Mule 3 vs Mule 4

Mule is a lightweight ESB, which is a built-in framework offered by MuleSoft. It is a full-featured platform based on JAVA, but it can connect to any other platform and APIs. MuleSoft enables the developers to connect with any application and interact, no matter the language used for building this application, in a highly flexible way. It also builds an active way of communication between the built-in application to send or share data on a trusted and secure platform. Mule 4 is the most recent and advanced release of Mule. It offers exciting integration technologies and API-led networking at a lower cost and in a simplified manner to support organizational efforts towards full digitalization, when Compared to its previous upgrade of Mule 3. In this post, let us learn about mule 3 and mule 4, their differences, and the reasons why we need to upgrade to mule4.

Mule 3 vs. Mule 4:

  • Mule runtime engine: After getting enormous attention with mule 3, many organizations began to develop a lot of APIs, ETLs, microservices, and integration interfaces into their huge enterprise settings. While Mule 3 helped the developers to reduce development stages and improve productivity, obtaining excellent performance remained a challenge for large companies. That is the reason Mule 4 came into the picture. Mule 4 is designed with a self-tuning runtime engine that will allocate the resources, thread-pool, and threads. The runtime engine automatically and intelligently allocates the thread pools to the Mule 4 connectors according to the situation, regardless of CPU or IO sensitivity. The thread pool is manually configured using the conf/scheduler-pools.conf file.

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  • Mule message structure: In mule 3, the mule message consists of two parts. They are payload and message header. Again, the message header contains some inbound and outbound properties. Mule 3 variables represent message metadata. But mule 4 looks more like a model based on an event, where each mule event is composed of a message and relevant variables. There are no inbound or outbound properties in mule 4. But there is one attribute which holds all relevant headers and other properties.
    For example: In mule 3, the syntax to read an HTTP method from an HTTP request is - #[message.inboundProperties[‘http.method’] But in mule 4, it is written as #[attributes.method].

                                                                                                             [Related Article: Mule Message Structure]

  • DataWeave replaces MEL: Now, we cannot find Mule Expression Language in mule 4. Dataweave 1.0 was introduced in mule 3 as a substitute for their DataMapper. DataWeave is extremely simple and powerful. It is based on lambda calculus and functional programming. Mule 4 began with the release of DataWeave 2.0 and replaced MEL with that. Later, Mulesoft released their latest version of DataWeave 2.2.0 and expanded it with more features and libraries. A very cool feature was added in this release which erases the whole context when the script of DataWeave fails.

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  • Project Structure: Mulesoft has launched an updated version of Anypoint Studio version 7, which runs only the Mule 4 application. Anypoint studio 6.x.x or less can run only mule 3. The project structure of Mule 3 is not recognized in Anypoint studio 7.x.x.  
    Mule 3 had two kinds of projects: 
  • Mule project 
  • Mulesoft application with the Maven project

But, in Mule 4, only one option is available. All the Mule 4 applications are based on Maven now. Anypoint studio 7.x. x incorporates Maven and a default configuration. But they are not found in Anypoint studio 6.x. x or lower versions. Another great change in Mule 4 is, Mule 4 is now a jar file, and it is not a deployable zip package anymore. This jar file can be distributed to deploy or shared with others. The option Import into Anypoint studio 7.x. x can develop the Mule project out of the jar.

                                                                                                                                  [Related Article: Anypoint studio]

  • Error handling: Mule 3 is based on the implementation of developers based on the Java exception and does not really have a specific framework for identifying the type and nature of errors. Mule 4 went one step further and found a few groups of errors, types, and different ways to deal with them. It is much cleaner, more readable, and easier now. And there are many other changes made in mule 4.

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Mule 4 increases the speed of developers and reduces the duration of integration. Mule 4, by providing a single thread pool of the overall application development flow, enhanced message models, effective streaming and self-tuning of runtime engines, etc., strengthens developers' confidence and helps companies maximize their performance.

Though mule 4 appears to be great and strong, it is yet considered at its early developmental stage. As a result, experiencing different kinds of bugs and problems are common. Few significant problems are Anypoint Studio operates very slowly when it loads a lot of apps. A few memory leaks in version 7.3.2 have been corrected in Anypoint studio version 7.3.3 recently. However, mule 4 is the base for Mule ESB to help developers write robust microservices in an agile way.

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Kavya Gowda
Kavya Gowda
Research Analyst
Kavya works for HKR Trainings institute as a technical writer with diverse experience in many kinds of technology-related content development. She holds a graduate education in the Computer science and Engineering stream. She has cultivated strong technical skills from reading tech blogs and also doing a lot of research related to content. She manages to write great content in many fields like Programming & Frameworks, Enterprise Integration, Web Development, SAP, and Business Process Management (BPM). Connect her on LinkedIn and Twitter.