol ORMI on OC4J default port 23791, use a URL similar to the following: ormi://<session-host-IP>:23791 where session-host-IP is the IP address of the host on which this session is deployed.

Configuring an Announcement Delay

Use the announcement delay option to set the amount of time (in milliseconds) that a session should wait between the time that it is available and the time that it broadcasts its announcement message to the members of the coordinated cache. This additional delay may be necessary to give some systems more time to post their connections into the naming service (see "Configuring a Naming Service Type").

Table 88-10 summarizes which coordinated caches support announcement delay configuration.

Table 88-10 Coordinated Cache Support for Announcement Delay Configuration

Coordinated Cache	Using TopLink Workbench	Using Java
JMS Coordinated Cache
RMI Coordinated Cache
CORBA Coordinated Cache
Custom Coordinated Cache

In addition to announcement delay, you may also need to consider packet time-to-live configuration (see "Configuring a Packet Time-to-Live").

Using TopLink Workbench

To specify the announcement delay (in milliseconds) for an RMI coordinated cache, use this procedure:

1. Select a session or session broker in the Navigator. Its properties appear in the Editor.

2. Click the Cache Coordination tab. The Cache Coordination tab appears.

3. Ensure the Enable Cache Coordination option is selected, then select the appropriate coordinated cache Type (see Table 88-10). The cache coordination options appear on the tab.

   Figure 88-7 Cache Coordination Tab, Announcement Delay Field

   
   Description of "Figure 88-7 Cache Coordination Tab, Announcement Delay Field"
   
   

4. Select the amount of time (in milliseconds) that this session should wait between the time that it is available and the time that it broadcasts its announcement message to the members of the coordinated cache.

Configuring Connection Handling

The session's transport manager creates connections to the various members of the coordinated cache. If a communication error occurs on one of these connections, you can configure the session to either ignore the error or remove the connection.

Table 88-11 summarizes which coordinated caches support connection handling configuration.

Table 88-11 Coordinated Cache Support for Connection Handling Configuration

Coordinated Cache	Using TopLink Workbench	Using Java
JMS Coordinated Cache
RMI Coordinated Cache
CORBA Coordinated Cache
Custom Coordinated Cache

If you configure the session to remove the connection on error, the next time the session tries to communicate with that coordinated cache member, it will construct a new connection.

If you configure the session to ignore the error, the next time the session tries to communicate with that coordinated cache member, it will continue to use the same connection.

Using TopLink Workbench

To specify how TopLink handles session connections in the event of an error, use this procedure:

1. Select a session or session broker in the Navigator. Its properties appear in the Editor.

2. Click the Cache Coordination tab. The Cache Coordination tab appears.

3. Ensure the Enable Cache Coordination option is selected, then select the appropriate coordinated cache Type (see Table 88-11). The cache coordination options appear on the tab.

   Figure 88-8 Cache Coordination Tab, Remove Connection on Error Option

   
   Description of "Figure 88-8 Cache Coordination Tab, Remove Connection on Error Option"
   
   

4. Select the Remove Connection on Error option to configure the session to remove the data source connection in the event of an error.

Configuring Context Properties

When you configure a coordinated cache to use a JNDI naming service (see "Configuring a Naming Service Type"), you can add new environment properties to the environment of the initial JNDI context.

Table 88-12 summarizes which coordinated caches support context properties.

Table 88-12 Coordinated Cache Support for Context Properties

Coordinated Cache	Using TopLink Workbench	Using Java
JMS Coordinated Cache
RMI Coordinated CacheFoot 1
CORBA Coordinated CacheFootref 1
Custom Coordinated Cache

^Footnote 1 When JNDI naming service is selected (see "Configuring a Naming Service Type").

Using TopLink Workbench, TopLink uses the new environment properties you add to create the initial context for both local and remote JNDI access.

Using Java, you can configure different properties for local and remote JNDI access using a session customizer class to call TransportManager methods setLocalContextProperties and setRemoteContectProperties (for more information, see "Configuring Customizer Class").

Using TopLink Workbench

To define JNDI context properties, use this procedure:

1. Select a session or session broker in the Navigator. Its properties appear in the Editor.

2. Ensure the Enable Cache Coordination option is selected, then select the appropriate coordinated cache Type (see Table 88-12). The cache coordination options appear on the tab.

3. Ensure the JNDI Naming Service option is selected. See "Configuring a Naming Service Type".

4. In the JNDI Naming Service area, click Properties. The Edit Properties dialog box appears.

   Figure 88-9 Edit Properties Dialog Box

   
   Description of "Figure 88-9 Edit Properties Dialog Box"
   
   

5. Click Add to create a new property. The Add New Property dialog box appears.

   To change (or delete) an existing property, select the property and click Edit (or Remove).

Use this table to enter data in the following fields on the dialog box.

Field	Description
Name	The name of the property.
Value	The value of the property.

Configuring a Packet Time-to-Live

The packet time-to-live is the number of hops that session data packets can take before expiring. The default is 2. This allows for a hub and an interface card, and prevents the data packets from leaving the local network. If sessions are hosted on different local area networks (LANs) that are part of wide area network (WAN), or if a firewall configuration prevents it, the announcement sent by one session may not reach the other sessions in the coordinated cache. In this case, consult your network administrator for the correct time-to-live value.

Table 88-13 summarizes which coordinated caches support packet time-to-live configuration.

Table 88-13 Coordinated Cache Support for Packet Time-to-Live Configuration

Coordinated Cache	Using TopLink Workbench	Using Java
JMS Coordinated Cache
RMI Coordinated Cache
CORBA Coordinated Cache
Custom Coordinated Cache

In addition to configuring packet time-to-live, you may also need to configure announcement delay (see "Configuring an Announcement Delay").

Using TopLink Workbench

To specify the number of hops that session data packets can take before expiring, use this procedure:

1. Select a session or session broker in the Navigator. Its properties appear in the Editor.

2. Ensure the Enable Cache Coordination option is selected, then select the appropriate coordinated cache Type (see Table 88-12). The cache coordination options appear on the tab.

   Figure 88-10 Cache Coordination Tab, Packet Time to Live Field

   
   Description of "Figure 88-10 Cache Coordination Tab, Packet Time to Live Field"
   
   

In the Packet Time to Live field, specify the number of hops (default = 2) that session data packets can take before expiring.