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commit a93137d6145f47ba6dfba8a3277045417f161c70
Author: Claus Ibsen <claus.ib...@gmail.com>
AuthorDate: Sat Dec 30 14:56:02 2023 +0100
CAMEL-19749: Add variables as concept to Camel
---
.../engine/DefaultVariableRepositoryFactory.java | 9 ++-
.../mbean/ManagedVariableRepositoryMBean.java | 4 +-
.../working-with-camel-core/pages/index.adoc | 1 +
docs/user-manual/modules/ROOT/pages/variables.adoc | 82 ++++++++++++++++++++++
4 files changed, 91 insertions(+), 5 deletions(-)
diff --git
a/core/camel-base-engine/src/main/java/org/apache/camel/impl/engine/DefaultVariableRepositoryFactory.java
b/core/camel-base-engine/src/main/java/org/apache/camel/impl/engine/DefaultVariableRepositoryFactory.java
index 2190fc9242a..0410f5afc1c 100644
---
a/core/camel-base-engine/src/main/java/org/apache/camel/impl/engine/DefaultVariableRepositoryFactory.java
+++
b/core/camel-base-engine/src/main/java/org/apache/camel/impl/engine/DefaultVariableRepositoryFactory.java
@@ -47,11 +47,14 @@ public class DefaultVariableRepositoryFactory extends
ServiceSupport implements
@Override
public VariableRepository getVariableRepository(String id) {
- if ("global".equals(id)) {
+ if (global != null && "global".equals(id)) {
return global;
}
VariableRepository repo = CamelContextHelper.lookup(camelContext, id,
VariableRepository.class);
+ if (repo == null) {
+ repo = CamelContextHelper.lookup(camelContext, id +
"-variable-repository", VariableRepository.class);
+ }
if (repo == null) {
// try via factory finder
Class<?> clazz = factoryFinder.findClass(id).orElse(null);
@@ -79,8 +82,8 @@ public class DefaultVariableRepositoryFactory extends
ServiceSupport implements
protected void doStart() throws Exception {
super.doStart();
- VariableRepository repo
- = CamelContextHelper.lookup(camelContext,
GLOBAL_VARIABLE_REPOSITORY_ID, VariableRepository.class);
+ // let's see if there is a custom global repo
+ VariableRepository repo = getVariableRepository("global");
if (repo != null) {
LOG.info("Using VariableRepository: {} as global repository",
repo.getId());
global = repo;
diff --git
a/core/camel-management-api/src/main/java/org/apache/camel/api/management/mbean/ManagedVariableRepositoryMBean.java
b/core/camel-management-api/src/main/java/org/apache/camel/api/management/mbean/ManagedVariableRepositoryMBean.java
index 8614f2b812c..6a976f07bee 100644
---
a/core/camel-management-api/src/main/java/org/apache/camel/api/management/mbean/ManagedVariableRepositoryMBean.java
+++
b/core/camel-management-api/src/main/java/org/apache/camel/api/management/mbean/ManagedVariableRepositoryMBean.java
@@ -18,11 +18,11 @@ package org.apache.camel.api.management.mbean;
import java.util.Set;
+import javax.management.openmbean.TabularData;
+
import org.apache.camel.api.management.ManagedAttribute;
import org.apache.camel.api.management.ManagedOperation;
-import javax.management.openmbean.TabularData;
-
public interface ManagedVariableRepositoryMBean extends ManagedServiceMBean {
@ManagedAttribute(description = "Repository ID")
diff --git a/docs/main/modules/working-with-camel-core/pages/index.adoc
b/docs/main/modules/working-with-camel-core/pages/index.adoc
index fa5127d92e6..4ce6e00653a 100644
--- a/docs/main/modules/working-with-camel-core/pages/index.adoc
+++ b/docs/main/modules/working-with-camel-core/pages/index.adoc
@@ -94,6 +94,7 @@ Learn about additional ways to customize your integrations.
