src/main/jbake/content/admin/configuration/containers.adoc

= Resources
:jbake-date: 2016-03-16
:jbake-type: page
:jbake-status: published
:jbake-tomeepdf:

All containers will be created automatically - which means you don't need to define them
if you don't need to tune their configuration - when a bean of their type if found.

To avoid that use `openejb.offline` property and set it to `true`. See link:server.html[Server Configuration] for more detail.

=== @Stateless

A `@Stateless` container.

Declarable in tomee.xml via

[source,xml]
----
<Container id="Foo" type="STATELESS">
    AccessTimeout = 30 seconds
    MaxSize = 10
    MinSize = 0
    StrictPooling = true
    MaxAge = 0 hours
    ReplaceAged = true
    ReplaceFlushed = false
    MaxAgeOffset = -1
    IdleTimeout = 0 minutes
    GarbageCollection = false
    SweepInterval = 5 minutes
    CallbackThreads = 5
    CloseTimeout = 5 minutes
    UseOneSchedulerThreadByBean = false
    EvictionThreads = 1
</Container>
----

Declarable in properties via

[source,bash]
----
Foo = new://Container?type=STATELESS
Foo.AccessTimeout = 30 seconds
Foo.MaxSize = 10
Foo.MinSize = 0
Foo.StrictPooling = true
Foo.MaxAge = 0 hours
Foo.ReplaceAged = true
Foo.ReplaceFlushed = false
Foo.MaxAgeOffset = -1
Foo.IdleTimeout = 0 minutes
Foo.GarbageCollection = false
Foo.SweepInterval = 5 minutes
Foo.CallbackThreads = 5
Foo.CloseTimeout = 5 minutes
Foo.UseOneSchedulerThreadByBean = false
Foo.EvictionThreads = 1
----

==== Configuration

===== AccessTimeout

Specifies the time an invokation should wait for an instance
of the pool to become available.

After the timeout is reached, if an instance in the pool cannot
be obtained, the method invocation will fail.

Usable time units: nanoseconds, microsecons, milliseconds,
seconds, minutes, hours, days.  Or any combination such as
"1 hour and 27 minutes and 10 seconds"

Any usage of the `javax.ejb.AccessTimeout` annotation will
override this setting for the bean or method where the
annotation is used.

===== MaxSize

Specifies the size of the bean pools for this stateless
SessionBean container.  If StrictPooling is not used, instances
will still be created beyond this number if there is demand, but
they will not be returned to the pool and instead will be
immediately destroyed.

===== MinSize

Specifies the minimum number of bean instances that should be in
the pool for each bean.  Pools are prefilled to the minimum on
startup.  Note this will create start order dependencies between
other beans that also eagerly start, such as other `@Stateless`
beans with a minimum or `@Singleton` beans using `@Startup`.  The
start order.

The minimum pool size is rigidly maintained.  Instances in the
minimum side of the pool are not eligible for `IdleTimeout` or
`GarbageCollection`, but are subject to `MaxAge` and flushing.

If the pool is flushed it is immediately refilled to the minimum
size with `MaxAgeOffset` applied.  If an instance from the minimum
side of the pool reaches its `MaxAge`, it is also immediately
replaced.  Replacement is done in a background queue using the
number of threads specified by `CallbackThreads`.

===== StrictPooling

StrictPooling tells the container what to do when the pool
reaches it's maximum size and there are incoming requests that
need instances.

With strict pooling, requests will have to wait for instances to
become available. The pool size will never grow beyond the the
set `MaxSize` value.  The maximum amount of time a request should
wait is specified via the `AccessTimeout` setting.

Without strict pooling, the container will create temporary
instances to meet demand. The instances will last for just one
method invocation and then are removed.

Setting `StrictPooling` to `false` and `MaxSize` to `0` will result in
no pooling. Instead instances will be created on demand and live
for exactly one method call before being removed.

===== MaxAge

Specifies the maximum time that an instance should live before
it should be retired and removed from use.  This will happen
gracefully.  Useful for situations where bean instances are
designed to hold potentially expensive resources such as memory
or file handles and need to be periodically cleared out.

