7. Administrator's Console

  
7.1 Overview

Every time a database is started on a server, admin should be able to view certain information about the connections to the specific database in order to perform the tasks that the administration of a database server entails. Administrator Console lets admins view the following types of information (specific to a database) by clicking the relevant link at the top of the page.

• Error Log
• HTTP Log
• Connections
• HTTP sessions
• Fibers

7.2 Operation

Administrator Console has an HTML-based interface,  so you can access it through any Web browser. Points from where to reach Administrator Console are:

• the link Administrator's Console of the database index screen (see section 4.7)
• the link Console from Roadmap or SQL Terminal.

(see section 4.7). In case you are working with SQL Terminal or Roadmap, navigational links at the top of these pages get you to Administrator Console.

Note: For better results it is recommended that you use the Ovrimos navigation options (back, forth, etc.) instead of your browser's.

To operate Administrator Console, authentication as user admin is required. For first time users, the required password is pegasus  .
Refer to section 8.4 about Dynamic Internal Resources for more technical information.

   
7.2.1 Error Log

To view the Error Log, click the relevant link at the top of Administrator Console's page. The Error Log displays informational, warning and error messages about the database. User dbman can also view this log by clicking the View Log button on Database Manager's home page (refer to Chapter 4 about Database Manager).

Reference: HTTP Log is explained in section 8.7

  
7.2.2 Connections

Figure 7.1 shows the type of information displayed for each connection. The columns of the Connections table are explained here:

  

Figure 7.1: Connections screen with Connection 0 expanded

• Num: Ordinal number of the connection.
• From: In case the connection is made through SQL Terminal or a Scheme script it is considered to be Internal. In any other case, the connection is considered external (i.e. through SQL Query Tool) and the IP address of the computer which made the request is displayed.
• On since: The time when the connection was established, e.g. 2000-01-17 15:41:42
• Idle since: The time when the connection was last used.
• User: Name of the user who established the connection.
• Status: Whether the connection is Ready or Busy. A connection has status Busy when it waits for a lock. In all other cases, it has status Ready.

• WaitCount: Among open connections, a specific number of them is allowed to be inside a transaction at any one time. This is called funneling because it restricts the demand on resources. Waiting connections are placed in a priority queue on a FIFO basis. Connections finishing their transaction are put back in the queue. If the WaitCount number of the specific connection is bigger than zero, then the connection is outside the "funnel". The bigger this number is, the higher priority the waiting connection has.

• Delivered: Number of messages having been exchanged. When a connection to a database is made then data transfer between client and database server entails an exchange of messages between them.

• Statements: When the client connects to a database server, a connection handle is allocated and prior to submitting SQL requests, a statement handle is also requested. Since each connection can have one or more statement processing streams, each connection handle can have multiple statement handles associated with it. However, each statement handle is associated with exactly one connection handle. The lower part of figure 7.1 shows information about the statement streams which appear on the screen, when the relevant link is clicked.

  Statements table shows the following type of information :

  • Num: Ordinal number of the Statement stream.
  • Status: In the current version of Ovrimos, a statement stream has always status Active.
  • State: Indicates that the statement stream is in one of the following states: When it starts processing another SQL statement it is Ready. Then if parameter data are needed, it goes through the Params state to Prepared which indicates that the SQL statement is prepared. Finally, the SQL statement is either in the Executed state or is a Cursor statement and has been executed.
  • Isolation level: Shows the isolation level of the transaction being executed. Four isolation levels are supported, refer to section 13.1.2.(Isolation Levels).
  • SQL: Shows the currently executed SQL statement, if any. The SQL statement is processed at this point threfore it appears slightly different from the original.

  
7.2.3 HTTP Sessions

Currently, HTTP servers respond to each client request without relating that request to previous or subsequent requests. Ovrimos gets over this limitation by implementing a mechanism for tracking the state of your interactions with the server. This mechanism allows the HTTP server of each database to maintain state information by placing HTTP requests and responses within a larger context, which we term an HTTP session. For example, the demo bookstore uses HTTP sessions to keep track of information about the user's selections while they are aggregated before purchase. See 8.5.3.(HTTP Server and Persistent Sessions). Initiating an HTTP session doesn't imply a connection to the SQL server.

Figure 7.2 shows the type of information displayed for each HTTP session and the columns of this table are explained here:

• Id: Session's Id.
• From: Computer's IP address which initiated the session.
• On since: Time stamp which marks the beginning of the session.
• Idle since: Time stamp which marks the instance since the session was last used.
• Initial User: Username of the user who initially logged in to the specific database.
• User: Username of the user currently authenticated.
• Realms : Among Ovrimos components, SQL Terminal and Roadmap can initiate an HTTP session. External sources, such as a Scheme script or a CGI program, can also initiate an HTTP session. Displayed SQL Terminal realms are links which get you to the relevant URL. For example, if an SQL Terminal has initiated a session which has remained idle for a long time (as you can find out by comparing the columns On since and Idle since) then you can terminate the specific connection by clicking the Disconnect link on SQL Terminal's page.

Reference: See chapter 8 about the HTTP server

  

Figure 7.2: HTTP Sessions

   
7.2.4 Fibers

  

Figure 7.3: Ovrimos Fibers

Figure 7.3 shows the type of information displayed for each fiber.

• Id: Fiber's Id.
• Kind: HTTP and SQL indicate that the fiber is currently processing an HTTP request (e.g. initiated by SQL Terminal or a Scheme script) or an SQL request (e.g. initiated by SQL Query Tool) accordingly.
• Status: Idle indicates that the fiber is not running, Busy indicates that the fiber is active and Wait indicates that the connection served by the specific fiber waits for a lock.
• User: User owning the connection which is served by the specific fiber
• Serving: Indicates the Connection served by the specific fiber.
• Waiting for: In case the fiber has status Wait, it indicates the Connection that the fiber is waiting for.