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JOURNAL OF COMPUTERS, VOL. 8, NO. 6, JUNE 2013 1575
we regard capability and service as “peripheral”, thus
capability or service id is these “peripherals” address.
Metadata management engine, which is the CPU of
MCCAVS, can locate any capability or service according
to the "peripheral” id through meta-data bus. Individual
capability or service metadata description file and path to
the file metadata management are stored in the tag
meta_location. We take capability described metadata file
as an example to expound the entity format of individual
capability metadata in the following
***
***
***
***
***
***
***
**
......
Besides containing the capability id and other basic
information, capability description metadata file also
contains version tag used for controlling capability
version information, location tag indicates the real
location of the capability products in the capability pool,
loadclass tag indicates the entrance classes of the
capability part; dependentCapability tag indicates
dependency relationship with other capability
components.
Figure 3. Interface language UML static structure
C. Metadata Management Engine
Metadata management engine, which takes responsible
for parsing the interface command and translates it into
system commands, is the "central processor" and the core
component of the system. We define a set of interface
commands based on object-oriented language JAVA to
facilitate developers. As shown in fig.3, interface
language is divided into three categories: the system input
and output (IOSystem), the scheduling interface
(Schedule), and the web service interface(WS). Interface
command is the abstraction method provided by these
interfaces and the command parameter is the method
parameter. Table 1 shows a typical interface and the
interface commands.
D. Bus Structure
According to the design of the bus structure in the
model, three types of buses in the MCCVAS system are
defined: capability bus, service bus and control bus. For
the purpose of quick addressing and maintaining
resources of storage efficiently, HashMap, which can
complete key-value mapping and time complexity is O(1),
is used to organize system capability and service.
Capability or service id is the key and capability or
service object instance is the value. Three bus
declarations are followed:
protected class ControlBus extends HashMap
implements Bus
protected class CapabilityBus extends HashMap
implements Bus
protected class ServiceBus extends HashMap implements
Bus
Interface
IOSystem
Schedule
WS
TABLE I.
TYPICAL INTERFACE AND INTERFACE COMMAND
Interface
commands
join()
exit()
login()
load()
start()
update()
Parameter
Component: the
Parent interface
of Capability and
Service
ditto
ditto
ditto
ditto
ditto
Function Declaration
To Generate metadata entity
when Capability or Service
enters.
To make Capability or
Service exits the system.
To allocate component ID
when register to the system
Capability or Service.
To load Capability or Service
on the system, which requests
metadata management engine
mounted components to the
corresponding meta- data bus
through interrupt mode.
To start-up Capability or
Service.
To update Capability or
Service.
stop() ditto To stop Capability or Service.
logout() ditto
To log out Capability or
Service, log out components,
exit the bus system.
To generate service.xml and
convert() ditto wsdl.xml for Capability or
Service.
publish() ditto
To publish Capability or
Service as a web service.
E. Input and Output Interface in Server Side
Server-side input interface includes capability
metadata generator and service metadata generator. It
shields metadata manipulation for outside of the system
and generates metadata entity as described in Section 3.2.
Output interface releases system capability and service to
meet the invoking of terminals by using standardization
web service interface. As shown in fig.2, we use AXIS2
as release engine.
F. Client Access
As the server-side uses web service technology to
provide resources, the system supports transparent access
heterogeneous multi-platform capability and service of
cloud side. Client interface work steps are as follows:
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