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+ Version : $Revision: 1.5 $
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<titlepage>
<title>Gnucomo - Computer Monitoring</title>
<subtitle>Design description</subtitle>
-<!--
<para><picture src='logo.png' eps='logo' scale='0.7'/></para>
--->
<author>Arjen Baart <code><arjen@andromeda.nl></code></author>
<author>Brenno de Winter<code><brenno@dewinter.com></code></author>
- <date>December 17, 2002</date>
+ <author>Peter Roozemaal<code><mathfox@xs4all.nl></code></author>
+ <date>August 06, 2003</date>
<docinfo>
- <infoitem label="Version">0.2</infoitem>
+ <infoitem label="Version">0.5</infoitem>
<infoitem label="Organization">Andromeda Technology & Automation</infoitem>
<infoitem label="Organization">De Winter Information Solutions</infoitem>
</docinfo>
</para>
<para>
+At the left of the diagram, information is aquired from the monitored system.
+Several agents can be used to obtain information from this system, in
+active or passive ways.
+A passive agent uses information which is available on the system anyway,
+such as log files or other lists.
+An active agent, requests explicit data from the monitored system.
+One example of a passive agent is <emph>logrunner</emph>, a program which
+monitores system log files and sends regular updates to the <strong>gnucomo</strong>
+server.
+The agents on the monitored system send the data to some kind of transportation channel.
+This can be any form of transport, such as Email, SOAP, plain file copying or
+some special network connection.
+If desired, the transportation may provide security.
+Once arrived at the server, the information from monitored systems is captured
+by the <emph>gcm_input</emph> process.
+This process can obtain the data through many forms of transport and from
+a number of input formats.
+<emph>Gcm_input</emph> will try to recognize as much as possible from an
+input message and store the obtained information into the <emph>Raw Storage</emph>
+database.
+The <emph>Raw Storage</emph> data is processed further and analyzed by
+the <emph>gcm_daemon</emph>, which scans the data, gathers statistics and
+stores its results into the <emph>Derived Storage</emph> database where
+it is available for human review and further analysis.
+</para>
+
+<para>
Architectural items to consider:
<itemize>
<item>Active and passive data acquisition</item>
</para>
<para>
-Other methods provide access to the database.
+Other methods provide access to the database in a low-level manner.
There will be lots more in the future, but here are a few to begin with:
<itemize>
-<item>Find the objectid of a host, given its hostname</item>
-<item>Insert a log record into the log table</item>
+<item>Send a SQL query to the database.</item>
+<item>Read a tuple from a result set.</item>
+<item>Obtain the userid for the current database session.</item>
</itemize>
</para>
+
+<para>
+The information stored in the database as tuples is represented by classes in
+other programming languages such as C++ of PHP.
+Each class models a particular type of tuple (an <emph>entity</emph>)
+in the database.
+Such classes maintain the relation with the database on one end,
+while providing methods that are specific to the entity on the other end.
+All database communication and SQL queries are hidden inside the
+entity's class.
+This includes, for example, handling database result sets and access control.
+</para>
+<para>
+Properties and operations that are common to all classes that represent
+entities in the database are caught in a common base class.
+The base class, named <emph>database_entity</emph> provides default
+implementations for loading and storing tuples, construction and destruction
+and iteration.
+Most derived classes will override these functions.
+Two examples of classes that represent entities in the database
+are <emph>object</emph> and <emph>service</emph>.
+Both are derived from a <emph>database_entity</emph>, as show below:
+<para>
+ <picture src='class-database_entity.png' eps='class-database_entity'/>
+</para>
+</para>
+
+<para>
+Constructors of classes derived from <emph>database_entity</emph> come in
+two variaties: with or without database interaction.
+Constructors that do not interact with the database have only one argument:
+a reference to the <emph>gnucomo_database</emph> object which handles
+the low-level interaction with the database server.
