Errors occurs all the time. All you can do is to implement error handling. In this article I will describe how to use introduced layer of abstraction in exceptions area. Prior to Mule 4, developer only could access raw Java exception as Mule is a Java based ESB. This lead to situation where you, as a developer, needed analyse documentation to find exact exception that you would like to handle. Now an Error concept was introduced.
Anyone who has designed RESTfull API appreciate API Kit Router available in Mule. It not only generates flows based on API definition but also route and validate messages. Our flows looks more concise and easy to read. This feature is available for both Community and Enterprise editions. For SOAP Web Services SOAP Router is available. However this time this utility works only for Enterprise Edition. Some time ago I developed a couple of services on Mule Community Edition. All services have WSDL contracts and I must say that when I now think about the implementation I would appreciate such router. So I have decided to write something similar that would work for Mule CE.
I have already presented how to call Java code using messages processors with the newest Java Module for Mule 4.x. For earlier mule’s version Entry Point Resolvers were used to invoke custom Java code. However for scenarios when we would like to use custom code in DataWeave, for transformations, another approach is needed. Approach presented in this article will be more concise comparing to using message processors. It was highly extended comparing to possibilities of Mule 3.x version. Mule 3 allowed to invoke static methods. In contract Mule 4 not only permits to call static methods but also instantiate classes and access its instance attributes.
Tip number 2 is about converting decimal number into integer one. This may seem tricky at first. You may say that we do not need to do anything special and DataWeave engine will handle it underneath. However there is a nuance that you should be aware of. In transformation to XML this may not actually works. This tip is primary dedicated to DataWeave 1.0 as in DataWeave 2.0 this does not occur.
Tip number 1 will be about data existence check. There are often situation that nearly the same conditions need to be checked in every line. I have seen many transformations that were really long and complex. Reading them were not only difficult but a lot of repeatable conditional checks were made. Here I will show you an example that will evolve to point where we reuse everything that was possible. As a result we should achieve more concise and readable transformation. As new DataWeave is about to be released, examples will be both in 1.0 and 2.0.
Sometime it is needed to use custom JAVA code to processes current message. Developed custom code is known as Java Component. How mule knows which method should invoke and what parameters should be there passed? There are some rules that your class may full fill in order to work without any additional configuration. However when you have more sophisticated use case or class is fairly complex you would probably need Entry Point Resolver configured. I will explain on simple examples some of them. This is valid for Mule version 3.x. In next article I will describe in more detail new Java Module available in version 4.x.
For high-workload application it is important to manage resources efficiently. One of the tricks that can save resource usage is caching. In RESTful services this technic is used in GET methods. However it may by used in other cases when operation of getting particular resource can be reused. In this blog post I will extend previously design rest service by adding caching to two operations. Mule uses Cache Scope component. Apart from describing it I will show you possible obstacles and how to handle them.
HTTP GET method’s simple design has been published in previous article. We designed account service using RAML and Open API specifications. It is time, now, to implement that service so our potential users could consume it. To implement the service I use new Mule’s Design Center available on Anypoint Platform. To follow my steps you would not need to download any software on your PC at all. All will be done within web browser. On the other hand Anypoint Studio is the main IDE to design Mule’s services so I will not omit this tool. Within it I show the possibilities of APIkit message processor.
This article is an intro into a blog series about HTTP methods usage in RESTful services. As a GET is the most common I will start with it. This method is used for retrieving collection of resources or a single resource. In other words this could be used for searching purposes. However the more advanced search criteria I will describe in next article.
To design a service I will use two most commonly used specifications such as RAML and OpenAPI.