SIP Server

About the SIP Protocol

SIP, standing for Standard Interchange Protocol, was developed by the 3M corporation to be a common protocol for data transfer between ILS' (referred to in SIP as an ACS, or Automated Circulation System) and a third party device. Originally, the protocol was developed for use with 3M SelfCheck (often abbreviated SC, not to be confused with Staff Client) systems, but has since expanded to other companies and devices. It is now common to find SIP in use in several other vendors' SelfCheck systems, as well as other non-SelfCheck devices. Some examples include:

  • Patron Authentication (computer access, subscription databases)

  • Automated Material Handling (AMH)

    • The automated sorting of items, often to bins or book carts, based on shelving location or other programmable criteria

Installing the SIP Server

This is a rough intro to installing the SIP server for Evergreen.

Getting the code

Current SIP server code lives at in the Evergreen git repository:

cd /opt
git clone git://git.evergreen-ils.org/SIPServer.git SIPServer

Configuring the Server

  1. Type the following commands from the command prompt:

    $ sudo su opensrf
    $ cd /openils/conf
    $ cp oils_sip.xml.example oils_sip.xml
  2. Edit oils_sip.xml. Change the commented out <server-params> section to this:

     <server-params
        min_spare_servers='1'
        max_spare_servers='2'
        min_servers='3'
        max_servers='25'
    />
  3. max_servers will directly correspond to the number of allowed SIP clients. Set the number accordingly, but bear in mind that too many connections can exhaust memory. On a 4G RAM/4 CPU server (that is also running evergreen), it is not recommended to exceed 100 SIP client connections.

Setting the encoding

SIPServer looks for the encoding in the following places:

  1. An encoding attribute on the account element for the currently active SIP account.

  2. The encoding element that is a child of the institution element of the currently active SIP account.

  3. The encoding element that is a child of the implementation_config element that is itself a child of the institution element of the currently active SIP account.

  4. If none of the above exist, then the default encoding (ASCII) is used.

Option 3 is a legacy option. It is recommended that you alter your configuration to move this element out of the implementation_config element and into its parent institution element. Ideally, SIPServer should not look into the implementation config, and this check may be removed at some time in the future.

Datatypes

The msg64_hold_datatype setting is similar to msg64_summary_datatype, but affects holds instead of circulations. When set to barcode, holds information will be delivered as a set of copy barcodes instead of title strings for patron info requests. With barcodes, SIP clients can both find the title strings for display (via item info requests) and make subsequent hold-related action requests, like holds cancellation.

Adding SIP Users

  1. Type the following commands from the command prompt:

    $ sudo su opensrf
    $ cd /openils/conf
  2. In the <accounts> section, add SIP client login information. Make sure that all <logins> use the same institution attribute, and make sure the institution is listed in <institutions>. All attributes in the <login> section will be used by the SIP client.

  3. In Evergreen, create a new profile group called SIP. This group should be a sub-group of Users (not Staff or Patrons). Set Editing Permission as group_application.user.sip_client and give the group the following permissions:

    COPY_CHECKIN
    COPY_CHECKOUT
    CREATE_PAYMENT
    RENEW_CIRC
    VIEW_CIRCULATIONS
    VIEW_COPY_CHECKOUT_HISTORY
    VIEW_PERMIT_CHECKOUT
    VIEW_USER
    VIEW_USER_FINES_SUMMARY
    VIEW_USER_TRANSACTIONS

    OR use SQL like:

    INSERT INTO permission.grp_tree (name,parent,description,application_perm)
    VALUES ('SIP', 1, 'SIP2 Client Systems', 'group_application.user.sip_client');
    INSERT INTO
      permission.grp_perm_map (grp, perm, depth, grantable)
    SELECT
      g.id, p.id, 0, FALSE
    FROM
      permission.grp_tree g,
      permission.perm_list p
    WHERE
      g.name = 'SIP' AND
      p.code IN (
        'COPY_CHECKIN',
        'COPY_CHECKOUT',
        'RENEW_CIRC',
        'VIEW_CIRCULATIONS',
        'VIEW_COPY_CHECKOUT_HISTORY',
        'VIEW_PERMIT_CHECKOUT',
        'VIEW_USER',
        'VIEW_USER_FINES_SUMMARY',
        'VIEW_USER_TRANSACTIONS'
     );

    Verify:

    SELECT *
    FROM permission.grp_perm_map pgpm
        INNER JOIN permission.perm_list ppl ON pgpm.perm = ppl.id
        INNER JOIN permission.grp_tree pgt ON pgt.id = pgpm.grp
    WHERE pgt.name = 'SIP';
  4. For each account created in the <login> section of oils_sip.xml, create a user (via the staff client user editor) that has the same username and password and put that user into the SIP group.