Usable time units: nanoseconds, microsecons, milliseconds,
seconds, minutes, hours, days.  Or any combination such as
`1 hour and 27 minutes and 10 seconds`

===== ReplaceAged

When `ReplaceAged` is enabled, any instances in the pool that
expire due to reaching their `MaxAge` will be replaced immediately
so that the pool will remain at its current size.  Replacement
is done in a background queue so that incoming threads will not
have to wait for instance creation.

The aim of his option is to prevent user requests from paying
the instance creation cost as `MaxAge` is enforced, potentially
while under heavy load at peak hours.

Instances from the minimum side of the pool are always replaced
when they reach their `MaxAge`, this setting dictates the
treatment of non-minimum instances.

===== ReplaceFlushed

When `ReplaceFlushed` is enabled, any instances in the pool that
are flushed will be replaced immediately so that the pool will
remain at its current size.  Replacement is done in a background
queue so that incoming threads will not have to wait for
instance creation.

The aim of his option is to prevent user requests from paying
the instance creation cost if a flush performed while under
heavy load at peak hours.

Instances from the minimum side of the pool are always replaced
when they are flushed, this setting dictates the treatment of
non-minimum instances.

A bean may flush its pool by casting the `SessionContext` to
`Flushable` and calling `flush()`.  See `SweepInterval` for details on
how flush is performed.

[source,java]
----
import javax.annotation.Resource;
import javax.ejb.SessionContext;
import javax.ejb.Stateless;
import java.io.Flushable;
import java.io.IOException;

public class MyBean {

    private SessionContext sessionContext;

    public void flush() throws IOException {

        ((Flushable) sessionContext).flush();
    }
}
----

===== MaxAgeOffset

Applies to MaxAge usage and would rarely be changed, but is a
nice feature to understand.

When the container first starts and the pool is filled to the
minimum size, all those "minimum" instances will have the same
creation time and therefore all expire at the same time dictated
by the `MaxAge` setting.  To protect against this sudden drop
scenario and provide a more gradual expiration from the start
the container will spread out the age of the instances that fill
the pool to the minimum using an offset.

The `MaxAgeOffset` is not the final value of the offset, but
rather it is used in creating the offset and allows the
spreading to push the initial ages into the future or into the
past.  The pool is filled at startup as follows:

[source,java]
----
for (int i = 0; i < poolMin; i++) {
    long ageOffset = (maxAge / poolMin * i * maxAgeOffset) % maxAge;
    pool.add(new Bean(), ageOffset));
}
----

The default `MaxAgeOffset` is -1 which causes the initial
instances in the pool to live a bit longer before expiring.  As
a concrete example, let's say the MinSize is 4 and the MaxAge is
100 years.  The generated offsets for the four instances created
at startup would be 0, -25, -50, -75.  So the first instance
would be "born" at age 0, die at 100, living 100 years.  The
second instance would be born at -25, die at 100, living a total
of 125 years.  The third would live 150 years.  The fourth 175
years.

A `MaxAgeOffset` of 1 would cause instances to be "born" older
and therefore die sooner.  Using the same example `MinSize` of 4
and `MaxAge` of `100 years`, the life spans of these initial four
instances would be 100, 75, 50, and 25 years respectively.

A `MaxAgeOffset` of 0 will cause no "spreading" of the age of the
first instances used to fill the pool to the minimum and these
instances will of course reach their MaxAge at the same time.
It is possible to set to decimal values such as -0.5, 0.5, -1.2,
or 1.2.

===== IdleTimeout

Specifies the maximum time that an instance should be allowed to
sit idly in the pool without use before it should be retired and
removed.

Usable time units: nanoseconds, microsecons, milliseconds,
seconds, minutes, hours, days.  Or any combination such as
"1 hour and 27 minutes and 10 seconds"

===== GarbageCollection

Allows Garbage Collection to be used as a mechanism for shrinking
the pool.  When set to true all instances in the pool, excluding
the minimum, are eligible for garbage collection by the virtual
machine as per the rules of `java.lang.ref.SoftReference` and can be
claimed by the JVM to free memory.  Instances garbage collected
will have their `@PreDestroy` methods called during finalization.

