LIS65 4 lecture 3 omeka installation and system overview start

1. LIS654lecture 3 omeka installation and system overview start Thomas Krichel 2011-09-29

2. this lecture • Introduction to the Internet. • Introduction to wotan. • Introduction to omeka.

3. Internet application protocols • Most of the time in digital libraries, we assume that Internet access works. • What we need are protocols that make the Internet do something useful. • Such protocols are called Internet application protocols. • The most important one of them is the domain name system.

4. Domain Name System • Domain Name System allows us to associate human-friendly names with IP addresses. These names are called domains names. • Domain names can be leased from domain nate registrars. • A machine with a domain name on the Internet is called a host. • When we know the domain name of the host, we can communicate with the host.

5. protocols to communicate with hosts • There are two protocol we use in this class. • We use http to work with the omeka web interface • We use ssh for some special operations. • Both protocols are client/server protocols. • You run as ssh or http client on your local machine. • You communicate with a machine that runs ssh or http server software.

6. the ssh protocol • ssh is protocol that uses public key cryptography to encrypt a stream of communication between client and server. • This allows us to privately manipulate the server. Or “manipulations” are really just changes to files on the server that contain our web pages. • The ssh client software we use on the PC is called WinSCP. It is a file transfer program.

7. the host key • When an ssh client opens a connection with a host, it requests its key. • If you have not connected to the host before, you get a warning that your ssh client does not know the host with that key. When you accept, your ssh client remembers the key. • If you connect to the a host you have a key stored for and the key changes, your ssh client will warn you. This may be a host controlled by a mafioso.

8. our server • Is the machine wotan.liu.edu • We also say it is a “host” on the Internet. • wotan is the head of the gods in the Germanic legend. The name has nothing to do with Chinese food. • It is a humble PC. • It runs the testing version of Debian/GNU Linux. • It runs both http and ssh server software. • It is maintained by Thomas Krichel.

9. user name & password • To open a meaningful ssh session on wotan, you need a use name and a password. • You can choose your user name as a short form of your own name. • It should be all lowercases and can not have spaces. • Please don't choose an insecure password.

10. the web site • As part of the course, you are being provided with web space on the server wotan.liu.edu, at the URL http://wotan.liu.edu/home/user where user is a user name that you have chosen. • This shows a list of available fails as prepared by the web server at wotan. • This is a page that Thomas has prepared for you.

11. omeka • Omeka is an open-source software for image-based repositories. • Each of you gets a complete installation of omeka installed in your home directory. • Omeka uses PHP [2 slides]. • Omeka uses mySQL [2 slides].

12. PHP • Omeka is written in PHP. PHP is the PHP Hypertext Processor, a high level scripting language. • PHP code is interpreted by the web server. • On wotan we run the Apache web server. • Apache on wotan is configured in such a way as to interpret PHP.

13. Apache interprets PHP • When Apache on wotan finds a file that has the ending .php, it does not send it to the web client directly. • Instead it scans the page for special processing instructions, <?php … ?> and sends these processing instructions to a PHP interpreter. • Then it sends the processed code (usually in HTML) to the client. • This verry slow and inefficient.

14. mySQL • Omeka uses the mySQL database system to store data. It keeps as set of databases. • Your database has the same name as your user name. • The database was created by Thomas before today’s class by running the mySQL commands CREATE DATABASE user; GRANT ALL ON user.* to 'user'@'localhost' IDENTIFIED BY 'secret' WITH GRANT OPTION; where user is your username and secret is your secret word.

15. the PHPmyadmin site • At http://wotan.liu.edu/phpmyadmin we have the PHPmyadmin installation. • PHPmyadmin is a web interface, written for the administration of mySQL, written in PHP. Thus you don’t have to learn mySQL commands. • You gain access to the interface by login with your user name and your secret word.

16. the omeka site • As part of the course, you are being provided with web space on the server wotan.liu.edu, at the URL http://wotan.liu.edu/omeka/user where user is a user name that you have chosen. • This URL will initially redirect to an initialization screen. Fill it out.