+The example below shows a few of these constructors:
+<verbatim>
+
+ database_entity::database_entity(gnucomo_database &gdb)
+
+ object::object(gnucomo_database &gdb)
+
+ service::service(gnucomo_database &gdb)
+
+</verbatim>
+The objective of this type of constructor is to cerate a fresh tuple and
+store it in the database later on.
+All these constructors do is establish the connection to the database
+server and fill in the defaults for the fields in the tuple.
+A destructor will put the actual tuple into the database if any
+information in the object has changed.
+This mey be by sending an INSERT if the object is completely fresh
+or an UPDATE if an already existing tuple was changed.
+The state information about the freshness of an object is a property
+common to all database entities and is therefore maintained in
+the <emph>database_entity</emph> class.
+</para>
+<para>
+Constructors that do interact with the database accept additional
+arguments after the initial <emph>gnucomo_database</emph> reference.
+These extra arguments are used to retreive a tuple from the database.
+Examples of such constructors are:
+<verbatim>
+
+ object::object(gnucomo_database &gdb, String hostname)
+
+ object::object(gnucomo_database &gdb, long long oid)
+
+ service::service(gnucomo_database &gdb, String name)
+
+</verbatim>
+The set of arguments must of course correspond to a set of fields that
+uniquely identify the tuple.
+The primary key of the database table would be ideally suitable.
+If the tuple is not found in the database, data members of the object
+are set to default values and the object is marked as being fresh and
+not changed.
+</para>
+
+<para>
+Methods with the same name as a field in a tuple read or change the
+value of that field.
+Without an argument, such a method returns the current value of the field.
+With a single argument, the field is set to the new value passed in the
+argument and the method returns the original value.
+Whenever a field is set to a new value, the object is marked as being
+'changed'.
+A destructor will then save the tuple to the database.
+</para>
</section>
<section>
the system-wide value.
</para>
<para>
-At the moment, the gnucomo configuration has one section, holding
-four parameters which define how to access the gnucomo database:
+The following sections and parameters are defined for the Gnucomo
+configuration:
<itemize>
-<item>type</item>
-<item>name</item>
-<item>user</item>
-<item>password</item>
+<item>database
+ <itemize>
+ <item>type</item>
+ <item>name</item>
+ <item>user</item>
+ <item>password</item>
+ <item>host</item>
+ <item>port</item>
+ </itemize>
+</item>
+<item>logging
+ <itemize>
+ <item>method</item>
+ <item>destination</item>
+ <item>level</item>
+ </itemize>
+</item>
+<item>gcm_input
+ <itemize>
+ <item>dbuser</item>
+ <item>password</item>
+ </itemize>
+</item>
+<item>gcm_daemon
+ <itemize>
+ <item>dbuser</item>
+ <item>password</item>
+ </itemize>
+</item>
</itemize>
-The <emph>type</emph> parameter must have the content <code>PostgreSQL</code>.
+The <emph>database</emph> section defines how the database is accessed.
+The <emph>database/type</emph> parameter must have the content <code>PostgreSQL</code>.
Other database systems are not supported yet.
+The <emph>database/user</emph> and <emph>database/password</emph> provide default
+login information onto the database server.
+Specific user names and passwords may be specified for separate applications, such
+as <emph>gcm_input</emph> and <emph>gcm_daemon</emph>.
</para>
<subsection>
Here are a few examples:
<itemize>
-<item>Copied directly from a local client's file system.</item>
+<item>Obtained directly from a local client's file system.</item>
+<item>From the output of another process, through standard input.</item>
<item>Copied remotely from a client's file system, e.g. using
-<code>ftp</code>, <code>rcp</code> or <code>scp</code>.</item>
+ <code>ftp</code>, <code>rcp</code> or <code>scp</code>.
+ This is usually handled through spooled files.
+</item>
<item>Through an email.</item>
+<item>As a SOAP web service, carried through HTTP or SMTP.</item>
+<item>Through a TCP connection on a special socket.</item>
</itemize>
On top of that, any message may be encrypted, for example with PGP or GnuPG.
