lock

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Module

The lock accessor is exported by the urn:org:ten60:netkernel:ext:sys module. Import this module to gain access to the accessor.

Syntax

URI

active:lock

Argument	Rules	Description
operand	Mandatory	the resource to be locked

Example Usage

DPML

<instr>
  <type>lock</type>
  <operand>file:/inventory.xml</operand>
</instr>

NetKernel Foundation API

    request = context.createSubRequest("active:lock");
    request.addArgument("operand","ffcpl:/some/URI"));
    context.issueSubRequest(request);

Purpose

The lock accessor is used to place a lock on the resource specified in the operand. When a resource is locked, the current request prevents other processes from obtaining the same lock until it is released by the first process with a call to the unlock accessor. A second request to lock an already locked resource will block indefinately until the existing lock is released with the unlock accessor.

The lock accessor can be used with <exception> handling blocks to create robust transactional applications.