Internal Site Search Engine

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Introduction

The Search Engine module will search an entire page also dynamic pages for matching keyword(s) or a phrase and will count how many times the keyword(s) or phrase are found on the page, and display the results with the highest matches first. The module will search all files with the extensions that you can easily place the extension name into the web.config file where indicated. Files or folders that you don't want searched can be placed in the web.config where indicated, so these files and folders are not searched. Also now you can choose the encoding of your choice.

This updated article contains tips to globalize and enhance the code. .

Note: It is best suited for small sites. Also you can modify this code to crawl pages internally by using regular expressions. For larger site you will need to write to XML file once periodically and then read from XML file. I have offered tips at the end of the section to do so. I have also included a demo project that reads and writes to XML.

Background

Site Search Engine helps a user to trace the pages of his interest. When I was working on an ASP.NET project, I had to add the site search module. I had one in ASP but not in .NET. Hence the birth of this site search engine. My first version was just a single web form and I had not exploited the full features of the object oriented .NET language. In my spare time, I reworked my code to make the maximum use of the object oriented language. For this article, I further enhanced my design on the basis of the experience and the good practices suggested by different authors.

Mr. Song Tao from Beijing, China approached me with queries how to convert the module to Chinese. With his help I enhanced the code to support other languages. Also a few users encountered article errors when the SiteSearch.aspx was placed in the root. I modified the code to rectify the error.

Source Code Overview

The structure of the Site Search Engine is as follows:

Classes

The ability to define a class and create instances of classes is one of the most important capabilities of any object-oriented language. In the coming section, we see the classes that we have used in the search module.

Class Name	Description
SiteSearch	Class for the web form where the user can search the site for certain words.
Searches.CleanHtml	Class to clean the HTMl content
Searches.FileContent	Class to get the content form the HTML File
Searches.Page	Class to store data of the pages
Searches.PagesDataset	Class to create and store results in dataset
Searches.Site	Class to read the configurations of the site
Searches.UserSearch	Class to store the search information per user

SiteSearch.aspx

Web Forms are one of the new, exciting features in Microsoft's .NET initiative. SiteSearch.aspx is a web form which is also the start page for the search module.

A Web Forms page consists of a page (ASPX file) and a code behind file (.aspx.cs file or .aspx.vb file). Our web form consists of SiteSearch.aspx and SiteSearch.aspx.vb. I will be treating them simultaneously touching on the main elements of the web form.

ASP.NET is an event-driven programming environment. We will see some event handlers and methods in the coming section.

Page_Load

The server controls are loaded on the Page object and the view state information is available at this point. The Page_Load event checks if sSite is nothing and assigns the Session("Site") variable to it.

Private Sub Page_Load(ByVal sender As System.Object, _
 ByVal e As System.EventArgs) Handles MyBase.Load
  If IsNothing(sSite) Then
    sSite = Session("Site")
  End If
End Sub

srchbtn_Click

The search button event is fired when the search button is clicked. Here we put the code to change control settings or display text on the page. Here we check if the search contains text and then call the SearchSite method. DisplayContent() is called to assign values to different controls in the web page.

'*********************************************************
'
' srchbtn_Click event
'
' Add code to this event.
'
'**********************************************************
Private Sub srchbtn_Click(ByVal sender As System.Object, _
 ByVal e As System.EventArgs) Handles srchbtn.Click
  Dim strSearchWords As String
  'If there is no words entered by the user to search for
  'then don't carryout the file search routine
  pnlSearchResults.Visible = False
  strSearchWords = Trim(Request.Params("search"))

  If Not strSearchWords.Equals("") Then
    Searchs.Site.ApplicationPath = String.Format("http://{0}{1}",
     Request.ServerVariables("HTTP_HOST"), Request.ApplicationPath)
    sSite = SearchSite(strSearchWords)
    Session("Site") = sSite
    dgrdPages.CurrentPageIndex = 0
    DisplayContent()

  End If
End Sub

DisplayContent

DisplayContent() is called to assign values to different controls in the web page. The DataGrid content is set by calling the BindDataGrid method. ViewState("SortExpression") is used to store the sort expression.

'*********************************************************************
'
' DisplayContent method
'
' The data is bound to the respective fields.
'
'*********************************************************************
Private Sub DisplayContent()
  If Not IsNothing(sSite.PageDataset) Then
    pnlSearchResults.Visible = True
    lblSearchWords.Text = sSite.SearchWords

    If ViewState("SortExpression") Is Nothing Then
      ViewState("SortExpression") = "MatchCount Desc"
    End If

    BindDataGrid(ViewState("SortExpression"))
    lblTotalFiles.Text = sSite.TotalFilesSearched
    lblFilesFound.Text = sSite.TotalFilesFound
  End If
End Sub

Search

The main call to the search takes place in this method. UserSearch class which we will cover shortly stores the entire search information and the result of the search. UserSearch object, i.e. srchSite is created and its properties like SearchWords and SearchCriteria assigned. Also srchSite.Search method is called.

 '************************************************************
 '
 ' SearchSite method
 '
 ' The sSite.PageDataset is used to populate the datagrid.
 '
 '************************************************************
 Private Function SearchSite(ByVal strSearch_
        As String) As Searchs.UserSearch
  Dim srchSite As Searchs.UserSearch
  srchSite = New Searchs.UserSearch()
  'Read in all the search words into one variable
  srchSite.SearchWords = strSearch

  If Phrase.Checked Then
    srchSite.SearchCriteria = Searchs.SearchCriteria.Phrase
  ElseIf AllWords.Checked Then
    srchSite.SearchCriteria = Searchs.SearchCriteria.AllWords
  ElseIf AnyWords.Checked Then
    srchSite.SearchCriteria = Searchs.SearchCriteria.AnyWords
  End If

  srchSite.Search(Server.MapPath("./"))
  Return srchSite
End Function

DataGrid

The DataGrid control renders a multi-column, fully templated grid and is by far the most versatile of all data bound controls. Moreover the DataGrid control is the ASP.NET control of choice for data reporting. Hence, I have used it to display the search results. Since the focus of the article is the internal search engine, I will just give a brief overview of the features of the DataGrid used here.

