Package: pip-services3-components
Component definitions for PythonThis module is a part of thePip.Servicespolyglot microservices toolkit.The Components module contains standard component definitions that can be used to build applications and services.The module contains the following packages:Auth- authentication credential storesBuild- basic factories for constructing objectsCache- distributed cacheConfig- configuration readers and managers, whose main task is to deliver configuration parameters to the application from wherever they are being storedConnect- connection discovery and configuration servicesCount- performance countersInfo- context info implementations that manage the saving of process information and sending additional parameter setsLock-  distributed lock componentsLog- basic logging components that provide console and composite logging, as well as an interface for developing custom loggersTest- minimal set of test components to make testing easierComponent- the root packageQuick links:LoggingConfigurationAPI ReferenceChange LogGet HelpContributeUseInstall the Python package aspipinstallpip_services3_componentsExample how to use Logging and Performance counters.
Here we are going to use CompositeLogger and CompositeCounters components.
They will pass through calls to loggers and counters that are set in references.frompip_services3_commons.configimportConfigParams,IConfigurablefrompip_services3_commons.referimportIReferences,IReferenceablefrompip_services3_components.countimportCompositeCountersfrompip_services3_components.logimportCompositeLoggerclassMyComponent(IConfigurable,IReferenceable):__logger=CompositeLogger()__counters=CompositeCounters()defconfigure(self,config):self.__logger.configure(config)defset_references(self,references):self.__logger.set_references(references)self.__counters.set_references(references)defmy_method(self,correlation_id,param1):try:self.__logger.trace(correlation_id,"Executed method mycomponent.mymethod")self.__counters.increment("mycomponent.mymethod.exec_count",1)timing=self.__counters.begin_timing("mycomponent.mymethod.exec_time")# ...timing.end_timing()exceptExceptionasex:self.__logger.error(correlation_id,ex,"Failed to execute mycomponent.mymethod")self.__counters.increment("mycomponent.mymethod.error_count",1)Example how to get connection parameters and credentials using resolvers.
The resolvers support "discovery_key" and "store_key" configuration parameters
to retrieve configuration from discovery services and credential stores respectively.frompip_services3_commons.configimportConfigParams,IConfigurablefrompip_services3_commons.referimportIReferences,IReferenceablefrompip_services3_commons.runimportIOpenablefrompip_services3_components.authimportCredentialParams,CredentialResolverfrompip_services3_components.connectimportConnectionParams,ConnectionResolverclassMyComponent(IConfigurable,IReferenceable,IOpenable):__connection_resolver=ConnectionResolver()__credential_resolver=CredentialResolver()defconfigure(self,config):self.__connection_resolver.configure(config)self.__credential_resolver.configure(config)defset_references(self,references):self.__connection_resolver.set_references(references)self.__credential_resolver.set_references(references)# ...defopen(self,correlation_id):connection=self.__connection_resolver.resolve(correlation_id)credential=self.__credential_resolver.lookup(correlation_id)host=connection.get_post()port=connection.get_port()user=credential.get_username()pas=credential.get_password()# ...# Using the componentmy_component=MyComponent()my_component.configure(ConfigParams.from_tuples('connection.host','localhost','connection.port',1234,'credential.username','anonymous','credential.password','pass123'))my_component.open(None)Example how to use caching and locking.
Here we assume that references are passed externally.frompip_services3_commons.referimportDescriptor,References,IReferences,IReferenceablefrompip_services3_components.cacheimportICache,MemoryCachefrompip_services3_components.lock.ILockimportILockfrompip_services3_components.lock.MemoryLockimportMemoryLockclassMyComponent(IReferenceable):__cache:ICache__lock:ILockdefset_references(self,references:IReferences):self.__cache=references.get_one_required(Descriptor("*","cache","*","*","1.0"))self.__lock=references.get_one_required(Descriptor("*","lock","*","*","1.0"))defmy_method(self,correlation_id,param1):# First check cache for resultresult=self.__cache.retrieve(correlation_id,'mykey')# Lock..self.__lock.acquire_lock(correlation_id,"mykey",1000,1000,)# Do processing# ...# Store result to cache asyncself.__cache.store(correlation_id,'mykey',result,3600000)# Release lock asyncself.__lock.release_lock(correlation_id,'mykey')returnresult# Use the componentmy_component=MyComponent()my_component.set_references(References.from_tuples(Descriptor("pip-services","cache","memory","default","1.0"),MemoryCache(),Descriptor("pip-services","lock","memory","default","1.0"),MemoryLock(),))result=my_component.my_method(None,param1)If you need to create components using their locators (descriptors) implement
component factories similar to the example below.frompip_services3_commons.referimportDescriptorfrompip_services3_components.buildimportFactoryclassMyFactory(Factory):my_component_descriptor=Descriptor("myservice","mycomponent","default","*","1.0")def__init__(self):super(MyFactory,self).__init__()self.register_as_type(MyFactory.my_component_descriptor,MyFactory)# Using the factorymy_factory=MyFactory()my_component1=my_factory.create(Descriptor("myservice","mycomponent","default","myComponent1","1.0"))my_component2=my_factory.create(Descriptor("myservice","mycomponent","default","myComponent2","1.0"))...DevelopFor development you shall install the following prerequisites:Python 3.7+Visual Studio Code or another IDE of your choiceDockerInstall dependencies:pipinstall-rrequirements.txtRun automated tests:pythontest.pyGenerate API documentation:./docgen.ps1Before committing changes run dockerized build and test as:./build.ps1
./test.ps1
./clear.ps1ContactsThe initial implementation is done bySergey Seroukhov. Pip.Services team is looking for volunteers to
take ownership over Python implementation in the project.