The expiration date will affect the SIP users' connection so you might want to make a note of this somewhere.

Running the server

To start the SIP server type the following commands from the command prompt:

$ sudo su opensrf
$ oils_ctl.sh -a [start|stop|restart]_sip

Logging-SIP

Syslog

It is useful to log SIP requests to a separate file especially during initial setup by modifying your syslog config file.

  1. Edit syslog.conf.

    $ sudo vi /etc/syslog.conf  # maybe /etc/rsyslog.conf
  2. Add this:

    local6.*                -/var/log/SIP_evergreen.log
  3. Syslog expects the logfile to exist so create the file.

    $ sudo touch /var/log/SIP_evergreen.log
  4. Restart sysklogd.

    $ sudo /etc/init.d/sysklogd restart
Syslog-NG

  1. Edit logging config.

    sudo vi /etc/syslog-ng/syslog-ng.conf
  2. Add:

    # +SIP2+ for Evergreen
    filter    f_eg_sip { level(warn, err, crit) and facility(local6); };
    destination eg_sip { file("var/log/SIP_evergreen.log"); };
    log { source(s_all); filter(f_eg_sip); destination(eg_sip); };
  3. Syslog-ng expects the logfile to exist so create the file.

    $ sudo touch /var/log/SIP_evergreen.log
  4. Restart syslog-ng

    $ sudo /etc/init.d/syslog-ng restart

Testing Your SIP Connection

  • In the root directory of the SIPServer code:

    $ cd SIPServer/t
  • Edit SIPtest.pm, change the $instid, $server, $username, and $password variables. This will be enough to test connectivity. To run all tests, you’ll need to change all the variables in the Configuration section.

    $ PERL5LIB=../ perl 00sc_status.t

    This should produce something like:

    1..4
    ok 1 - Invalid username
    ok 2 - Invalid username
    ok 3 - login
    ok 4 - SC status
  • Don’t be dismayed at Invalid Username. That’s just one of the many tests that are run.

More Testing

Once you have opened up either the SIP OR SIP2 ports to be accessible from outside you can do some testing via telnet. In the following tests:

  • Replace $server with your server hostname (or localhost if you want to skip testing external access for now);

  • Replace $username, $password, and $instid with the corresponding values in the <accounts> section of your SIP configuration file;

  • Replace the $user_barcode and $user_password variables with the values for a valid user.

  • Replace the $item_barcode variable with the values for a valid item.

  1. Start by testing your ability to log into the SIP server:

    We are using 6001 here which is associated with SIP2 as per our configuration.

    $ telnet $server 6001
    Connected to $server.
    Escape character is '^]'.
    9300CN$username|CO$password|CP$instid

    If successful, the SIP server returns a 941 result. A result of 940, however, indicates an unsuccessful login attempt. Check the <accounts> section of your SIP configuration and try again.

  2. Once you have logged in successfully, replace the variables in the following line and paste it into the telnet session:

    2300120080623    172148AO$instid|AA$user_barcode|AC$password|AD$user_password

    If successful, the SIP server returns the patron information for $user_barcode, similar to the following:

    24  Y           00120100113    170738AEFirstName MiddleName LastName|AA$user_barcode|BLY|CQY
    |BHUSD|BV0.00|AFOK|AO$instid|

    The response declares it is a valid patron BLY with a valid password CQY and shows the user’s $name.

  3. To test the SIP server’s item information response, issue the following request:

    1700120080623    172148AO$instid|AB$item_barcode|AC$password

    If successful, the SIP server returns the item information for $item_barcode, similar to the following:

    1803020120160923    190132AB30007003601852|AJRégion de Kamouraska|CK001|AQOSUL|APOSUL|BHCAD
    |BV0.00|BGOSUL|CSCA2 PQ NR46 73R

    The response declares it is a valid item, with the title, owning library, permanent and current locations, and call number.