Databinding

Data binding is the process of retrieving data from a source and dynamically associating it to a property of a visual element. Because a DataGrid handles (or at least has in memory) more items simultaneously, you should associate the DataGrid explicitly with a collection of data—that is, the data source.

The content of a DataGrid is set by using its DataSource property. The entire search result is stored in the sSite.PageDataset.Tables("Pages"). Hence the content of the DataGrid is set to dvwPages i.e. sSite.PageDataset.Tables("Pages").DefaultView. BindDataGrid method is called every time the page loads.

'************************************************************
'
' BindDataGrid method
'
' The sSite.PageDataset is used to populate the datagrid.
'
'************************************************************
Private Sub BindDataGrid(ByVal strSortField As String)
   Dim dvwPages As DataView
   dvwPages = sSite.PageDataset.Tables("Pages").DefaultView
   dvwPages.Sort = strSortField
   dgrdPages.DataSource = dvwPages
   dgrdPages.DataBind()
End Sub

The control has the ability to automatically generate columns that are based on the structure of the data source. Auto-generation is the default behavior of DataGrid, but you can manipulate that behavior by using a Boolean property named AutoGenerateColumns. Set the property to False when you want the control to display only the columns you explicitly add to the Columns collection. Set it to True (the default) when you want the control to add as many columns as is required by the data source. Auto-generation does not let you specify the header text, nor does it provide text formatting. Hence, here I have set it to False. You typically bind columns using the <columns> tag in the body of the <asp:datagrid> server control.

 <Columns>
 <asp:TemplateColumn>
  <ItemTemplate>
   <%# DisplayTitle(Container.DataItem( "Title" ), _
        Container.DataItem( "Path" )) %>
   <br>
   <%# Container.DataItem( "Description" ) %>
   <br>
   <span class="Path">
    <%# String.Format("{0} - {1}kb", DisplayPath( _
         Container.DataItem( "Path" )) , _
         Container.DataItem( "Size" ))%>
   </span>
   <br>
   <br>
  </ItemTemplate>
 </asp:TemplateColumn>
</Columns>

DisplayTitle method and DisplayPath method are used to display customized information to the columns in the DataGrid.

'****************************************
'
' DisplayTitle method
'
' Display title of searched pages
'
'****************************************
Protected Function DisplayTitle(ByVal Title _
    As String, ByVal Path As String) As String
   Return String.Format("<A href="{1}">{0}</A>", Title, Path)
End Function

'****************************************
'
' DisplayPath method
'
' Path of the file is returned
'
'****************************************
Protected Function DisplayPath(ByVal Path As String) As String
   Return String.Format("{0}{1}/{2}", _
    Request.ServerVariables("HTTP_HOST"), _
    Request.ApplicationPath, Path)
End Function

Pagination

Unlike the DataList control, the DataGrid control supports data pagination, that is, the ability to divide the displayed data source rows into pages. The size of our data source easily exceeds the page real estate. So to preserve scalability on the server and to provide a more accessible page to the user, you display only a few rows at a time. To enable pagination of the DataGrid control, you need to tell the control about it. You do this through the AllowPaging property.

The pager bar is an interesting and complimentary feature offered by the DataGrid control to let users easily move from page to page. The pager bar is a row displayed at the bottom of the DataGrid control that contains links to available pages. When you click any of these links, the control automatically fires the PageIndexChanged event and updates the page index accordingly. dgrdPages_PageIndexChanged is called when the page index changes.

'*****************************************************************
'
' dgrdPages_PageIndexChanged event
'
' The CurrentPageIndex is Assigned the page index value.
' The datagrid is then populated using the BindDataGrid function.
'
'*****************************************************************
Protected Sub dgrdPages_PageIndexChanged(ByVal s As Object, _
  ByVal e As DataGridPageChangedEventArgs) _
  Handles dgrdPages.PageIndexChanged
dgrdPages.CurrentPageIndex = e.NewPageIndex
DisplayContent()
End Sub

You control the pager bar by using the PagerStyle property’s Mode attribute. Values for the Mode attribute come from the PagerMode enumeration. Here we have chosen a detailed series of numeric buttons, each of which points to a particular page.

<PagerStyle CssClass="GridPager" Mode="NumericPages"></PagerStyle>

Sorting

The DataGrid control does not actually sort rows, but it provides good support for sorting as long as the sorting capabilities of the underlying data source are adequate. The data source is always responsible for returning a sorted set of records based on the sort expression selected by the user through the DataGrid control’s user interface. The built-in sorting mechanism is triggered by setting the AllowSorting property to True.

dgrdPages_SortCommand is called to sort the DataGrid. The SortCommand event handler knows about the sort expression through the SortExpression property, which is provided by the DataGridSortCommandEventArgs class. In our code, the sort information is persisted because it is stored in a slot in the page’s ViewState collection.

Note: In my pages, I have disabled the header but if the header is shown, you can use it to sort the DataGrid.

'*****************************************************************
'
' dgrdAdditionalItems_SortCommand event
'
' The ViewState( "SortExpression" ) is Assigned
' the sort expression value.
' The datagrid is then populated using the BindDataGrid function.
'
'*****************************************************************
Protected Sub dgrdPages_SortCommand(ByVal s As Object, _
    ByVal e As DataGridSortCommandEventArgs) _
    Handles dgrdPages.SortCommand
   ViewState("SortExpression") = e.SortExpression
   DisplayContent()
End Sub

Page.vb

The role of the Page object is to store the data related to each page of the site.

