-<!-- $Id: frontend.xml,v 1.3 2001-07-19 23:29:40 adam Exp $ -->
- <chapter><title id="server">Making an IR Server for Your Database</title>
-
+<!-- $Id: frontend.xml,v 1.11 2002-03-05 12:45:48 mike Exp $ -->
+ <chapter id="server"><title>Generic server</title>
<sect1><title>Introduction</title>
<para>
If you aren't into documentation, a good way to learn how the
- backend interface works is to look at the <filename>backend.h</filename>
+ back end interface works is to look at the <filename>backend.h</filename>
file. Then, look at the small dummy-server in
- <filename>ztest/ztest.c</filename>. Finally, you can have a look at
- the <filename>seshigh.c</filename> file, which is where most of the
- logic of the frontend server is located. The <filename>backend.h</filename>
+ <filename>ztest/ztest.c</filename>. The <filename>backend.h</filename>
file also makes a good reference, once you've chewed your way through
the prose of this file.
</para>
<para>
The backend interface was designed in anticipation of a specific
integration task, while still attempting to achieve some degree of
- generality. We realise fully that there are points where the
+ generality. We realize fully that there are points where the
interface can be improved significantly. If you have specific
functions or parameters that you think could be useful, send us a
mail (or better, sign on to the mailing list referred to in the
- toplevel README file). We will try to fit good suggestions into future
+ top-level README file). We will try to fit good suggestions into future
releases, to the extent that it can be done without requiring
too many structural changes in existing applications.
</para>
</note>
</sect1>
-
- <sect1><title>The Database Frontend</title>
+
+ <sect1 id="server.frontend"><title>The Database Frontend</title>
<para>
We refer to this software as a generic database frontend. Your
<listitem><para>
Extended Services (optional).
</para></listitem>
-
+
<listitem><para>
Result-Set Delete (optional).
</para></listitem>
<listitem><para>
Result-Set Sort (optional).
</para></listitem>
-
+
</itemizedlist>
<para>
</para>
</sect1>
- <sect1><title>The Backend API</title>
+ <sect1 id="server.backend"><title>The Backend API</title>
<para>
- The headers files that you need to use the interface are in the
- <filename>include/yaz</filename> directory. They are called
- <filename>statserv.h</filename> and <filename>backend.h</filename>. They
- will include other files from the <filename>include/yaz</filename>
- directory, so you'll probably want to use the -I option of your
- compiler to tell it where to find the files. When you run
- <literal>make</literal> in the toplevel &yaz; directory,
- everything you need to create your server is put the
- <filename>lib/libyaz.a</filename> library.
+ The header file that you need to use the interface are in the
+ <filename>include/yaz</filename> directory. It's called
+ <filename>backend.h</filename>. It will include other files from
+ the <filename>include/yaz</filename> directory, so you'll
+ probably want to use the -I option of your compiler to tell it
+ where to find the files. When you run
+ <literal>make</literal> in the top-level &yaz; directory,
+ everything you need to create your server is to link with the
+ <filename>lib/libyaz.la</filename> library.
</para>
</sect1>
- <sect1><title>Your main() Routine</title>
+ <sect1 id="server.main"><title>Your main() Routine</title>
<para>
As mentioned, your <function>main()</function> routine can be quite brief.
</para>
<synopsis>
- int statserv_main(int argc, char **argv,
- bend_initresult *(*bend_init)(bend_initrequest *r),
- void (*bend_close)(void *handle));
+int statserv_main(int argc, char **argv,
+ bend_initresult *(*bend_init)(bend_initrequest *r),
+ void (*bend_close)(void *handle));
</synopsis>
<para>
according to the parameters given. When connection requests are received,
the event handler will typically <function>fork()</function> and
create a sub-process to handle a new connection.
- Alternatively the server may be setup to create threads for each connection.
+ Alternatively the server may be setup to create threads for each
+ connection.
If you do use global variables and forking, you should be aware, then,
that these cannot be shared between associations, unless you explicitly
disable forking by command line parameters.