17. omeka’smySQL tables • Each database has a set of tables inside. • The tables that omeka creates, and then uses, all have a name starting with “omeka_”. • You can create other tables in your mySQL database but choose names that don’t start with “omeka_”. • You can see the tables created once you have filled out the installation form.

18. some generalities about Debian • Debian is an open-source computer operating system developed and maintained by a large group of volunteer. • Debian packages together a very large set of pieces of software into a coherent system. • Wotan runs the testing version. • It provides a version of the UNIX operating system using Linux.

19. files, directories and links • Files are continuous chunks data on disks that are required for software applications. • Directories are files that contain other files. Microsoft calls them folders. • In UNIX, the directory separator is “/” • The top directory is “/” on its own.

20. users and groups • “root” is the user name of the superuser. • The superuser has all privileges. • There are other physical users, i.e. persons using the machine • There are users that are virtual, usually created to run a daemon. For example, the web sever in run by a user www-data. • Arbitrary users can be put together in groups.

21. permission model • Permission of files are given • to the owner of the file • to the group of the file • and to the rest of the world • A group is a grouping of users. Unix allows to define any number of groups and make users a member of it. • The rest of the world are all other users who have access to the system. That includes www-data!

22. winscp • In winscp, the client that we use here most of the time, we don't make advanced use of public keys, we simply give a password. • Note that winscp does not establish a connection to wotan. It simply uses ssh as a means to transfer files. • When winscp saves a file, it may require to open a new connection and will ask you the password again. This request may be in a window you can't immediately see.

23. ssh and mac os/x • In the past I told Mac users to investigate investigate a software called fugu: http://rsug.itd.umich.edu/software/fugu/ • A student made me aware of TextWrangler at http://www.barebones.com/products/textwrangler/ • This is an editor, not an ssh client but • It has support for remote file storing via ssh. • I think it also has a HTML editing mode. • My student was pleased with it.

24. open a wotan session with winscp • If you see a list of session, click on “new session”. • The host name is “wotan.liu.edu”. • Give your user name. • Click on “save”, this will save the session, after “ok”. • You will be lead to the list of saved sessions, double-click to open a session. • At initial connection, you will be shown a warning message that you can ignore. • When saving or duplicating files, you may be asked to enter your password again. Watch out for that.

25. home directory • When your connection with wotan, and you have authenticated as a certain user, you will be shown your home directory. • On wotan this is /home/user where user is your user name. • There you see a bunch of files starting with a dot. Leave them alone. • And you see a bunch of directories.

26. initial files on wotan • A directory called public_html. This is your web site. • A directory called omeka-version where version is a version number. • A symbolic link (aka symlink, aka shortcut) called omeka leading to omeka-version. This there for updating the installation later.

27. web home directory • The web home directory is /var/www. • There you see a directory home, with a series of links • they have a user name as file name • they go to your home/public_html directory • There you see a directory omeka with a series of links • they have a user name as file name • they go to your omeka directory

28. web site address • http://wotan.liu.edu/ goes to the /var/www directory. There it shows the file index.html. • http://wotan.liu.edu/home/user goes to the /var/www/home directory, where it finds the link to the public_html directory of the user user. • http://wotan.liu.edu/omeka/user goes to the /var/www/omeka directory, where it finds the link to the omeka directory. There it shows index.php.

29. the admin interface • The admin interface for your omeka site is at http://wotan.liu.edu/omeka/user/admin. • You simply add ‘admin’ to your omeka address. For trivial security, there is no link to this place. Bookmark it in your browser.

30. omeka/db.ini • This contains the instructions that allow to connect to your database. • Since PHP is executed by the web server as www-data, and that is not a member of a group with you, the file has to be readable by all. • Security of omeka is not Fort Knox.

31. omeka/themes • There we have themes. Each theme is in a directory. • You can install a new theme by downloading a theme from the omeka theme web site http://omeka.org/add-ons/themes/, upload it and then selected it from the admin interface. • Let us try this out now.

32. http://openlib.org/home/krichel Please shutdown the computers when you are done. Thank you for your attention!