The Page class defines the following properties

Path	Stores the path of the file
Title	Stores the text in HTML title tag
Keywords	Stores the text in HTML meta keywords tags
Description	Stores the text in HTML meta description tags
Contents	Stores the text in HTML page
Matchcount	Stores the matches found in HTML page

'***************************************************
'
' Size Property
'
' Assign and retrieve size of the file
'
'***********************************************

Public Property Size() As Decimal
  Get
    Return m_size
  End Get
  Set(ByVal Value As Decimal)
    m_size = Value
  End Set
End Property

'***************************************************
'
' Path Property
'
' Assign and retrieve path of the file
'
'***********************************************

Public Property Path() As String
  Get
    Return m_path
  End Get
  Set(ByVal Value As String)
    m_path = Value
  End Set
End Property

'***********************************************
'
' Title Property
'
'Assign and retrieve title of the file
'
'***********************************************
Public Property Title() As String
  Get
    Return m_title
  End Get
  Set(ByVal Value As String)
    m_title = Value
  End Set
End Property

'***********************************************
'
' Keywords Property
'
' Assign and retrieve Keywords
' (meta tags) of the file
'
'***********************************************
Public Property Keywords() As String
  Get
    Return m_keywords
  End Get
  Set(ByVal Value As String)
    m_keywords = Value
  End Set
End Property


'***********************************************
'
' Description Property
'
' Assign and retrieve description
' (meta tags) of the file
'
'***********************************************
Public Property Description() As String
  Get
    Return m_description
  End Get
  Set(ByVal Value As String)
    m_description = Value
  End Set
End Property

'***********************************************
'
' Contents Property
'
' Assign and retrieve contents of the file
'
'***********************************************
Public Property Contents() As String
  Get
    Return m_contents
  End Get
  Set(ByVal Value As String)
    m_contents = Value
  End Set
End Property


'***********************************************
'
' Contents Property
'
' Assign and retrieve MatchCount of the file
'
'***********************************************
Public Property MatchCount() As Integer
  Get
    Return m_matchcount
  End Get
  Set(ByVal Value As Integer)
    m_matchcount = Value
  End Set
End Property

The Page class has two private methods and two public methods. It defines the following methods:

CheckFileInfo Method

It is a public method which checks if title, description and content exists. If the text for title is empty then it assigns the default value "No Title". If the text for description is empty then it either assigns the contents of the file or default value "There is no description available for this page".

'*************************************************
'
' CheckFileInfo method
'
' Subroutine to the check the file contains
' title and decription
'
'*************************************************
Public Sub CheckFileInfo()

  'If the page contains no title then Page Title
  ' variable the appropriate message to display
  If IsNothing(m_title) Or m_title.Trim().Equals("") Then
   m_title = "No Title"
  End If


  'If the page contains no title then Page Description
  'variable the appropriate message to display
  If IsNothing(m_description) Or _
    m_description.Trim().Equals("") Then
   If IsNothing(m_contents) Or _
    m_contents.Trim().Equals("") Then
     m_description = _
      "There is no description available for this page"
   Else
     If m_contents.Length > 200 Then
      m_description = m_contents.Substring(0, 200)
     Else
      m_description = m_contents
     End If
   End If
  End If
End Sub

Search method

Search method is a public method which calls SearchPhrase and SearchWords methods depending on the search criteria. SearchPhrase method searches for phrases while SearchWords searches for all or any words. Both these methods calls SearchPattern metod which uses regular expressions to search the files.

'*******************************************
'
' Search method
'
' Subroutine to the search file
'
'*******************************************
Public Sub Search(ByVal strSearchWords As String, _
      ByVal SrchCriteria As SearchCriteria)

  'If the user has choosen to search by phrase
  If SrchCriteria = SearchCriteria.Phrase Then
    SearchPhrase(strSearchWords)
    'Else the search is either by all or any words
  Else
    SearchWords(strSearchWords, SrchCriteria)
  End If

End Sub

'******************************************************
'
' SearchPhrase method
'
' Subroutine to the search file
'
'******************************************************
Private Sub SearchPhrase(ByVal strSearchWords As String)

  Dim mtches As MatchCollection

  mtches = SearchPattern(strSearchWords)

  'Check to see if the phrase has been found
  If mtches.Count > 0 Then
    'Get the number of times the phrase is matched
    m_matchcount = mtches.Count
  End If
End Sub

'**************************************************
'
' SearchWords method
'
' Subroutine to the search file
'
'**************************************************
Private Sub SearchWords(ByVal strSearchWords As String, _
   ByVal SrchCriteria As SearchCriteria)
  Dim intSearchLoopCounter As Integer
  Dim sarySearchWord As String()
    'Array to hold the words to be searched for
  Dim mtches As MatchCollection

  'Split each word to be searched up and place in an array
  sarySearchWord = Split(Trim(strSearchWords), " ")

  'Loop round to search for each word to be searched
  For intSearchLoopCounter = 0 To UBound(sarySearchWord)

    'Set the pattern to search for
    mtches = SearchPattern(sarySearchWord(_
    intSearchLoopCounter))

    If SrchCriteria = SearchCriteria.AnyWords Then
      m_matchcount = m_matchcount + mtches.Count
    ElseIf SrchCriteria = SearchCriteria.AllWords Then
      'Check to see if any of the words have been found
      If mtches.Count > 0 Then
        'Get the number of times the search word is matched

        If m_matchcount = 0 Or (m_matchcount > 0 _
            And m_matchcount > mtches.Count) Then
          m_matchcount = mtches.Count
        End If
      Else
        'If the search word is not found then set the
        'search found variable back to false as one of
        'the words has not been found
        m_matchcount = 0
        Exit Sub

      End If
    End If
  Next
End Sub

The escaped character \b is a special case. In a regular expression, \b denotes a word boundary (between \w and \W characters) except within a [] character class, where \b refers to the backspace character. In a replacement pattern, \b always denotes a backspace.
We might need to drop the word boundary when your are using encoding other than UTF-8.

