File: comstack.common.html

package info (click to toggle)
yaz 3.0.34-2
  • links: PTS, VCS
  • area: main
  • in suites: lenny
  • size: 13,404 kB
  • ctags: 12,108
  • sloc: xml: 116,075; ansic: 52,205; sh: 9,746; tcl: 2,043; makefile: 1,141; yacc: 347
file content (135 lines) | stat: -rw-r--r-- 9,775 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>3.�Common Functions</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2"><link rel="start" href="index.html" title="YAZ User's Guide and Reference"><link rel="up" href="comstack.html" title="Chapter�9.�The COMSTACK Module"><link rel="prev" href="comstack.introduction.html" title="2.�Introduction"><link rel="next" href="comstack.client.html" title="4.�Client Side"></head><body><link rel="stylesheet" type="text/css" href="common/style1.css"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">3.�Common Functions</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="comstack.introduction.html">Prev</a>�</td><th width="60%" align="center">Chapter�9.�The COMSTACK Module</th><td width="20%" align="right">�<a accesskey="n" href="comstack.client.html">Next</a></td></tr></table><hr></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="comstack.common"></a>3.�Common Functions</h2></div></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="comstack.managing.endpoints"></a>3.1.�Managing Endpoints</h3></div></div></div><pre class="synopsis">
     COMSTACK cs_create(CS_TYPE type, int blocking, int protocol);
    </pre><p>
     Creates an instance of the protocol stack - a communications endpoint.
     The <code class="literal">type</code> parameter determines the mode
     of communication. At present the following values are supported:
    </p><div class="variablelist"><dl><dt><span class="term"><code class="literal">tcpip_type</code></span></dt><dd><p>TCP/IP (BER over TCP/IP or HTTP over TCP/IP)
       </p></dd><dt><span class="term"><code class="literal">ssl_type</code></span></dt><dd><p>Secure Socket Layer (SSL). This COMSTACK 
        is experimental and is not fully implemented. If
        HTTP is used, this effectively is HTTPS.
       </p></dd><dt><span class="term"><code class="literal">unix_type</code></span></dt><dd><p>Unix socket (unix only). Local Transfer via
        file socket. See <span class="citerefentry"><span class="refentrytitle">unix</span>(7)</span>.
       </p></dd></dl></div><p>
     The <code class="function">cs_create</code> function returns a null-pointer
     if a system error occurs.
     The <code class="literal">blocking</code> parameter should be one if
     you wish the association to operate in blocking mode, zero otherwise.
     The <code class="literal">protocol</code> field should be
     <code class="literal">PROTO_Z3950</code> or <code class="literal">PROTO_HTTP</code>.
     Protocol <code class="literal">PROTO_SR</code> is no longer supported.
    </p><pre class="synopsis">
     int cs_close(COMSTACK handle);
    </pre><p>
     Closes the connection (as elegantly as the lower layers will permit),
     and releases the resources pointed to by the
     <code class="literal">handle</code>
     parameter. The
     <code class="literal">handle</code>
     should not be referenced again after this call.
    </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
      We really need a soft disconnect, don't we?
     </p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="comstack.data.exchange"></a>3.2.�Data Exchange</h3></div></div></div><pre class="synopsis">
     int cs_put(COMSTACK handle, char *buf, int len);
    </pre><p>
     Sends
     <code class="literal">buf</code>
     down the wire. In blocking mode, this function will return only when a
     full buffer has been written, or an error has occurred. In nonblocking
     mode, it's possible that the function will be unable to send the full
     buffer at once, which will be indicated by a return value of 1. The
     function will keep track of the number of octets already written; you
     should call it repeatedly with the same values of <code class="literal">buf</code>
     and <code class="literal">len</code>, until the buffer has been transmitted.
     When a full buffer has been sent, the function will return 0 for
     success. -1 indicates an error condition (see below).
    </p><pre class="synopsis">
     int cs_get(COMSTACK handle, char **buf, int *size);
    </pre><p>
     Receives a PDU or HTTP Response from the peer. Returns the number of
     bytes read.
