pvWay.OracleLogWriter.Fw 1.0.1

Oracle Log Writer for .Net Framwork by pvWay

This nuGet exposes two log writer methods (one sync and one async) for persisting rich log rows into an Oracle database. This can be used in conjunction with the pvWay.MethodResultWrapper.Core nuGet package for enabling this package to persist logs into an Oracle Database

Singleton

This class is implemented as a Singleton because at instantiation it checks that all conditions are met by quering the DDL from the DB. It then stores the max lenght of each column so that further insertions can be truncated if necessary

Pre-conditions for this service to work properly

The connection string provided should allow inserting rows into a table that should conform to the following DDL.

Log table definition example

    CREATE TABLE LOG_ENTRY (
	    LOG_ID			    INT             NOT NULL,   -- Oracle Identity
	    LOG_USER_ID		    VARCHAR2(36)    NULL,
        LOG_COMPANY_ID	    VARCHAR2(36)    NULL, 
	    LOG_SEVERITY_CODE	CHAR(1)         NOT NULL,   -- [D]Debug... [F] Fatal (see SeverityEnum)
	    LOG_MACHINE_NAME	VARCHAR2(50)    NOT NULL,   -- Environment.MachineName
	    LOG_TOPIC			VARCHAR2(50)    NULL,       -- enables to group log items for a given Topic
	    LOG_CONTEXT		    VARCHAR2(512)   NOT NULL,   -- concats membername, filepath, line number...
	    LOG_MESSAGE		    VARCHAR2(4000)  NOT NULL,   -- the message
	    LOG_CREATE_DATE     TIMESTAMP(11)   NOT NULL,   -- timestamp in universal central time
    );
    

Columns

Id

The Id column is not required and will not be populted by the service. However it might be convenient to have a numeric primary column sorted DESC so that the last logs will be at the top of a select statement by default. If you define this column make sure the database will fill it accordingly by for example using the IDENTITY paradigm

UserId

• You can provide your own column name for this column
• The UserId column persists the identification of the connected user if any
• This column should be nullable
• This column should be of type varchar
• The logger will truncate any info exceding the max column length

CompanyId

• You can provide your own column name for this column
• The CompanyId column persists the identification of the company of the connected user if any
• This column should be nullable
• This column should be of type varchar
• The logger will truncate any info exceding the max column length

SeverityCode

• You can provide your own column name for this column
• The SeverityCode column persists the MethodResultWrapper.SeverityEnum code
• This column should be non nullable
• This column should be of type char (one char is enough)

   // Exemple of Sevirity enum and corresponding codes
   // -------------------------------------
   public enum SeverityEnum
    {
        Ok, // "O"
        Debug, // "D"
        Info, // "I"
        Warning, // "W"
        Error, // "E"
        Fatal, // "F"
    }

MachineName

This column is certainly usefull in web farms

• You can provide your own column name for this column
• The MachineName column persists Environment.MachineName
• This column should be non nullable
• This column should be of type varchar
• The logger will truncate any info exceding the max column length

Topic

This column lets you group logs for a given topic

• You can provide your own column name for this column
• This column should be nullable
• This column should be of type varchar
• The logger will truncate any info exceding the max column length

Context

Where did it happened

• You can provide your own column name for this column
• The Context column persists method name, filepath and code line number.
• This column should be non nullable.
• This column should be of type varchar
• The logger will truncate any info exceding the max column length

Message

What happened

• You can provide your own column name for this column
• The Message column persists the message info
• This column should be non nullable.
• This column should be of type varchar
• The logger will truncate any info exceding the max column length

CreateDate

When does it happened

• You can provide your own column name for this column
• The Message column persists the UTC date.
• This column should be non nullable.
• This column should be of type datetime

Usage

using pvWay.MethodResultWrapper.Model;
using pvWay.OracleLogWriter.Fw;

namespace OracleLogWriterLab.Fw
{
    internal static class Program
    {
        private static void Main(/*string[] args*/)
        {
            const string cs = "YOUR CONNECTION STRING";

            // let's start by creating the LogWriter
            // using all default values for table and columns names
            var oracleLogWriter = OracleLogWriterSingleton.GetInstance(cs);

            // let's now instantiate the PersistenceLogger class
            // from the pvWay.MethodResultWrapper.Core nuGet
            // The constructor for this class needs 3 params
            // (1) the dispose method of the logWriter
            // (2) a tuple delegate with named params for the WriteLog method
            // (3) a tuple delegate with named params for the WriteLogAsync method

            var persistenceLogger = new PersistenceLogger(
                oracleLogWriter.Dispose,
                p => oracleLogWriter.WriteLog(
                    p.userId, p.companyId, p.topic,
                    p.severityCode, p.machineName,
                    p.memberName, p.filePath, p.lineNumber,
                    p.message, p.dateUtc),
                async p => await oracleLogWriter.WriteLogAsync(
                    p.userId, p.companyId, p.topic,
                    p.severityCode, p.machineName,
                    p.memberName, p.filePath, p.lineNumber,
                    p.message, p.dateUtc));

            // set some values for userId, companyId, and topic
            // so that the log columns will have some data
            persistenceLogger.SetUser("UserId", "CompanyId");
            persistenceLogger.SetTopic("Topic");

            // fire the pvWay.MethodResultWrapper PersistenceLogger.Log method
            // that will under the cover call the (sync) delegate
            // msSqlLogWriter.WriteLog method passed in the constructor
            // with the appropriate parameters
            persistenceLogger.Log("Hello Log");

            // this last line of code will generate an entry in the oracle Log table
        }
    }
}

Happy coding