</para>
-
+
<para>
The server provides a mechanism for controlling some of its behavior
without using command-line options. The function
</para>
<synopsis>
- statserv_options_block *statserv_getcontrol(void);
+statserv_options_block *statserv_getcontrol(void);
</synopsis>
<para>
- Will return a pointer to a <literal>struct statserv_options_block</literal>
+ will return a pointer to a <literal>struct statserv_options_block</literal>
describing the current default settings of the server. The structure
contains these elements:
-
+
<variablelist>
- <varlistentry><term>int dynamic</term><listitem><para>
+ <varlistentry><term>
+ <literal>int dynamic</literal></term><listitem><para>
A boolean value, which determines whether the server
will fork on each incoming request (TRUE), or not (FALSE). Default is
TRUE. This flag is only read by UNIX-based servers (WIN32 based servers
doesn't fork).
</para></listitem></varlistentry>
-
- <varlistentry><term>int threads</term><listitem><para>
+
+ <varlistentry><term>
+ <literal>int threads</literal></term><listitem><para>
A boolean value, which determines whether the server
will create a thread on each incoming request (TRUE), or not (FALSE).
- Default is FALSE. This flag is only read by UNIX-based servers that offer
- POSIX Threads support. WIN32-based servers always operate in threaded mode.
+ Default is FALSE. This flag is only read by UNIX-based servers
+ that offer POSIX Threads support.
+ WIN32-based servers always operate in threaded mode.
</para></listitem></varlistentry>
-
- <varlistentry><term>int inetd</term><listitem><para>
+
+ <varlistentry><term>
+ <literal>int inetd</literal></term><listitem><para>
A boolean value, which determines whether the server
will operates under a UNIX INET daemon (inetd). Default is FALSE.
</para></listitem></varlistentry>
-
- <varlistentry><term>int loglevel</term><listitem><para>
+
+ <varlistentry><term>
+ <literal>int loglevel</literal></term><listitem><para>
Set this by ORing the constants defined in
<filename>include/yaz/yaz-log.h</filename>.
</para></listitem></varlistentry>
-
- <varlistentry><term>char logfile[ODR_MAXNAME+1]</term>
+
+ <varlistentry><term>
+ <literal>char logfile[ODR_MAXNAME+1]</literal></term>
<listitem><para>File for diagnostic output ("": stderr).
</para></listitem></varlistentry>
- <varlistentry><term>char apdufile[ODR_MAXNAME+1]</term>
+
+ <varlistentry><term>
+ <literal>char apdufile[ODR_MAXNAME+1]</literal></term>
<listitem><para>
- Name of file for logging incoming and outgoing APDUs ("": don't
- log APDUs, "-": <literal>stderr</literal>).
+ Name of file for logging incoming and outgoing APDUs
+ ("": don't log APDUs, "-":
+ <literal>stderr</literal>).
</para></listitem></varlistentry>
- <varlistentry><term>char default_listen[1024]</term>
+ <varlistentry><term>
+ <literal>char default_listen[1024]</literal></term>
<listitem><para>Same form as the command-line specification of
listener address. "": no default listener address.
Default is to listen at "tcp:@:9999". You can only
specify one default listener address in this fashion.
</para></listitem></varlistentry>
- <varlistentry><term>enum oid_proto default_proto;</term>
- <listitem><para>Either <literal>PROTO_SR</literal> or
- <literal>PROTO_Z3950</literal>. Default is <literal>PROTO_Z39_50</literal>.
+ <varlistentry><term>
+ <literal>enum oid_proto default_proto;</literal></term>
+ <listitem><para>Either <literal>PROTO_Z3950</literal> or
+ <literal>PROTO_SR</literal>.
+ Default is <literal>PROTO_Z39_50</literal>.
</para></listitem></varlistentry>
- <varlistentry><term>int idle_timeout;</term>
+
+ <varlistentry><term>
+ <literal>int idle_timeout;</literal></term>
<listitem><para>Maximum session idletime, in minutes. Zero indicates
no (infinite) timeout. Default is 120 minutes.