'****************************************************
'
' SearchPattern method
'
' Subroutine to the search file
'
'****************************************************
Private Function SearchPattern( _
   ByVal strSearchWord As String) As MatchCollection
  Dim regexp As Regex
  Dim strPattern

  'Set the pattern to search for
  regexp = New Regex("", RegexOptions.IgnoreCase)

  'Search the file for the phrase
  If Searchs.Site.Encoding.Equals("utf-8") Then
    strPattern = "\b{0}\b"
  Else
    strPattern = "{0}"
  End If

  Return regexp.Matches(m_contents, String.Format(strPattern, _
   strSearchWord), RegexOptions.IgnoreCase)

End Function

UserSearch.vb

It contains the following properties:

SearchCriteria	The user choice of search is stored and retrieved from here
SearchWords	The search words used by the user is stored and retrieved from here
TotalFilesSearched	Total Files Searched is read from here
TotalFilesFound	Total Files Searched found is read from here

'**********************************************************
'
' SearchCriteria Property
'
' Assign and retrieve SearchCriteria of the site
'
'**********************************************************
Public Property SearchCriteria() As Searchs.SearchCriteria
  Get
    Return m_searchCriteria
  End Get
  Set(ByVal Value As Searchs.SearchCriteria)
    m_searchCriteria = Value
  End Set
End Property

'**********************************************************
'
' SearchWords Property
'
'Assign and retrieve SearchWords of the site
'
'**********************************************************
Public Property SearchWords() As String
  Get
    Return m_searchWords
  End Get
  Set(ByVal Value As String)
    m_searchWords = Value
  End Set
End Property

'**********************************************************
'
' TotalFilesSearched Property
'
' Retrieve TotalFilesSearched of the site
'
'**********************************************************
Public ReadOnly Property TotalFilesSearched() As Integer
  Get
    Return m_totalFilesSearched
  End Get
End Property

'**********************************************************
'
' TotalFilesFound Property
'
' Retrieve TotalFilesFound of the site
'
'**********************************************************
Public ReadOnly Property TotalFilesFound() As Integer
  Get
    Return m_totalFilesFound
  End Get
End Property

'**********************************************************
'
' PageDataset Shared Property
'
' Retrieve data of the entire site of the site
'
'**********************************************************
Public ReadOnly Property PageDataset() As DataSet
  Get
    Return m_dstPages
  End Get
End Property

Search Method

Actual processing of the search begins here. DataSet to store the search results is created here and ProcessDirectory method is called.

'********************************************
'
' Search Method
'
' Search the entire site
'
'********************************************
Public Function Search(ByVal targetDirectory As String) As DataSet
  'If the site is in English then use the server HTML encode method
  If Searchs.Site.EnglishLanguage = True Then
    'Replace any HTML tags with the HTML codes
    'for the same characters (stops people entering HTML tags)
    m_searchWords = m_page.Server.HtmlEncode(m_searchWords)
    'If the site is not english just change the script tags
  Else
    'Just replace the script tag <> with HTML encoded < and >
    m_searchWords = Replace(m_searchWords, "<", "<", 1, -1, 1)
    m_searchWords = Replace(m_searchWords, ">", ">", 1, -1, 1)
  End If
  If m_dstPages Is Nothing Then
    m_dstPages = Searchs.PagesDataset.Create()
  End If
  ProcessDirectory(targetDirectory)
  Return m_dstPages
End Function

ProcessDirectory Method

The ProcessDirectory loops through all the files and calls the ProcessFile method. Later, it also loops through the subdirectories and calls itself.

'*********************************************
'
' ProcessDirectory Method
'
' Files in the directories are searched
'
'********************************************
Private Sub ProcessDirectory(ByVal targetDirectory As String)
  Dim fileEntries As String()
  Dim subdirectoryEntries As String()
  Dim filePath As String
  Dim subdirectory As String

  fileEntries = Directory.GetFiles(targetDirectory)

  ' Process the list of files found in the directory

  For Each filePath In fileEntries
    m_totalFilesSearched += 1
    ProcessFile(filePath)
  Next filePath

  subdirectoryEntries = Directory.GetDirectories(targetDirectory)
  ' Recurse into subdirectories of this directory

  For Each subdirectory In subdirectoryEntries

    'Check to make sure the folder about to be searched
    'is not a barred folder if it is then don't search
    If Not InStr(1, Searchs.Site.BarredFolders, _
     Path.GetFileName(subdirectory), vbTextCompare) > 0 Then
      'Call the search sub prcedure to search the web site
      ProcessDirectory(subdirectory)
    End If

  Next subdirectory

End Sub 'ProcessDirectory

ProcessFile Method

The ProcessFile calls the GetInfo which returns the Searchs.Page object which contains all the information of the particular file. Later, it checks if the matchcount is greater than 0 and calls the CheckFileInfo to clean up the information stored in the Page object. It then stores the file in the PagesDataset.

'*******************************************************
'
' ProcessFile Method
'
' Real logic for processing found files would go here.
'
'*******************************************************
Private Sub ProcessFile(ByVal FPath As String)
  Dim srchFile As Searchs.Page

  srchFile = GetInfo(FPath)
  If Not IsNothing(srchFile) Then

    srchFile.Search(m_searchWords, m_searchCriteria)
    If srchFile.MatchCount > 0 Then
      m_totalFilesFound += 1
      'Response.Write(srchFile.Contents)
      srchFile.CheckFileInfo()
      Searchs.PagesDataset.StoreFile(m_dstPages, srchFile)
    End If

  End If

End Sub 'ProcessFile

GetInfo Method

The GetInfo method's main task is to get the data of the file. It calls the shared method Searchs.FileContent.GetFileInfo where much of the work is done.

