Encapsulate backend specifics with custom Camel component that wraps existing component - apache-camel

Question

We have different backends (mostly SOAP so I will focus on this) each with its own specifics (security, default timeout, error handling etc).
On the other hand we have a lot of integration services that orchestrate calls to these backends. For example "service A" first calls "backend 1" and then "backend 2" with SOAP requests. Finally it uses the responses of both backends to create a response.
There are a lot of services like "service A", each of them has an individual orchestration. Each of them is an individual project with its own repository and is deployed as a small Spring-Boot unit.
Let's say that 4 out of 10 services call "backend 1". They do not necessarily call the same service of "backend 1", but they all need to implement the specifics of this same backend. For example send special headers, a specific security token, use a retry strategy for this backend etc.
To avoid that every integration service repeats the specifics for "backend 1" or "backend 2", I would like to somehow encapsulate these specifics.
Because we use Apache Camel, I assume that I could do this with a custom Camel component. But because components typically integrate a new type of backend, I don't know if I should do this or if it is a bad idea. My backend types (for example SOAP) already exist as components, I would just wrap them with specifics.
For example to "encapsulate" a SOAP backend I could create a custom component that delegates to the CXF component to create concrete service endpoints with the common specifics of this backend (headers, security, etc).
In the Camel route the endpoints would perhaps look somehow like this
MyBackend://serviceUri?option1=value1
and under the hood it would create
cxf://serviceUri?backendSpecific1=valueA&backendSpecific2=valueB&option1=value1
Or are there other, better suited extension points to use for this use case?

Answer 1

There is a way to achieve this to some level. Its called endpoint reuse. Let me take you on how I typically tackle a problem like this.
I normally declare all my SOAP and JMS enpoints in my camel-context.xml. I then create xml files for each route and reference the endpoints defined in my camel-context.xml from there.
Here is a short example of my camel-context.xml note the routeContextRef element:
<bp:blueprint
xmlns="http://camel.apache.org/schema/blueprint"
xmlns:bp="http://www.osgi.org/xmlns/blueprint/v1.0.0"
xmlns:cm="http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.1.0"
xmlns:ext="http://aries.apache.org/blueprint/xmlns/blueprint-ext/v1.2.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
http://camel.apache.org/schema/blueprint http://camel.apache.org/schema/blueprint/camel-blueprint.xsd
http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.1.0 http://aries.apache.org/schemas/blueprint-cm/blueprint-cm-1.1.0.xsd
http://aries.apache.org/blueprint/xmlns/blueprint-ext/v1.2.0 http://aries.apache.org/schemas/blueprint-ext/blueprint-ext-1.2.xsd">
<camelContext id="foo-bar" trace="{{camel.context.trace}}" autoStartup="true" useMDCLogging="true" useBreadcrumb="true" depends-on="jms" threadNamePattern="#camelId#-thread-#counter#" managementNamePattern="#camelId#-#version#" allowUseOriginalMessage="false" streamCache="false">
<routeContextRef ref="foo-bar-routes"/>
<endpoint id="jms-gateway-v1" uri="jms:queue:Foo.Bar.System.Evt.1.0.T" />
<endpoint id="rs-gateway-v1" uri="cxfrs://bean://rs-gateway-impl-v1" />
</camelContext>
I then create a foo-bar-routes.xml and I reference the endpoint from there like so:
<bp:blueprint xmlns="http://camel.apache.org/schema/blueprint"
xmlns:bp="http://www.osgi.org/xmlns/blueprint/v1.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ers="http://www.fooxml.com/events/resourceitem/service/v1"
xsi:schemaLocation="http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
http://camel.apache.org/schema/blueprint http://camel.apache.org/schema/blueprint/camel-blueprint.xsd">
<routeContext id="foo-bar-routes">
<!--
This route receives an event from the JMS queue
-->
<route id="jms-gateway-route-v1">
<from ref="jms-gateway-v1" />
<to ref="rs-gateway-v1" />
</route>
</bp:blueprint>
So in short I wrap my SOAP and JMS components in endpoint definitions and then reuse these in routes that are defined in the own xml document. I could add a second route in another XML file and reuse the endpoint in that route just add, rinse and repeat.
I know the JavaDSL has similar functionality so it is achievable as well using the JavaDSL as well.