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PHP Web Services

Cover of PHP Web Services by Lorna Jane Mitchell Published by O'Reilly Media, Inc.
  1. Preface
    1. Conventions Used in This Book
    2. Using Code Examples
    3. Safari® Books Online
    4. How to Contact Us
  2. 1. Introduction
  3. 2. HTTP
    1. Examining HTTP
      1. Curl
      2. Browser Tools
      3. PHP
  4. 3. Request and Response
    1. Clients and Servers
  5. 4. HTTP Verbs
    1. GET
    2. POST
    3. Other HTTP Verbs
  6. 5. Headers
    1. Request and Response Headers
    2. Common HTTP Headers
      1. User-Agent
      2. Headers for Content Negotiation
      3. Authorization
      4. Custom Headers
  7. 6. Cookies
    1. Cookie Mechanics
    2. Working With Cookies in PHP
  8. 7. JSON
    1. When to Choose JSON
    2. Handling JSON with PHP
    3. JSON in Existing APIs
  9. 8. XML
    1. When To Choose XML
    2. XML in PHP
    3. XML in Existing APIs
  10. 9. RPC and SOAP Services
    1. RPC
    2. SOAP
      1. WSDL
      2. PHP SOAP Client
      3. PHP SOAP Server
      4. Generating a WSDL File from PHP
      5. PHP Client and Server with WSDL
  11. 10. REST
    1. RESTful URLs
    2. Resource Structure and Hypermedia
    3. Data and Media Types
    4. HTTP Features in REST
      1. Create Resources
      2. Read Records
      3. Update Records
      4. Delete Records
    5. Additional Headers in RESTful Services
      1. Authorisation Headers
      2. Caching Headers
    6. RESTful vs Useful
  12. 11. Debugging Web Services
    1. Debug Output
    2. Logging
    3. Debugging From Outside Your Application
      1. Wireshark
      2. Charles Proxy
    4. Finding the Tool for the Job
  13. 12. Making Service Design Decisions
    1. Service Type Decisions
    2. Consider Data Formats
    3. Customisable Experiences
    4. Pick Your Defaults
  14. 13. Building a Robust Service
    1. Consistency is Key
      1. Consistent and Meaningful Naming
      2. Common Validation Rules
      3. Predictable Structures
    2. Making Design Decisions for Robustness
  15. 14. Error Handling in APIs
    1. Output Format
    2. Meaningful Error Messages
    3. What To Do When You See Errors
  16. 15. Documentation
    1. Overview Documentation
    2. API Documentation
    3. Interactive Documentation
    4. Tutorials and the Wider Ecosystem
  17. A. A Guide To Common Status Codes
  18. B. Common HTTP Headers
  19. About the Author
  20. Copyright
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Chapter 9. RPC and SOAP Services

In this chapter we’ll talk about two closely-related types of service: RPC (Remote Procedure Call) services, and SOAP. These two feel fairly similar to use as they involved calling functions and passing parameters, but their implementations are a stark contrast as the RPC is a very loose way of describing a service, whereas SOAP is very tightly specified.


RPC services quite literally call procedures (i.e. functions) remotely. These types of API will typically have a single endpoint, so all requests are made to the same URL. Each request will include the name of the function to call, and may include some parameters to pass to it. Working with RPC services feels familiar to us as developers because we know how to call functions, and we simply do so over HTTP.

As a quick example, let’s revisit the call we made to flickr earlier (see Fetching data from Flickr’s XMLRPC service). The URL we made for that example was:

Within the URL, you can see the name of the function in the “method” parameter, and the additional fields we pass in; tags to search for a particular tag and a format parameter to ask for the response in XML-RPC format.

There is a distinct difference between using an RPC-style service, with function names and parameters as part of the data we pass, and having a service that is true XML-RPC[14], which is a very defined format. Which ...

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