SIP Communication

SIP generally communicates over a TCP connection (either raw sockets or over telnet), but can also communicate via serial connections and other methods. In Evergreen, the most common deployment is a RAW socket connection on port 6001.

SIP communication consists of strings of messages, each message request and response begin with a 2-digit ``command'' - Requests usually being an odd number and responses usually increased by 1 to be an even number. The combination numbers for the request command and response is often referred to as a Message Pair (for example, a 23 command is a request for patron status, a 24 response is a patron status, and the message pair 23/24 is patron status message pair). The table in the next section shows the message pairs and a description of them.

For clarification, the ``Request'' is from the device (selfcheck or otherwise) to the ILS/ACS. The response is… the response to the request ;).

Within each request and response, a number of fields (either a fixed width or separated with a | [pipe symbol] and preceded with a 2-character field identifier) are used. The fields vary between message pairs.

Pair

Name

Supported?

Details

01

Block Patron

Yes

01/Block_Patron - ACS responds with 24 Patron Status Response

09-10

Checkin

Yes (with extensions)

09/10_Checkin

11-12

Checkout

Yes (no renewals)

11/12_Checkout

15-16

Hold

Partially supported

15/16_Hold

17-18

Item Information

Yes (no extensions)

17/18_Item_Information

19-20

Item Status Update

No

19/20_Item_Status_Update - Returns Patron Enable response, but doesn’t make any changes in EG

23-24

Patron Status

Yes

23/24_Patron_Status - 63/64 ``Patron Information'' preferred

25-26

Patron Enable

No

25/26_Patron_Enable - Used during system testing and validation

29-30

Renew

Yes

29/30_Renew

35-36

End Session

Yes

35/36_End_Session

37-38

Fee Paid

Yes

37/38_Fee_Paid

63-64

Patron Information

Yes (no extensions)

63/64_Patron_Information

65-66

Renew All

Yes

65/66_Renew_All

93-94

Login

Yes

93/94_Login - Must be first command to Evergreen ACS (via socket) or SIP will terminate

97-96

Resend last message

Yes

97/96_Resend

99-98

SC-ACS Status

Yes

99/98_SC_and_ACS_Status

01 Block Patron

A selfcheck will issue a Block Patron command if a patron leaves their card in a selfcheck machine or if the selfcheck detects tampering (such as attempts to disable multiple items during a single item checkout, multiple failed pin entries, etc).

In Evergreen, this command does the following:

  • User alert message: CARD BLOCKED BY SELF-CHECK MACHINE (this is independent of the AL Blocked Card Message field).

  • Card is marked inactive.

The request looks like:

01<card retained><date>[fields AO, AL, AA, AC]

Card Retained: A single character field of Y or N - tells the ACS whether the SC has retained the card (ex: left in the machine) or not.

Date: An 18 character field for the date/time when the block occurred.

Format: YYYYMMDDZZZZHHMMSS (ZZZZ being zone - 4 blanks when local time, ``Z'' (3 blanks and a Z) represents UTC(GMT/Zulu)

Fields: See Fields for more details.

The response is a 24 ``Patron Status Response'' with the following:

  • Charge privileges denied

  • Renewal privileges denied

  • Recall privileges denied (hard-coded in every 24 or 64 response)

  • hold privileges denied

  • Screen Message 1 (AF): blocked

  • Patron

09/10 Checkin

~The request looks like:

09<No block (Offline)><xact date><return date>[Fields AP,AO,AB,AC,CH,BI]

No Block (Offline): A single character field of Y or N - Offline transactions are not currently supported so send N.

xact date: an 18 character field for the date/time when the checkin occurred. Format: YYYYMMDDZZZZHHMMSS (ZZZZ being zone - 4 blanks when local time, ``Z'' (3 blanks and a Z) represents UTC(GMT/Zulu)

Fields: See Fields for more details.

The response is a 10 ``Checkin Response'' with the following:

10<resensitize><magnetic media><alert><xact date>[Fields AO,AB,AQ,AJ,CL,AA,CK,CH,CR,CS,CT,CV,CY,DA,AF,AG]

Example (with a remote hold):

09N20100507    16593720100507    165937APCheckin Bin 5|AOBR1|AB1565921879|ACsip_01|
101YNY20100623    165731AOBR1|AB1565921879|AQBR1|AJPerl 5 desktop reference|CK001|CSQA76.73.P33V76 1996
|CTBR3|CY373827|DANicholas Richard Woodard|CV02|

Here you can see a hold alert for patron CY 373827, named DA Nicholas Richard Woodard, to be picked up at CT BR3''. Since the transaction is happening at AO BR1'', the alert type CV is 02 for hold at remote library. The possible values for CV are:

  • 00: unknown

  • 01: local hold

  • 02: remote hold

  • 03: ILL transfer (not used by EG)

  • 04: transfer

  • 99: other

The logic for Evergreen to determine whether the content is magnetic_media comes from or search_config_circ_modifier. The default is non-magnetic. The same is true for media_type (default 001). Evergreen does not populate the collection_code because it does not really have any, but it will provide the call_number where available.

Unlike the item_id (barcode), the title_id is actually a title string, unless the configuration forces the return of the bib ID.

Don’t be confused by the different branches that can show up in the same response line.

  • AO is where the transaction took place,

  • AQ is the ``permanent location'', and

  • CT is the destination location (i.e., pickup lib for a hold or target lib for a transfer).

11/12 Checkout

15/16 Hold

Evergreen supports the Hold message for the purpose of canceling holds. It does not currently support creating hold requests via SIP2.

17/18 Item Information

The request looks like:

17<xact_date>[fields: AO,AB,AC]

The request is very terse. AC is optional.

The following response structure is for SIP2. (Version 1 of the protocol had only 6 total fields.)

18<circulation_status><security_marker><fee_type><xact_date>
[fields: CF,AH,CJ,CM,AB,AJ,BG,BH,BV,CK,AQ,AP,CH,AF,AG,+CT,+CS]

Example:

1720060110    215612AOBR1|ABno_such_barcode|
1801010120100609    162510ABno_such_barcode|AJ|
1720060110    215612AOBR1|AB1565921879|
1810020120100623    171415AB1565921879|AJPerl 5 desktop reference|CK001|AQBR1|APBR1|BGBR1
|CTBR3|CSQA76.73.P33V76 1996|

The first case is with a bogus barcode. The latter shows an item with a circulation_status of 10 for in transit between libraries. The known values of circulation_status are enumerated in the spec.

EXTENSIONS: The CT field for destination location and CS call number are used by Automated Material Handling systems.

19/20 Item Status Update

23/24 Patron Status

Example:

2300120060101    084235AOUWOLS|AAbad_barcode|ACsip_01|ADbad_password|
24YYYY          00120100507    013934AE|AAbad_barcode|BLN|AOUWOLS|
2300120060101    084235AOCONS|AA999999|ACsip_01|ADbad_password|
24  Y           00120100507    022318AEDoug Fiander|AA999999|BLY|CQN|BHUSD|BV0.00|AFOK|AOCONS|
2300120060101    084235AOCONS|AA999999|ACsip_01|ADuserpassword|LY|CQN|BHUSD|BV0.00|AFOK|AOCONS|
24  Y           00120100507    022803AEDoug Fiander|AA999999|BLY|CQY|BHUSD|BV0.00|AFOK|AOCONS|
  1. The BL field (SIP2, optional) is valid patron, so the N value means bad_barcode doesn’t match a patron, the Y value means 999999 does.

  2. The CQ field (SIP2, optional) is valid password, so the N value means bad_password doesn’t match 999999’s password, the Y means userpassword does.

So if you were building the most basic SIP2 authentication client, you would check for |CQY| in the response to know the user’s barcode and password are correct (|CQY| implies |BLY|, since you cannot check the password unless the barcode exists). However, in practice, depending on the application, there are other factors to consider in authentication, like whether the user is blocked from checkout, owes excessive fines, reported their card lost, etc. These limitations are reflected in the 14-character patron status string immediately following the 24 code. See the field definitions in your copy of the spec.

25/26 Patron Enable

Not yet supported.

29/30 Renew

Evergreen supports the Renew message. Evergreen checks whether a penalty is specifically configured to block renewals before blocking any SIP renewal.

35/36 End Session

3520100505    115901AOBR1|AA999999|
36Y20100507    161213AOCONS|AA999999|AFThank you!|

The Y/N code immediately after the 36 indicates success/failure. Failure is not particularly meaningful or important in this context, and for evergreen it is hardcoded Y.

