ExternalCacheAdapter (IBM WebSphere Application Server, Release 8.5)

```
public interface ExternalCacheAdapter
```
This is the service provider's interface (SPI) for plugging in an external cache (eg, the AFPA cache, a web server cache, a proxy server cache or a sprayer cache). Each implementation of this interface encapsulates the particular protocol supported by an external cache. The CacheCoordinator calls this interface to manage pages in external caches. It is always called locally.
Restrictions on JSP fragments cached externally are the following:
- It must be a top-level fragment (ie, an externally requested page).
- It must not have any security access restrictions. This restriction can be relaxed if the external cache supports some form of access control.
- It must not need access statistics gathered. This restriction can be relaxed if the external cache supports some form of statistics gathering.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`clear()` This method invalidates all pages from the external cache.
`void`	`invalidateIds(java.util.Iterator ids)` This method invalidates dependency ids that are in the external cache.
`void`	`invalidatePages(java.util.Iterator urls)` This method invalidates pages that are in the external cache.
`void`	`postInvoke(ServletCacheRequest sreq, javax.servlet.http.HttpServletResponse sresp)` This method is invoked after processing a cache hit or miss of an externally cacheable element
`void`	`preInvoke(ServletCacheRequest sreq, javax.servlet.http.HttpServletResponse sresp)` This method is invoked before processing a cache hit or miss of an externally cacheable element
`void`	`setAddress(java.lang.String address)` This method sets the TCP/IP address of the cache adapter
`void`	`writePages(java.util.Iterator externalCacheEntries)` This method writes pages to the external cache.

- Method Detail
  - setAddress
```
void setAddress(java.lang.String address)
```
    This method sets the TCP/IP address of the cache adapter
    
    Parameters:
    address - Address of the cache adapter
  - writePages
```
void writePages(java.util.Iterator externalCacheEntries)
```
    This method writes pages to the external cache.
    
    Parameters:
    externalCacheEntries - The Enumeration of ExternalCacheEntry objects for the pages that are to be cached.
  - invalidatePages
```
void invalidatePages(java.util.Iterator urls)
```
    This method invalidates pages that are in the external cache.
    
    Parameters:
    urls - The List of URLs for the pages that have previously been written to the external cache and need invalidation.
  - invalidateIds
```
void invalidateIds(java.util.Iterator ids)
```
    This method invalidates dependency ids that are in the external cache.
    
    Parameters:
    ids - The Enumeration of dependency ids that must be invalidated
  - preInvoke
```
void preInvoke(ServletCacheRequest sreq,
             javax.servlet.http.HttpServletResponse sresp)
```
    This method is invoked before processing a cache hit or miss of an externally cacheable element
    
    Parameters:
    sreq - The request object being used for this invocation
    sresp - The response object being used for this invocation
  - postInvoke
```
void postInvoke(ServletCacheRequest sreq,
              javax.servlet.http.HttpServletResponse sresp)
```
    This method is invoked after processing a cache hit or miss of an externally cacheable element
    
    Parameters:
    sreq - The request object being used for this invocation
    sresp - The response object being used for this invocation
  - clear
```
void clear()
```
    This method invalidates all pages from the external cache.

setAddress

writePages

invalidatePages

invalidateIds

preInvoke

postInvoke

clear