THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
...
Getting
...
Started
...
with
...
Tuscany
...
using
...
the
...
Command
...
Line
...
This
...
guide
...
takes
...
a
...
command
...
line
...
based
...
approach
...
to
...
getting
...
started
...
with
...
Apache
...
Tuscany
...
Java
...
SCA.
...
For
...
the
...
Eclipse
...
users
...
amongst
...
us
...
there
...
are
...
other
...
...
that
...
show
...
how
...
to
...
install
...
the
...
distribution
...
into
...
Eclipse
...
or
...
how
...
to
...
exploit
...
Tuscany
...
SCA
...
Java
...
using
...
the
...
Eclipse
...
plugin
...
that
...
is
...
has
...
been
...
built
...
as
...
part
...
of
...
the
...
project.
...
This
...
article
...
however
...
just
...
uses
...
the
...
downloaded
...
Tuscany
...
SCA
...
Java
...
distribution,
...
Java,
...
Maven
...
or
...
Ant
...
and
...
the
...
command
...
line.
...
So
...
if
...
you
...
want
...
to
...
feel
...
close
...
to
...
the
...
action
...
this
...
is
...
where
...
to
...
start!
...
Tuscany
...
ships
...
with
...
a
...
number
...
of
...
samples.
...
One
...
of
...
the
...
most
...
straightforward
...
of
...
these
...
is
...
the
...
calculator
...
sample.
...
We
...
will
...
use
...
this
...
to
...
make
...
sure
...
that
...
you
...
installing
...
is
...
working
...
properly.
...
As
...
the
...
name
...
indicates,
...
this
...
example
...
performs
...
typical
...
calculator
...
operations.
...
It
...
is
...
given
...
two
...
numbers
...
and
...
asked
...
to
...
perform
...
an
...
operation
...
on
...
them.
...
Our
...
calculator
...
will
...
handle
...
add,
...
subtract,
...
multiply
...
and
...
divide.
...
First
...
of
...
all
...
we
...
will
...
walk
...
through
...
running
...
the
...
calculator
...
sample
...
to
...
make
...
sure
...
you
...
installation
...
is
...
working
...
correctly.
...
Then
...
we
...
will
...
walk
...
through
...
the
...
steps
...
taken
...
to
...
implement
...
the
...
calculator
...
sample
...
in
...
the
...
first
...
place.
...
Following
...
this
...
you
...
should
...
be
...
familiar
...
with
...
how
...
to
...
build
...
a
...
basic
...
SCA
...
application
...
that
...
runs
...
in
...
a
...
single,
...
stand-alone,
...
SCA
...
runtime.
...
The
...
next
...
step
...
is
...
to
...
update
...
the
...
sample
...
to
...
use
...
some
...
of
...
the
...
other
...
Tuscany
...
SCA
...
java
...
extensions.
...
Finally
...
we
...
will
...
use
...
the
...
calculator
...
sample
...
to
...
show
...
you
...
how
...
you
...
can
...
build
...
a
...
distributed
...
Service
...
Oriented
...
Architecture
...
using
...
Tuscany
...
SCA
...
Java.
...
Getting
...
Set
...
Up
...
- Download
...
- the
...
...
...
...
...
- .
From this page you can get binary and source releases for both windows and linux. For this exercise you will need the binary release for your preferred platform. You can use the source code release but you will have to use Maven at all stages. - Download java
Java 5 - Download a build tool
Maven 2.0.7+
OR
Ant 1.7.0
Running The Calculator Sample
The calculator sample is provided with the Tuscany SCA Java binary distribution. You can find it in the samples/calculator direc
Let's first run the sample before we go about building it. It is easy!
- Go to the directory ..\samples\calculator
Code Block ant run
Alternatively if you want to run the sample directly from the command line try the following.
- if you are using Windows issue the command:
Code Block java -cp ..\..\lib\tuscany-sca-manifest.jar;target\sample-calculator.jar calculator.CalculatorClient
...
- if you are using *nix issue the command:
Code Block java -cp ../../lib/tuscany-sca-manifest.jar:target/sample-calculator.jar calculator.CalculatorClient
...
You
...
should
...
see
...
the
...
following
...
result:
...
3
...
+
...
2=5.0
...
3
...
-
...
2=1.0
...
3
...
*
...
2=6.0
...
3
...
/
...
2=1.5
...
If you are using the source disitribution then we suggest you use Maven to build and run the calculator sample because the tuscany-sca-manifest.jar
...
is
...
not
...
provided
...
with
...
the
...
source
...
distribution.
