RESTful Web Services – Addressing

RESTful web services are a popular way to build web-based systems. A distinctive characteristic of these services is the transfer of resources from one system to another using HTTP messages. The resource can be anything like an image, a document or even a person. Addressing the resource correctly in a RESTful web service is of utmost importance. There are several ways to address a resource in a RESTful web service. In this article, we will explore different addressing schemes for RESTful web services.

What is Addressing?

Addressing is the process of uniquely identifying a resource on the World Wide Web. Every resource in a RESTful web service should have a unique and permanent identifier, called a URI. The URI is used to locate and identify the resource on the network. The correct addressing is crucial in a RESTful web service, as it enables the client to interact with the resource effectively.

Addressing with Absolute URI

An absolute URI contains the complete address of the resource on the network. It includes the protocol, hostname and resource path. Absolute URI is useful when the client needs to access the resource using a different protocol or hostname. A client can directly access the resource using its Absolute URI. Here is a sample code for an Absolute URI for a resource:

“`http://hostname/path/to/resource“`

This is an example of addressing a resource using an Absolute URI. In this case, the resource address contains the protocol http, hostname hostname and resource path /path/to/resource.

Addressing with Relative URI

Relative URI is an address of a resource relative to the current document. This addressing scheme is useful when the client requires accessing the resource on the same server or protocol. The server prepends the base URI to a relative URI to obtain the absolute URI for that resource. The base URI is the address of the current document. Here is sample code for addressing a resource using a relative URI.

<a href="/path/to/resource">Resource Link</a>

This is an example of addressing a resource using a relative URI. In this case, the resource address contains only the path /path/to/resource. The server prepends the base URI to the relative URI to get the absolute URI.

Addressing with Query Parameters

Query Parameters are used to pass data to the server. They are part of the URI and come after the question mark ?.The client can pass the parameters with the resource address to retrieve a specific resource. The server can interpret the query parameters and return the corresponding resource. Here is sample code for retrieving a user resource using a query parameter:

“`http://hostname/api/users?id=123“`

In this example, the query parameter id is used to retrieve a user with ID 123.

Addressing with Matrix Parameters

Matrix Parameters are used to pass data to the server. They are part of the URI and come after the semicolon ;. The client can pass the parameters with the resource address to retrieve a specific resource. The server can interpret the matrix parameters and return the corresponding resource. Here is sample code for retrieving a user resource using a Matrix Parameter:

http://hostname/api/users;id=123

In this example, the Matrix parameter id is used to retrieve a user with ID 123.

Addressing with Path Parameters

Path Parameters are used to pass data to the server. They are part of the URI and come after the resource path. The client can pass the parameters with the resource address to retrieve a specific resource. The server can interpret the path parameters and return the corresponding resource. Here is sample code for retrieving a user resource using a Path Parameter:

“`http://hostname/api/users/{id}“`

In this example, the Path parameter id is used to retrieve a user with ID 123. The path parameter syntax is different for each programming language.

Conclusion

Addressing is an essential aspect of developing RESTful web services. The correct addressing scheme makes it possible for a client to interact with a resource effectively. Absolute URI is useful when the client needs to access the resource using a different protocol or hostname. Relative URI is useful when the client requires accessing the resource on the same server or protocol. Query Parameters, Matrix Parameters and Path Parameters are used to pass data to the server. Each parameter has its syntax, which differs from one programming language to another. It is crucial for developers to understand addressing in RESTful web services to create efficient and effective applications.