37/38 Fee Paid

Evergreen supports the Fee Paid message.

63/64 Patron Information

Attempting to retrieve patron info with a bad barcode:

6300020060329    201700          AOBR1|AAbad_barcode|
64YYYY          00020100623    141130000000000000000000000000AE|AAbad_barcode|BLN|AOBR1|

Attempting to retrieve patron info with a good barcode (but bad patron password):

6300020060329    201700          AOBR1|AA999999|ADbadpwd|
64  Y           00020100623    141130000000000000000000000000AA999999|AEDavid J. Fiander|BHUSD|BV0.00
|BD2 Meadowvale Dr. St Thomas, ON Canada
90210|[email protected]|BF(519) 555 1234|AQBR1|BLY|CQN|PB19640925|PCPatrons
|PIUnfiltered|AFOK|AOBR1|

See 23/24 Patron Status for info on BL and CQ fields.

65/66 Renew All

Evergreen supports the Renew All message.

93/94 Login

Example:

9300CNsip_01|CObad_value|CPBR1|
[Connection closed by foreign host.]
...
9300CNsip_01|COsip_01|CPBR1|
941

941 means successful terminal login. 940 or getting dropped means failure.

When using a version of SIPServer that supports the feature, the Location (CP) field of the Login (93) message will be used as the workstation name if supplied. Blank or missing location fields will be ignored. This allows users or reports to determine which selfcheck performed a circulation.

97/96 Resend

99/98 SC and ACS Status

99<status code><max print width><protocol version>

All 3 fields are required:

  • 0: SC is OK

  • 1: SC is out of paper

  • 2: SC shutting down

  • status code - 1 character

  • max print width - 3 characters - the integer number of characters the client can print

  • protocol version - 4 characters - x.xx

    98<on-line status><checkin ok><checkout ok><ACS renewal policy>
    <status update ok><offline ok><timeout period>
    <retries allowed><date/time sync><protocol version><institution id>
    <library name><supported messages><terminal
    location><screen message><print line>

Example:

9910302.00
98YYYYNN60000320100510    1717202.00AOCONS|BXYYYYYYYYYNYNNNYN|

The Supported Messages field BX appears only in SIP2, and specifies whether 16 different SIP commands are supported by the ACS or not.

Fields

All fixed-length fields in a communication will appear before the first variable-length field. This allows for simple parsing. Variable-length fields are by definition delimited, though there will not necessarily be an initial delimiter between the last fixed-length field and the first variable-length one. It would be unnecessary, since you should know the exact position where that field begins already.

Patron privacy and the SIP protocol

SIP traffic includes a lot of patron information, and is not encrypted by default. It is strongly recommended that you encrypt any SIP traffic.

SIP server configuration

On the SIP server, use iptables or etc/hosts to allow SSH connections on port 22 from the SIP client machine. You will probably want to have very restrictive rules on which IP addresses can connect to this server.

SSH tunnels on SIP clients

SSH tunnels are a good fit for use cases like self-check machines, because it is relatively easy to automatically open the connection. Using a VPN is another option, but many VPN clients require manual steps to open the VPN connection.

  1. If the SIP client will be on a Windows machine, install cygwin on the SIP client.

  2. On the SIP client, use ssh-keygen to generate an SSH key.

  3. Add the public key to /home/my_sip_user/.ssh/authorized_keys on your SIP server to enable logins without using the UNIX password.

  4. Configure an SSH tunnel to open before every connection. You can do this in several ways:

    1. If the SIP client software allows you to run an arbitrary command before each SIP connection, use something like this:

      ssh -f -L 6001:localhost:6001 [email protected]_sip_server.com sleep 10
    2. If you feel confident that the connection won’t get interrupted, you can have something like this run at startup:

      ssh -f -N -L 6001:localhost:6001 [email protected]_sip_server.com
    3. If you want to constantly poll to make sure that the connection is still running, you can do something like this as a cron job or scheduled task on the SIP client machine:

#!/bin/bash
instances=`/bin/ps -ef | /bin/grep ssh | /bin/grep -v grep | /bin/wc -l`
if [ $instances -eq 0 ]; then
  echo "Restarting ssh tunnel"
  /usr/bin/ssh -L 6001:localhost:6001 [email protected]_sip_server.com -f -N
fi