Attach Manager

EntireX includes an Attach Manager (ATM) for Linux and Windows. This is used to start servers if a client requests a particular service from the Broker, but a server for that service is not active. This document covers the following topics:

• Prerequisites

• Setting up the Attach Manager

• Configuration File Syntax

• Sample Configuration File

• Operating the Attach Manager

Prerequisites

The Attach Manager needs the following:

• An active task registered at the Broker. As of EntireX 9.9, the ATM task is no longer launched automatically on each computer where EntireX is installed. See Setting up the Attach Manager for how to start the Attach Manager automatically or manually.

• A list of services the ATM is responsible for, and information on how to start the corresponding server for a particular service. The Attach Manager can start only processes that are local to where it is running, that is, the process that is attached will be run from the command line. There is no restriction, however, on what the started command-line process does, including starting a remote process on another system that will REGISTER as the server that satisfies the attach request.

• A configuration file that contains the service list the ATM is responsible for, information on how to start the corresponding server and additional configuration parameter to control the ATM functionality.

Setting up the Attach Manager

If you do not need the ATM for your own services, you do not need to perform any configuration for the ATM. For the default configuration EXXATM, a default configuration file EXXATM.cfg comes with the EntireX installation and contains the necessary configuration to start the EntireX sample servers. The file is located in directory EntireX/config/service/appl.EXXATM.

Notes:

1. In the current version of EntireX, the ATM is not launched automatically by default.
2. The command etbsrv uses the default section defined in the configuration file.

To launch the Attach Manager automatically

• Activate automatic start after a reboot or after a restart of the Broker Adminstrator Service with the following command:

  etbsrv SERVICE ATTR <configuration name> AUTOSTART=YES

  For example:

  etbsrv SERVICE ATTR EXXATM AUTOSTART=YES

  With the next reboot, ATM is then launched automatically. The working directory is EntireX/config/service/appl.EXXATM. All log files are written to this directory. It also contains the configuration file EXXATM.cfg of the Attach Manager. See Configuration File Syntax.

To deactivate automatic start of the Attach Manager

• Enter command:

  etbsrv SERVICE ATTR <configuration name> AUTOSTART=NO

To check the status of the Attach Manager

• Enter command:

  etbsrv SERVICE STATUS <configuration name>

To start and stop the Attach Manager

• Enter one of the following commands:

  etbsrv SERVICE START <configuration name>

  etbsrv SERVICE RESTART <configuration name>

  etbsrv SERVICE STOP <configuration name>

To show the current status

• Enter command:

  etbsrv SERVICE STATUS

The Attach Manager is located in the bin subdirectory under the installed EntireX directory. The name of the executable is exxatm.exe. If you need to start an ATM manually for any reason, start it using this executable. Without further command-line arguments, the ATM uses the default section within the default configuration file. See Operating the Attach Manager for possible command-line arguments.

If you need multiple ATM instances, we recommend using a separate ATM configuration.

To create an Attach Manager configuration

• Enter the following command:

  etbsrv SERVICE CREATE <configuration name>

  Note:
  The created configuration is located in EntireX directory config/service/appl.<configuration name>

Configuration File Syntax

• Introduction

• Parameters of the ATM Section

• Parameters of the Service List Section

• Parameters of the Service Section

Introduction

The syntax of the text-based configuration file is simple and is very similar to a Windows INI file.

There are three different types of sections in the configuration file:

• The ATM section to configure a particular ATM instance. The ATM section with the name "Default" is the default section. If no section with the name "Default" is found, the first ATM section in the file is the default section. Each ATM section contains the configuration parameters of the corresponding ATM instance and has one related Service List section, which refers to the services that this ATM supports. Each ATM section needs exactly one ATM server attaching the related servers if requested.

• The Service List section contains a list of names of Service sections. The name of the Service List section is the name of the related ATM section appended by "_Services".

• The Service section configures a service, which consists of the service name and how to start the corresponding server.

The general structure of the configuration file is the following:

[Default]
;  The parameters of the Default ATM
[Default_Services]
SERVICE1=
SERVICE2=
[SERVICE1]
;  The parameters for SERVICE1
[SERVICE2]
;  The parameters for SERVICE1

Parameters of the ATM Section

These sections define the Attach Manager itself and contain the keywords indicated in this table. There can be up to 16 of these sections.

etbnattr --echo_password_only -w clear_text_password

Parameters of the Service List Section

This section names the Service sections that will be used to define the services that will be attached. The prefix of the name of the section must match a specific instance of the AttachManager(n) sections.

Example: Assume there are three services to be attached. They can be logically defined as follows:

[Default_Services]
payroll=
inventory=
qualitycontrol=

Therefore, there will be three optional sections following: [payroll], [inventory], and [qualitycontrol].

Parameters of the Service Section

There can be any number of Service sections attached to an ATM by means of its corresponding Service List section. The Service sections are used to define the actual commands that will be issued by ATM to attach servers to respond to Broker requests

The following keywords can be used:

Example from table above: If there are no instances of the service ACLASS/ASERVER/ASERVICE REGISTERED, the command indicated in the Command= keyword will be issued three times.

