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Running ScalienDB the first time
A ScalienDB cluster consists of controllers and shard servers.
ScalienDB takes one command argument: the configuration file. Note that all paths in the configuration file such as database.dir must either be absolute or relative to the working directory. So, if the ScalienDB executable is in /home/joe/scaliendb/bin, the configuration file is in /home/joe/scaliendb/0/scaliendb.conf and the configuration file specifies database.dir = 0, then you should probably launch ScalienDB from /home/joe/scaliendb using:
$ bin/scaliendb 0/scaliendb.conf
First, start the controller(s). When the controllers start, they elect a master controller, which is shown on the console. Note that for master election to be successful a majority of controller nodes have to be up and running. You should see something like this:
2011-05-09 11:13:26.450566: ScalienDB v0.9.9 started as CONTROLLER
2011-05-09 11:13:26.451811: Opening readonly: test/control/0/db/chunks/chunk.00000000000000000004
...
2011-05-09 11:13:26.452144: Replaying log segments...
2011-05-09 11:13:26.452242: Replaying log segment test/control/0/db/logs/log.00000000000000000013...
...
2011-05-09 11:13:26.452359: Replaying done.
2011-05-09 11:13:26.452368: Checking for orphaned chunks...
2011-05-09 11:13:26.452408: Checking done.
2011-05-09 11:13:26.452420: Existing environment opened.
2011-05-09 11:13:26.453759: Opening log segment 15
2011-05-09 11:13:26.453844: My nodeID is 0
...
2011-05-09 11:13:29.874038: Node 1 became the master
Once the controllers are up and running, you can connect to the cluster using the web-based management console. The management console is a Javascript application, so you can run it from anywhere. It is located in the webadmin directory of your ScalienDB distribution, so if you downloaded ScalienDB to /home/joe/scaliendb, you should open:
file:///home/joe/scaliendb/webadmin/index.html
in your browser. Supported browsers are Firefox, Chrome and Safari.
Alternatively, the management console may also be accessed through the built-in ScalienDB HTTP server. This serves files according to the http.documentRoot and http.staticPrefix configuration settings. By default, if a ScalienDB instance is listening on 192.168.1.1 port 8080 you should also be able to access the management console at:
http://192.168.1.1:8080/webadmin
After opening the management console, you first have to specify the HTTP endpoint of one of the controllers. You don't have to specify the master here, as any controller will redirect to the master. So, if you have controllers listening on HTTP 192.168.1.1:8080, 192.168.1.2:8080, 192.168.1.3:8080 then you can connect to either one.
If this the first time you are starting the cluster, no shard servers will have connected at this time, the list of shard servers on the Dashboard tab will be empty.
Now you can start the shard servers. As shard servers start, the master controller will assign nodeIDs to them, starting at 100. The shard servers will show up on the list of shard servers on the Dashboard tab of the management console.
Now that the controllers and shard servers are running, it's time to create quorums. Quorums are the basic unit of replication, and consist of one or more shard servers.
To create a quorum, click the Quorums tab of the management console and then click Create new quorum. Next, enter the node IDs of the shard servers you would like to have in this quorum, for example 100, 101, 102 creates a 3-way replicated quorum.
Now that you have created a quorum, we can create databases and tables. Click the Schema tab of the management console and click Create new database to create a database. Then click Create new table to create a new table. ScaliendB tables are key-value namespaces and are split into into shards and when a new table is created its first shard is automatically created with it. When you create table, you have to specify which quorum the table's first shard should be placed in.
Once you have created the table, you can examine the shards by clicking the Show shards button.
Once you have created the table, let's try to set hello => world into it. Let's use the shard server's HTTP server for this. Suppose one of the shard servers in the quorum is 192.168.1.5 and is listening on HTTP port 8080. Then we can use our browser to set:
http://192.168.1.5:8080/set?tableID=1&key=hello&value=world
Here tableID is the ID of the table we just created, it starts at 1 and may be looked up under the Schema tab of the management console. Now, check that we can read back what we just wrote:
http://192.168.1.5:8080/get?tableID=1&key=hello