https://github.com/apache/incubator-retired-gossip
Mirror of Apache Gossip Incubator
https://github.com/apache/incubator-retired-gossip
retired
Last synced: 8 months ago
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Mirror of Apache Gossip Incubator
- Host: GitHub
- URL: https://github.com/apache/incubator-retired-gossip
- Owner: apache
- License: apache-2.0
- Archived: true
- Created: 2016-05-28T07:00:05.000Z (about 10 years ago)
- Default Branch: master
- Last Pushed: 2018-08-27T14:37:13.000Z (almost 8 years ago)
- Last Synced: 2024-10-02T05:23:36.190Z (over 1 year ago)
- Topics: retired
- Language: Java
- Size: 1.35 MB
- Stars: 247
- Watchers: 40
- Forks: 111
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-java - Apache Gossip
README
# Gossip 
Gossip protocol is a method for a group of nodes to discover and check the liveliness of a cluster. More information can be found at http://en.wikipedia.org/wiki/Gossip_protocol.
The original implementation was forked from https://code.google.com/p/java-gossip/. Several bug fixes and changes have already been added.
A set of easily-run examples, illustrating various features of Gossip, are available in the gossip-examples module. The README.md file, in that module described how to run those examples.
Below, a list of code snippits which show how to incorproate Apache Gossip into your project.
Usage
-----
To gossip you need one or more seed nodes. Seed is just a list of places to initially connect to.
```java
GossipSettings settings = new GossipSettings();
int seedNodes = 3;
List startupMembers = new ArrayList<>();
for (int i = 1; i < seedNodes+1; ++i) {
URI uri = new URI("udp://" + "127.0.0.1" + ":" + (50000 + i));
startupMembers.add(new RemoteGossipMember(cluster, uri, i + ""));
}
```
Here we start five gossip processes and check that they discover each other. (Normally these are on different hosts but here we give each process a distinct local ip.
```java
List clients = new ArrayList<>();
int clusterMembers = 5;
for (int i = 1; i < clusterMembers+1; ++i) {
URI uri = new URI("udp://" + "127.0.0.1" + ":" + (50000 + i));
GossipService gossipService = new GossipService(cluster, uri, i + "",
startupMembers, settings, (a,b) -> {});
}
```
Later we can check that the nodes discover each other
```java
Thread.sleep(10000);
for (int i = 0; i < clusterMembers; ++i) {
Assert.assertEquals(4, clients.get(i).getGossipManager().getLiveMembers().size());
}
```
Usage with Settings File
-----
For a very simple client setup with a settings file you first need a JSON file such as:
```json
[{
"cluster":"9f1e6ddf-8e1c-4026-8fc6-8585d0132f77",
"id":"447c5bec-f112-492d-968b-f64c8e36dfd7",
"uri":"udp://127.0.0.1:50001",
"gossip_interval":1000,
"cleanup_interval":10000,
"members":[
{"cluster": "9f1e6ddf-8e1c-4026-8fc6-8585d0132f77","uri":"udp://127.0.0.1:5000"}
]
}]
```
where:
* `cluster` - is the name of the cluster
* `id` - is a unique id for this node (you can use any string, but above we use a UUID)
* `uri` - is a URI object containing IP/hostname and port to use on the default adapter on the node's machine
* `gossip_interval` - how often (in milliseconds) to gossip list of members to other node(s)
* `cleanup_interval` - when to remove 'dead' nodes (in milliseconds) (deprecated may be coming back)
* `members` - initial seed nodes
Then starting a local node is as simple as:
```java
GossipService gossipService = new GossipService(
StartupSettings.fromJSONFile( "node_settings.json" )
);
gossipService.start();
```
And then when all is done, shutdown with:
```java
gossipService.shutdown();
```
Event Listener
------
The status can be polled using the getters that return immutable lists.
```java
public List getLiveMembers()
public List getDeadMembers()
```
These can be accessed from the `GossipManager` on your `GossipService`, e.g:
`gossipService.getGossipManager().getLiveMembers();`
Users can also attach an event listener:
```java
GossipService gossipService = new GossipService(cluster, uri, i + "", startupMembers,
settings, new GossipListener() {
@Override
public void gossipEvent(GossipMember member, GossipState state) {
System.out.println(System.currentTimeMillis() + " Member " + j + " reports "
+ member + " " + state);
}
});
//The lambda syntax is (a,b) -> { } //NICE!
```