</para>
<para>
The primary function of <strong>gcm_input</strong> is to store lines from a client's
-log files into the <emph>log</emph> table.
+log files into the <emph>log</emph> table or scan a report from a probe and update
+the <emph>parameter</emph> table.
To do this, we need certain information about the client message that is usually not
in the content of a log file.
This information includes:
Sometimes, this information is available from the message itself, as in an email header.
On other occasions, the information needs to be supplied externally,
e.g. by using command line options.
+In any case, this type of 'header' information is relevant to the message
+as a whole.
+As a result, <emph>gcm_input</emph> can accept one and only one message at a time.
+For example, it is not possible to connect the standard output of
+<emph>logrunner</emph> to the standard input of <emph>gcm_input</emph> and have
+a continuous stream of messages from different log sources.
+Each message should be fed to <emph>gcm_input</emph> separately.
+Also when <emph>logrunner</emph> uses a special socket to send logging data,
+a new connection must be created for each message.
+The dataflow diagram below shows how a message travels from the input source
+to the database.
+</para>
+
+<para>
+ <picture src='gcm_input-dataflow.png' eps='gcm_input-dataflow'/>
+</para>
+
+<para>
+Internally, <emph>gcm_input</emph> handles <ref to='XML_input'>XML input</ref>
+and each input item must have its data fields split into appropriate XML elements.
+when data is offered in some other form, this data must be filtered
+and transformed into XML before <emph>gcm_input</emph> can handle it.
+Two levels of transformation are possible.
+At the highest level, the whole message is transformed into an XML
+document with a <code><message></code> root element and the
+appropriate <code><header></code> and <code><data></code>
+elements, all of which are put in the proper namespace.
+At the lowest level, each line of the message's data can be transformed
+into a <code><cooked> <log></code> element.
+Two classes of replaceable filter objects take care of these transformations.
+Depending on the content of the message and/or command line options to
+<emph>gcm_input</emph>, and appropriate filter object is inserted into
+the data stream.
+</para>
+
+<para>
+The <ref to='line_cooker'><emph>line_cooker</emph></ref>
+operates on a node in the DOM tree which is
+supposed to be a <raw> <log> element that contains one line
+from a log file.
+The <emph>line_cooker</emph> transforms a <emph>raw</emph> log line into
+its constituent parts that make up en <cooked> element.
+Since each type of logfile uses a different layout and syntax,
+different line cookers can be used, depending on the type of log.
+This type is indicated by the <messagetype> element in the header
+part of the message.
+Clearly, the <emph>line_cooker</emph> is a polymorphic entity.
+Exactly which <emph>line_cooker</emph> is used is determined through
+<ref to='classifying'>classifying</ref>
+the content of the message or the message type indicated in the header.
+The <emph>line_cooker</emph> base class provides a default implementation
+for most methods, while derived classes provide the actual cooking.
+</para>
+
+<para>
+Ouput created by <emph>gcm_input</emph> for logging and debugging purposes
+can be sent to one of several destinations:
+<itemize>
+<item>standard error.</item>
+<item>a log file.</item>
+<item>the system log.</item>
+<item>an email address.</item>
+</itemize>
+The actual destination is stated in the <strong>gnucomo</strong>
+configuration file. The default is stderr.
+A <emph>log</emph> object filters output according to the debug level.
</para>
+
+<subsection>
+<heading><label name='classifying'/>Classifying messages</heading>
+
<para>
Apart from determining information about the client's message, the content
of the message needs to be analyzed in order to handle it properly.
<itemize>
<item>System log file</item>
<item>Apache log file</item>
-<item>Report from a Gnucomo agent</item>
+<item>Report from a Gnucomo agent or other probe, for example "rpm -qa"
+ or "df -k".</item>
+<item>Generic XML input</item>
<item>Something else...</item>
</itemize>
+Basically, <strong>gcm_input</strong> acceepts two kinds of input: Log lines
+and parameter reprots.
