Strategies For Scaling ColdFusion

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Strategies for Scaling ColdFusion Caching
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Page Request Supply Chain
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Typical Work Breakdown
Avg. Page Response time 7 seconds
SQL Queries
CF Logic
Web Server
Internet
IE NS
5 x 30 ms 150 ms
5 x 100 ms 500 ms
5000 ms
1000 ms
50 ms
Transport
Data Access
Client Rendering
Business Logic
Presentation
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Generating Pages Faster
1. Smaller pages smaller images less whitespace
2. Faster transport over network
3. Faster CF page generation
4. Faster DB access
SQL Queries
CF Logic
Web Server
Internet
IE NS
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What is Caching?

• Temporary storage of the data from a prior
  process as possible to the next data consumer
• Cached data can be accessed programmatically
  served by network appliances/processes
• Optimized data format

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Opportunities for Caching
Business Logic
Client
Transport
Data
Middleware
Application Servers
Internet
Web Server
File System
COM
Network
RDBMS
Cold Fusion Application Server
EJB
Web Browser
Web Server
JDBC
Routers
OTHER local
MQ
OTHER remote
Request Processing
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Caching Techniques
Web Browser
Cold Fusion Application Server
RDBMS
Routers
Web Server
Java
Network
Webserver Caching xCache caches fully or
partially rendered CF pages and strips
whitespaces
DB Caching Most database systems have have
facilitates to cache frequently requested
data. Additionally, 3rd party tools like
timesten offer remote DB caching
CF Caching Stores optimized, rendered and/or
processed data.
Client cache Caches entire page on browser
Cache appliance Caches text or images
Object Caching PowerTier maintains
a transactional, distributed cache of java
memory objects. Can be configured to write back
to RDBMS or other data providers.
Cache network Akamai, Sandpiper
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Caching Checklist

• DB caching
• CF caching
• Frequently used queries
• Frequently used data structures
• Rendered HTML (components, partial pages)
• Entire pages (CFCACHE)
• Web server caching
• xCache
• Cache appliances
• Reverse proxy server
• Cache network

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Database Caching

• Most major databases allow for caching of data in
  RAM on the database server
• This will minimize the work the database server
  needs to do to process each request
• 3rd party tools such as TimesTen
  (www.timesTen.com) allows for full RDBMS
  functions to be provided in a RAM based database

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CF Cached Queries

• ColdFusion allows for commonly used queries to be
  cached in RAM
• This is done through the use of the CACHEDWITHIN
  and CACHEDAFTER parameters of the CFQUERY tag
• Using cached queries reduces the number of
  network calls, as well as reducing the load on
  the database

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Caching Data in CF Structures

• Using CF structures, it is possible to load large
  sections of data into persistent memory variables
  (server, application, session or request),
  reducing the need for network connections and
  database processing of each query

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Caching Data in CF Structures - Advantages

• Extremely fast queries. Serving data directly
  from RAM removes costly network connections and
  database processing time
• Removes points of failure from the application.
  Application can continue to run, even if the
  database server fails

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Caching Data in CF Structures - Disadvantages

• Requires significant amounts of RAM
• Difficulties are introduced when data is updated
  and must be kept consist across all machines in
  a cluster
• Requires more knowledgeable developers to query a
  database stored in structures than it does to use
  a CFQUERY tag
• Requires lengthy scripts to run as a server comes
  online to populate structures in RAM

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Page Caching Using CFCACHE

• CFCACHE allows page rendering speed to be
  increased considerably
• For pages that do not require dynamic content to
  be retrieved for each user, CFCACHE will create
  temporary files that contain the static HTML
  returned from a particular run of the ColdFusion
  page
• Can be used to specify server or client side
  caching, as well as cache timeouts
• Can only respond to URL variables

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CFCACHE

• Advantages
• Cache can be programmatically purged
• Easy to use
• Excellent for caching page data polled using
  CFHTTP

• Disadvantages
• ColdFusion still involved in processing requested
  file
• URL driven, can not customize based on form (or
  other) variables

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Caching Semi Static Pages

• Semi static pages are any pages which are
  database driven, yet identical for all users who
  view it. This can include
• Product information
• Company information
• Job listings

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Caching Semi Static Pages

• Static pages can be created from production data,
  either using home built CFFILE solution, or 3rd
  party applications such as Post Point xBuilder
  (www.xcache.Com)
• Verity collections can be used to search the
  static HTML pagse, negating the need for a SQL
  search
• Index pages can be created, which link to the
  static HTML

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Caching Semi Static Pages

• Advantages
• ColdFusion is not used in the process of
  displaying the page
• No database interaction to display the page

• Disadvantages
• Can only work for pages which are identical to
  all users
• Requires more space on hard drive

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Web Server Caching xCache

• xCache allows for full and partial page caching
• xCache works along side ColdFusion, and parses
  incoming requests before it does
• Parts of pages which should not be cached can be
  marked with ltxcacheoutputgt tags, which tells
  xCache to let CF parse that section of a page
• Pages which should not be cached can be marked
  with ltmeta namepragma no-cachegt tags
• xCache administrator can be used to set caching
  for sites, directories or pages

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xCache Advantages

• No coding changes necessary
• Easy to administer
• Dynamic ColdFusion at static HTML speeds
• Partial page caching possible.
• Compression eliminates whitespace
• No additional hardware necessary

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xCache Disadvantages

• Only works with Microsoft Internet Information
  server
• Entirely URL driven, making personalization more
  difficult
• Current release is language / browser ignorant
  (multi-lingual sites more difficult)

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Sample xCache Metrics
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Reverse Proxy Servers

• Reverse proxy servers are hardware based caching
  appliances
• Sit between Web server and clients.
• Can be set to cache static files (.Html, .jpg,
  .Gif, .Js, etc.)
• Popular commercial products include Intel
  NetStructure 1500 Cache Appliance and F5 edge
  FX cache

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Reverse Proxy Server - Advantages

• Non dynamic content can be served as static HTML
  files, removing the need for ColdFusion to touch
  the file
• Uses a separate Web server offloading the work
  needed by the Web server ColdFusion uses
• One cache server can cache files for entire
  cluster

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Reverse Proxy Servers - Disadvantages

• Hardware based caching servers are more expensive
  than software based solutions
• Can not cache partial pages
• No programmatic control of cache

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Sample Intel NetStructure 1500 Cache Appliance
Metrics
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Adding A Reverse Proxy Server
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Caching Networks

• A recent trend in application architecture has
  been to distribute application caches
• Allows for users to download pages and graphics
  from the server geographically closest
• Reduces internet latency
• Removes points of failure

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Caching Networks Suppliers

• Akamai (www.akamai.com) offers distributed
  caching services
• F5 (www.f5.com) sells 3-DNS and EDGE-FX
  controllers, allowing users to build their own
  caching network
• Cisco (www.cisco.com) sells DistributedDirector,
  which allows customers to optimize server load by
  distributing the load across disparate networks

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Conclusion

• Caching can help performance of all of the
  slowest aspects of any application
• Planning caching early can help save time and
  money in scaling applications
• Effective caching helps existing hardware handle
  more requests, helping to save the costs of
  additional servers
• With effective caching, any application can be
  scaled to handle extreme traffic