...
This
...
jar
...
is
...
part
...
of
...
the
...
binary
...
distribution
...
and
...
collects
...
together
...
all
...
of
...
the
...
tuscany
...
jars
...
in
...
one
...
place
...
so
...
that
...
the
...
java
...
command
...
line
...
is
...
nice
...
and
...
short
...
when
...
running
...
samples.
...
Building
...
The
...
Calculator
...
Sample
...
In
...
Java
...
This
...
example
...
illustrates
...
how
...
to
...
define
...
your
...
application
...
while
...
staying
...
focused
...
on
...
the
...
business
...
logic.
...
It
...
walks
...
you
...
through
...
the
...
steps
...
of
...
building
...
the
...
calculator
...
sample.
...
All
...
connections
...
between
...
the
...
components
...
within
...
the
...
composite
...
are
...
local
...
and
...
described
...
using
...
Java
...
interfaces.
...
Step
...
1
...
-
...
Define
...
what
...
building
...
blocks
...
are
...
needed:
...
Think
...
about
...
how
...
your
...
application
...
can
...
be
...
broken
...
down
...
into
...
smaller
...
functions/services.
...
Each
...
block
...
is
...
a
...
logical
...
unit
...
of
...
operation
...
that
...
can
...
be
...
used
...
in
...
the
...
overall
...
application.
...
In
...
this
...
case,
...
calculator
...
application
...
can
...
be
...
divided
...
into
...
five
...
blocks:
...
AddService
...
block,
...
SubstractService
...
block,
...
MultiplyService
...
block
...
and
...
DivideService
...
block
...
and
...
a
...
main
...
block
...
that
...
takes
...
a
...
request
...
and
...
routes
...
it
...
to
...
the
...
right
...
operation.
...
We
...
have
...
called
...
this
...
main
...
block
...
the CalculatorService
Step 2 - Implement each block: Now that you have identified the blocks of functionality in your application, you are ready to create each block. In SCA the blocks of functionality are referred to as components so let's look at how we implement a component. We'll take the AddService component as our first example.
The AddService component will provide a service that adds two numbers together. The CalculatorService component uses the AddService component whenever it is asked to perform additions. If we were writing the AddService component in plain old Java we would start by describing a (Java) interface.
| Code Block |
|---|
CalculatorService !calculatorblocks.png|align=centre! *Step 2 - Implement each block:* Now that you have identified the blocks of functionality in your application, you are ready to create each block. In SCA the blocks of functionality are referred to as components so let's look at how we implement a component. We'll take the AddService component as our first example. The AddService component will provide a service that adds two numbers together. The CalculatorService component uses the AddService component whenever it is asked to perform additions. If we were writing the AddService component in plain old Java we would start by describing a (Java) interface. {code} public interface AddService { double add(double n1, double n2); } {code} |
Now,
...
we
...
provide
...
an
...
implementation
...
of
...
this
...
interface.
| Code Block |
|---|
} public class AddServiceImpl implements AddService { public double add(double n1, double n2) { return n1 + n2; } } {code} |
But
...
wait!
...
Aren't
...
we
...
writing
...
an
...
SCA
...
component?
...
It
...
must
...
be
...
more
...
complicated
...
than
...
plain
...
old
...
Java
...
interface
...
and
...
implementation,
...
right?
...
Well,
...
actually,
...
an
...
SCA
...
component
...
can
...
just
...
be
...
plain
...
old
...
Java
...
so
...
we
...
have
...
just
...
done
...
all
...
the
...
coding
...
we
...
needed
...
to
...
implement
...
the
...
SCA
...
AddService
...
component.
...
We
...
can
...
use
...
SCA
...
to
...
expose
...
the
...
service
...
that
...
the
...
AddService
...
component
...
provides
...
over
...
any
...
of
...
the
...
supported
...
bindings,
...
for
...
example,
...
WebServices,
...
JMS
...
or
...
RMI,
...
without
...
changing
...
out
...
the
...
AddService
...
implementation.
...
Let's
...
take
...
a
...
look
...
at
...
the
...
CalculatorService
...
component.
...
This
...
is
...
interesting
...
because
...
it's
...
going
...
to
...
call
...
the
...
AddService
...
component.
...
In
...
the
...
full
...
application
...
it
...
will
...
call
...
the
...
SubtractService,
...
MultiplyService
...
and
...