</para></listitem></varlistentry>
-
- <varlistentry><term>int maxrecordsize;</term>
+
+ <varlistentry><term>
+ <literal>int maxrecordsize;</literal></term>
<listitem><para>Maximum permissible record (message) size. Default
- is 1Mb. This amount of memory will only be allocated if a client requests a
- very large amount of records in one operation (or a big record). Set it
- to a lower number
- if you are worried about resource consumption on your host system.
+ is 1Mb. This amount of memory will only be allocated if a
+ client requests a very large amount of records in one operation
+ (or a big record).
+ Set it to a lower number if you are worried about resource
+ consumption on your host system.
</para></listitem></varlistentry>
- <varlistentry><term>char configname[ODR_MAXNAME+1]</term>
+ <varlistentry><term>
+ <literal>char configname[ODR_MAXNAME+1]</literal></term>
<listitem><para>Passed to the backend when a new connection is received.
</para></listitem></varlistentry>
- <varlistentry><term>char setuid[ODR_MAXNAME+1]</term>
+ <varlistentry><term>
+ <literal>char setuid[ODR_MAXNAME+1]</literal></term>
<listitem><para>Set user id to the user specified, after binding
the listener addresses.
</para></listitem></varlistentry>
-
- <varlistentry>
- <term>void (*bend_start)(struct statserv_options_block *p)</term>
+
+ <varlistentry><term>
+ <literal>void (*bend_start)(struct statserv_options_block *p)</literal>
+ </term>
<listitem><para>Pointer to function which is called after the
command line options have been parsed - but before the server
starts listening.
When the server operates as an NT service this handler is called
whenever the service is started.
</para></listitem></varlistentry>
-
- <varlistentry>
- <term>void (*bend_stop)(struct statserv_options_block *p)</term>
- <listitem><para>Pointer to function which is called whenver the server
+
+ <varlistentry><term>
+ <literal>void (*bend_stop)(struct statserv_options_block *p)</literal>
+ </term>
+ <listitem><para>Pointer to function which is called whenever the server
has stopped listening for incoming connections. This function pointer
has a default value of NULL in which case it isn't called.
When the server operates as an NT service this handler is called
whenever the service is stopped.
</para></listitem></varlistentry>
- <varlistentry><term>void *handle</term>
+ <varlistentry><term>
+ <literal>void *handle</literal></term>
<listitem><para>User defined pointer (default value NULL).
This is a per-server handle that can be used to specify "user-data".
Do not confuse this with the session-handle as returned by bend_init.
a static area. You are allowed to change the contents of the structure,
but the changes will not take effect before you call
</para>
-
+
<synopsis>
- void statserv_setcontrol(statserv_options_block *block);
+void statserv_setcontrol(statserv_options_block *block);
</synopsis>
<note>
</note>
</sect1>
- <sect1><title>The Backend Functions</title>
+ <sect1 id="server.backendfunctions"><title>The Backend Functions</title>
<para>
For each service of the protocol, the backend interface declares one or
<sect2><title>Init</title>
<synopsis>
- bend_initresult (*bend_init)(bend_initrequest *r);
+bend_initresult (*bend_init)(bend_initrequest *r);
</synopsis>
<para>
Z_ReferenceId *referenceId;/* reference ID */
char *peer_name; /* dns host of peer (client) */
+ char *implementation_id;
char *implementation_name;
char *implementation_version;
int (*bend_sort) (void *handle, bend_sort_rr *rr);
<para>
The members <literal>peer_name</literal>,
+ <literal>implementation_id</literal>,
<literal>implementation_name</literal> and
- <literal>implementation_version</literal> holds DNS of client, name
+ <literal>implementation_version</literal> holds DNS of client, ID of implementor, name
of client (Z39.50) implementation - and version.
</para>
<sect2><title>Search and retrieve</title>
<para>We now describe the handlers that are required to support search -
- and retrieve. You must support two functions - one for seearch - and one
+ and retrieve. You must support two functions - one for search - and one
for fetch (retrieval of one record). If desirable you can provide a
third handler which is called when a present request is received which
allows you to optimize retrieval of multiple-records.
corresponding to the resultSetIndicator field in the protocol.