In the OpenJDK VM the `-XX:SoftRefLRUPolicyMSPerMB` flag can adjust
how aggressively SoftReferences are collected.  The default
OpenJDK setting is 1000, resulting in inactive pooled instances
living one second of lifetime per free megabyte in the heap, which
is very aggressive.  The setting should be increased to get the
most out of the `GarbageCollection` feature of the pool.  Much
higher settings are safe.  Even a setting as high as 3600000 (1
hour per free MB in the heap) does not affect the ability for the
VM to garbage collect SoftReferences in the event that memory is
needed to avoid an `OutOfMemoryException`.

===== SweepInterval

The frequency in which the container will sweep the pool and
evict expired instances.  Eviction is how the `IdleTimeout`,
`MaxAge`, and pool "flush" functionality is enforced.  Higher
intervals are better.

Instances in use are excluded from sweeping.  Should an instance
expire while in use it will be evicted immediately upon return
to the pool.  Effectively `MaxAge` and flushes will be enforced as
a part of normal activity or sweeping, while IdleTimeout is only
enforcable via sweeping.  This makes aggressive sweeping less
important for a pool under moderate load.

Usable time units: nanoseconds, microsecons, milliseconds,
seconds, minutes, hours, days.  Or any combination such as
`1 hour and 27 minutes and 10 seconds`

===== CallbackThreads

When sweeping the pool for expired instances a thread pool is
used to process calling `@PreDestroy` on expired instances as well
as creating new instances as might be required to fill the pool
to the minimum after a Flush or `MaxAge` expiration.  The
`CallbackThreads` setting dictates the size of the thread pool and
is shared by all beans deployed in the container.

===== CloseTimeout

PostConstruct methods are invoked on all instances in the pool
when the bean is undeployed and its pool is closed.  The
`CloseTimeout` specifies the maximum time to wait for the pool to
close and `PostConstruct` methods to be invoked.

Usable time units: nanoseconds, microsecons, milliseconds,
seconds, minutes, hours, days.  Or any combination such as
`1 hour and 27 minutes and 10 seconds`

===== UseOneSchedulerThreadByBean

back to previous behavior (TomEE 1.x) where 1 scheduler thread was used for stateless eviction
by bean (ie for 500 stateless beans you get 500 eviction threads)

===== EvictionThreads

number of threads to associate to eviction threads (1 is not bad for most applications)


=== @Stateful

A `@Stateful` container.

Declarable in tomee.xml via

[source,xml]
----
<Container id="Foo" type="STATEFUL">
    AccessTimeout = 30 seconds
    Cache = org.apache.openejb.core.stateful.SimpleCache
    Passivator = org.apache.openejb.core.stateful.SimplePassivater
    TimeOut = 20
    Frequency = 60
    Capacity = 1000
    BulkPassivate = 100
</Container>
----

Declarable in properties via

[source,bash]
----
Foo = new://Container?type=STATEFUL
Foo.AccessTimeout = 30 seconds
Foo.Cache = org.apache.openejb.core.stateful.SimpleCache
Foo.Passivator = org.apache.openejb.core.stateful.SimplePassivater
Foo.TimeOut = 20
Foo.Frequency = 60
Foo.Capacity = 1000
Foo.BulkPassivate = 100
----

==== Configuration

===== AccessTimeout

Specifies the maximum time an invocation could wait for the
`@Stateful` bean instance to become available before giving up.

After the timeout is reached a `javax.ejb.ConcurrentAccessTimeoutException`
will be thrown.

Usable time units: nanoseconds, microsecons, milliseconds,
seconds, minutes, hours, days.  Or any combination such as
"1 hour and 27 minutes and 10 seconds"

Any usage of the `javax.ejb.AccessTimeout` annotation will
override this setting for the bean or method where the
annotation is used.

===== Cache

The cache is responsible for managing stateful bean
instances.  The cache can page instances to disk as memory
is filled and can destroy abandoned instances.  A different
cache implementation can be used by setting this property
to the fully qualified class name of the Cache implementation.

===== Passivator

The passivator is responsible for writing beans to disk
at passivation time. Different passivators can be used
by setting this property to the fully qualified class name
of the `PassivationStrategy` implementation. The passivator
is not responsible for invoking any callbacks or other
processing, its only responsibly is to write the bean state
to disk.