The message is analyzed to obtain information about what the message entails
and where it came from.
+The message classification embodies the way in which a message must be
+handled and in what way information from the message can be put into
+the database.
+Aspects for handling the message are for example:
+<itemize>
+<item>Strip lines at the beginning or end.</item>
+<item>Store each line separately or store the message as a whole.</item>
+<item>How to extract hostname, arrival time and service from the message.</item>
+<item>How to break up the message into individual fields for a <emph>log</emph> record.</item>
+</itemize>
+These aspects are all handled in polymorphic <emph>message_filter</emph>
+and <emph>line_cooker</emph> classes.
+The result of classifying a message is the selection of the proper
+objects derived from these classes from a collection of such objects.
+</para>
+
+<para>
The <strong>classify()</strong> method tries to extract that information.
Sometimes, this information can not be determined with absolute 100% certainty.
The certainty expresses how sure we are about the contents in the message.
Decrypting is possible only if someone or something provides a secret key.
<verbatim>
+<?xml version='1.0'?>
+</verbatim>
+
+The XML header declares the message to be generic XML input.
+The structure of the XML message that <strong>gcm_input</strong> accepts
+is described in the next section.
+
+<verbatim>
Sep 1 04:20:00 kithira kernel: solo1: unloading
</verbatim>
Similar matches can be used to find Apache log lines or output from the <emph>dump</emph>
backup program or anything else.
</para>
+</subsection>
+
+<subsection>
+<heading><label name='XML_input'/>Generic XML input</heading>
<para>
-The message classification embodies the way in which a message must be
-handled and in what way information from the message can be put into
-the database.
-Aspects for handling the message are for example:
+
+Since <strong>gcm_input</strong> can not understand every conceivable form
+of input, a client can offer its input in a more generic form which reflects
+the structure of the Gnucomo database.
+In this case, the input is structured in an XML document that contains the input
+data in a form that allows <strong>gcm_input</strong> to store the information
+into the database without knowing the nature of the input.
+The XML root element for <strong>gcm_input</strong> is a <emph><message></emph>, defined
+in the namespace with namespace name <code>http://gnucomo.org/transport/</code>.
+All other elements and attributes of the <emph><message></emph> must be defined
+within this namespace.
+</para>
+<para>
+Within the <emph><message></emph> element there is a <emph><header></emph>
+and a <emph><data></emph> element.
+The <emph><data></emph> element may contain the logdata in an externally
+specified format.
+The <emph><header></emph> element contains a number of elements (fields), some
+mandatory, some optional. The text of the element contains the value of
+the element.
+The following elements have been defined:
+
<itemize>
-<item>Strip lines at the beginning or end.</item>
-<item>Store each line separately or store the message as a whole.</item>
-<item>How to extract hostname, arrival time and service from the message.</item>
-<item>How to break up the message into individual fields for a <emph>log</emph> record.</item>
+<item>
+<emph><mesagetype></emph> mandatory
+ <para>
+ The type (format) of the logdata in the data element. The message type
+ determines the way in which raw log elements are parsed and split up
+ into separate fields for insertion into the database.
+ The message types gcm_input understands are:
+ <itemize>
+ <item><code>system log</code> : The most common form of UNIX system logs.
+ Also used in most Linux distributions.
+ </item>
+ <item><code>IRIX system log</code> : Variation of system log, used by SGI.
+ </item>
+ <item><code>apache access log</code> : Access log of the Apache http daemon,
+ in default form.
+ </item>
+ <item><code>apache error log</code> : Error log of the Apache http daemon,
+ in default form.
+ </item>
+ </itemize>
+ There mnust also be a 'generic' system log in case all elements are
+ cooked already.
+ </para>
+</item>
+<item>
+<emph><hostname></emph> mandatory
+ <para>
+ The name of the system that generated the data in the data block.
