Modern Internet applications use various software platforms to develop web applications. Some applications can be developed in Java, others in. Net, Angular JS, Node.js. Based on this, the question may arise, what are web services and how they are applied. Basically, the working environment is invisible to ordinary users.
Most of the time, these unique applications require some kind of communication between them. Since they are built using different development languages, it becomes really difficult to provide accurate communication between applications.
Relevance of developments
Considering the question of what web services are, it is worth determining how relevant such development is and whether it has analogues. The presented technology generalizes services and applications and allows them to communicate with each other.
Web services provide a common platform that allows multiple applications built in different programming languages to be able to communicate with each other.
In articlewill go into more detail about what web services are, the various elements that make them up, and a bit about SOA (Service Oriented Architecture) principles. Technologies, although they have complex definitions, are an accessible environment for development and programming.
Technology Definition
Answering the question what web services are, we can say that this is a standardized environment for distributing communication between client and server applications on the World Wide Web. It can be edited and have upgrade packs.
In addition, a web service can be defined as a software module designed to perform a specific set of tasks. Application building blocks can be found on the Web, and can also be called appropriately. When called, the web service will be able to provide functionality to the client that requests this portal. This happens within a couple of seconds.
Operation principle
When talking about what web services are, it is necessary to consider their working conditions. This will allow you to understand how the system functions.
The client will make a series of calls to the web service by making requests to the server that will host the actual web service.
These requests are made through what are known as remote procedure calls. Remote Procedure Calls (RPC) are method calls that are placed in the corresponding request.
Amazon is an example of a web service. The organization has a network of online stores and systemsdeliveries. It provides a web service that requests prices for products sold online through amazon.com. The outer layer or presentation layer can be in. Net or Java, but any programming language interacts with a web service in its own way. This happens on a common platform.
Components
The main component of web services on the internet is the data that is passed between the client and the server, and it is XML (Extensible Markup Language). It is analogous to HTML and is easily understood by an intermediate language that many programming languages understand. So when applications communicate with each other, they are actually communicating in XML. This provides a common platform for applications developed in different programming languages to communicate with each other.
Portals use something called SOAP (Simple Object Access Protocol) to send XML data between applications. The data is sent over regular HTTP. Information that is sent from a web service to an application is called a SOAP message.
A SOAP message is nothing but an XML document. Because the document is written in XML, the client application that calls the web service can be written in any programming language.
What are the types of apps
There are basically two types of web services:
- SOAP.
- RESTful.
In order for the developed environment to be fully functional, it is necessary to havecertain components. These components must be present regardless of which development language is used to program a particular request. You can create a web service yourself. To do this, you need to create a portal to host it and install a programming workbench.
SOAP (Simple Object Access Protocol)
The use of web services depends on the technology used. With their help, the necessary conversion and configuration of outgoing and streaming data transmitted by the system takes place. SOAP is known as a version and system independent messaging protocol. It is based on the transmission of XML data as encoded messages. Each message contains an XML document. Only the structure of an XML document follows a certain pattern, not the content. The best part about web services and SOAP is that they are all sent over HTTP, which is the standard web protocol.
This is what a SOAP message consists of:
- Every SOAP document must have a root element, known as the. The root element is the first element in the XML document.
- "Envelope", in turn, is divided into 2 parts. The first is the title and the next is the body.
- The header contains routing data, which is basically information about which client the XML document should be sent to.
- The body will contain the actual message.
WSDL (Application Description Language)
A web service cannot be used if it cannot befound. The client calling the service needs to know where its protocol actually resides.
In addition, the client application must know what a particular service is actually doing so that it can call the correct web service. This is done using WSDL, known as Web Services Description Language. The WSDL file is again an XML based file that basically tells the client application what the web service is doing. Using the WSDL document, the client application will be able to understand where the web service is located and how it can be used.
Development Benefits
Web services originated primarily to provide a platform that would allow different applications to communicate with each other.
Now we need to look at some other benefits of why it's important to use web services:
- Representation of business functions on the Web. A web service is a unit of managed code that provides some functionality to client applications or end users. This function can be called over HTTP, which means it can also be called over the Internet. Currently, all applications are on the Internet, which makes assigning web services more useful. This means that a web service can be anywhere on the Internet and provide the desired functionality as needed.
- Interaction between applications - Web services allow different applications to communicate with each other and exchange data and services among themselves. All types of applications can communicate with each other. Thus, instead of writing specific code that can only be understood by certain applications, it is now possible to write generic code that is understandable by all applications.
- A standardized protocol that everyone understands - Web services use a standardized industry protocol for communication. All four layers (Service Transfer, XML Message, Service Description, and Service Discovery layers) use well-defined protocols in the system.
- Reduce communication cost - Web services use SOAP over HTTP, so you can use the existing low-cost Internet to implement web services.
This is one of the main advantages that portal owners and developers highlight. It is worth noting that if an error occurs when calling the web service, you need to check the outgoing data. It is possible that the server or the application itself is disconnected from the common base, which prevents the transfer of data and sending requests via the specified protocols.
Application architecture
Development of web services is a simple task, but quite voluminous. It is necessary to develop our own environment where all working protocols will be uploaded in the future, as well as connect databases.
Every framework needs some kind of architecture to make sure the whole portal works as it should. Similarly, web services have an architecture that consists of three distinct roles, as listed below:
- The provider creates a web service and makes it available to a client application thatwants to use it.
- A requester is a client application that needs to contact a web service. The client application can be. Net, Java, or any other language application that looks for some functionality through a web service.
- Broker is an application that provides access to UDDI. UDDI allows a client application to locate a web service.
Interaction with other systems
Without local and virtual databases, applications cannot function. Web services allow the use of protocols and queries to process and receive information from all media. Administrators can independently connect directories and form new directions.
For work and interaction between systems and applications, there are 3 main types of request:
- Publishing is the action where a provider informs a broker (service registry) of the existence of a web service using the broker's publishing interface to make the service available to clients.
- Find - A requester consulting a broker to find a published web service.
- Binding. After receiving information from the web service obtained from the broker (service registry), the requester can bind or invoke the web service.
Development Features
All incoming information in the system is redirected to the root directories. Every operation on the Network while the protocol is running is logged. Description of web services on each specific portal givesthe ability to quickly integrate and connect the necessary source of information.
They have the following special behavioral characteristics:
- They are based on XML - Web services use XML to represent data in presentation and data transport layers. Using XML removes any dependencies on networks, operating systems, or platforms because XML is a common language that everyone understands.
- A loosely coupled system means that the client and the web service are not coupled to each other. Even if the application changes over time, it should not change how the client invokes the web service. The use of a loosely coupled architecture makes software systems more manageable and simplifies integration between different systems.
- Synchronous or asynchronous functionality - synchronicity refers to the binding of a client to the execution of a service. In synchronous operations, the client will actually wait for the web service to complete the operation. An example of this is probably a scenario where reads and writes to a database are performed. If data is read from one database and subsequently written to another, then the operations must be performed sequentially. Asynchronous operations allow a client to call a service and then execute other functions in parallel. This is one of the most common and probably the most preferred methods of ensuring that other services are not stopped when performing a certain operation.
- Ability to support remote procedure calls (RPC) - Web services allow clients to callprocedures, functions, and methods for remote objects using an XML-based protocol. Remote procedures provide input and output parameters that the web service must support.
- Support document exchange. One of the key advantages of XML is its general way of representing not only data but also complex documents. These documents can be as simple as presenting the current address, or as complex as representing the entire book.
The listed parameters describe in detail the structure and properties of services on the Internet. With their help, application developers and portal owners can integrate various scenarios of operation, while using different programming languages.
