Subversion Repositories planix.SVN

.TH WIKIFS 4

.SH NAME

wikifs, wikipost \- wiki file system

.SH SYNOPSIS

.B wikifs

[

.B -DM

]

[

.B -a

.I announce

]...

[

.B -m

.I mtpt

]

[

.B -p

.I perm

]

[

.B -s

.I service

]

.I dir

.PP

.B ip/httpd/wikipost

.RB [ -b

.IR inbuf ]

.RB [ -d

.IR domain ]

.RB [ -r

.IR remoteip ]

.RB [ -w

.IR webroot ]

.RB [ -N

.IR netdir ]

.I method version uri

.RI [ search ]

.SH DESCRIPTION

A

.I wiki

is a web server that facilitates easy editing of the pages it contains.

.I Wikifs

presents a wiki in two forms: as web pages to be served

via

.IR httpd (8)

and as text files to be viewed via the

.IR acme (1)

wiki client

(see

.BR /acme/wiki/guide ).

.PP

.I Wikifs

presents a file system interface to the wiki data stored

in

.IR dir .

By default,

.I wikifs

mounts itself at

.BR /mnt/wiki ;

the

.B -m

flag specifies a different mount point,

and the

.B -M

flag causes

.I wikifs

not to mount at all.

.I Wikifs

also announces 9P network services on the addresses

given as arguments to

.B -a

options.

If the

.B -s

option is given,

.I wikifs

will post a service file descriptor in

.BI /srv/ service

with permission

.I perm

(default 600).

The

.B -D

flag causes a transcript of the 9P conversation

to be written to standard error.

.PP

The wiki holds both the current pages and also

all versions of all pages that have ever existed.

All pages have time stamps associated with them.

When a user wants to edit a page, he reads the 

current page from the wiki, noting the time stamp

on the page.

When a user writes changes to a page, he includes the time stamp

of the page he started with.  If the page has been updated

by someone else while he was editing, the write will fail.

This is called a ``conflicting write.''

The submission is still saved in the history, so that

the user can compare the page he submitted with the changes

that were made while he was editing.

.PP

Each version of each page is described by a text file containing 

one or more metadata lines followed by the page contents.

The metadata lines begin with a capital letter specifying the type of data.

Currently the metadata types are:

.TP

.B D

The date this page was written, in decimal seconds since the epoch.

.TP

.B A

The author of this version of the page.  Typically the rest of the line

takes the form

.I name

.IR ip-address .

.TP

.B X

This page's contents were submitted but rejected due to a

conflicting write.

.PD

.PP

After the metadata comes the actual page contents; each line of

page contents is prefixed with a

.B #

character.

.PP

The directory

.IB dir /d

contains all the wiki data.  Typically it is world-writable

so that

.I wikifs

can run as none.

Each page on the wiki has a unique sequence number

.IR n ;

for each page, the

.B d

directory contains three files

.IR n ,

.IB n .hist \fR,

and

.BI L .n \fR.

The file

.I n

holds the current version of the page: the first line of

.I n

is the page title, followed by page metadata and contents as described above.

The append-only file

.IB n .hist

holds the history of the page.

The first line of

.IB n .hist

is the title of the page.

The rest of the file is the metadata and contents of every

version of the page that has been submitted to the wiki.

.BI L .n

is a lock file for the page: it must be 

held while reading or writing

.I n

and

.IB n .hist \fR.

The lock files allow multiple instances of

.I wikifs

to coexist peacefully.

Finally, the

.B map

file (with associated lock

.BR L.map )

provides a mapping from

sequence numbers to

to page titles.

Each map line is a decimal

.IR n ,

a single space,

and then the title.

Since titles are presented as names by

.IR wikifs ,

they cannot contain slashes.

.PP

.I Wikifs

presents a three-level file system.

The top level contains per-page directories

named by the page titles with spaces turned

into underscores.

Each page also has a number associated with it

(see the discussion of the wiki data files below).

The number corresponding to a page may

also be used to access it, although directory

listings will always present the title.

The

.B new

file is used to add new or revised pages to the wiki:

writes to the file should be in the usual textual format:

a title line, metadata lines, and page contents.

Once all the contents have been written, a final zero-length

message should be written to mark the end of the page.

This last write will return an error if a conflicting

write has occurred.

After writing the file, the client may read from

.B new

to obtain the canonical title for the page, as presented

by the file system.

.PP

The page directories contain subdirectories representing

the history of the page, named

by the decimal time stamp corresponding to each version.

In addition to these history directories,

the page directories contain the following files:

.TP

.B current

The current raw data file for the page.

.TP

.B diff.html

A web page listing the contents of every version of

the page that has ever appeared on the wiki.

The text is grey by default:

differences between versions appear in black.

.TP

.B edit.html

A web form for editing the the current version of the page.

.TP

.B history.html

A web page listing the time stamps of the historical versions of the page.

Each time stamp links to a page showing just

that version.

.TP

.B history.txt

A textual formatting of the history.  Each time stamp is prefixed with

the name of the directory corresponding to that version.

.TP

.B index.html

An HTML formatting of the current version of the page.

.TP

.B index.txt

A textual formatting of the current version of the page.

.TP

.B werror.html

An HTML error page to be returned by

.I wikipost

on conflicting writes.

.PD

.LP

The HTML files are generated from the templates with the same names

in

.IR dir ,

except that

.B index.html

and

.B index.txt

are generated from the templates

.B page.html

and

.BR page.txt .

.PP

The history directories

are similar to the page directories but only contain

.BR current ,

.BR index.html ,

and

.BR index.txt .

This

.B index.html

and

.B index.txt

are generated from the templates

.B oldpage.html

and

.BR oldpage.txt .

.PP

The

.IR httpd (8)

helper program

.I wikipost

is used to process editing requests posted

to the web server by users.

It expects the posted form to contain these

(usually hidden) fields:

.BR TITLE ,

the title of the page;

.BR VERSION ,

the time stamp of the page that is being edited;

.BR service ,

the service name associated with this wiki

.RI ( wikipost

looks for

.BI /srv/wiki. service \fR);

and

.BR base ,

the base for wiki URLs in the response.

.PP

After mounting the wiki,

.I wikipost

writes a page update request to

.B /mnt/wiki/new

and then returns the contents of one HTML

file in

.BR /mnt/wiki/ title \fR.

If the write succeeds,

.I wikipost

returns

.BR index.html .

if the write fails due to a conflicting write,

.I wikipost

returns

.BR werror.html .

.SH EXAMPLE

The Plan 9 wiki at Bell Labs is started by running:

.EX

.ta +4n

	wikifs -p 666 -s wiki.plan9 -a tcp!*!wiki /sys/lib/wiki

.EE

.PP

The wiki is mounted for

.IR httpd (8)

by an entry in

.BR /lib/namespace.httpd :

.EX

.ta +4n

	# wiki

	mount -b #s/wiki.plan9 /usr/web/wiki/plan9

.EE

Notice that the wiki service was explicitly posted with

mode 666 so that

.I httpd

(running as none)

would be able to mount it.

.PP

In the Plan 9 distribution, the directory

.B /sys/lib/wiki

contains sample files similar to those used

to start the current Plan 9 wiki.

.SH SOURCE

.B /sys/src/cmd/wikifs

.br

.B /sys/src/cmd/ip/httpd/wikipost.c

.SH SEE ALSO

The original wiki,

.B http://c2.com/cgi/wiki?WikiWikiWeb

.br

.B /acme/wiki/guide