     In nonblocking mode, it is possible that not all of the packet can be
     read at once. In this case, the function returns 1. To simplify the
     interface, the function is
     responsible for managing the size of the buffer. It will be reallocated
     if necessary to contain large packages, and will sometimes be moved
     around internally by the subsystem when partial packages are read. Before
     calling
     <code class="function">cs_get</code>
     for the fist time, the buffer can be initialized to the null pointer,
     and the length should also be set to 0 - cs_get will perform a
     <code class="function">malloc(2)</code>
     on the buffer for you. When a full buffer has been read, the size of
     the package is returned (which will always be greater than 1). -1
     indicates an error condition.
    </p><p>
     See also the <code class="function">cs_more()</code> function below.
    </p><pre class="synopsis">
     int cs_more(COMSTACK handle);
    </pre><p>
     The <code class="function">cs_more()</code> function should be used in conjunction
     with <code class="function">cs_get</code> and
     <code class="function">select(2)</code>.
     The <code class="function">cs_get()</code> function will sometimes
     (notably in the TCP/IP mode) read more than a single protocol package
     off the network. When this happens, the extra package is stored
     by the subsystem. After calling <code class="function">cs_get()</code>, and before
     waiting for more input, You should always call
     <code class="function">cs_more()</code>
     to check if there's a full protocol package already read. If
     <code class="function">cs_more()</code>
     returns 1,
     <code class="function">cs_get()</code>
     can be used to immediately fetch the new package. For the
     mOSI
     subsystem, the function should always return 0, but if you want your
     stuff to be protocol independent, you should use it.
    </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
      The <code class="function">cs_more()</code>
      function is required because the RFC1729-method
      does not provide a way of separating individual PDUs, short of
      partially decoding the BER. Some other implementations will carefully
      nibble at the packet by calling
      <code class="function">read(2)</code>
      several times. This was felt to be too inefficient (or at least
      clumsy) - hence the call for this extra function.
     </p></div><pre class="synopsis">
     int cs_look(COMSTACK handle);
    </pre><p>
     This function is useful when you're operating in nonblocking
     mode. Call it when
     <code class="function">select(2)</code>
     tells you there's something happening on the line. It returns one of
     the following values:
    </p><div class="variablelist"><dl><dt><span class="term">CS_NONE</span></dt><dd><p>
	No event is pending. The data found on the line was not a
        complete package.
       </p></dd><dt><span class="term">CS_CONNECT</span></dt><dd><p>
	A response to your connect request has been received. Call
	<code class="function">cs_rcvconnect</code>
	to process the event and to finalize the connection establishment.
       </p></dd><dt><span class="term">CS_DISCON</span></dt><dd><p>
	The other side has closed the connection (or maybe sent a disconnect
	request - but do we care? Maybe later). Call
	<code class="function">cs_close</code> to close your end of the association
        as well.
       </p></dd><dt><span class="term">CS_LISTEN</span></dt><dd><p>
	A connect request has been received.
        Call <code class="function">cs_listen</code> to process the event.
       </p></dd><dt><span class="term">CS_DATA</span></dt><dd><p>
	There's data to be found on the line.
        Call <code class="function">cs_get</code> to get it.
       </p></dd></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
      You should be aware that even if
      <code class="function">cs_look()</code>
      tells you that there's an event event pending, the corresponding
      function may still return and tell you there was nothing to be found.
      This means that only part of a package was available for reading. The
      same event will show up again, when more data has arrived.
     </p></div><pre class="synopsis">
     int cs_fileno(COMSTACK h);
    </pre><p>
     Returns the file descriptor of the association. Use this when
     file-level operations on the endpoint are required
     (<code class="function">select(2)</code> operations, specifically).
    </p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="comstack.introduction.html">Prev</a>�</td><td width="20%" align="center"><a accesskey="u" href="comstack.html">Up</a></td><td width="40%" align="right">�<a accesskey="n" href="comstack.client.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">2.�Introduction�</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">�4.�Client Side</td></tr></table></div></body></html>