DivideService
...
components
...
as
...
well,
...
but
...
we
...
will
...
ignore
...
these
...
for
...
the
...
time
...
being
...
as
...
they
...
follow
...
the
...
same
...
pattern
...
as
...
we
...
will
...
implement
...
for
...
the
...
AddService
...
component.
...
Again
...
we
...
will
...
start
...
by
...
defining
...
an
...
interface
...
because
...
CalcultorService
...
is
...
itself
...
providing
...
an
...
interface
...
that
...
others
...
will
...
call.
| Code Block |
|---|
} public interface CalculatorService { double add(double n1, double n2); double subtract(double n1, double n2); double multiply(double n1, double n2); double divide(double n1, double n2); } {code} |
Now
...
we
...
implement
...
this
...
interface.
| Code Block |
|---|
{code} public class CalculatorServiceImpl implements CalculatorService { private AddService addService; private SubtractService subtractService; private MultiplyService multiplyService; private DivideService divideService; @Reference public void setAddService(AddService addService) { this.addService = addService; } ...set methods for the other attributes would go here public double add(double n1, double n2) { return addService.add(n1, n2); } ...implementations of the other methods would go here } {code} |
So
...
we
...
now
...
have
...
some
...
components
...
implemented
...
using
...
Java.
...
Each
...
component
...
has
...
a
...
well
...
defined
...
interface,
...
using
...
Java
...
interfaces
...
in
...
this case.
Step 3 - Assembling the application:
So all well and good but how do we actually run these two components. Well of course the java programmer in us wants to get down to it, write a mainline to connect our two components together and run then. We could still do that easily in this case.
| Code Block |
|---|
case. !calculator3.png|align=centre! *Step 3 - Assembling the application:* So all well and good but how do we actually run these two components. Well of course the java programmer in us wants to get down to it, write a mainline to connect our two components together and run then. We could still do that easily in this case. {code} public class CalculatorClient { public static void main(String[] args) throws Exception { CalculatorServiceImpl calculatorService = new CalculatorServiceImpl(); AddService addService = new AddServiceImpl(); calculatorService.setAddService(addService); System.out.println("3 + 2=" + calculatorService.add(3, 2)); // calls to other methods go here if we have implemented SubtractService, MultiplyService, DivideService } } {code} |
But
...
this
...
doesn't
...
run
...
using
...
the
...
Tuscany
...
SCA
...
runtime
...
and
...
extending
...
this
...
code
...
to
...
provide
...
web
...
services
...
interfaces,
...
for
...
example,
...
would
...
be
...
a
...
little
...
more
...
complicated.
...
What
...
do
...
we
...
have
...
to
...
do
...
to
...
make
...
it
...
run
...
in
...
Tuscany
...
where
...
we
...
get
...
all
...
things
...
like
...
web
...
service
...
support
...
for
...
free?
...
Well,
...
not
...
much
...
actually.
...
First
...
let's
...
change
...
the
...
client
...
to
...
fire
...
up
...
the
...
Tuscany
...
SCA
...
runtime
...
before
...
calling
...
our
...
components.
| Code Block |
|---|
{code} public class CalculatorClient { public static void main(String[] args) throws Exception { SCADomain scaDomain = SCADomain.newInstance("Calculator.composite"); CalculatorService calculatorService = scaDomain.getService(CalculatorService.class, "CalculatorServiceComponent"); System.out.println("3 + 2=" + calculatorService.add(3, 2)); // calls to other methods go here if we have implemented SubtractService, MultiplyService, DivideService scaDomain.close(); } } {code} |
You
...
can
...
see
...
that
...
we
...
start
...
by
...
using
...
a
...
static
...
method
...
on
...
SCADomain
...
to
...
create
...
a
...
new
...
instance
...
of
...
itself.
...
The
...
SCADomain
...
is
...
a
...
concept
...
in
...
SCA
...
that
...
represents
...
the
...
boundary
...
of
...
an
...
SCA
...
system.
...
This
...
could
...
be
...
distributed
...
across
...
many
...
processors.
...
For
...
now,
...
lets
...
concentrate
...
on
...
getting
...
this
...
working
...
inside
...
a
...
single
...
Java
...
VM.
...
The
...
parameter
...
"Calculator.composite"
...
refers
...
to
...
an
...
XML
...
file
...
that
...
tells
...
SCA
...
how
...
the
...
components
...
in
...
our
...
calculator
...
application
...
are
...
assembled
...
into
...
a
...
working
...
application.
...
Here
...
is
...
the
...
XML
...
that's
...
inside
...
