![[Java programming language only]](./images/ngjava.gif)
The WebSphere® Application
Server provides
a dynamic cache service that is available to deployed Java™ EE applications.
This service is used to cache data such as output from servlet, JSP,
or commands, and object data programmatically specified within an
enterprise application with the DistributedMap APIs. By setting up this capability, you can enable
applications that use the dynamic cache service, to use the features
and performance capabilities of the WebSphere DataPower® XC10 Appliance.
Initially, the only service provider for the dynamic cache service was the default dynamic cache engine that is built into WebSphere Application Server. You can also specify WebSphere DataPower XC10 Appliance to be the cache provider for any cache instance. By setting up this capability, you can enable applications that use the dynamic cache service, to use the features and performance capabilities of .
You can install and configure the dynamic cache provider as described in Configuring the default dynamic cache instance (baseCache).
Deciding how to use WebSphere DataPower XC10 Appliance
The available features in WebSphere DataPower XC10 Appliance significantly increase the distributed capabilities of the dynamic cache service beyond what is offered by the default dynamic cache provider and data replication service. With eXtreme Scale, you can create caches that are truly distributed between multiple servers, rather than just replicated and synchronized between the servers. Also, eXtreme Scale caches are transactional and highly available, ensuring that each server sees the same contents for the dynamic cache service. WebSphere DataPower XC10 Appliance offers a higher quality of service for cache replication provided via DRS.
However, these advantages do not mean that the eXtreme Scale dynamic cache provider is the right choice for every application. Use the decision trees and feature comparison matrix below to determine what technology fits your application best.
Decision tree for migrating existing dynamic cache applications
Decision tree for choosing a cache provider for new applications
Feature comparison
| Cache features | Default provider | eXtreme Scale provider | eXtreme Scale API |
|---|---|---|---|
Local, in-memory caching |
Yes |
via Near-cache capability |
via Near-cache capability |
Distributed caching |
via DRS |
Yes |
Yes |
Linearly scalable |
No |
Yes |
Yes |
Reliable replication (synchronous) |
No |
Yes |
Yes |
Disk overflow |
Yes |
N/A |
N/A |
Eviction |
LRU/TTL/heap-based |
LRU/TTL (per partition) |
LRU/TTL (per partition) |
Invalidation |
Yes |
Yes |
Yes |
Relationships |
Dependency / template ID relationships |
Yes |
No (other relationships are possible) |
Non-key lookups |
No |
No |
via Query and index |
Back-end integration |
No |
No |
via Loaders |
Transactional |
No |
Yes |
Yes |
Key-based storage |
Yes |
Yes |
Yes |
Events and listeners |
Yes |
No |
Yes |
WebSphere Application Server integration |
Single cell only |
Multiple cell |
Cell independent |
Java Standard Edition support |
No |
Yes |
Yes |
Monitoring and statistics |
Yes |
Yes |
Yes |
Security |
Yes |
Yes |
Yes |
Dynamic cache engine and eXtreme Scale functional differences
Users should not notice a functional difference between the two caches except that the WebSphere DataPower XC10 Appliance backed caches do not support disk offload or statistics and operations related to the size of the cache in memory.
No appreciable difference exists in the results returned by most dynamic cache API calls, regardless of whether you are using the default dynamic cache provider or the eXtreme Scale cache provider. For some operations, you cannot emulate the behavior of the dynamic cache engine with eXtreme Scale.
Dynamic cache statistics
MBean calls
The WebSphere eXtreme Scale dynamic cache provider does not support disk caching. Any MBean calls relating to disk caching do not work.
Dynamic cache replication policy mapping
The eXtreme Scale dynamic cache provider's remote topology supports a replication policy that most closely matches the SHARED_PULL and SHARED_PUSH_PULL policy (using the terminology used by the default WebSphere Application Server dynamic cache provider). In an eXtreme Scale dynamic cache, the distributed state of the cache is consistent between all the servers.
Global index invalidation
You can use a global index to improve invalidation efficiency in large partitioned environments; for example, more than 40 partitions. Without the global index feature, the dynamic cache template and dependency invalidation processing must send remote agent requests to all partitions, which results in slower performance. When you configure a global index, invalidation agents are sent only to applicable partitions that contain cache entries that are related to the Template or Dependency ID. The potential performance improvement is greater in environments with large numbers of partitions configured. You can configure a global index with the Dependency ID and Template ID indexes, which are available in the example dynamic cache objectGrid descriptor XML files.Near cache
You can configure a dynamic cache instance to create and maintain a near cache, which resides locally within the application server JVM. The near cache contains a subset of the entries that are contained within the remote dynamic cache instance. For more information, see Configuring a near cache for the dynamic cache. There are also custom properties for tuning the near-cache. For more information, see Dynamic cache custom properties.
![[Version 2.5 and later]](./images/25plus.gif)
Multi-master replication
You can choose to enable multi-master replication on the WebSphere DataPower XC10 Appliance dynamic cache provider. For more information, see Configuring multi-master replication between collectives.
Additional information
- Dynamic cache Redbook
- Dynamic cache documentation
- DRS documentation