allex

AllEx JS Runtime

This module brings the crucial program, the allexmaster

allexmaster

This is the AllexJS Machine Manager. It does exactly what its name says - manages all the processes on your machine.

However, the mechanics for that management job is divided into several layers.

Reading the conf

The configuraton file is written in JSON format in the allexmasterconfig.json file.

When allexmaster is started in a particular directory, it looks for allexmasterconfig.json in that directory. If such a file is not found, a default configuration is created.

{
  "lanmanageraddress":"127.0.0.1",
  "portrangestart":{
    "tcp":15000,
    "http":16000,
    "ws":17000
  }
}

lanmanageraddress

This is the address where allexmaster will be looking for for the Lan Manager allexlanmanager, on the default port 23552, on the default protocol 'ws' (WebSockets). Support for different ports/protocols is about to come

portrangestart

allexmaster will be spawning new processes for various Services. Each new process will be told to start listening on

• tcp
• http
• ws protocols, and for each protocol a different port will be declared.

For each of the three protocols, allexmaster maintains a list of open ports (via allex_portofficeserverruntimelib), so that each new process will be declared the first free port for the protocol - starting from a number defined in allexmasterconfig.json

Unix socket protocol

Unix sockets (or pipes) are sockets that work only within a single machine. In order for all spawned child processes to be capable of talking to allexmaster, and vice versa, Unix socket servers will be opened like this:

• allexmaster listens on /tmp/allexmachinemanager for U#ix based machines, or \\\\x\\pipe\allexmachinemanager on Windows based machines (taken care of by allex_temppipedirserverruntimelib)
• a child process with pid, for example, 355 will be listening on /tmp.allexprocess.355

Because the "port" for Unix sockets is controlled by the OS kernel (that assigns process pids), there is no starting port number in allexmasterconfig.json.

Satisfying the needs of LanManager

allexmaster

1. connects to allexlanmanager on the declared address, on the predefined port with the predefined ws protocol
2. reads the list of unsatisfied needs (list of Services that should be instantiated)
3. for each unsatisfied need spawns a new child process with ports assigned to protocols
4. notifies the allexlanmanager about the new process
5. lets allexlanmanager to check the declared ports if it can reach them
6. once allexlanamanger approves the listening ports, it will delete the satisfied need from a list of needs and put up a new record in the list of running Services so that the whole cloud can use it

Reporting "Service down" events

Because allexmaster is directly connected to its child process (in a Parent-Child relationship), it is the first to know if the program stopped working. At that moment it notifies allexlanmanager about this event.

When notified, allexlanmanager will remove the corresponding record from the list of running Services and recreate the appropriate Service need record in the list of Services that should start.