SANSparallel is an MPI implementation of a suffix array neighborhood search client-server. 

SANSparallel takes FASTA formatted sequences as input and returns similar sequences from the sequence database.

SANSparallel was tested on Linux and its memory usage is about nine bytes per character in sequence database.


1. tar -zxvf SANSparallel.2.3.tar.gz
2. cd SANSparallel.2/
3. open in a text editor and modify $HOME on lines 17 and 30
4. module add openmpi-x86_64
5. make clean
6. make 

- step 4 prepares the MPI environment
- ignore warnings from C compiler in step 6

Benchmark data:

1. tar -zxvf benchmark.tar.gz
2. you get the following files:
        - benchid.dat = the reference of truth, tuples (query id, reference id, e-value, sequence identity)
        - uniprot_ECCB.fasta = reference sequence database in FASTA format
        - dickeya_solanii.fasta = test set query sequences in FASTA format

Running SANSparallel:

SANSparallel runs as a client and a server. The server holds the database in memory. 
Client processes call the server and transmit the result to the user. 
The client can run on the same host as the server or on a different host.

1. Update database

	1.1 Fetch database by anonymous ftp

ftp> cd /pub/databases/uniprot/current_release/knowledgebase/complete
ftp> get uniprot_sprot.fasta.gz
ftp> get uniprot_trembl.fasta.gz
ftp> cd /pub/databases/uniprot/current_release/uniref/uniref50
ftp> get uniref50.fasta.gz
ftp> cd /pub/databases/uniprot/current_release/uniref/uniref90
ftp> get uniref90.fasta.gz
ftp> cd /pub/databases/uniprot/current_release/uniref/uniref100
ftp> get uniref100.fasta.gz

	1.2 Index database

perl /home/luholm/sansserver/ uniprot /data/uniprot/uniprot_sprot.fasta.gz /data/uniprot/uniprot_trembl.fasta.gz
perl /home/luholm/sansserver/ uniref100 /data/uniprot/uniref100.fasta.gz
perl /home/luholm/sansserver/ uniref90 /data/uniprot/uniref90.fasta.gz
perl /home/luholm/sansserver/ uniref50 /data/uniprot/uniref50.fasta.gz
perl /home/luholm/sansserver/ swiss /data/uniprot/uniprot_sprot.fasta.gz

- replace path to according to your installation
- the first argument of is a name for the database. Index files have this name as prefix. 
- the rest are FASTA-formatted sequence files. Gzipped files are accepted, but all files must be of the same type (gz or text). 
- replace the path /data/uniprot/ by wherever you copied the databases in step 1.1.

2. Start server 

module add openmpi-x86_64
nohup mpirun -np 16 -output-filename x /home/luholm/sansserver/server uniprot 54321 uniprot.Apr2015 &

- replace path to server according to your installation
- the server is left to run in the background
- mpirun options -np = number of processes; -output-filename = prefix of log file for each process
- the first argument is the name for the database (from step 1.2). A path can be included if the database was installed elsewhere than the current working directory.
- the second argument is the port number. The client must connect to this socket (see step 3).
- the third argument is the version of the database. This will be echoed in the output.
- there can only be one server connected to one port at a time. If the server is killed, there is a short timeout before the port number can be re-used.

3. Run client 

/home/luholm/sansserver/client [OPTIONS] < input.fasta > output.txt

-h integer = number of hits
-R integer = number of rejected tests (evalue > evalue-cutoff)
-x integer = width of suffix array window 
-W integer = width of diagonal band in vote clustering
-w integer = width of diagonal band in alignment
-s integer = minumum vote in suffix array search
-E real = evalue-cutoff
-T integer = minimum BLOSUM62 score of 4-tuple to find alignment diagonal
-H string = host name, where the server is running. Default is localhost.
-P integer = server port number, must match port number selected in step 2
-V integer = size of vote list
-m integer: < 0 = no alignment, 0 = alignment, 2 = alignment with iteration until convergence of Hth alignment score  

The web server uses the following pre-set parameter combinations ("protocols"):
Option    protocol  -X  -V      -R     -m
verifast    <0       H   H       H     -3
fast         0       H   100+H   H      0
slow         1       H   100+2H  V      2
verislow     2       H   4000    2000   2

4. Output format
The output of SANSparallel is a FASTA file with tagged additional information. The general format is:

< DATABASE= db-version >
< QUERY query attributes >
 < SBJCT sbjct attributes > 
 < /SBJCT >
 ... n SBJCT blocks ...
< /QUERY >
... m QUERY blocks ...

4.1 Query attributes

nid= integer: sequential number of query in input 
vote_cutoff= integer: H database sequences have vote better or equal 
LSEQ= integer: length of sequence

4.2 Sbjct attributes

VOTE= integer: initial score used for sorting database
TUPS= integer; secondary score used to re-sort shortlisted candidates
PIDE= real; number of identities divided by the number of aligned residues
LALI= integer; number of aligned residues
BITS= real; bitscore of alignment
EVALUE= real; evalue calculated applying Karlin-Altschul statistics
DIAG= integer; (query-sbjct) diagonal used for banded alignment 
LSEQ= integer; length of sequence
QFROM= integer; start position of alignment in query sequence
QTO= integer; end position of alignment in query sequence
SFROM= integer; start position of alignment in database sequence
STO= integer; end position of alignment in database sequence 

4.3 Error messages

ERROR in connect: server is down, or server is loading the database. 

Big databases take many hours to index and load.