Milestone #2 - Communication contract for String Parsing Microservice

This microservice leverages the remote procedure call Python library RPyC to receive a string input and parse it based on the client's specification.

• Documentation
• RPyC Services Tutorial

These instructions will help you get a copy of the microservice installed on your local machine.

• Python 3+
• pip3

From the command line, navigate to the directory where you want the microservice files to live and copy the source code from the repository:

https://github.com/markyjordan/CS361-Microservices-Implementation.git

Next, navigate to the newly cloned repository and install the RPyC python module.

NOTE: You can execute the below instructions with pip if pip3 has been aliased to pip in your system.

pip3 install rpyc

First, change your directory to the microservice directory.

cd microservice-folder-name

Next, install the virtualenv Python module if your system doesn't already have it installed.

pip3 install virtualenv

Initialize a new virtual env.

virtual venv

Activate the virtual environment.

source venv/bin/activate

In the directory containing the microservice server file, open a command line window and run the following:

python3 server.py

NOTE: By default, the microservice is configured to run on PORT 18861. If you need to configure the microservice to run on a different PORT, you can modify the global PORT variable defined in both the client.py and server.py files.

At this point, the microservice server should be active and ready to receive requests from a client.

To terminate the microservice server, enter Ctrl + C in the command line window.

Inorder to send a request to the microservice, your client file will need to import the rpyc Python module and configure the global PORT variable with a port number that matches the server port number defined in the server.py file. Then, you will need to establish a connection to the microservice server by calling rpyc.connect("localhost", PORT).

import rpyc

# Configure the port number to match the server's port number.
PORT = 18861

# Establish a connection to the server
connection = rpyc.connect("localhost", PORT)

Using the variable in the client.py file that was used to establish the connection to the microservice server (i.e. connection in the client.py example above), the client can access two of the microservice server's exposed string parsing methods as outlined below:

This method takes a multiline string as input and returns to the client a new string with an HTML <br> tag inserted after each punctuation mark.

sample_string = "Hello. This is a multiline string. With periods. Split me with HTML. And here is an exclamation point! And then a question mark? And what about multiple?? No problem!! It just works."

splitWithHTML = connection.root.splitStringWithHTML(sample_string)

The variable splitWithHTML shown above will contain the string returned by the microservice server.

This method takes a string as input and returns to the client a list of strings where each element is a word in the input string. If the word is the last word in a sentence, the punctuation mark is included as part of the word in the list element.

sample_string = "Hello. This is a multiline string. With periods. Split me with HTML. And here is an exclamation point! And then a question mark? And what about multiple?? No problem!! It just works."

stringToList = connection.root.splitStringToList(sample_string)

The variable stringToList shown above will contain the list of strings returned by the microservice server.

NOTE: The server.py file exposes its methods to a client by prefixing them with 'exposed_' (i.e. exposed_splitStringWithHTML(self, input)).

When calling an exposed method on the client side, the exposed_ prefix is not included (i.e. connection.root.splitStringWithHTML(input)).

Mark Jordan

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