+ This can be different from the computer composing the message.
+ </para>
+</item>
+<item>
+<emph><service></emph> optional
+ <para>
+ The (default) value of the service running on the host that
+ generated the message data. For logfiles that don't contain the
+ service name embedded in them.
+ </para>
+</item>
+<item>
+<emph><time></emph> optional
+ <para>
+ The best approximation to the time that the data was generated.
+ For (log)data that doesn't contain an embedded datestamp.
+ </para>
+</item>
+</itemize>
+
+The following example shows an XML message for <strong>gcm_input</strong>
+with a filled-in header and an empty <emph><data></emph> element:
+
+<verbatim>
+ <gcmt:message xmlns:gcmt='http://gnucomo.org/transport/'>
+ <gcmt:header>
+ <gcmt:messagetype>apache error log</gcmt:messagetype>
+ <gcmt:hostname>client.gnucomo.org</gcmt:hostname>
+ <gcmt:service>httpd</gcmt:service>
+ <gcmt:time>2003-04-17 14:40:46.312895+01:00</gcmt:time>
+ </gcmt:header>
+ <gcmt:data/>
+ </gcmt:message>
+</verbatim>
+</para>
+
+<para>
+The <emph>data</emph> element can hold one of two possible child
+elemnts: <emph><log></emph> or <emph><parameters></emph>.
+The <emph><log></emph> element may contain any number of lines from
+a system's log file, each line in a separate element.
+A single log line is the content of either a <emph><raw></emph> or
+a <emph><cooked></emph> element.
+The <emph><raw></emph> element contains the log line "as is" and nothing more.
+This is the easiest way to provide XML data for <strong>gcm_input</strong>.
+However, the log line itself must be in a form that <strong>gcm_input</strong>
+can understand.
+After all, <strong>gcm_input</strong> still needs to extract meaningfull information
+from that line, such as the timestamp and the service that created the log.
+The client can also choose to provide that information separately by encapsulating
+the log line in a <emph><cooked></emph> element.
+This element may have up to four child elements, two of which are mandatory:
+<itemize>
+<item><emph><timestamp></emph> mandatory.
+ <para>
+ The time at which the log line was generated by the client.
+ </para>
+</item>
+<item><emph><hostname></emph> optional.
+ <para>
+ For logs that include a hostname in each line. This hostname is checked
+ against the hostname in the <emph><header></emph> element.
+ </para>
+</item>
+<item><emph><service></emph> optional.
+ <para>
+ If the service that generated the log is not provided in the <emph><header></emph>
+ the service must be stated for each log line separately.
+ Othewise, each log line is assumed to be generated by the same service.
+ </para>
+</item>
+<item><emph><raw></emph> mandatory.
+ <para>
+ The content of the full log line. This would have the same content of the singular
+ <emph><raw></emph> element if the log line was not provided in a
+ <emph><cooked></emph> element.
+ </para>
+</item>
</itemize>
+The following shows an example of the log message with two lines in the
+<emph><log></emph> element, one raw and one cooked:
+
+<verbatim>
+ <gcmt:data xmlns:gcmt='http://gnucomo.org/transport/'>
+ <gcmt:log>
+ <gcmt:raw>
+ Apr 13 04:31:03 schiza kernel: attempt to access beyond end of device
+ </gcmt:raw>
+ <gcmt:cooked>
+ <gcmt:timestamp>2003-04-13 04:31:03+02:00</gcmt:timestamp>
+ <gcmt:hostname>schiza</gcmt:hostname>
+ <gcmt:service>kernel</gcmt:service>
+ <gcmt:raw>
+ Apr 13 04:31:03 schiza kernel: 03:05: rw=0, want=1061109568, limit=2522173
+ </gcmt:raw>
+ </gcmt:cooked>
+ </gcmt:log>
+ </gcmt:data>
+</verbatim>
+</para>
+
+<para>
+The <emph><parameters></emph> element contains a list of parameters
+of the same class. The class is provided as an attribute in the
+<emph><parameters></emph> open tag.
+There is a <emph><parameter></emph> element for each parameter in the list.
+The child elements of a <emph><parameter></emph> are one optional
+<emph><description></emph> element and zero or more <emph><property></emph>
+elements.
+The names of a parameter and a property are provided by the mandatory <emph>name</emph>
+attributes in the respective elements.
+The following example shows a possible parameter report from a "df -k":
+<verbatim>
+ <gcmt:data xmlns:gcmt='http://gnucomo.org/transport/'>
+ <gcmt:parameters gcmt:class='filesystem'>
+ <gcmt:parameter gcmt:name='root'>
+ <gcmt:description>Root filesystem</gcmt:description>
+ <gcmt:property gcmt:name='size'>303344</gcmt:property>
+ <gcmt:property gcmt:name='used'>104051</gcmt:property>
+ <gcmt:property gcmt:name='available'>183632</gcmt:property>
+ <gcmt:property gcmt:name='device'>/dev/hda1</gcmt:property>
+ <gcmt:property gcmt:name='mountpoint'>/</gcmt:property>
+ </gcmt:parameter>
+ <gcmt:parameter gcmt:name='usr'>
+ <gcmt:description>Usr filesystem</gcmt:description>
+ <gcmt:property gcmt:name='size'>5044188</gcmt:property>
+ <gcmt:property gcmt:name='used'>3073716</gcmt:property>
+ <gcmt:property gcmt:name='available'>1714236</gcmt:property>
+ <gcmt:property gcmt:name='device'>/dev/hdd2</gcmt:property>
+ <gcmt:property gcmt:name='mountpoint'>/usr</gcmt:property>
+ </gcmt:parameter>
+ </gcmt:parameters>
+ </gcmt:data>
+</verbatim>
</para>
+</subsection>
+
+<subsection>
+<heading>Gcm_input classes</heading>
<para>
The figure below shows the class diagram that is used for <strong>gcm_input</strong>:
<para>
</para>
The heart of the application is a <emph>client_message</emph> object.
-This object reads the message through the <emph>message_buffer</emph> from some
+This object reads the message through the
+<ref to='message_buffer'><emph>message_buffer</emph></ref> from some
input stream (file, string, stdin or socket), classifies the message and
enters information from the message into the database.
It has a relationship with a <emph>gnucomo_database</emph> object which
These are the methods for the <emph>client_message</emph> class:
<itemize>
-<item>client_message::client_message(istream *in, gnucomo_database *db)
+<item><code>client_message::client_message(istream *in, gnucomo_database *db)</code>
<para>
Constructor.
</para>
</item>
-<item>double client_message::classify(String host, date arrival_d, hour arrival_t, String serv)
+<item><code>void add_cooker(line_cooker *lc)</code>
+ <para>
+ Add another <emph>line_cooker</emph> object to the collection.
+ </para>
+</item>
+<item><code>double client_message::classify(String host, date arrival_d,
+ hour arrival_t, String serv)</code>
<para>
Try to classify the message and return the certainty with which the class of the
message could be determined.
If the hostname, arrival time and service can not be extracted from the message,
use the arguments as default.
+ This will try to select one of the <emph>line_cooker</emph> objects
+ from the collection built with the <emph>add_cooker</emph> method.
</para>
</item>
-<item>int enter()
+<item><code>int enter()</code>
<para>
Insert the message contents into the <emph>log</emph> table of the gnucomo
database.
</itemize>
</para>
+
+<subsubsection>
+<heading><label name='line_cooker'/>line_cooker</heading>
+<para>
+To turn a raw line from a log file onto separate parts that can be stored
+in the database, i.e. parse the line, the <emph>client_message</emph>
+object uses a <emph>line_cooker</emph> object.
