In this module, we will explore how to interface MUMPS with APIs and web services. This is crucial for integrating MUMPS applications with modern web technologies and other systems.

• Definition: APIs are sets of rules and protocols for building and interacting with software applications. They allow different software systems to communicate with each other.
• Types:
  • REST (Representational State Transfer): Uses standard HTTP methods (GET, POST, PUT, DELETE).
  • SOAP (Simple Object Access Protocol): Uses XML for message format and relies on other application layer protocols, such as HTTP or SMTP.

• Definition: Web services are a type of API that operate over a network, typically the internet. They allow different applications to communicate and share data and services among themselves.
• Types:
  • RESTful Web Services: Use REST architecture.
  • SOAP Web Services: Use SOAP protocol.

• Ensure you have a working MUMPS environment.
• Install necessary libraries or tools for HTTP requests (e.g., cURL).

A GET request is used to retrieve data from a server.

Example: GET Request

Explanation:

• SET url="http://api.example.com/data": Define the URL.
• SET command=curl_" -X GET "_url: Construct the cURL command.
• OPEN "pipe":(command:readonly)::"pipe": Open a pipe to execute the command.
• USE "pipe" READ response: Read the response.
• CLOSE "pipe": Close the pipe.
• WRITE response: Output the response.

A POST request is used to send data to a server.

Example: POST Request

Explanation:

• SET data="name=John&age=30": Define the data to be sent.
• SET command=curl_" -X POST -d '"_data_"' "_url: Construct the cURL command with data.
• The rest of the steps are similar to the GET request.

Explanation:

• SET jsonResponse="{""name"":""John"",""age"":30}": Define a JSON response.
• SET name=$PIECE($PIECE(jsonResponse,""name"":""",2),""",",1): Extract the name.
• SET age=$PIECE($PIECE(jsonResponse,""age"":",2),"}",1): Extract the age.
• WRITE "Name: ",name,!, "Age: ",age,!": Output the parsed data.

1. Objective: Write a MUMPS program to fetch data from a public API and display it.
2. Steps:
   • Choose a public API (e.g., https://jsonplaceholder.typicode.com/posts/1).
   • Write a GET request to fetch data.
   • Parse the JSON response.
   • Display the parsed data.

Solution

• Mistake: Forgetting to close the pipe after reading the response.
  • Tip: Always ensure to close the pipe to free up resources.
• Mistake: Incorrectly parsing JSON due to improper string handling.
  • Tip: Double-check the JSON structure and use appropriate string functions.

In this section, we covered the basics of APIs and web services, how to make HTTP requests in MUMPS, and how to parse JSON responses. These skills are essential for integrating MUMPS applications with modern web technologies. In the next module, we will explore interfacing MUMPS with SQL databases.