ELOG Electronic Logbook Home Page

Introduction

The logbook functionality is implemented by a single daemon elogd program which is written in C. It uses structured ASCII files to store logbook pages, which can be retrieved through any web browser. Logbook entries can either be entered with a command line program or through the Web interface. Since only forms and tables are used, no Java or Javascript are necessary, which makes the logbook display very fast.

One the left upper panel one can see a typicl logbook page displayd by Netscape Navigator. Each logbook page can contain attachments in a similar way to emails. This makes it possible to store images or text files and retrieve them easily. One can for example attach an example configuration file which can later be copied to the local machine with the "Save As..." function of the Web browser. Several logbooks can be served though a single elogd daemon. Each logbook can use attributes for message. The logbook can then be searched using these attributes. The right pane on the left image shows a search for all messages of with attribute "Type" equal to "Configuration", and the lower pane shows the search result. It is also possible to use full-text search in attributes and the message body. While logbook entries are usually displayed one entry per page, they can also be listed consecutively which makes it easily possible to produce a paper printout of a logbook. Logbook pages can be edited or deleted. This feature can be turned off in the configuration file so that a logbook entries cannot be changed after it has been submitted. An additional feature is the automatic generation of a notification email messages based on a certain type or category of a logbook entry.

The features of ELOG make it useful for several applications:

• Personal Logbooks. Personal notes can be witten into ELOG and can then be retrieved from anywhere with a Web browser. This makes it handy for PC supporters who have to go around in companies or laboratories and don't want to carry their paper logbook with them. The same holds true for people traveling around a lot. The logbook database consists of plain ASCII files which can copied easily between different computers to have local access, for example on a notebook with no network connection.
• Shared Logbooks. Logbooks can be shard by several people, for reading and optionlly for writing. This way collaborations can share and exchange information similar to a news group. This is supported by the Reply command in ELOG with which one can create "Threads" of messages. Users can be notified by email when new entries are added to the logbook. Compared to a news server, the installation of ELOG is much simpler.
• Small Databases. Since arbitrary attributes can be defined for a logbook, it can be used as a small database with search facilities.
• Problem collections. A system can consist of two logbooks, one where users can enter bugs or problems. If someone adds a problem, an email is automatically sent to the administrator, who can then copy the message to the second logbook and add the solution to the problem. Users can then look up all fixed problems.
• Shift Logbooks. If the Allow delete and Allow edit flags are off in ELOG, one cannot modify a message once it's entered. This can be useful for shift logbooks for example in accelerator control rooms where each message becomes a "document" with a time and author stamp. ELOG was orginally developed as a shift logbook for the PiBeta and Muegamma particle experiments at PSI.
• File collections. Since files can be attached to ELOG messages, the system can be used to store and retrieve files. This can be used to store UNIX configuration files, which need to be accessible by several people over the web, or to store images. Since ELOG features an elaborate query facility, messages can be searched for by specifying several categories.

Installation

ELOG is part of the MIDAS data acquisition system, but it can also be downloaded separately.

UNIX installation

elogd -p 8080

where the -p flag specifies the port. Without the -p flag, the server uses the standard WWW port 80. Note that ports below 1024 can only be uses if elogd is started a root, or the "sticky bit" is set on the executable.

If the program complains with something like "cannot bind to port...", it could be that the network is not started on the Linux box. This can be checked with the /sbin/ifconfig program, which must show that eth0 is up and running.

To start the daemon automatically, it can be run from the /etc/rc.d/init.d system. Please consult your distribution to find out how to do that. I use a script which I put under /etc/rc.d/init.d. Then I call

chkconfig --add elogd

which works fine under RedHat 6.x.

