Recursively scraping web pages for embedded links and files

[Ker_01]

This is a followup to a post from yesterday (Thanks to Tim Williams for
responding). I have more information now, and felt it warranted a second try
to see if there is way to do this now that we've gotten the documents
exposed via the web interface. Using XL2003 on WinXP.

We have a corporate web application that exposes various documents in
multiple levels of subdirectories. My belief is that these are stored in a
database, but now they are directly accessible via web links through this
web application, so where they come from hopefully doesn't affect what I am
trying to accomplish.

Starting from the main page of the web application, I need to scrape the
entire directory tree and capture some of the details (javascript links to
..doc and .pdf files that can be opened through IE6 via 'dedicated' URLs for
each document). I'm sure I'll have more questions once I start dissecting
the HTML, but for starters I need to understand how to even scrape multiple
levels within the directory tree of a website. I've copied in some of the
URLS (changed slightly for corporate security) to give a sense of what I'm
working with.

Top of tree:
http://ourserver.com/rtsa-bin/PermaSite.dll/aaumain.htm?site=omatcone&pagetitle=M S - L

I can click a link to go to the next level of subfolder:
http://ourserver.com/rtsa-bin/Perma...00cdb6&foldername=M+R&se=omatcone&pagetitle=M

Third level of folder:
http://ourserver.com/rtsa-bin/Perma...=EPD+100000-109999&site=omatconec&pagetitle=M

and so on.

A sample link for a single document within one of the pages in the web
tree/directory is:
javascriptpenDocument('0900043d802b3528');

where clicking that link ultimately opens:
http://ourserver.com/Documentation/03451TRs142.pdf

Ultimately I need to recreate all the links in an Excel workbook so users
can click on a hyperlink and access the relevant document. An Excel
hyperlink that uses the javascriptpendocument command is totally fine with
me, but first I need to collect them all. Alternatively I'll have to figure
out how to cycle through each javascript command anyway, then identify the
URL it opened (which sounds harder).

Any advice or code snippets greatly appreciated- I haven't done anything
with HTML at all.

Thanks,
Keith

 

[Tim Williams]

Starting from the main page you could identify all of the "folder" links by
looking at the URL: each could be clicked in order to drill down into
subfolders, and each of these listed etc etc.

Grabbing URL's to the files will be more difficult: you'll have to
deconstruct the "openDocument()" javascript code to see how it determines
what URL to open. You can't use the javascript href directly in Excel: it
depends on having the js function available.

If you're new to working with HTML docs from Excel then it may be a long
haul. I can help you with specific points but can't provide a solution. If
you prefer you can follow up via email (tim j williams at gmail dot com: no
spaces, etc.).

Tim

 

[Ker_01]

Tim- thank you again for your response. I may send some specific questions
via email, but right now my questions are general enough that responses in
the public record may help others.

I've managed to get the HTML of a target page (the top page of interest)
using the code at the bottom of this post. I have two questions;

(1) The returned object (SourceHTMLText)- what exactly is it? I tried
setting Sheet1.range("A1").text equal to it and got an error; either it
isn't text, or maybe there is some limit where I can't assign a string over
a certain size to a cell? I pushed it to a msgbox, and it did show on the
screen (although truncated, because the HTML is long for a messagebox).

(2) What is the best way to parse the content for each instance that starts
with "<A HREF= " and ends with the next ">"?
In the past, I've read flat files but I could read a line at a time and look
for what I wanted. Now I have the whole text at once, so I have to handle it
all together. Also, the text may span more than one line, which wouldn't
work with the way I used to look for short strings anyway. Should I be using
Regex? I saw some "simple" tutorials that tried to cover every aspect of
regex, but since they cover a lot more than I need to know, I found it
difficult to extract how to look for strings that have a specific start
sequence ("<A HREF="), and always terminate with the very next instance of
another (">"). Pointers to any tutorials that are relatively easy to
understand would be very helpful.

(2b) In case any referred tutorials don't include the info- if I do use
Regex, and I do expect multiple matches within the document, what is best
practice for storing those matches and using them- does Regex automatically
build an array of matches?

Many thanks,
Keith
XL2003


Sub GrabPage()

Set objHTTP = CreateObject("MSXML2.ServerXMLHTTP")
URL = "http://ourdomain/targetpage"
objHTTP.Open "GET", URL, False
objHTTP.setRequestHeader "User-Agent", "Mozilla/4.0 (compatible; MSIE
6.0; Windows NT 5.0)"
objHTTP.send ("")

SourceHTMLText = objHTTP.responseText

End Sub

 

[Ker_01]

I've gotten a little farther- the following with the regex works, but it is
only debug.printing the first match in the page. There are more target
matches in the page, so either my regex is incorrect, or how I am collecting
the matches is incorrect. Any advice or corrections welcome!
Keith

Sub GrabPage()

Set objHTTP = CreateObject("MSXML2.ServerXMLHTTP")
URL = "http://ourdomain/targetpage"
objHTTP.Open "GET", URL, False
objHTTP.setRequestHeader "User-Agent", "Mozilla/4.0 (compatible; MSIE
6.0; Windows NT 5.0)"
objHTTP.send ("")

SourceHTMLText = objHTTP.responseText

Dim re As RegExp
Set re = New RegExp
Dim s As String
re.Pattern = "^<A HREF=.*>"
re.Global = False
re.IgnoreCase = True
re.MultiLine = True
s = SourceHTMLText
Dim matches As MatchCollection
Set matches = re.Execute(s)
Dim mcmatch As Match
For Each mcmatch In matches
Debug.Print mcmatch.Value
Next


End Sub

 

[Ker_01]

I got it- I started with a snippet from the web, and it took a while to find
a definition for what "Global" does. I set it to true, and have all my
matches.

I'll start a new thread for further questions.
Thanks,
Keith