Android Web Services
In this article, we will cover web services in android. Web services are quite essential while dealing with any applications. Most of the applications running these days use web services. Web services, in simple terms, mean providing service over the web.
In other words, web services make your application capable of communicating to the server or other applications. With the help of web services, your application gets an edge to access and send data over the internet.
From this article, you will understand what web services are and understand the several protocols used to communicate between systems or applications.
What are Android Web Services?
Android Web Services is a standardised system that helps various applications and systems to communicate with each other. While communicating, they can exchange information and also share some services among themselves. Android web services can run on the internet or private local networks depending on the requirements. Android Web Services are pretty helpful in establishing connections and ensuring security while sharing data in the network.
Below is a ubiquitous example of android web services, which would help you understand the android web services. Suppose your application can seek restaurant data from the server and then display it in your application. The application can then send back the desired list of items to the server, and then the admins can fulfil your order.
So, you can notice that data has to flow from server to application and from application back to the server. In such scenarios, Android Web Services play a significant role in establishing and deciding the protocols for communication.
How do Web Servers work?
When we consider web services, there are two essential parts of a web service known as client and server.
Client: The client is the user or the requesting application that requests data or information from a server.
Server: Server is like an admin who responds to client’s requests. Servers can handle more than one client and decide whether to fulfil or decline client requests. The server is the place where our web service is hosted globally or locally.
The below figure describes how web servers work and how client and server interact.
Components of Android Web Services
Now, let’s see some of the components present in the web server and understand their role.
1. Publisher – The publisher provides web services to clients and is also known as a service provider. It hosts and maintains the web service, ensuring it is accessible and functional for users. The publisher also defines the service’s interface and contracts, which detail how the service can be used and what it offers.
2. Subscriber – The subscriber is the user or the application that requests services from the publisher. Subscribers consume the web services by sending requests and receiving responses. They rely on the publisher to provide the necessary data and functionality needed to perform their tasks or operations.
3. Broker – Usually, the subscriber is unaware of the specific publisher and needs something to guide the location of the web service. The broker is the application that helps the subscriber identify the appropriate web service. It acts as an intermediary, providing a directory of available services and their descriptions, often using UDDI (Universal Description, Discovery, and Integration). This helps subscribers find and connect to the right web service without knowing the details of the publisher.
Now, let’s see the roles and operations each of them carries out.
- Publish – Publish means creating the web service and describing its location to the broker for its easy identification by subscribers.
- Subscribe – Subscribe means that the subscriber locates the web service with the help of the broker.
- Bind – After the subscriber successfully fetches the location, the subscriber binds itself with the web service to exchange information.
Characteristics of Web Services in Android
I hope until now you are clear with what web services are and the components involved in them. Now, it’s time for us to look at some of the web services in android.
a. Web Services are XML-Based – Both client and server use XML as their communication language. In other words, the client requests in XML and receives a response, which is XML.
b. Web services are not tied to one specific operating system or programming language. For example, a Java-based application can communicate with a Perl based application.
c. Web Services are available on both the internet or on the local network.
d. Web Services are not tightly coupled. In other words, the client-side web service and the provider side web service are not directly tied.
e. Web Services can be either synchronous or asynchronous. By being synchronous, the clients can directly perform functionalities without establishing a connection. By being asynchronous, the client first needs to establish a connection and then perform the functionalities.
f. Web Services allow you to share multiple files, including documents and complex ones.
XML Remote Procedure Calls (RPC)
One of the best ways to communicate documents and information across computers is through remote procedure calls. Let’s look at some XML-RPC details:
1. It does Remote Calls using XML messages.
2. These queries are sent over HTTP POST and are encoded in XML.
3. XML responses are integrated similarly to HTTP responses.
4. XML- RPC is platform-agnostic as well as language-agnostic.
5. It enables several apps to communicate with one another.
6. It was created in accordance with W3C guidelines.
Types of Web Services in Android
There are four types of Web Services available in android and are listed below:
1. XML-RPC
XML-RPC, popularly known as Remote Procedure Calls, are used to exchange information among large devices. Every call is encoded using XML, and HTTP is used for its transmission. It allows a client to invoke methods on a remote server and receive results, enabling communication between different systems regardless of their underlying platforms or programming languages.
2. UDDI
It stands for Universal Description, Discovery, and Integration. It is an XML-based standard designed to describe, publish, and discover web services across a network. UDDI acts as a directory service where businesses can register their services and find other services available on the network, facilitating interoperability and integration between different web services.
3. SOAP
SOAP, which stands for Simple Object Access Protocol, is an XML-based protocol used for exchanging information and documents over the internet. It operates over standard web protocols such as HTTP or SMTP and is designed to enable communication between different applications, regardless of their platform or language, through a standardized messaging protocol. SOAP supports complex operations and transactions with built-in error handling and security features.
4. REST
REST, or REpresentational State Transfer, is an architectural style that facilitates efficient communication between web service-based systems. RESTful systems adhere to principles like statelessness, where each request from a client to a server must contain all the information needed to understand and process the request. REST separates the client and server concerns, making it easier to scale and maintain web services, and supports various data formats including XML, JSON, and HTML.
Advantages of Android Web Services
1. Web services make it possible for various applications to communicate with one another.
2. Reusability is one of the essential benefits of using web services.
3. Web services allow for more efficient communication within and across applications and organisations.
4. They communicate across various apps using a high-quality industry-standard protocol.
5. They employ SOAP over HTTP to enable web services via a low-cost internet connection.
6. Web Services are made available using conventional internet protocols.
7. They enable us to make the functionalities of current programmes available to the public via the internet.
Limitations of Android Web Services
Even though web services are pretty beneficial still there are certain demerits of Web Service, which are as below:
1. They don’t take advantage of new Web advancements.
2. Web services can’t be accessed using a browser.
3. Web services utilise the HTTP protocol, which is unreliable and unsafe.
Summary
Through this article, you came across web services and understood what it means. You came across the working and the components of web services. You saw what is meant by client and server and also saw the mode of communication they follow. Then you came across the characteristics of web services in android.
Moving further, your XML-RPC and also saw the other types of web services present in android. Finally, you came across the advantages and demerits of having a web service.