<literal>num_bases/basenames</literal> is a length of/array of character
pointers to the database names provided by the client.
- The <literal>query</literal> is the full query structure as defined in the
- protocol ASN.1 specification.
+ The <literal>query</literal> is the full query structure as defined in
+ the protocol ASN.1 specification.
It can be either of the possible query types, and it's up to you to
determine if you can handle the provided query type.
Rather than reproduce the C interface here, we'll refer you to the
allocating space for structured data records.
The stream will be reset when all records have been assembled, and
the response package has been transmitted.
- For unstructured data, the backend is responsible for maintaining a static
- or dynamic buffer for the record between calls.
+ For unstructured data, the backend is responsible for maintaining a
+ static or dynamic buffer for the record between calls.
</para>
<para>
oid_value format; /* One of the CLASS_RECSYN members */
Z_ReferenceId *referenceId;/* reference ID */
Z_RecordComposition *comp; /* Formatting instructions */
- ODR stream; /* encoding stream - memory source if required */
+ ODR stream; /* encoding stream */
ODR print; /* printing stream */
bend_request request;
bend_association association;
<sect2><title>Delete</title>
<para>
- For backends that supports delete of a result set only one handler
+ For back-ends that supports delete of a result set only one handler
must be defined.
</para>
<note>
<para>
- The delete set function definition is rather primitive, mostly because we
- have had no practical need for it as of yet. If someone wants
+ The delete set function definition is rather primitive, mostly because
+ we have had no practical need for it as of yet. If someone wants
to provide a full delete service, we'd be happy to add the
extra parameters that are required. Are there clients out there
that will actually delete sets they no longer need?
</sect2>
</sect1>
- <sect1><title>Application Invocation</title>
+ <sect1 id="server.invocation"><title>Application Invocation</title>
<para>
The finished application has the following
<variablelist>
- <varlistentry><term>-a <replaceable>file</replaceable></term>
+ <varlistentry><term><literal>-a </literal>
+ <replaceable>file</replaceable></term>
<listitem><para>
Specify a file for dumping PDUs (for diagnostic purposes).
The special name "-" sends output to
<literal>stderr</literal>.
</para></listitem></varlistentry>
- <varlistentry><term>-S</term>
+ <varlistentry><term><literal>-S</literal></term>
<listitem><para>
Don't fork or make threads on connection requests. This is good for
debugging, but not recommended for real operation: Although the
current users.
</para></listitem></varlistentry>
- <varlistentry><term>-T</term>
+ <varlistentry><term><literal>-T</literal></term>
<listitem><para>
Operate the server in threaded mode. The server creates a thread
for each connection rather than a fork a process. Only available
on UNIX systems that offers POSIX threads.
</para></listitem></varlistentry>
- <varlistentry><term>-s</term>
+ <varlistentry><term><literal>-s</literal></term>
<listitem><para>
Use the SR protocol (obsolete).
</para></listitem></varlistentry>
- <varlistentry><term>-z</term>
+ <varlistentry><term><literal>-z</literal></term>
<listitem><para>
Use the Z39.50 protocol (default). These two options complement
each other. You can use both multiple times on the same command
concurrently, on different local ports.
</para></listitem></varlistentry>
- <varlistentry><term>-l <replaceable>file</replaceable></term>
+ <varlistentry><term><literal>-l </literal>
+ <replaceable>file</replaceable></term>
<listitem><para>The logfile.
</para></listitem></varlistentry>
- <varlistentry><term>-c <replaceable>config</replaceable></term>
+ <varlistentry><term><literal>-c </literal>
+ <replaceable>config</replaceable></term>
<listitem><para>A user option that serves as a specifier for some
sort of configuration, e.g. a filename.
The argument to this option is transferred to member
<literal>statserv_options_block</literal>.
