created multi-page wsgi-based web application

bookapp.py

@@ -1,23 +1,75 @@
 import re
+import traceback
 
 from bookdb import BookDB
 
 DB = BookDB()
 
 
 def book(book_id):
-    return "<h1>a book with id %s</h1>" % book_id
+    page = """
+<h1>{title}</h1>
+<table>
+    <tr><th>Author</th><td>{author}</td></tr>
+    <tr><th>Publisher</th><td>{publisher}</td></tr>
+    <tr><th>ISBN</th><td>{isbn}</td></tr>
+</table>
+<a href="/">Back to the list</a>
+"""
+    book = DB.title_info(book_id)
+    if book is None:
+        raise NameError
+    return page.format(**book)
 
 
 def books():
-    return "<h1>a list of books</h1>"
+    all_books = DB.titles()
+    body = ['<h1>My Bookshelf</h1>', '<ul>']
+    item_template = '<li><a href="/book/{id}">{title}</a></li>'
+    for book in all_books:
+        body.append(item_template.format(**book))
+    body.append('</ul>')
+    return '\n'.join(body)
+
+
+def resolve_path(path):
+    funcs = {
+        '': books,
+        'book': book,
+    }
+    path = path.strip('/').split('/')
+    func_name = path[0]
+    args = path[1:]
+
+    try:
+        func = funcs[func_name]
+    except KeyError:
+        raise NameError
+
+    return func, args
 
 
 def application(environ, start_response):
     status = "200 OK"
     headers = [('Content-type', 'text/html')]
-    start_response(status, headers)
-    return ["<h1>No Progress Yet</h1>".encode('utf8')]
+    try:
+        path = environ.get('PATH_INFO', None)
+        if path is None:
+            raise NameError
+        func, args = resolve_path(path)
+        body = func(*args)
+        status = "200 OK"
+    except NameError:
+        status = "404 Not Found"
+        body = "<h1>Not Found</h1>"
+    except Exception:
+        status = "500 Internal Server Error"
+        body = "<h1>Internal Server Error</h1>"
+        print(traceback.format_exc())
+    finally:
+        headers.append(('Content-length', str(len(body))))
+        start_response(status, headers)
+        return [body.encode('utf8')]
 
 
 if __name__ == '__main__':

wsgi_1.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 import datetime
+import os
 
 default = "No Value Set"
 
@@ -21,11 +22,11 @@ def application(environ, start_response):
 
     response_body = body.format(
         software=environ.get('SERVER_SOFTWARE', default),
-        path="aaaa",
-        month="bbbb",
-        date="cccc",
-        year="dddd",
-        client_ip="eeee"
+        path=environ.get('PATH_INFO', default),
+        month=datetime.datetime.now().strftime('%B'),
+        date=datetime.datetime.now().day,
+        year=datetime.datetime.now().year,
+        client_ip=environ.get('REMOTE_ADDR', default)
     )
     status = '200 OK'