Calculator.composite.
| Code Block |
|---|
{code} <composite xmlns="http://www.osoa.org/xmlns/sca/1.0" name="Calculator"> <component name="CalculatorServiceComponent"> <implementation.java class="calculator.CalculatorServiceImpl"/> <reference name="addService" target="AddServiceComponent" /> <!-- references to SubtractComponent, MultiplyComponent and DivideComponent --> </component> <component name="AddServiceComponent"> <implementation.java class="calculator.AddServiceImpl"/> </component> <!-- definitions of SubtractComponent, MultiplyComponent and DivideComponent --> </composite> {code} |
You
...
can
...
see
...
that
...
we
...
define
...
two
...
components
...
here
...
and
...
specify
...
the
...
Java
...
implementation
...
classes
...
that
...
Tuscany
...
SCA
...
needs
...
to
...
load
...
to
...
make
...
them
...
work.
...
These
...
are
...
the
...
classes
...
we
...
have
...
just
...
implemented.
...
Also
...
note
...
that
...
the
...
CalculatorServiceComponent
...
has
...
a
...
reference
...
named
...
"addService".
...
In
...
the
...
XML,
...
this
...
reference
...
targets
...
the
...
AddServiceComponent.
...
It
...
is
...
no
...
coincidence
...
that
...
the
...
reference
...
name,
...
"addService",
...
matches
...
the
...
name
...
of
...
the
...
addService
...
field
...
we
...
created
...
when
...
we
...
implemented
...
CalculatorServiceImpl.
...
The
...
Tuscany
...
SCA
...
runtime
...
parses
...
the
...
information
...
from
...
the
...
XML
...
composite
...
file
...
and
...
uses
...
it
...
to
...
build
...
the
...
objects
...
and
...
relationships
...
that
...
represent
...
our
...
calculator
...
application.
...
It
...
first
...
creates
...
instances
...
of
...
AddServiceImpl
...
and
...
CalcualtorSreviceImpl.
...
It
...
then
...
injects
...
a
...
reference
...
to
...
the
...
AddServiceImpl
...
object
...
into
...
the
...
addService
...
field
...
in
...
the
...
CalculatorServiceImpl
...
object.
...
If
...
you
...
look
...
back
...
at
...
how
...
we
...
implemented
...
the
...
CalculatorService
...
you
...
will
...
see
...
an
...
@Reference
...
annotation
...
that
...
tells
...
SCA
...
which
...
fields
...
are
...
expecting
...
to
...
be
...
set
...
automatically
...
by
...
SCA.
...
This
...
is
...
equivalent
...
to
...
this
...
piece
...
of
...
code
...
from
...
our
...
normal
...
Java
...
client.
| Code Block |
|---|
} CalculatorServiceImpl calculatorService = new CalculatorServiceImpl(); AddService addService = new AddServiceImpl(); calculatorService.setAddService(addService); {code} |
Once
...
the
...
composite
...
file
...
is
...
loaded
...
into
...
the
...
SCADomain
...
our
...
client
...
code
...
asks
...
the
...
SCADomain
...
to
...
give
...
us
...
a
...
reference
...
to
...
the
...
component
...
called
...
"CalculatorServiceComponent".
| Code Block |
|---|
{code} CalculatorService calculatorService = scaDomain.getService(CalculatorService.class, "CalculatorServiceComponent"); {code} |
We
...
can
...
now
...
use
...
this
...
reference
...
as
...
though
...
we
...
had
...
created
...
it
...
ourselves,
...
for
...
example,
...
from
...
the
...
CalculatorServiceImpl.add()
...
method
...
implementation.
| Code Block |
|---|
} return addService.add(n1, n2); {code} |
The
...
SCA
...
specifications
...
often
...
describe
...
SCA
...
applications
...
is
...
diagrammatic
...
form.
...
This
...
often
...
helps
...
give
...
a
...
quick
...
overview
...
of
...
what
...
components
...
are
...
part
...
of
...
an
...
application
...
and
...
how
...
they
...
are
...
wired
...
together.
...
If
...
we
...
draw
...
a
...
diagram
...
of
...
what
...
we
...
have
...
build
...
in
...
the
...
calculator
...
sample
...
we
...
come
...
up
...
with
...
something
...
like.
You will notice that diagrams are provided with all of our samples. If you like to take a visual approach to things this may help you become quickly familiar with the components in the samples. Take a look at the ".png" files in the top level directory of each sample.
