In the architecture of modern e-business applications (such as SOA), loosely coupled systems are becoming more and more important. Reliable messaging is one important technology for this type of system.
Reliable RPC is the EntireX implementation of a reliable messaging system. It combines EntireX RPC technology and persistence, which is implemented with units of work (UOWs).
Reliable RPC allows asynchronous calls ("fire and forget")
Reliable RPC is supported by most EntireX wrappers
Reliable RPC messages are stored in the Broker's persistent store until a server is available
Reliable RPC clients are able to request the status of the messages they have sent
Reliable RPC is used to send messages to a persisted Broker service. The
messages are described by an IDL program that contains only IN parameters. The
client interface object and the server interface object are generated from this
IDL file, using the respective Software AG component.
Reliable RPC is enabled at runtime. The client has to set one of two different modes before issuing a reliable RPC request:
AUTO_COMMIT
CLIENT_COMMIT
While AUTO_COMMIT commits each RPC message implicitly after sending it, a
series of RPC messages sent in a unit of work (UOW) can be committed or rolled
back explicitly using CLIENT_COMMIT mode.
The server is implemented and configured in the same way as for normal RPC.
A Broker configuration with PSTORE is recommended. This enables the Broker
to store the messages for more than one Broker session. These messages are
still available after Broker restart. The attributes
STORE, PSTORE,
and PSTORE-TYPE in the Broker attribute file can
be used to configure this feature. The lifetime of the messages and the status
information can be configured with the attributes
UWTIME and
UWSTAT-LIFETIME. Other attributes such as
MAX-MESSAGES-IN-UOW,
MAX-UOWS and
MAX-UOW-MESSAGE-LENGTH may be used in addition
to configure the units of work. See Broker Attributes.
The following rules apply:
The result of the method
RPCService.getStatusOfMessage depends on the
configuration of the unit of work status lifetime. If the status is not stored
longer than the message, the method returns (not
available).
The result of the procedure
ERXGetReliableStatus
depends on the configuration of the unit of work status lifetime in the EntireX
Broker configuration. If the status is not stored longer than the message, the
procedure returns the error code 00780305 (no matching UOW
found).
The result of the generic RPC function call "RS" - get reliable status depends on the
configuration of the unit of work status lifetime in the EntireX Broker
configuration. See COMM-FUNCTION in the COBOL Wrapper documentation. If the status is not stored longer than the message, the
function call returns the error code 00780305 (no matching UOW
found).
The result of the function
Service.GetReliableStatus depends on the configuration
of the unit of work status lifetime in the EntireX Broker configuration. If the
status is not stored longer than the message, the function returns the error
code 00780305 (no matching UOW found).
The result of the function RPCService.get_StatusOfMessage
depends on the configuration of the unit of work status lifetime in the EntireX
Broker configuration. If the status is not stored longer than the message, the
function returns the error code 00780305 (no matching UOW
found).
