The development of microservices is challenging, and getting them right is quite hard. Is there something we can do to make this process easier? It turns out that there are a couple of guidelines that, if followed, can help a lot in getting microservices right. So, let's take a look at these guidelines, as shown in the following list:

• Design before developing: When microservices development takes place, they are usually supposed to model a particular domain of responsibility. But this is also the point where the biggest mistakes occur. Usually, the boundaries of a service are not defined. During the later stages, as the domain evolves, the microservice also becomes complex so as to handle the increased context of the domain. This complexity makes the microservice bulky and increases the cost of running and maintaining the microservice.
• Single responsibility principle (SRP): Following on from the preceding point, the principle of single responsibility comes into the picture. This principle states that a microservice should do only one task and do it well. As the underlying domain increases, new microservices should be rolled out instead of adding newer and newer functionalities to the existing microservice.
• Maintain the abstractions: A microservice should provide an increased independence. If a service requires the other services to have knowledge about its internals to allow them proper integration, then there is something wrong with the design. A good microservice design will focus on providing services that act as black boxes for the other services that take in a response in a well-defined format and produce a response in a well-defined format.
• Keep the message format simple: The message format through which the microservices communicate with each other should be simple enough to enable the simple processing of data without stressing too much about the decoding of the data.
• Every service should be self-sustained: When designing the microservices, it should be kept in mind that every microservice should be able to handle all of the operations related to its functionality independently. This may involve logic to process a particular message or store data.
• Avoid centralization of data: To efficiently employ the use of microservices architecture and to have increased failure resiliency, the microservices should not utilize a single data source for handling the data. If all the services use a single data source, then in the event of the data source going down, all the services will fail to operate, thereby ending up with a single point of failure, which is not a desired pattern inside the microservices architecture.

Now, we know about a few simple tips, which, if followed, can help us avoid a lot of hardships that may be experienced when using a microservices architecture. But even when we follow these principles, there are still a few questions that need to be answered, questions such as what will happen if a particular service goes down, how much time it will take for a particular microservice to respond to a request, and so on.

To answer these questions, usually, the teams write agreements that provide guarantees about the uptime of the microservices, how these services will be monitored, their response times, and the requests they can take at any given point in time. These agreements are called service-level agreements (SLAs), and provide a contract that is followed by the services. So, let's take a look at what these SLAs do and how they can help us in the development of microservices.