Step 4 - Deploying the applcation:
So as long as the "Calculator.composite" file is present on our class path, along with the rest of the tuscany jars, we can run our sample as we did previously. The samples come with an Ant build.xml file that allows the sample files to be rebuilt so if you want to experiment with the sample code you can do so and then recompile it.
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ant compile
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Once recompiled you can run it as before in the Running The Calculator Sample section, for example, we provide a run target in the Ant build.xml file so the calculator sample can also be run using.
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ant run
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Using Alternative Bindings
Looking back, the client code we have written to start the calculator application using the Tuscany SCA runtime is no longer than a normal Java client for the application. However we do now have the XML composite file that describes how our application is assembled.
This concept of assembly is a great advantage as our applications become more complex and we want to change them, reuse them, integrate them with other applications or just further develop them using a programming model consistent with all our other SCA applications. Regardless of what language is used to implement each of them.
For example, lets say our calculator sample is so poweful and popular that we want to put it on the company intranet and let other people access it as a service directly from their browser based Web2.0 applications. It's at this point we would normally start reaching for the text books to work out how to make this happen. As we have an XML file that describes our application it's easy in Tuscany SCA. The following should do the trick.
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!calculator4.png|align=centre! You will notice that diagrams are provided with all of our samples. If you like to take a visual approach to things this may help you become quickly familiar with the components in the samples. Take a look at the ".png" files in the top level directory of each sample. *Step 4 - Deploying the applcation:* So as long as the "Calculator.composite" file is present on our class path, along with the rest of the tuscany jars, we can run our sample as we did previously. The samples come with an Ant build.xml file that allows the sample files to be rebuilt so if you want to experiment with the sample code you can do so and then recompile it. {code} ant compile {code} Once recompiled you can run it as before in the [Running The Calculator Sample|SCA Java User Guide#Running The Calculator Sample] section, for example, we provide a run target in the Ant build.xml file so the calculator sample can also be run using. {noformat} ant run {noformat} h3. {anchor:What Next}{bgcolor:#C3CDA1}Using more advanced features in calculator{bgcolor} Looking back, the client code we have written to start the calculator application using the Tuscany SCA runtime is no longer than a normal Java client for the application. However we do now have the XML composite file that describes how our application is assembled. This concept of assembly is a great advantage as our applications become more complex and we want to change them, reuse them, integrate them with other applications or just further develop them using a programming model consistent with all our other SCA applications. Regardless of what language is used to implement each of them. For example, lets say our calculator sample is so poweful and popular that we want to put it on the company intranet and let other people access it as a service directly from their browser based Web2.0 applications. It's at this point we would normally start reaching for the text books to work out how to make this happen. As we have an XML file that describes our application it's easy in Tuscany SCA. The following should do the trick. {code} <composite xmlns="http://www.osoa.org/xmlns/sca/1.0" name="Calculator"> <service name="CalculatorService" promote="CalculatorServiceComponent/CalculatorService"> <interface.java interface="calculator.CalculatorService"/> <binding.jsonrpc/> </service> <component name="CalculatorServiceComponent"> <implementation.java class="calculator.CalculatorServiceImpl"/> <reference name="addService" target="AddServiceComponent" /> <!-- references to SubtractComponent, MultiplyComponent and DivideComponent --> </component> <component name="AddServiceComponent"> <implementation.java class="calculator.AddServiceImpl"/> </component> <!-- definitions of SubtractComponent, MultiplyComponent and DivideComponent --> </composite> {code} |
All
...
we
...
have
...
done
...
is
...
added
...
the
...
<service>
...
element
...
which
...
tells
...
Tuscany
...
SCA
...
how
...
to
...
expose
...
our
...
CalculatorServiceComponent
...
as
...
a
...
JSONRPC
...
service.
...
Note
...
that
...
we
...
didn't
...
have
...
to
...
change
...
the
...
Java
...
code
...
of
...
our
...
components.
...
This
...
is
...
just
...
a
...
configuration
...
change.
...
The
...
helloworld-jsonrpc
...
sample
...
shows
...
a
...
working
...
example
...
of
...
the
...
jsonrpc
...
binding.
...
TODO - we don't
...
have
...
a
...
JSONRPC
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version
...
of
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the
...
calculator
...
sample
...
If
...
we
...
really
...
wanted
...
a
...
SOAP/HTTP
...
web
...
service
...
we
...
can
...
do
...
that
...
easily
...
too.
