3-1) Introducing Mule Applications
Mule applications accept and process messages through a series of message
processors plugged together in a flow.
Message source ---> Message processor(s) ---> Message processor(s) ---> Connector endpoint
Mule runtime is a JVM server that:
- Can handle many concurrent requests for different Java
(Mule) applications in a single JVM
- Decouples point-to-point integrations by having all
(non-Mule) applications talk to the bus (to a Mule runtime) instead of directly
to each other
- Enforces policies for API governance
Mule CE is
open source.
Mule EE is a
hardened code line with support and additional capabilities.
Mule EE is required
for:
Visual Debugging, DataWeave and DataSense, Batch module,
Additional connectors and more...
A typical flow has:
- A message source
(external source triggers the execution of the flow)
- Message
processors (transform/filter/enrich/process the message)
A Mule message:
Inbound properties <--- from="" message="" o:p="" set="" source="" the="">
Outbound properties <--- added="" by="" message="" o:p="" processor="">
Payload <--- core="" message="" o:p="" of="" the="">
Attachments <--- ancillary="" info="" message="" o:p="" the="" to="">
3-2) Creating Mule
applications with Anypoint Studio
Image: Anatomy of a
flow: Visual
Image: Anypoint
Studio anatomy
How to test applications:
- A browser
- A cURL command-line utility
- A browser extension like Postman
- MUnit (a Mule
application testing framework for building automated tests)
3-3) Understanding
Mule application building blocks
Mule application building blocks are separated into
categories in the Mule Palette:
- Connectors
- Scopes
- Components
- Transformers
- Filters
- Flow Control
- Error Handling
3-4) Connecting to
Databases
- Can connect to almost any JDBC-compliant relational
database.
- Supports operations including: SELECT, INSERT, UPDATE,
DELETE, Stored Procedures, Bulk Execute, CREATE, ALTER...
Image: Example
Database Query in Anypoint Studio (RAW output returned)
3-5) Transforming
Data
DataWeave:
- is a
full-featured and fully native framework for querying and transforming data on
Anypoint Platform
- can be used for all your transformations (simple to
complex)
- enables very high performance transformations
- is fully integrated with DataSense allowing a
payload-aware development.
Image: DataWeave:
Transform Message: Code Auto-Completion
Image: Converting
SQL Output to JSON is as simple as adding an ‘Object to JSON’ transformer (but
it is better to use DataWeave)
Image: Converting
Database Output using ‘Transform Message’ (DataWeave)
Image: Transform
Messsage
3-6) Creating
RESTful Interfaces Manually for Mule Applications
Image: Adding {ID}
to Path
{} states that we’re
not just expecting /flights but also some type of dynamic value after flights
in the URI.
Set Payload Example:
Set Payload >
Settings > Value:
{"message":
"Flight added (but not really)"}
3-7) Generating
RESTful interfaces automatically using APIkit
APIkit is an
open-source toolkit that includes:
- A Router element
for Mule applications
- A Proxy element
for Mule applications
- APIkit Mapping
Exception Strategy
- APIkit Anypoint
Studio plugin
The Anypoint Studio APIkit plugin can generate an
interface automatically from a RAML API definition.
It generates a main routing flow (that uses APIkit
Router) and flows for each of the resource / method pairs.
You add processors to the resource flows (usually Flow
References) to hook up to your backend logic.
Image: The APIkit automatically
generated interface
APIkit allows a seamless API design to implementation
experience:
- When you create a project with APIkit components and a
RAML file on Anypoint Platform, a connection is made to that RAML file
--- The remote RAML is polled periodically and compared
to the local version
- Use the APISync view to pull/push/compare between
Anypoint Studio and API Desginer
Image: Creating a
New Mule Project and Adding APIkit Components
3-8) Connecting
Interfaces to Implementations
Passing Messages to Other Flows:
- Flows can be broken into multiple flows.
Image: Copying Mule
Flow XML from one project to another
Note: The red cross is because we need to copy the MySQL driver from
‘Referenced Libraries’ in the original project, to the new project.
Walkthrough:
Implement a RESTful web service
- Pass a message from one flow to another
- Create new logic for nested resource call
- Call the backend flows
- Test the web service in the APIkit Consoles view and
Postman
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