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.