Solaris

gcc -L/usr/lib/ -ldl -lresolv -lm -ldl -lnsl -lsocket elogd.c -o elogd

Windows installation

Under Windows NT/2000, elogd can be started also as a service, which is not possible on Windows 95/98/ME. To do so, one needs the programs srvany.exe and instsrv.exe from the Windows Resource Kit. If you don't have the Resource Kit, these programs can probably be downloaded from various places like this.. Then follow these steps:

1. Copy SRVANY.EXE to %window%\system32\.
2. Use INSTSRV to install SRVANY.EXE as a service named "elogd":

   INSTSRV ELogd %windir%\system32\srvany.exe

3. Run REGEDIT and find "My Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\elogd".
4. Under the Elogd registry key, create a new key called Parameters via Edit/New/Key.
5. Under the new key Parameters, create the following three STRING values:
   • Application set to "c:\elog\elogd.exe" (or wherever you installed the elogd program)
   • AppDirectory set to "c:\elog" (or wherever you installed the elogd.cfg file)
   • AppParameters set to "-p 8080" (or any other port which you would like to use, put an empty string for port 80)
6. Under NT4, open the Services entry in the control panel, under Windows 2000 right-click on "My Computer", click to "Manage", select "Services and Applications", expand it and select "Services". On the right panel, double-click "ELogd". Then start the service manually and change the startup type to "Automatic". This way the elogd program gets started automatically on every reboot.

Configuration

elogd -p 8080 -c /usr/local/elog/elogd.cfg -D

where the -D flag tells elogd to start as a daemon in the background (does not work under NT). Once the configuration file is changed, the daemon has to be restarted.

To test the daemon, connect to your host via

http://your.host:8080/

If port 80 is used, the port can be omitted in the URL. If several logbooks are defined on a host, they can be specified in teh URL like

http://your.host/<logbook>

The contents of the configuration file elogd.cfg are described on a separate page.

Secure connections

1. Start elogd. If another Web server is running on port 80, use a different port.

2. Install the stunnel program if not already done and start it with:

   stunnel -d 443 -r your.host.name:80

   Substitute the port 80 if you started elgod on another port. This causes stunnel to receive requests on the https port 443 and forwards them to the elogd port.

3. Connect to your logbook with a browser which supports SSL via:

   https://your.host.name/

ssh -L 1234:your.server.name:8080 your.server.name

Submitting pages via the Web

It is possible to submit the text as HTML text, so one can put HTML formatting tags inside the text. Note that one then needs the tag <P> tag to start a new paragraph.

Attachments can be submitted similar to email attachments. Enter the file name or push the Browse button to select a local file. This file gets submitted into the logbook. If it is a picture (GIF or JPEG), it gets displayed in the logbook page. Otherwise only a link to the file inside the logbook is shown. By clicking at that link, the original file can be downloaded to the local hard disk again. This feature can be used to store things like Linux configuration files, which can then be retrieved easily without any copy and paste.

It is possible to pre-populate the author, type, category and subject field. This can be useful if always the same author for example submits entries from one PC. In this case, she/he needs a bookmark of the form:

http://your.host/your_logbook/?cmd=New&pauthor=joe&ptype=Info

Submitting pages via elog

elog -h hostname [-p port] [-l logbook]
     [-w password]
     -a <attribute1>=<value1>
     -a <attribute2>=<value2>
     ...
     -f attachment1
     -f attachment2
     ...
     -m textfile | text

The elog program makes it possible to submit logbook entries automatically by the system or from scripts. In some shift logbooks this feature is used to enter alarm messages automatically into the logbook.

How it works

The database ELOG save messages is a plain ASCII format. One file is created for each day in the form YYMMDD.log where YY is the year, MM the montdh and DD the day. The only non-ASCII character is a form-feed at the end of each message. If one sends a log file directly to a printer, each message is therefore printed on a separate page. Note that the log files should not be edited manually, since this could invalidate the internal database structure (each header contains the message length in bytes which then would become wrong).

If attachment are submitted, they are saved as separate files with the name YYMMDD_HHMMSS_name where in addition to the date the time is specified and name is the original file name of the attachment. To copy the database to another computer, only the *.log files and the attachment files need to be copied. To copy for example all files form March 2001, one can select them with 0103??.log and 0103??_*.

Visits to this page since 23 May 2001: