Creando Proveedores para usar con Zend_Tool_Framework
In general, a provider, on its own, is nothing more than the shell for a
developer to bundle
up some capabilities they wish to dispatch with the
command line (or other) clients. It is an
analogue to what a
"controller" is inside of your
MVC
application.
How Zend Tool finds your Providers
By default Zend Tool uses the IncludePathLoader to find all
the providers that you can
run. It recursivly iterates all
include path directories and opens all files that end
with "Manifest.php" or "Provider.php". All classes in these
files are inspected if they
implement either
Zend_Tool_Framework_Provider_Interface
or
Zend_Tool_Framework_Manifest_ProviderManifestable
.
Instances of the provider interface make up for the real functionality
and all their
public methods are accessible as provider actions.
The ProviderManifestable interface
however requires the implementation of a method
getProviders()
which returns an array of
instantiated provider interface instances.
The following naming rules apply on how you can access the providers
that were found by
the IncludePathLoader:
The last part of your classname split by underscore is used
for the provider
name, e.g. "My_Provider_Hello" leads to your
provider being accessible by the
name "hello".
If your provider has a method
getName()
it will be used instead of the previous method to determine
the name.
If your provider has "Provider" as prefix, e.g. it is called
My_HelloProvider
it will be stripped
from the name so that the provider will be called "hello".
The IncludePathLoader does not follow symlinks, that means
you cannot link provider functionality into your include paths,
they have to be physically present in the include paths.
Exposing Your Providers with a Manifest
You can expose your providers to Zend Tool by offering a manifest
with a special
filename ending with "Manifest.php".
A Provider Manifest is an implementation of the
Zend_Tool_Framework_Manifest_ProviderManifestable
and requires the
getProviders()
method to return
an array of instantiated providers. In anticipation of our first
own
provider
My_Component_HelloProvider
we will create the following manifest:
Basic Instructions for Creating Providers
As an example, if a developer wants to add the capability of showing
the version of a
datafile that his 3rd party component is working
from, there is only one class the
developer would need to implement.
Assuming the component is called
My_Component
, he would
create a class named
My_Component_HelloProvider
in a
file named
HelloProvider.php
somewhere on the
include_path
. This class would implement
Zend_Tool_Framework_Provider_Interface
, and the body of
this file would only have to look like the following:
Given that code above, and assuming the developer wishes to access
this functionality
through the console client, the call would look
like this:
The response object
As discussed in the architecture section Zend Tool allows to hook different clients for
using your Zend Tool providers. To keep compliant with different clients you should
use
the response object to return messages from your providers instead of using
echo()
or a similiar output mechanism. Rewritting our hello
provider with this knowledge it
looks like:
_registry->getResponse
->appendContent("Hello from my provider!");
}
}
]]>
As you can see one has to extend the
Zend_Tool_Framework_Provider_Abstract
to gain access to the Registry which holds the
Zend_Tool_Framework_Client_Response
instance.
Advanced Development Information
Passing Variables to a Provider
The above "Hello World" example is great for simple commands, but
what about
something more advanced? As your scripting and tooling
needs grow, you might find
that you need the ability to accept
variables. Much like function signatures have
parameters, your
tooling requests can also accept parameters.
Just as each tooling request can be isolated to a method within a
class, the
parameters of a tooling request can also be isolated in a
very well known place.
Parameters of the action methods of a
provider can include the same parameters you
want your client to
utilize when calling that provider and action combination. For
example, if you wanted to accept a name in the above example, you
would probably do
this in OO code:
The above example can then be called via the command line
zf say hello Joe
. "Joe" will be supplied to the provider as
a parameter of the method call. Also
note, as you see that the
parameter is optional, that means it is also optional on
the command
line, so that
zf say hello
will still work, and default
to the name "Ralph".
Prompt the User for Input
There are cases when the workflow of your provider requires
to prompt the user for
input. This can be done by requesting
the client to ask for more the required input
by calling:
_registry
->getClient()
->promptInteractiveInput("Whats your name?");
$name = $name->getContent();
echo 'Hello' . $name . ', from my provider!';
}
}
]]>
This command throws an exception if the current client is not
able to handle
interactive requests. In case of the default Console Client
however you will be asked
to enter the name.
Pretending to execute a Provider Action
Another interesting feature you might wish to implement is
pretendability
. Pretendabilty is the ability
for your provider to "pretend" as if it is doing the
requested
action and provider combination and give the user as much
information about
what it
would
do without
actually doing it. This might be an important notion when doing
heavy
database or filesystem modifications that the user might not
otherwise want to do.
Pretendability is easy to implement. There are two parts to this
feature: 1)
marking the provider as having the ability to "pretend",
and 2) checking the request
to ensure the current request was indeed
asked to be "pretended". This feature is
demonstrated in the code
sample below.
_registry->getRequest()->isPretend()) {
echo 'I would say hello to ' . $name . '.';
} else {
echo 'Hello' . $name . ', from my provider!';
}
}
}
]]>
To run the provider in pretend mode just call:
Verbose and Debug modes
You can also run your provider actions in "verbose" or "debug" modes.
The semantics
in regard to this actions have to be implemented by you
in the context of your
provider. You can access debug or verbose modes
with:
_registry->getRequest()->isVerbose()) {
echo "Hello::say has been called\n";
}
if($this->_registry->getRequest()->isDebug()) {
syslog(LOG_INFO, "Hello::say has been called\n");
}
}
}
]]>
Accessing User Config and Storage
Using the Enviroment variable
ZF_CONFIG_FILE
or the
.zf.ini in your home directory you can inject configuration parameters into
any Zend Tool provider. Access to this configuration is available via the
registry
that is passed to your provider if you extend
Zend_Tool_Framework_Provider_Abstract
.
_registry->getConfig()->username;
if(!empty($username)) {
echo "Hello $username!";
} else {
echo "Hello!";
}
}
}
]]>
The returned configuration is of the type
Zend_Tool_Framework_Client_Config
but internally the
__get()
and
__set()
magic methods
proxy to a
Zend_Config
of the given configuration type.
The storage allows to save arbitrary data for later reference. This can be useful
for batch
processing tasks or for re-runs of your tasks. You can access the storage
in a similar way
like the configuration:
_registry->getStorage()->get("myUsername");
echo "Hello $aValue!";
}
}
]]>
The API of the storage is very simple:
When designing your providers that are config or storage aware remember to
check if the required user-config or storage keys really exist for a user.
You
won't run into fatal errors when none of these are provided though,
since empty
ones are created upon request.