'*****************************************************************
'
' GetInfo Method
'
' File data is picked in this method
'
'*****************************************************************
Private Function GetInfo(ByVal FPath As String) As Searchs.Page

  Dim fileInform As New FileInfo(FPath)
  Dim sr As StreamReader
  Dim srchFile As New Searchs.Page()
  Dim strBldFile As New StringBuilder()
  Dim strFileURL As String 'Holds the path to the file on the site


  'Check the file extension to make sure the file
  'is of the extension type to be searched

  If InStr(1, Searchs.Site.FilesTypesToSearch, _
   fileInform.Extension, vbTextCompare) > 0 Then
    'm_page.Trace.Warn("File ext.", fileInform.Extension)
    'Check to make sure the file about to be searched
    'is not a barred file if it is don't search the file
    If Not InStr(1, Searchs.Site.BarredFiles, _
     Path.GetFileName(FPath), vbTextCompare) > 0 Then
      'm_page.Trace.Warn("File", FPath)

      If Not File.Exists(FPath) Then
        'm_page.Trace.Warn("Error", _
        'String.Format("{0} does not exist.", FPath))
        'Add throw excetion here
        '
        '
        Return Nothing
      End If

      Searchs.FileContent.GetFileInfo(FPath, srchFile)

      Return srchFile

    End If
  End If
  Return Nothing
End Function

FileContent.vb

GetFileInfo Method

Here the chunk of the data in the page is retrieved. The file content is either read from the source if the files are static using the GetStaticFileContent method. If the files are dynamic then content is retreived from server using the GetDynamicFileContent method. Title information is retrieved from the title tags, and description and keywords from meta tags by calling the GetMetaContent method. Contents of the file is stripped from the HTML page by calling Searchs.CleanHtml.Clean method.

    '**********************************************
    '
    ' GetFileInfo Method
    '
    ' File data is picked in this method
    '
    '**********************************************
    Public Shared Sub GetFileInfo(ByVal FPath As String, _ 
         ByVal srchFile As Searchs.Page)
       Dim fileInform As New FileInfo(FPath)
        Dim strBldFile As New StringBuilder()
        Dim fileSize As Decimal = fileInform.Length \ 1024
      
      srchFile.Size = fileSize
      GetFilePath(FPath, srchFile)

      If InStr(1, Searchs.Site.DynamicFilesTypesToSearch, _
        fileInform.Extension, vbTextCompare) > 0 Then
        m_page.Trace.Warn("Path", String.Format("{0}/{1}", "", _
         srchFile.Path))
        GetDynamicFileContent(srchFile)
      Else
        GetStaticFileContent(FPath, srchFile)
      End If

          If Not srchFile.Contents.Equals("") Then

    
        srchFile.Contents = sr.ReadToEnd()

        'Read in the title of the file
        srchFile.Title = GetMetaContent(srchFile.Contents,_
             "<title>", "</title>")
        'm_page.Trace.Warn("Page Title", strPageTitle)

        'Read in the description meta tag of the file
        srchFile.Description = GetMetaContent(srchFile.Contents,_
           "<meta name=""description"" content=""", ",""">")
        'm_page.Trace.Warn("Page Desc", strPageDescription)

        'Read in the keywords of the file
        srchFile.Keywords = GetMetaContent(srchFile.Contents,_
          "<meta name=""keywords"" content=""", ",""">")
        'm_page.Trace.Warn("Page Keywords", strPageKeywords)

        srchFile.Contents = _
          Searchs.CleanHtml.Clean(srchFile.Contents)

        srchFile.Contents = _
          strBldFile.AppendFormat("{0} {1} {2} {3}", _
          srchFile.Contents, srchFile.Description, _
          srchFile.Keywords, srchFile.Title).ToString.Trim()
        'm_page.Trace.Warn("File Info", strBldFile.ToString) 
        End If
              End Sub
         
     '******************************************************
    '
    ' GetStaticFileContent Method
    '
    ' File Content is picked in this method
    '
    '*******************************************************
    Private Shared Sub GetStaticFileContent(_
ByVal FPath As String, ByVal srchFile As Searchs.Page)
      Dim sr As StreamReader

      If Searchs.Site.Encoding.Equals("utf-8") Then
        sr = File.OpenText(FPath)
      Else
        sr = New StreamReader(FPath, _
Encoding.GetEncoding(Searchs.Site.Encoding))
      End If

      Try
        srchFile.Contents = sr.ReadToEnd()
        sr.Close()
      Catch ex As Exception
        m_page.Trace.Warn("Error", ex.Message)
        srchFile.Contents = ex.Message
      End Try
    End Sub

GetDynamicFileContent

GetDynamicFileContent branches into two method viz GetDynamicFileContentOther or GetDynamicFileContentUTF depending on the encoding.

'*********************************************************************
'
' GetDynamicFileContent Method
'
' File Content is picked in this method
'
'*********************************************************************
Private Shared Sub GetDynamicFileContent(ByVal srchFile As Searchs.Page)
  Dim wcMicrosoft As System.Net.WebClient

  If Searchs.Site.Encoding.Equals("utf-8") Then
    GetDynamicFileContentUTF(srchFile)
  Else
    GetDynamicFileContentOther(srchFile)
  End If

End Sub

System.Net.WebClient provides common methods for sending data to and receiving data from a resource identified by a URI. We make use of the DownloadData which downloads data from a resource and returns a byte array.

Applications that target the common language runtime use encoding to map character representations from the native character scheme (Unicode) to other schemes. Applications use decoding to map characters from nonnative schemes (non-Unicode) to the native scheme. The System.Text Namespace provides classes that allow you to encode and decode characters.

'****************************************************************
'
' GetDynamicFileContentOther Method
'
' File Content is picked in this method
' according to the encoding provided
'
'****************************************************************
Private Shared Sub GetDynamicFileContentOther( _
       ByVal srchFile As Searchs.Page)
  Dim wcMicrosoft As System.Net.WebClient
  Dim fileEncoding As System.Text.Encoding

  Try
    fileEncoding = System.Text.Encoding.GetEncoding(_
   Searchs.Site.Encoding)
    srchFile.Contents = fileEncoding.GetString( _
    wcMicrosoft.DownloadData(String.Format("{0}/{1}", _
  Searchs.Site.ApplicationPath, srchFile.Path)))
  Catch ex As System.Net.WebException
    m_page.Trace.Warn("Error", ex.Message)
    srchFile.Contents = ex.Message
  Catch ex As System.Exception
    m_page.Trace.Warn("Error", ex.Message)
    srchFile.Contents = ex.Message
  End Try

End Sub

UTF8Encoding class encodes Unicode characters using UCS Transformation Format, 8-bit form (UTF-8). This encoding supports all Unicode character values and surrogates.

