I had been thinking of adding a database to Plan 9 for a while.
Here's my design:
The DBMS is a 9P server. Upon mounting, it takes as arguments two files:
- the list of names of records and fields
- the data itself
It then parses the data into virtual files in the location given with
the mount command.
For example, let's say I have a customer database for a kitchenware
distributor stored in two files: customer_fields (the list of field
and record names) and customer_data. I can load it with:
9dbms
mount /srv/9dbms /n/customers customer_fields customer_data
If that's not possible, these two filenames are stored in another file.
Now here's what this /n/customers will have. If the fields file looks
like this:
!record:uvlong # records are numbered
name:string * 1
address:string * 2
phoneno:string[10]
wants:list of string
and we have customers numbered 4, 9, and 30:
cpu% cd /n/database
cpu% ls
4
9
30
cpu% ls 4
name
address
phoneno
wants
cpu% cat 4/wants
3 of 30-inch deep pots
4 sets of 20 Imperial-grade steel forks
cpu%
You see what's going on? The use of 9P means there will be NO special
API for accessing the database: you just use open, read, write, &c,
or rc and the standard tools. This makes report generation a breeze:
#!/bin/rc
rfork e
cd /n/database
{
echo '.DS'
for(i in *){
cat $i/name
cat $i/address
cat $i/phoneno
echo 'REQUESTS:
cat $i/wants
echo
}
echo '.DE'
} | troff -ms
Or, for a more elaborate report:
#!/bin/rc
rfork e
cd /n/database
{
cat <<\END
.TS
center;
c s
lfB lfB lfB lfB
l l l l.
\fBREPORT\fP
Name Address Phone Number Wants
END
for(i in *){
cd $i
name=`{cat name}
addr=`{cat address}
pn=`{cat phoneno}
echo $"name^' '^$"addr^' '^$"pn^' T{'
cat wants
echo 'T}'
cd ..
}
} | tbl | troff -ms
Then, if you use bitsy, you can write a program with libcontrol and
the networking commands to make a portable remote customer editor!
