Advanced Message Queuing Protocol - AMQP

AMQP meaning

AMQP refers to Advanced Message Queuing Protocol. 

Globally recognized standard that works on the application layer essentially, it is mainly used for developing unmatched communication operability between client and broker parties. 

The publisher bears the responsibility of message generation while clients collect and administer them. 

The role of brokers, such as RabbitMQ, in this whole process is to make a sure message, part of the exchange, goes directly from the publisher to the client. 

Speaking of its key functionality, routing, message orientation, and queuing are the top ones. Use of AMQP makes interoperability an achieved goal, featuring different configurations and infrastructure. It allows developers to bring all the protocol-approved compliant client library and broker offered into action.  

History of AMQP

First created by John O’ Hara in 2003, AMQP has evolved a lot since its inception and has a rich history. While John originated AMQP, he was working with JPMorgan Chase and the company retained all the rights of AMQP and used it to contract with iMatrix Corporation. Both these two firms used AMQP to design protocols documentation as well as C broker. This usage of AMPQ continued until mid-2006.  

However, JPMorgan Chase decided to make AMQP famous and ready to use for other firms as well. This is why, in the mid of 2005, the firm made efforts to form a user group for AMQP that included top IT giants like Cisco, Red Hat, IONA Technologies, and TWIST.

Slowly, the group expanded and featured 23 companies. Some of the newly added members were Barclays. IIT Software, Bank of America, Credit Suisse, Progress Software, and Informatica. 

AMQP 1.0 was launched in October 2011, and soon after this, i.e. on 1st November, OASIS Technical Committee was introduced to the world. Its key responsibility was to keep an eye on AMQP 1.0 advancement.

The first and second drafts, as per the feedback of the working committee, were launched in February 2012 and June 2012 respectively. 

A few months later, towards the end of October 2012, AMQP became the authorized OASIS standard. 

In 2014, OASIS AMQP standard got acceptance from international standards like IEC and ISO too.

AMQP Terminology

While one plans to bring AMQP into action, getting to know some of its key terminologies is imperative. In this post part, we have explained the widely used ones.

• Broker (or server) plays a crucial role in AMQP protocol enablement. It is responsible for connection building that ensure better data routing and queuing at the client-side. 
• The job of queues generation and message acknowledgement is taken care of by consumer. 
• Redirection of data taken from exchanges and its placement in queues is taken care of by producer. 

Components of AMQP

Other than the above AMQP terminologies, developers must be aware of certain components used for AMQP model deployment. 

• Exchanges (and their classification)
  

Exchange handles the responsibility of fetching messages and placing them carefully in the right queue. Its 4 categories are: Fanout, Headers, Topic, and Direct. To detail you on it further, it is an indispensable component of the broker.

• Channel
  

Channel refers to a multiplexed virtual connection among AMQP peers, which is built inside an existing connection.

• Message Queue
  

It is an identified entity that helps link messages with their resources or point of origin.

• Binding
  

Bindings denote a set of predefined instructions related to queues as well as exchanges. It administers the sending of message and their delivery.

• Virtual Hosts
  

vhost is a platform offering the segregation facility inside the broker. Based upon users and their access rights, there could be multiple vhost functional at a time.

How AMQP Exchanges work?

The functional mechanism that AMQP follows is simple; however, only after everything is set and system is ready for communication. 

The exchanges play a crucial role in trading messages as they start with delivering the messages to client, perform processing as per the rules, and direct the output of previous stage to 1 or multiple queues. Its type in use decides which routing method will be followed. 

For instance, in the case of ‘direct’ type, the newly-added data contains final message destination. Alternatively, Fanout exchange do not use any information routing method. Instead, It broadcasts the same piece of information to all queues attached.

API development with AMQP

Now that you are well-aware of what is AMQP and how it works, let us explain how it can help in API development. Using AMQP, APIs can:

• Direct send messages
• Cache messages them in queue for trigger-based sending;
• Can route information or bind exchanges to the designated queues;
• Establishes connection among exchanges in order to ensure efficient communication;
• Can send automated or manual acknowledgement.
  

You may consider a few scenarios where AMQP can be used in APIs, for example:

• Adding money to your digital wallets
• Credit or debit card transaction in retail stores
• In messengers or communication systems 
  

Let us take the first example and elaborate it now:

1. Adding money to your digital wallet, such as Paytm will require selecting a method for adding money. It will initiate the create service.
2. Now comes the authentication step. If verified the details, the next service will fetch money and add it to the wallet.
3. To give your user a chance to prevent transactions if he wants, you must have a cancel service.
4. Messages exchange entertained by AMQP is asynchronous. As transactions are crucial events and you won’t want inconsistency in them, there can be an extra service events that will keep track of the outcome of each message so that the next event could be triggered on time.
   

So, you see, asynchronous nature of AMQP will cause the need for callbacks in comparison to HTTP. Also, it is more complex to design ‘fetch’ endpoints using this protocol.

To conclude, if you could develop its API functionality well, AMQP can work well with HTTP too. As it is lightweight, it will improve your application’s performance significantly. If you cannot bear the complexity of the development process, HTTP can be used alone and it will be sufficient for the job. Interesting article about API Security.

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The Final word

AMQP is a futuristic message protocol constructed especially for consumers and publishers. This open-source app developers use it to enable communication without worrying about the underlying technologies and platforms for the app. This article briefed you on AMQP, its history, its components, and how it works in an elaborated manner. Hope you now have a better understanding of this protocol.