You can use a
JavaCompute node to store data
in a global map. You can then create another
JavaCompute node that can get
data from the global cache for processing or routing. The
JavaCompute node uses the MbGlobalMap
object to access the global cache
or external
grid. This class can be used to get a map, and to put or get
data in a map. You cannot create a map explicitly, but if you get
a map that does not exist, the map is created automatically.
When you get a global map from an
external grid, the getGlobalMap method makes a connection to the grid
if one does not exist. Interactions with the cache happen
outside the message flow transaction, and are committed immediately.
If an exception is thrown downstream of the node that interacts with
the cache, the cache interactions are not rolled back.
The
following steps describe how one message flow adds data to a map,
and another flow gets the data from that map.
- Create a message flow that contains a JavaCompute node.
You
can place the JavaCompute node
before or after an MQOutput node.
In the following example, the JavaCompute node is placed
after an MQOutput node
so that the JavaCompute node
can use the message ID of the output message.
- Double-click the JavaCompute node. The New Java Compute Node Class wizard
opens.
- On the Java Compute Node Class pane,
provide the appropriate information, then click Next. You can accept the default values by clicking Next.
- On the Java Compute Node Class Template pane,
select the appropriate template for your scenario, then click Finish.
The template Java file
opens in the editor, indicating where you can add your own code.
- To get a map from the embedded cache, or create the map
if it does not exist, add the MbGlobalMap object, as shown in the
following example. The MbGlobalMap object is also described
in the Java Plugin API documentation.
MbGlobalMap globalMap = MbGlobalMap.getGlobalMap("MyMap");
This
example gets the map called "MyMap". If the map does not exist, it
is created. Alternatively, when you are using the embedded cache,
you can use the default map by not specifying a map name, as shown
in the following example. When
you are connecting to an external grid, no default map exists. You
must specify a valid map name on the external grid.
MbGlobalMap globalMap = MbGlobalMap.getGlobalMap();
The
cache uses WebSphere eXtreme
Scale dynamic maps.
Any map name is allowed, apart from names that begin with SYSTEM.BROKER,
which is reserved for use by the broker. The default map is named
SYSTEM.BROKER.DEFAULTMAP; you can use or clear this map.
To get a map from an external grid,
add the MbGlobalMap object, specifying the name of the map on the
external grid and the name of the configurable service that is used
to connect to the grid:
MbGlobalMap xc10Map = MbGlobalMap.getGlobalMap("MyMap.LUT","xc10Connection");
In
this example, the map, "MyMap.LUT", is on an external grid on an XC10
appliance. The configurable service that is used to connect to the
grid is called "xc10Connection".
- Optional: Specify how long,
in seconds, the data remains in the global cache before it is removed
automatically.
This time is known as the time
to live and is counted from when that map entry is last updated.
You specify this time when you get an MbGlobalMap object. The value
applies to all cache entries that are created by using that MbGlobalMap
object. For detailed instructions, see Removing data from the global cache.
- To put data in the map, you must create a key and value
pair in the map, as shown in the following example. For
keys and values, Java primitive
types and strings are supported. Java objects
are supported as values. For the embedded grid only, keys can also
be arrays of primitives or strings. (To use your own Java classes with the global cache, put the
JAR files that contain the Java classes
in one of the shared-classes directories.)
globalMap.put(key, val);
- Save the message flow.
- To access the stored data from another message flow, create
a flow that contains a JavaCompute node.
For example, the following message flow contains a JavaCompute node that retrieves
the appropriate information from the map, then sends a response message
through an MQReply node.
- Repeat steps 2, 3, and 4 to create a Java file for your new JavaCompute node.
- Use the MbGlobalMap object to get the map that you created
in step 5, then get the data that you added to the map in step 6.
If you know that the data that you are retrieving is a string, for
example, specify string when you get the data, as shown in the following
example.
MbGlobalMap globalMap = MbGlobalMap.getGlobalMap("MyMap");
...
String val = (String)globalMap.get(key);
The following example shows how
to get the data that you added to a map on an external grid:
MbGlobalMap xc10Map = MbGlobalMap.getGlobalMap("MyMap.LUT","xc10Connection");
...
String val = (String)xc10Map.get(key);
To
prevent the cache from becoming too big, when you have finished with
a key and value pair, use the remove() method to delete that data
from the map.
You can use content assist to
list available options when you are constructing Java code. To access content assist, place the
cursor at the point of insertion, then either click or press Ctrl+Space. For example, if you type "myMap",
then press Ctrl+Space, you can choose from a list of options, including
the following actions.
- remove, which removes a single object from
a global cache
- containsKey, which indicates whether a key
exists in a map
- update, which updates an existing object
All available options are documented in the Javadoc for the Java Plugin
API (see
IBM Integration API). You can also access
the Javadoc for the Java Plugin API through the Start
menu at
.
- Save your message flow.
- Deploy your message flows.
Last updated Friday, 21 July 2017