Changes to Connection Pool Configuration to Support ClusterdPools

Original Request: 18 Aug 2006.

<pre>

> attributes :
> pool-name
> the pool-id associated with the resource.
> In case of clustered-pool, it can be a comma separated
> list of available connection pools.
>

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> attributes
>
> pool-name
> the pool-id associated with the resource.
> In case of clustered-pool, it can be a comma separated
> list of available connection pools.
>

Comments : This is only a description change.
Now pool-name can take comma-separated connection-pool ids. The DTD has no impact as such.

------------------------------------------------------------------------------------------------------

• DTD change associated with introduction of sun-specific-property

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> sun-specific-property
> To enable application server specific connection pool features.
> (See <sun-specific-property>)
>
> The following are the names and corresponding description for these
> properties
>
> LeakTracing
> To aid user in detecting potential connection leaks by
> application.
>
> ConnectionLeakTimeout
> The period after which connection is considered to
> be leaked.
>
> ConnectionCreationRetry
> To retry connection creation for specific number of
> times, at specified intervals
>
> ConnectionCreationRetryAttempts
> The number of attempt to create a new connection
> when requested by application
>
> ConnectionCreationRetryInterval
> The time interval between successive retry to create
> a connection
>
> ValidateAtmostPeriod
> Validates atmost once in the specified time-interval
>
> StatementTimeout
> Sets the timeout property of a connection to enable
> termination of abnormally long running queries.
>
> PollInterval
> The time interval between successive polling of failed node.
> Applicable only for clustered pool.
>

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< <!ELEMENT jdbc-connection-pool (description?, property*)>
—

> <!ELEMENT jdbc-connection-pool (description?, sun-specific-property* property*)>

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> sun-specific-property
> To enable application server specific connection pool features.
> (See <sun-specific-property>)
>
> The following are the names and corresponding description for these
> properties
>
> LeakTracing
> To aid user in detecting potential connection leaks by
> application.
>
> ConnectionLeakTimeout
> The period after which connection is considered to
> be leaked.
>
> ConnectionCreationRetry
> To retry connection creation for specific number of
> times, at specified intervals
>
> ConnectionCreationRetryAttempts
> The number of attempt to create a new connection
> when requested by application
>
> ConnectionCreationRetryInterval
> The time interval between successive retry to create
> a connection
>
> ValidateAtmostPeriod
> Validates atmost once in the specified time-interval
>
> PollInterval
> The time interval between successive polling of failed node.
> Applicable only for clustered pool.
>

Response from km105526@dev.java.net on 18 Aug 2006.

• the jdbc-resource and connector-resource are the elements that
  have pool-name as an attribute and that contains the value of
  the name of the jdbc/connector-connection-pool defined in the
  same config. So, in effect, you are suggesting changing the
  description of the "pool-name" attribute from this, to a list
  names that are comma separated. Is that right?

• if yes, then what are the implications of the same on the creation
  of jdbc-resource itself? For example, will the following kind
  of config now be seen in domain.xml:

resources
..
jdbc-resource jndi-name="jdbc/clustered-pool" pool-name="jcp1,jcp2" .../

jdbc-connection-pool name="jcp1" .../
jdbc-connection-pool name="jcp2" .../

/resources

• if yes, then this is not a change in the description alone. It gives me
  an impression that you are using existing infrastructure to expand
  the relationship between a resource and connection-pool. Currently, the
  relationship is one->one and you are extending it to be one->many.
  Is that right, or am I missing something?

• this is most likely going to complicate the behavior of --cascade option on
  delete-jdbc/connector-connection-pool commands. Can you give a little
  more thought to it? This is of course, if above is correct.

• Secondly, why do you need a <sun-specific-property> which is just
  same as <property> element? Why can't we reuse <property>? After all,
  <property> was designed to take care of vendor specific configuration
  options.

Lloyd's Response

From an API (eg AMX) perspective, I strongly dislike comma-separated lists of values. It forces the user to do an "all or none" whack of the value eg use a String[]. It forces the AMX code to parse the value to provide a decent API, which further couples the code:

String[] getPoolNames(); <= attribute must be parsed.

Also, we typically are lax about saying whether the following are all equivalent. Are these the same, or not?

{p1,p2,p3}

{p1,p2, p3}
{p1,p2, p3}

What about
{p1,,p2,p3}

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