Package de.businesscode.bcdui.web.cacheControl

Class DataModifiedFilter

java.lang.Object

de.businesscode.bcdui.web.cacheControl.DataModifiedFilter

All Implemented Interfaces:

jakarta.servlet.Filter

public class DataModifiedFilter
extends Object
implements jakarta.servlet.Filter

Cache control based on requested binding set name and data from scope_last_modified If a request matches a certain scope, we check its last_refreshed and compare it against the request's If-Modified-Since-Header If possible according to that, we send a 304 instead of forwarding to get new data - If the scope was found in bcd_cache_scope, we are active, otherwise we do chain.doFilter - If If-Modified-Since was sent, we compare that with the scopes scope_last_modified - If If-Modified-Since was not sent or data was out-dated, we call chain.doFilter and set expires to earliest_next_modified if given See bcdui4.DataModifiedFilter in web.xml for how to use

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	DataModifiedFilter.ScopeInfo	Holds information about a scope like when data was actually refreshed last time and possibly when it may be refreshed earliest next time

Field Summary

Fields

Modifier and Type	Field	Description
protected long	lastRefreshedMs
protected org.apache.logging.log4j.Logger	logger
static final int	REFRESH_PERIOD_DEFAULT
static final String	REFRESH_PERIOD_PARAM_NAME
protected long	refreshPeriodMs
protected Map<String,DataModifiedFilter.ScopeInfo>	scopesLamos
protected static final String	selectSQL
protected Calendar	utcCal

Constructor Summary

Constructors

Constructor	Description
DataModifiedFilter()

Method Summary

Modifier and Type	Method	Description
void	destroy()
protected boolean	didSend304(jakarta.servlet.ServletRequest req, jakarta.servlet.ServletResponse res)	Check whether we can send a 304 and do so of possible Will send "Last-Modified" header if the scope was found.
void	doFilter(jakarta.servlet.ServletRequest req, jakarta.servlet.ServletResponse res, jakarta.servlet.FilterChain chain)	Handle the request brings 304 or operation
protected String	getReqScope(jakarta.servlet.http.HttpServletRequest httpReq)	Derive the caching-scope from the request.
protected Long	getScopeLastModified(String scope)	Check whether we have a a last-modified for the scope and return it.
protected String	getSelectSql()	The query to get the scops' data
void	init(jakarta.servlet.FilterConfig filterConfig)
protected boolean	refreshNeeded(String scope)	Check whether we need to refresh the scope's data from bcd_cache_scope That is the case if refreshPeriodMs has passed since last update and earliestNextModified is not in the future
protected void	refreshScopes()	Read all scopes' information fresh from bcd_cache_scope

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

REFRESH_PERIOD_PARAM_NAME

public static final String REFRESH_PERIOD_PARAM_NAME

See Also:

• Constant Field Values

REFRESH_PERIOD_DEFAULT

public static final int REFRESH_PERIOD_DEFAULT

See Also:

• Constant Field Values

scopesLamos

protected Map<String,DataModifiedFilter.ScopeInfo> scopesLamos

logger

protected org.apache.logging.log4j.Logger logger

lastRefreshedMs

protected long lastRefreshedMs

refreshPeriodMs

protected long refreshPeriodMs

utcCal

protected Calendar utcCal

selectSQL

protected static final String selectSQL

See Also:

• Constant Field Values

Constructor Details

DataModifiedFilter

public DataModifiedFilter()

Method Details

doFilter

public void doFilter(jakarta.servlet.ServletRequest req,
 jakarta.servlet.ServletResponse res,
 jakarta.servlet.FilterChain chain)
              throws IOException,
jakarta.servlet.ServletException

Handle the request brings 304 or operation

Specified by:

doFilter in interface jakarta.servlet.Filter

Throws:

IOException

jakarta.servlet.ServletException

didSend304

protected boolean didSend304(jakarta.servlet.ServletRequest req,
 jakarta.servlet.ServletResponse res)

Check whether we can send a 304 and do so of possible Will send "Last-Modified" header if the scope was found. That triggers "If-Modified-Since" to be sent next time by the client

Parameters:

req -

res -

Returns:

false if 304 is not sufficient

getReqScope

protected String getReqScope(jakarta.servlet.http.HttpServletRequest httpReq)

Derive the caching-scope from the request. In this case we just use the BindingSet as the scope

Parameters:

httpReq -

Returns:

getScopeLastModified

protected Long getScopeLastModified(String scope)

Check whether we have a a last-modified for the scope and return it. Returns -1 if there was no entry found

Parameters:

scope -

Returns:

refreshNeeded

protected boolean refreshNeeded(String scope)

Check whether we need to refresh the scope's data from bcd_cache_scope That is the case if refreshPeriodMs has passed since last update and earliestNextModified is not in the future

Parameters:

scope -

Returns:

refreshScopes

protected void refreshScopes()

Read all scopes' information fresh from bcd_cache_scope

getSelectSql

protected String getSelectSql()

The query to get the scops' data

Returns:

init

public void init(jakarta.servlet.FilterConfig filterConfig)
          throws jakarta.servlet.ServletException

Specified by:

init in interface jakarta.servlet.Filter

Throws:

jakarta.servlet.ServletException

destroy

public void destroy()

Specified by:

destroy in interface jakarta.servlet.Filter