Sample Configuration File

[Default]
;
; Specify the broker to which the Attach Manager attaches and
; the channel on which the Attach Manager listens for command
; requests.
;
BrokerID=localhost:1971:TCP
ServerClass=System
ServerName=DefaultMain
Service=Command
UserID=%USERNAME%
Token={GeneratedToken}
Password=Hugo
WaitTime=30s
RecvLength=12000

; Activities will be written to the history file (optional)
HistoryFile=%TEMP%\Default.his
HistoryFileMode=a+t

; Log messages will be written to the log file (optional)
LogFile=%TEMP%\Default.log
; Append to an existing file
;LogFileMode=a+t
; Create a new file
LogFileMode=w

Sleep=10
Retries=0

ShutdownByUserRequest=1

;
;
; Default's services
;
[Default_Services]
AServer=
BServer=
;
[AServer]
ServerClass=ACLASS
ServerName=ASERVER
Service=ASERVICE
Min=2
Max=3
Increment=1
Command=myservera -c<ServerClass> -s<ServerName> -v<Service> -b<BrokerID> -i500
;
[BServer]
ServerClass=BCLASS
ServerName=BSERVER
Service=BSERVICE
Min=1
Max=1
Increment=1
Command=myserverb -c<ServerClass> -s<ServerName> -v<Service> -b<BrokerID> -i750
[AttachManager2]
;
; Specify the broker to which the Attach Manager attaches and
; the channel on which the Attach Manager listens for command
; requests.
;
BrokerID=localhost:1971:TCP
ServerClass=System
ServerName=AttachManager2Main
Service=Command
UserID=%USERNAME%
Token={GeneratedToken}
Password=Hugo
WaitTime=30s
RecvLength=12000

; Activities will be written to the history file (optional)
HistoryFile=%TEMP%\AttachManager2.his
HistoryFileMode=a+t

; Log messages will be written to the log file (optional)
LogFile=%TEMP%\AttachManager2.log
; Append to an existing file
;LogFileMode=a+t
; Create a new file
LogFileMode=w

Sleep=10

ShutdownByUserRequest=1
;
; AttachManager2's services
;
[AttachManager2_Services]
CServer=
;
[CServer]
ServerClass=CCLASS
ServerName=CSERVER
Service=CSERVICE
Min=1
Max=1
Increment=1
Command=myserverc -c<ServerClass> -s<ServerName> -v<Service> -b<BrokerID> -i1000

Operating the Attach Manager

Under normal circumstances, no manual operation is not necessary if the default ATM satisfies your needs. However, if you need to run multiple ATMs in your environment, this section describes how to perform the necessary operations. This section covers the following topics:

• Starting the Attach Manager

• Stopping the Attach Manager

• Logging the Attach Manager

• Attach Manager Processing

Starting the Attach Manager

To start an Attach Manager

• Enter command:

  etbsrv SERVICE <configuration name>

  Note:
  etbsrv starts with the default section defined in the configuration file.

  Or:
  Either from the bin directory of EntireX (or from any directory if the bin directory is in the PATH), enter the following command:

  exxatm -F<full-path of Configuration file> -N<AttachManager1> -N<AttachManager2> ...

Notes:

1. With the -N argument you specify the ATM section for which the Attach Manager is responsible for. If this argument is omitted the attach manager is responsible for the default section.
2. With the -F argument you specify the location of the configuration file. If this argument is omitted, the Attach Manager uses the default configuration file. All ATM instances should use the same configuration file, so we recommend you use the default file for the default ATM.
3. The Attach Manager writes output to stdout. If you start the Attach Manager as a background process, stdout must be redirected to a file.

Stopping the Attach Manager

Each attach manager corresponds to an particular broker and registers a command service defined with the configuration variables ServerClass/ServerName/Service in the ATM section.

To stop an Attach Manager

• Use the script etbsrv.

  Or:
  Use the command-line utility etbcmd.

  Or:
  Press CTRL-C.

  Or:
  Under Linux, enter command kill process-id.

Logging the Attach Manager

The ATM log file and a history file are defined by the ATM configuration parameters. For each order to launch a service, the ATM writes a record into the history file. The history record has the following format:

• date and time

• the service name as defined in the ATM config file

• server name, server class and service

• number of active replicates (this number is greater than 0 only if all running replicates are busy while a new client requests the service

• number of server lookups, that is, the number of clients requesting a new replicate of the server; this is greater than 1 only if two clients request a service in parallel

• replicate increment as defined in the ATM config file

• number of replicates actually launched; this differs from the increment only if the high watermark is exceeded

Attach Manager Processing

	Attach Manager registers with Broker, indicating that it will attach named services. These are called attach-managed services.
	Client requests a service that is attach-managed. Server may or may not be active. If it is not, a server will be started (attached).
	Attach request comes from the Broker.
	Attach Manager issues command to start the server application.
	Server application issues a LOGON to the Broker, then issues REGISTER and RECEIVE. It gets message from client, processes the message, and responds.
	Response from server is received by the client application.