</para></listitem></varlistentry>
- <varlistentry><term>-v <replaceable>level</replaceable></term>
+ <varlistentry><term><literal>-v </literal>
+ <replaceable>level</replaceable></term>
<listitem><para>
The log level. Use a comma-separated list of members of the set
{fatal,debug,warn,log,all,none}.
</para></listitem></varlistentry>
- <varlistentry><term>-u <replaceable>userid</replaceable></term>
+ <varlistentry><term><literal>-u </literal>
+ <replaceable>userid</replaceable></term>
<listitem><para>
Set user ID. Sets the real UID of the server process to that of the
given user. It's useful if you aren't comfortable with having the
privileged port.
</para></listitem></varlistentry>
- <varlistentry><term>-w <replaceable>dir</replaceable></term>
+ <varlistentry><term><literal>-w </literal>
+ <replaceable>dir</replaceable></term>
<listitem><para>
Working directory.
</para></listitem></varlistentry>
- <varlistentry><term>-i</term>
+ <varlistentry><term><literal>-i</literal></term>
+ <listitem><para>
+ Use this to make the the server run from the
+ <application>inetd</application> server (UNIX only).
+ </para></listitem></varlistentry>
+
+ <varlistentry><term><literal>-install</literal></term>
<listitem><para>
- Use this when running from the <application>inetd</application> server.
+ Use this to install the server as an NT service (Windows 2000/NT only).
+ Control the server by going to the Services in the Control Panel.
+ </para></listitem></varlistentry>
+
+ <varlistentry><term><literal>-remove</literal></term>
+ <listitem><para>
+ Use this to remove the server from the NT services (Windows 2000/NT only).
</para></listitem></varlistentry>
- <varlistentry><term>-t <replaceable>minutes</replaceable></term>
+ <varlistentry><term><literal>-t </literal>
+ <replaceable>minutes</replaceable></term>
<listitem><para>
Idle session timeout, in minutes.
</para></listitem></varlistentry>
- <varlistentry><term>-k <replaceable>size</replaceable></term>
+ <varlistentry><term><literal>-k </literal>
+ <replaceable>size</replaceable></term>
<listitem><para>
Maximum record size/message size, in kilobytes.
</para></listitem></varlistentry>
<para>
A listener specification consists of a transport mode followed by a
colon (:) followed by a listener address. The transport mode is
- either <literal>osi</literal> or <literal>tcp</literal>.
+ either <literal>tcp</literal> or <literal>ssl</literal>.
</para>
<para>
- For TCP, an address has the form
+ For TCP and SSL, an address has the form
</para>
<synopsis>
</para>
<para>
- For osi, the address form is
- </para>
-
- <synopsis>
- [t-selector /] hostname | IP-number [: portnumber]
- </synopsis>
-
- <para>
- The transport selector is given as a string of hex digits (with an even
- number of digits). The default port number is 102 (RFC1006 port).
- </para>
-
- <para>
Examples
</para>
<screen>
tcp:dranet.dra.com
- osi:0402/dbserver.osiworld.com:3000
+ ssl:ssl.enterprise.com:3000
</screen>
<para>
In both cases, the special hostname "@" is mapped to
- the address INADDR_ANY, which causes the server to listen on any local
- interface. To start the server listening on the registered ports for
- Z39.50 and SR over OSI/RFC1006, and to drop root privileges once the
- ports are bound, execute the server like this (from a root shell):
- </para>
-
- <screen>
- my-server -u daemon tcp:@ -s osi:@
- </screen>
-
- <para>
- You can replace <literal>daemon</literal> with another user, eg. your
- own account, or a dedicated IR server account.
- <literal>my-server</literal> should be the name of your
- server application. You can test the procedure with the
- <application>yaz-ztest</application> application.
+ the address <literal>INADDR_ANY</literal>, which causes the
+ server to listen on any local interface.
</para>
</sect1>
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document: "yaz.xml"
- sgml-local-catalogs: "../../docbook/docbook.cat"
+ sgml-local-catalogs: nil
sgml-namecase-general:t
End:
-->
projects / yaz-moved-to-github.git / blobdiff