Explore alternatives
** xref:manual::spring.adoc[Spring]
** xref:manual::spring-xml-extensions.adoc[Spring XML Extensions]
** xref:manual::validator.adoc[Validator]
+** xref:manual::variables.adoc[Variables]
** xref:manual::what-are-the-dependencies.adoc[Camel Requirements]
** xref:manual::testing.adoc[Testing]
diff --git a/docs/user-manual/modules/ROOT/pages/variables.adoc
b/docs/user-manual/modules/ROOT/pages/variables.adoc
new file mode 100644
index 00000000000..4715d124d98
--- /dev/null
+++ b/docs/user-manual/modules/ROOT/pages/variables.adoc
@@ -0,0 +1,82 @@
+= Variables
+
+*Available from Camel 4.4*
+
+In Camel 4.4, we have introduced the concept of _variables_.
+
+A variable is a key/value that can hold a value that can either be private per
`Exchange` or global shared
+in the `CamelContext`.
+
+NOTE: You can also use _exchange properties_ as variables but the exchange
properties are also used internally by Camel,
+and some EIPs and components. With the newly introduced _variables_ then these
are exclusively for end users.
+
+== Variable Repository
+
+The variables are stored in one or more
`org.apache.camel.spi.VariableRepository`. By default, there are the following
repositories
+
+- `ExchangeVariableRepository` - A private repository per `Exchange` that
holds variables that are private for the lifecycle of each `Exchange`.
+- `GlobalVariableRepository` - Uses `global` as id. A shared global repository
for the entire `CamelContext`.
+
+The `ExchangeVariableRepository` is special as its private per exchange and is
the default repository when used during routing.
+
+TIP: There is also `org.apache.camel.spi.BrowsableVariableRepository` which is
an extension to `VariableRepository` that
+has APIs to browse the currently variables. This is used by Camel with Camel
JBang, and JMX to be able to see the current variables
+from management tooling, CLI and the developer console.
+
+=== Custom variable repositories
+
+You can implement custom `org.apache.camel.spi.VariableRepository` and plugin
to be used out of the box with Apache Camel.
+For example, you can build a custom repository that stores the variables in a
database, so they are persisted.
+
+Each repository must have its own unique id. However, it's also possible to
replace the default `global` repository with another.
+
+== Getting and setting variables from Java API
+
+To get a local variable from the current exchange, you can do this via Java
API:
+
+[source,java]
+----
+String myValue = "...";
+exchange.setVariable("myKey", myValue);
+
+// and later to get the variable
+Object val = exchange.getVariable("myKey");
+
+// you can get the value as a specific type
+String str = exchange.getVariable("myKey", String.class);
+----
+
+The API on `Exchange` will by default get the variables from its local private
repository.
+However, you can also get variables from other repositories, such as the
`global` as show:
+
+[source,java]
+----
+Object val = exchange.getVariable("global:myGlobalKey");
+----
+
+And you can also assign a global variable by prefixing with `global:` as
follows:
+
+[source,java]
+----
+exchange.setVariable("global:myGlobalKey", someObjectHere);
+----
+
+There is also API on `CamelContext` to get variables. However, this API will
by default get from the `global` repository,
+as it's not possible to get variables from any inflight `Exchange` currently
being routed.
+
+[source,java]
+----
+Object val = context.getVariable("myGlobalKey");
+
+// you can get the value as a specific type
+String str = context.getVariable("myGlobalKey", String.class);
+----
+
+== Setting and getting variables from DSL
+
+It is also possible to use variables in Camel xref:routes.adoc[routes] using
the
+xref:components:eips:setVariable-eip.adoc[SetVariable], and
xref:components:eips:removeVariable-eip.adoc[RemoveVariable] EIPs.
+
+These EIPs makes it possible to set and remove variables from routes. And you
can also access variables from the
xref:components:languages:simple-language.adoc[Simple] language.
+
+TODO: Some examples here