Known implementations:

- org.apache.openejb.core.stateful.RAFPassivater
- org.apache.openejb.core.stateful.SimplePassivater

===== TimeOut

Specifies the time a bean can be idle before it is removed by the container.

This value is measured in minutes. A value of 5 would
result in a time-out of 5 minutes between invocations.
A value of -1 would mean no timeout.
A value of 0 would mean a bean can be immediately removed by the container.

Any usage of the `javax.ejb.StatefulTimeout` annotation will
override this setting for the bean where the annotation is used.

===== Frequency

Specifies the frequency (in seconds) at which the bean cache is checked for
idle beans.

===== Capacity

Specifies the size of the bean pools for this
stateful SessionBean container.

===== BulkPassivate

Property name that specifies the number of instances
to passivate at one time when doing bulk passivation.


=== @Singleton

A `@Singleton` container.

Declarable in tomee.xml via

[source,xml]
----
<Container id="Foo" type="SINGLETON">
    AccessTimeout = 30 seconds
</Container>
----

Declarable in properties via

[source,bash]
----
Foo = new://Container?type=SINGLETON
Foo.AccessTimeout = 30 seconds
----

==== Configuration

===== AccessTimeout

Specifies the maximum time an invocation could wait for the
`@Singleton` bean instance to become available before giving up.

After the timeout is reached a `javax.ejb.ConcurrentAccessTimeoutException`
will be thrown.

Usable time units: nanoseconds, microsecons, milliseconds,
seconds, minutes, hours, days.  Or any combination such as
`1 hour and 27 minutes and 10 seconds`

Any usage of the `javax.ejb.AccessTimeout` annotation will
override this setting for the bean or method where the
annotation is used.


=== @MessageDriven

A MDB container.

Declarable in tomee.xml via

[source,xml]
----
<Container id="Foo" type="MESSAGE">
    ResourceAdapter = Default JMS Resource Adapter
    MessageListenerInterface = javax.jms.MessageListener
    ActivationSpecClass = org.apache.activemq.ra.ActiveMQActivationSpec
    InstanceLimit = 10
    FailOnUnknowActivationSpec = true
</Container>
----

Declarable in properties via

[source,bash]
----
Foo = new://Container?type=MESSAGE
Foo.ResourceAdapter = Default JMS Resource Adapter
Foo.MessageListenerInterface = javax.jms.MessageListener
Foo.ActivationSpecClass = org.apache.activemq.ra.ActiveMQActivationSpec
Foo.InstanceLimit = 10
Foo.FailOnUnknowActivationSpec = true
----

==== Configuration

===== ResourceAdapter

The resource adapter delivers messages to the container

===== MessageListenerInterface

Specifies the message listener interface handled by this container

===== ActivationSpecClass

Specifies the activation spec class

===== InstanceLimit

Specifies the maximum number of bean instances that are
allowed to exist for each MDB deployment.

===== FailOnUnknowActivationSpec

Log a warning if true or throw an exception if false is an activation spec can't be respected


=== @Managed

A managed bean container.

Declarable in tomee.xml via

[source,xml]
----
<Container id="Foo" type="MANAGED" />
----

Declarable in properties via

[source,bash]
----
Foo = new://Container?type=MANAGED
----


=== CMP entity

A CMP bean container.

Declarable in tomee.xml via

[source,xml]
----
<Container id="Foo" type="CMP_ENTITY">
    CmpEngineFactory = org.apache.openejb.core.cmp.jpa.JpaCmpEngineFactory
</Container>
----

Declarable in properties via

[source,bash]
----
Foo = new://Container?type=CMP_ENTITY
Foo.CmpEngineFactory = org.apache.openejb.core.cmp.jpa.JpaCmpEngineFactory
----

==== Configuration

===== CmpEngineFactory

The engine to use for this container. By default TomEE only provides the JPA implementation.


=== BMP entity

A BMP entity container.

Declarable in tomee.xml via

[source,xml]
----
<Container id="Foo" type="BMP_ENTITY">
    PoolSize = 10
</Container>
----

Declarable in properties via

[source,bash]
----
Foo = new://Container?type=BMP_ENTITY
Foo.PoolSize = 10
----

==== Configuration

===== PoolSize

Specifies the size of the bean pools for this
bmp entity container.