'*********************************************************************
'
' GetDynamicFileContentUTF Method
'
' File Content is picked in this method according to the utf-8 encoding
'
'*********************************************************************
Private Shared Sub GetDynamicFileContentUTF( _
       ByVal srchFile As Searchs.Page)
  Dim wcMicrosoft As System.Net.WebClient
  Dim objUTF8Encoding As UTF8Encoding

  Try
    wcMicrosoft = New System.Net.WebClient()
    objUTF8Encoding = New UTF8Encoding()
    srchFile.Contents = objUTF8Encoding.GetString( _
    wcMicrosoft.DownloadData(String.Format("{0}/{1}", _
 Searchs.Site.ApplicationPath, srchFile.Path)))
  Catch ex As System.Net.WebException
    m_page.Trace.Warn("Error", ex.Message)
    srchFile.Contents = ex.Message
  Catch ex As System.Exception
    m_page.Trace.Warn("Error", ex.Message)
    srchFile.Contents = ex.Message
  End Try

End Sub

GetFilePath Method

The GetFilePath method coverts local folder path to reflect the URL of the site.

'*****************************************
'
' GetFilePath Method
'
' File path is modfied to be displayed
' as hyperlink in this method
'
'*****************************************
Private Shared Sub GetFilePath(ByVal strFileURL As String,_
            ByVal srchFile As Searchs.Page)
  'Turn the server path to the file into a URL path to the file
  strFileURL = Replace(strFileURL, m_page.Server.MapPath("./"), "")

  'Replace the NT backslash with the internet
  'forward slash in the URL to the file

  strFileURL = Replace(strFileURL, "\", "/")

  'Encode the file name and path into the URL code method

  strFileURL = m_page.Server.UrlEncode(strFileURL)

  'Just incase it's encoded any backslashes
  strFileURL = Replace(strFileURL.Trim(), _
           "%2f", "/", vbTextCompare)
  srchFile.Path = strFileURL

  m_page.Trace.Warn("Url", srchFile.Path)
End Sub

GetMetaContent Method

GetMetaContent method uses regular expressions to strip the tags and get the required information.

'************************************************
'
' GetMetaContent Method
'
' Metacontent is stripped in this method
'
'************************************************
Private Shared Function GetMetaContent(ByVal strFile As String, _
 ByVal strMetaStart As String, ByVal strMetaEnd As String) As String
  'List the text between the title tags:
  Dim regexp As Regex
  Dim strMeta As String
  Dim strPattern As String
  Dim strInPattern As String

  'If no description or keywords are found then you may be
  'using http-equiv= instead of name= in your meta tags
  If InStr(1, LCase(strFile), strMetaStart, 1) = 0 _
   And InStr(strMetaStart, "name=") Then
    'Swap name= for http-equiv=
    strMetaStart = Replace(strMetaStart, "name=", "http-equiv=")
  End If

  'Build Pattern
  strInPattern = "((.|\n)*?)"
  strPattern = String.Format("{0}{1}{2}", _
   strMetaStart, strInPattern, strMetaEnd)
  regexp = New Regex(strPattern, RegexOptions.IgnoreCase)

  'Match Pattern
  strMeta = regexp.Match(strFile).ToString

  'Build Pattern
  strInPattern = "(.*?)"
  strPattern = String.Format("{0}{1}{2}", _
   strMetaStart, strInPattern, strMetaEnd)

  'Get Pattern content
  strMeta = regexp.Replace(strMeta, strPattern,_
            "$1", RegexOptions.IgnoreCase)

  Return strMeta
End Function

PagesDataset.vb

This class is used to create and build the DataSet. It consists of two methods <codecreate>and StoreFile. Create method creates the DataSet to store the searched results and the Storefile is responsible for adding records to DataTable in the DataSet.

'*******************************************************
'
' Create Method - Shared method
'
' Creates a datset for the pages and returns the result
'
'********************************************************
Public Shared Function Create() As DataSet
  'Objects are defined
  Dim pgDataSet As New DataSet()
  Dim keys(1) As DataColumn

  'Table is created and added to table collection
  pgDataSet.Tables.Add(New DataTable("Pages"))

  'Schema of table is defined
  pgDataSet.Tables("Pages").Columns.Add("PageId", _
     System.Type.GetType("System.Int32"))
  pgDataSet.Tables("Pages").Columns.Add("Title",_
     System.Type.GetType("System.String"))
  pgDataSet.Tables("Pages").Columns.Add("Description", _
     System.Type.GetType("System.String"))
  pgDataSet.Tables("Pages").Columns.Add("Path", _
     System.Type.GetType("System.String"))
  pgDataSet.Tables("Pages").Columns.Add("MatchCount", _
     System.Type.GetType("System.Int32"))
        pgDataSet.Tables("Pages").Columns.Add("Size", _
     System.Type.GetType("System.Decimal"))

  'PageId is defined as indentity
  pgDataSet.Tables("Pages").Columns("PageID").AutoIncrement = True
  pgDataSet.Tables("Pages").Columns("PageID").AutoIncrementSeed = 1

  'PageId is defined as the primary key
  keys(0) = pgDataSet.Tables("Pages").Columns("PageId")
  pgDataSet.Tables("Pages").PrimaryKey = keys

  Return pgDataSet
End Function

'********************************************************
'
' StoreFile Method - Shared method
'
' Creates a datset for the pages and returns the result
'
'********************************************************
Public Shared Sub StoreFile(ByVal dstPgs As DataSet,_
              ByVal srchPg As Searchs.Page)
  'Objects are defined
  Dim pageRow As DataRow

  'New row is created
  pageRow = dstPgs.Tables("Pages").NewRow()

  'Data is added
  pageRow("Title") = srchPg.Title
  pageRow("Description") = srchPg.Description
  pageRow("Path") = srchPg.Path
  pageRow("MatchCount") = srchPg.MatchCount
         pageRow("Size") = srchPg.Size

  'Row is added to the dataset
  dstPgs.Tables("Pages").Rows.Add(pageRow)
End Sub

CleanHtml.vb

CleanHtml class contains a single public shared method which uses regular expressions to clean the HTML content.