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<composite xmlns="http://www.osoa.org/xmlns/sca/1.0" name="Calculator"> <service name="CalculatorService" promote="CalculatorServiceComponent/CalculatorService"> <interface.java interface="calculator.CalculatorService"/> <binding.jsonrpc/> <binding.ws/> </service> <component name="CalculatorServiceComponent"> <implementation.java class="calculator.CalculatorServiceImpl"/> <reference name="addService" target="AddServiceComponent" /> <!-- references to SubtractComponent, MultiplyComponent and DivideComponent --> </component> <component name="AddServiceComponent"> The helloworld-ws-service and helloworld-ws-reference samples show you how to work with web services. (?) TODO - we don't have a web services version of the calcualtor sample SCA allows other kinds of flexibility. We can rewire our components, for example, using a one of the remote bindings, like RMI, we could have the CalculatorServiceComponent running on one machine wired to a remote version of the application running on another machine. The calculator-rmi-service and calculator-rmi-reference samples show the RMI binding at work. We could also introduce components implemented in different languages, for example, let's add the SubtractServiceComponent implemented in Ruby. {code} <composite xmlns="http://www.osoa.org/xmlns/sca/1.0" name="Calculator"> <component name="CalculatorServiceComponent"> <implementation.java class="calculator.CalculatorServiceImplAddServiceImpl"/> </component> <reference name="addService" target="AddServiceComponent" /> <reference name="subtractService" target="SubtractServiceComponent" /> <!-- references to<!-- definitions of SubtractComponent, MultiplyComponent and DivideComponent --> </component> <component name="AddServiceComponent"> <implementation.java class="calculator.AddServiceImpl"/> </component> <component name="SubtractServiceComponent"> <implementation.script script="calculator/SubtractServiceImpl.rb"/> </component> <!-- definitions of MultiplyComponent and DivideComponent --> </composite> {code} Of course we need the Ruby code that implements the component. {code} def subtract(n1, n2) return n1 - n2 end {code} The Tuscany SCA runtime handles wiring Java components to Ruby components and performs any required data transformations. The calculator-script sample shows different script languages in use. So, now that our application is desribed as an SCA assembly there are lots of possibilities as we futher develop it and integration it with other applications. The following sections provide more detail on the features provided by Tuscany SCA. h2. {anchor:OnlineStore application}{bgcolor:#C3CDA1}Creating An OnLineStore SCA composite appllication{bgcolor} Now that you are familiar with SCA concepts you can use this step by step guide to create an OnlinStore composite SCA application which provides a web interface to a shopping cart. This excercise will take less than half an hour and it familiarizes you with the steps of creating and running a real SCA composite application. Although Eclipse IDE is used, no previous knowledge of Eclipse is required. You can easily see how the same steps can be used in your favorite IDE. [Want to Create my own OnlineStore SCA application|http://incubator.apache.org/tuscany/sca-java-releases.data/onlineStore.pdf]composite> |
We have added binding.ws here so that you calculator service is available over JSONRPC and WebService bindings at the same time. The helloworld-ws-service and helloworld-ws-reference samples show you how to work with web services.
TODO - we don't have a web services version of the calculator sample
SCA allows other kinds of flexibility. We can rewire our components, for example, using a one of the remote bindings, like RMI, we could have the CalculatorServiceComponent running on one machine wired to a remote version of the application running on another machine. The calculator-rmi-service and calculator-rmi-reference samples show the RMI binding at work.
Using Alternative Implementation Types
We could also introduce components implemented in different languages, for example, let's add the SubtractServiceComponent implemented in Ruby.
| Code Block |
|---|
<composite xmlns="http://www.osoa.org/xmlns/sca/1.0"
name="Calculator">
<component name="CalculatorServiceComponent">
<implementation.java class="calculator.CalculatorServiceImpl"/>
<reference name="addService" target="AddServiceComponent" />
<reference name="subtractService" target="SubtractServiceComponent" />
<!-- references to MultiplyComponent and DivideComponent -->
</component>
<component name="AddServiceComponent">
<implementation.java class="calculator.AddServiceImpl"/>
</component>
<component name="SubtractServiceComponent">
<implementation.script script="calculator/SubtractServiceImpl.rb"/>
</component>
<!-- definitions of MultiplyComponent and DivideComponent -->
</composite>
|
Of course we need the Ruby code that implements the component.
| Code Block |
|---|
def subtract(n1, n2)
return n1 - n2
end
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The Tuscany SCA runtime handles wiring Java components to Ruby components and performs any required data transformations. The calculator-script sample shows different script languages in use.
So, now that our application is desribed as an SCA assembly there are lots of possibilities as we further develop it and integrate it with other applications.