+This is a polymorphic object, so each type of log can have its own parser,
+while the <emph>client_message</emph> object uses a common interface
+for each one.
+For each message, one specific <emph>line_cooker</emph> object is
+selected as determined by the message type.
+E.g., the derived class <emph>syslog_cooker</emph> is used for system logs.
+When the <emph>client_message</emph> object encounters a <strong>raw</strong>
+log element, it takes the following steps to turn this into a
+<strong>cooked</strong> log element:
+<enumerate>
+<item>
+ Remove the TEXT node of the "raw" element and save its content.
+</item>
+<item>
+ Change the name of the element into "cooked".
+</item>
+<item>
+ Check if the content matches the syntax of the type of log we're
+ processing at the moment.
+ This depends on the message type and is therefore a task for the
+ <emph>line_cooker</emph> object.
+</item>
+<item>
+ Have the <emph>line_cooker</emph> parse the content and extract
+ the timestamp and optionally the hostname and service.
+</item>
+<item>
+ Insert new child elements into the cooked element.
+</item>
+</enumerate>
+After that, the <emph>cooked</emph> element is ready for further processing
+and possibly storing into the database.
+</para>
+
+<para>
+The <emph>line_cooker</emph> base class holds three protected members
+that must be filled with infomation by the derived classes:
+<itemize>
+<item><code>UTC ts</code> : the timestamp.</item>
+<item><code>String hn</code> : the hostname</item>
+<item><code>String srv</code> : the service</item>
+</itemize>
+Corresponding base class methods (<emph>timestamp</emph>,
+<emph>hostname</emph> and <emph>service</emph>) will do
+nothing more than return these values.
+It is up to the derived class's <emph>cook_this</emph> method
+to properly initialize these members.
+</para>
+
+<para>
+The methods for the <emph>line_cooker</emph> class are:
+<itemize>
+<item>
+ <code>bool line_cooker::check_pattern(String logline)</code>
+ <para>
+ Tries to match the <emph>logline</emph> against that patterns
+ that describe the message syntax.
+ In the <emph>line_cooker</emph> base class, this is a pure virtual function.
+ Returns true if the log line adheres to the message-specific syntax.
+ </para>
+</item>
+<item>
+ <code>bool line_cooker::cook_this(String logline, UTC arrival)</code>
+ <para>
+ Extracts information from the <emph>logline</emph>.
+ The <emph>arrival</emph> can be used to make corrections to incomplete
+ time stamps in the log file.
+ The implementation in a derived class must properly initialize the protected
+ members described above.
+ In the <emph>line_cooker</emph> base class, this is a pure virtual function.
+ Returns false if the pattern does not match.
+ </para>
+</item>
+<item>
+ <code>String line_cooker::message_type()</code>
+ <para>
+ Return the message type for which this line cooker is intended.
+ </para>
+</item>
+<item>
+ <code>UTC line_cooker::timestamp()</code>
+ <para>
+ Returns the timestamp that was previously extracted from the log line
+ or a 'null' timestamp if that information could nnot be extracted.
+ </para>
+</item>
+<item>
+ <code>String line_cooker::hostname()</code>
+ <para>
+ Returns the hostname that was previously extracted from the log line,
+ or an empty string if that information could not be extracted.
+ </para>
+</item>
+<item>
+ <code>String line_cooker::service()</code>
+ <para>
+ Returns the service that was previously extracted from the log line,
+ or an empty string if that information could not be extracted.
+ </para>
+</item>
+</itemize>
+</para>
+</subsubsection>
+
+<subsubsection>
+<heading><label name='message_buffer'/>message_buffer</heading>
<para>
Some kind of input buffering is needed when a client message is being processed.
The contents of the message are not entirely clear until a few lines are analyzed,
<item>message_buffer::operator ++</item>
</itemize>
</para>
+
+</subsubsection>
+</subsection>
+
<subsection>
<heading>Command arguments</heading>
projects / gnucomo.git / blobdiff