'*****************************************************
'
' CleanFileContent Method
'
' Subroutine to the clean the file of html content
'
'*****************************************************
Public Shared Function Clean(ByVal Contents As String) As String
  Dim regexp As Regex
  Dim strPattern As String

  strPattern = ""
  regexp = New Regex(strPattern, RegexOptions.IgnoreCase)

  Contents = regexp.Replace(Contents, _
   "<(select|option|script|style|title)(.*?)" & _
   ">((.|\n)*?)</(SELECT|OPTION|SCRIPT|STYLE|TITLE)>",_
   " ", RegexOptions.IgnoreCase)

  Contents = regexp.Replace(Contents, "&(nbsp|quot|copy);", "")

  'Contents = regexp.Replace(Contents, "<[^>]*>", "")

  Contents = regexp.Replace(Contents, "<([\s\S])+?>",_
    " ", RegexOptions.IgnoreCase).Replace(" ", " ")

  'Contents = regexp.Replace(Contents, "<[^<>]+>",_
    " ", RegexOptions.IgnoreCase)

  'Contents = regexp.Replace("(<(\w+)[^>]*?>(.*?)</\1>", "$1")

  Contents = regexp.Replace(Contents, "\W", " ")

  'Trace.Warn("File Contents", Contents)

  Return Contents

End Function

Site.vb

Site class consists of shared properties which store the configurations of the entire site. These properties get their values from the web.config file using the ConfigurationSettings.AppSettings.

Following are the properties of the site class:

FilesTypesToSearch	Returns the files types you want to search
DynamicFilesTypesToSearch	Returns dynamic files to search
BarredFolders	Returns the barred folders
EnglishLanguage	Returns a Boolean value whether the language is English or not.
Encoding	Returns the encoding for the site
BarredFiles	Returns barred files
ApplicationPath	Assign and returns the path of the application

'*************************************************
'
' FilesTypesToSearch ReadOnly Property
'
' Retrieve FilesTypesToSearch of the site
'
'*************************************************
Public Shared ReadOnly Property FilesTypesToSearch() As String
  Get
    Return ConfigurationSettings.AppSettings(
    "FilesTypesToSearch")
  End Get
End Property

'*************************************************
'
' DynamicFilesTypesToSearch ReadOnly Property
'
' Retrieve FilesTypesToSearch of the site
'
'*************************************************
Public Shared ReadOnly Property DynamicFilesTypesToSearch() As String
  Get
    Return ConfigurationSettings.AppSettings(_
     "DynamicFilesTypesToSearch")
  End Get
End Property
'*************************************************
'
' BarredFolders ReadOnly Property
'
' Retrieve BarredFolders of the site
'
'*************************************************
Public Shared ReadOnly Property BarredFolders() As String
  Get
    Return ConfigurationSettings.AppSettings("BarredFolders")
  End Get
End Property

'*************************************************
'
' BarredFiles ReadOnly Property
'
' Retrieve BarredFiles of the site
'
'*************************************************
Public Shared ReadOnly Property BarredFiles() As String
  Get
    Return ConfigurationSettings.AppSettings("BarredFiles")
  End Get
End Property

'*************************************************
'
' EnglishLanguage Property
'
' Retrieve EnglishLanguage of the site
'
'*************************************************
Public Shared ReadOnly Property EnglishLanguage() As String
  Get
    Return ConfigurationSettings.AppSettings("EnglishLanguage")
  End Get
End Property

'*********************************************************************
'
' Encoding Property
'
' Retreive Encoding of the site
'
'*********************************************************************
Public Shared ReadOnly Property Encoding() As String
  Get
    Return ConfigurationSettings.AppSettings("Encoding")
  End Get
End Property

'**********************************************************
'
' ApplicationPath Property
'
'Assign and retrieve ApplicationPath of the site
'
'**********************************************************
Public Property ApplicationPath() As String
  Get
    Return m_ApplicationPath
  End Get
  Set(ByVal Value As String)
    m_ApplicationPath = Value
  End Set
End Property

Web.config

The ASP.NET configuration system features an extensible infrastructure that enables you to define configuration settings at the time your ASP.NET applications are first deployed, so that you can add or revise configuration settings at any time, with minimal impact on operational Web applications and servers. Multiple configuration files, all named Web.config, can appear in multiple directories on an ASP.NET Web application server. Each Web.config file applies configuration settings to its own directory and all child directories below it. As mentioned earlier, the site configurations can be assigned in the web.config file.

<appSettings>

 <!-- Place the names of the files types you want searching 
 in the following line separated by commas -->

 <add key="FilesTypesToSearch" value=".htm,.html,.asp,.shtml,.aspx" 
 /> 
    <!-- Place the names of the dynamic files types you want 
 searching in the following line separated by commas -->
     
 <add key="DynamicFilesTypesToSearch" value=".asp,.shtml,.aspx" /> 

 <!-- Place the names of the folders you don't 
 want searched in the following line separated by commas--> 

 <add key="BarredFolders" 
  value="aspnet_client,_private,_vti_cnf,_vti_log,_vti_pvt,
_vti_script,_vti_txt,cgi_bin,_bin,bin,_notes,images,scripts" 
 />

 <!-- Place the names of the files you don't want searched in the 
 following line separated by commas include the file extension--> 

 <add key="BarredFiles" 
  value="localstart.asp,iisstart.asp,AssemblyInfo.vb,
          Global.asax,Global.asax.vb,SiteSearch.aspx" 
 />

 <!-- Set this boolean to False if you are not using 
 an English language web site--> 

 <add key="EnglishLanguage" value="True" /> 

 <!-- Set this to the Encoding of the web site-->   
 <add key="Encoding" value="utf-8" />  

 </appSettings>

How to integrate

The application has been tested with the web form SiteSearch.aspx in the root directory. So my suggestion is that you do the same. Later on, you can try moving it to any subfolder. All my classes I have placed in components folder. You can move them to any folder of your choice.

