sqlTransactionWrapper

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Module

urn:org:ten60:netkernel:mod:db

The sqlTransactionWrapper accessor is exported by the urn:org:ten60:netkernel:mod:db module. Import this module to gain access to the accessor.

Syntax

URI

active:sqlTransactionWrapper

Argument	Rules	Description
service	Mandatory	the URI of a service to wrap
rdbmsConfig	Optional	optional configuration document
myArg	Optional	Any number of optional arbitrarily named arguments which will be passed to the sub-requested service

Example Usage

DPML

<instr>
  <type>sqlTransactionWrapper</type>
  <service>myService.bsh</service>
  <rdbmsConfig>ffcpl:/myconfiguration/configRDBMS.xml</rdbmsConfig>
  <myArg1>...</myArg1>
  <myArgN>...</myArgN>
  <target>var:result</target>
</instr>

NetKernel Foundation API

req=context.createSubRequest("active:sqlTransactionWrapper");
req.addArgument("service", [resource representation, aspect, or URI] );
result=context.issueSubRequest(req);

Purpose

The sqlTransactionWrapper wraps an existing service in a transaction. It does this by aquiring a database connection and starting a transaction on it. It then invokes the service URI (specified by service and passes the database connection as a parameter. If the sub-request for the service succeeds then the transaction is commited. If an unhandled exception occurs in the sub-requested service then the transaction rollsback.

If an rdbms configuration as described here is passed then this is used to find the connection. If none is supplied the default configuration found at ffcpl:/etc/rdbmsConfig.xml is used.

A single transacted connection is then passed to the wrapped service by value as an argument named rdbmsConfig. The wrapped service should then use this supplied connection in all database requests for example:

<idoc>
  <instr>
    <type>sqlQuery</type>
    <configuration>this:param:rdbmsConfig</configuration>
    <operand>
      <sql>SELECT * FROM table;</sql>
    </operand>
    <target>this:response</target>
  </instr>
</idoc>

The sqlTransactionWrapper implements the 'mapper' pattern. All attached arguments in the request to wrapper are passed through to underlying service except service. For example in this DPML script:

active:sqlTransactionWrapper+service@active:beanshell+operator@ffcpl:/myScript.bsh

would create a sub-request:

active:beanshell+operator@ffcpl:/myScript.bsh+rdbmsConfig@[a transient pass-by value URI]