Logon Components,Connections and Connection Pools
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The Logon Connection’s Role in Pooling
The Logon Connection differs from the ordinary “host-direct” connection
resource in that it manages pooling (the sharing of connection instances and
Logon Component instances at runtime).
In the context of a Composer service, pooling not only allows reuse of (open)
connections at runtime, it also increases the effective bandwidth of a deployed
service. Consider the simple case where you’ve designed a 5250 component that
uses a regular connection resource. In creating the connection resource, you will
have specified a UserID and password for the resource to use so that at runtime,
the component can log in to the host. When an actual running instance of your
component is using that connection, no other instance of the component can log in
to the host using that same set of credentials. The bandwidth of your service is
limited to one connected instance at a time.
With a Logon Connection, on the other hand, numerous host connections can be
maintained in a “live” state so that multiple instances of your component can
access the host (each on its own connection) without waiting. Throughput is
dramatically increased.
The diagram below shows one possible runtime case where three component
instances (two instance of 5250 Terminal Component A and one instance of 5250
Terminal Component B) are executing on the server. Instance 1 of Component A
is using UserID ‘E’ to obtain a connection. This component has its own dedicated
instances of Logon Component M and Connection S.
Terminal Component B has just finished executing and is relinquishing its
connection (established through credentials defined by UID ‘F’). Note that
because connection pooling is in effect, Component B’s downstream resources (its
Logon Component instance, M2, and its Connection instance, S2) are not simply
discarded; they remain live. As a result, Terminal Component A2 is able to obtain
(reuse) the M2/S2 resource instances that were previously held by Terminal
Component B.