Note:

1. For those users who don't have Visual Studio .Net
   1. Download from the link 'Download latest version of demo project (Visual studio.net not required)'
   2. Place the SearchDotnet.dll in the bin folder in the root.
   3. Place the SiteSearch.aspx and web.config in the root.
      
2. To use the XML version
   1. Download from the link 'Download demo project which reads and writes to XML(VB.net)'
   2. The project contains following files.
      1. AdminSearch.aspx is used to write xml to file.
      2. SiteSearch.aspx is used to search files.
      3. All my classes I have placed in components folder.

Errors

When the application is place in the root you may get the following errors. The remote server returned an error: (401) Unauthorized.

OR

The remote server returned an error: (500) Internal Server Error.

This error is caused because

1. If server returns (401) Unauthorized, the application is unable to read the file because of right access.
2. If server returns (500) Internal Server Error, the page that it was trying to read returned an error. The page that application was trying to read either has an error or requires parameters because of which it returns error
   

Follow the steps to rectify the error

1. In the Web.config ensure that the BarredFolders list is comprehensive
   aspnet_client,_private,_vti_cnf, _vti_log,_vti_pvt,_vti_script,_vti_txt, cgi_bin,_bin,bin,_notes,images,scripts
2. Ensure that the BarredFiles list is comprehensive and contains localstart.asp,iisstart.asp

Globalization

The Search Engine module can be easily globalize. For this purpose we will see how to convert it into Chinese language.

Web.config

The XML declaration must appear as the first line of the document without other content, including white space, in front of the start <.

The XML declaration in the document map consists of the following:<?xml version="1.0" encoding="Your Encoding" ?>. By default the visual studio uses the utf-8 encoding this needs to be changed to encoding that you want to use. Here we will change to gb2312. Hence the XML Declaration needs to be modified as follows.

English

<?xml version="1.0" encoding="utf-8" ?>

Chinese

<?xml version="1.0" encoding="gb2312" ?>

The requestEncoding and responseEncoding specifies the assumed encoding of each incoming request and outgoing response. The default encoding is UTF-8, specified in the <globalization> tag included in the Machine.config file created when the .NET Framework is installed. If encoding is not specified in a Machine.config or Web.config file, encoding defaults to the computer's Regional Options locale setting. We will need to change requestEncoding and responseEncoding to reflect the change in encoding.

English

<globalization requestEncoding="utf-8" responseEncoding="utf-8" />

Chinese

<globalization requestEncoding="gb2312" responseEncoding="gb2312" />

In order to avoid building the code when the encoding changes we need to add the encoding key to the appsettings.

<!-- Set this to the Encoding of the web site-->   
<add key="Encoding" value="gb2312" />  

Also change the English Language key to false.

<!-- Set this boolean to False if you are not using
an English language web site-->

<add key="EnglishLanguage" value="True" />

SiteSearch.aspx

Last but not the least, the codepage attribute has to be added in the page directive.

English

<%@ Page Language="vb" Trace="False" AutoEventWireup="false"
 Codebehind="SiteSearch.aspx.vb" 
 Inherits="SearchDotnet.SiteSearch" debug="false" %>

Chinese

<%@ Page Language="vb" Trace="False" AutoEventWireup="false" 
 Codebehind="SiteSearch.aspx.vb" Inherits="SearchDotnet.SiteSearch" 
 debug="false" codePage="936" %>

Enhancing the code

The application is meant for small sites. For bigger sites, the code can be further enhanced. Infact you will need to write to database say XML file periodically and then read from it. I will offer a few tips to do so.(I have now included a demo project that reads and writes to XML.)

(1) In my code I search and filter the data using regular expression. Instead of this you will have to write entire data (not filtered data) to XML file using the following method.

Private Shared Sub WriteXmlToFile(ByVal thisDataSet As DataSet)
   If thisDataSet Is Nothing Then
     Return
   End If

   thisDataSet.WriteXml(XMLFile)
 End Sub

(2) Later you will need to read the xml from file save it to the shared dataset say Searchs.Site.PageDataset.Tables("Pages").

Private Shared Function ReadXmlFromFile() As DataSet
  ' Create a new DataSet.
  Dim newDataSet As New DataSet("New DataSet")

  ' Read the XML document back in.
  ' Create new FileStream to read schema with.
  Dim fsReadXml As New System.IO.FileStream(XMLFile,
    System.IO.FileMode.Open)

  ' Create an XmlTextReader to read the file.
  Dim myXmlReader As New System.Xml.XmlTextReader(fsReadXml)

  ' Read the XML document into the DataSet.
  newDataSet.ReadXml(myXmlReader)

  ' Close the XmlTextReader
  myXmlReader.Close()
  Return newDataSet

End Function

(3) For each search you will later need use the Select method of PageDataset.Tables to filter it according to search results. Filter dataset might look like this. FillDataset method contains logic to create and add search results (array of DataRow) to database.

Private Sub FiterPagesDatset()
  Dim strExpr As String
  Dim foundRows As DataRow()

  Dim Field() As String = {
   "Title", "Description", "Keywords", "Contents"}

  strExpr = SomeFunction 'Your function to build the query.


  foundRows = Searchs.Site.PageDataset.Tables(
    "Pages").Select(strExpr)
  FillDataset(foundRows)
End Sub

(4) The filtered result store it into another dataset and use it to display results

Points of Interest

When I was working on the project, the question was how to display the results. DataGrid was my choice as we can exploit a lot of its features which are not present in other list controls. Once my question was solved, the next was how to pass content to the DataGrid. DataSet was the only alternative. As I worked further before storing the information in DataSet, I had to move to and fro with bulk information about the page. I decided to use site object to store the information.

One of the authors suggested the following best practices:

1. The class should be small to have approximately half a dozen methods and properties.
2. Methods be short with again approximately half a dozen lines.

After carefully analyzing the code and keeping the best practices in mind, I redesigned the code to what it is now.

History

• Modified the code to read dynamic pages.
• Enhanced the code to support globalization.
• I have also include a demo project that reads and writes to XML.