The goal is to provide context for exploring Force.com within a corporate software development organization. If any of the following sentences describe you, this chapter is intended to help.
- You have read about cloud computing or PaaS and want to learn how Force.com compares to other technologies.
- You want to get started with Force.com but need to select a suitable first project.
- You have a project in mind to build on Force.com and want to learn how your existing development skills and process can be leveraged.
This chapter consists of three sections, listed below.
- Force.com in the Cloud Computing Landscape: Learn about PaaS and Force.com's unique features as a PaaS solution.
- Inside a Force.com Project: Examine how application development with Force.com differs from other technologies in terms of project selection, technical roles, and tools.
- Sample Application: A sample business application is referenced throughout this book to provide a concrete basis for discussing technical problems and their solutions. In this chapter the sample application's requirements and use-cases are outlined, as well as a development plan, mapped to chapters of the book.
Force.com in the Cloud Computing Landscape
Phrases like "cloud computing" and "Platform as a Service" have many meanings put forth by many vendors. This section provides definitions of the terms to serve as a basis for understanding Force.com and comparing it with other products in the market. With this background, you can make the best choice for your projects, whether that is Force.com, another PaaS product, or your own in-house infrastructure.
Platform as a Service (PaaS)
The platform is infrastructure for the development of software applications. The functionality of a platform's infrastructure differs widely across platform vendors, so this section focuses on a handful of the most established vendors. The suffix "as a Service" (aaS) means that the platform exists "in the cloud," accessible to customers via the Internet. There are many variations on this acronym, including SaaS (Software as a Service), DaaS (Development as a Service), and so forth.
PaaS is a category within the umbrella of cloud computing. "Cloud computing" is a phrase to describe the movement of computing resources away from physical data centers or servers in a closet in your company and into the network, where they can be provisioned, accessed, and deprovisioned instantly. You plug a lamp into an electrical socket to use the electrons in your region's power grid. It is usually not necessary to run a diesel generator in your basement. You trust that the power company is going to provide that service, and you pay the company as you use the service.
Cloud computing as a general concept spans every conceivable configuration of infrastructure, well outside the scope of this book. The potential benefits are reduced complexity and cost versus a traditional approach. The traditional approach is to invest in infrastructure by acquiring new infrastructure assets and staff or redeploying or optimizing existing investments. Cloud computing provides an alternative.
Many companies provide PaaS products. The following subsections introduce the mainstream PaaS products and include brief descriptions of their functionality. Consult the Web sites of each company for further information.
Amazon Web Services
Amazon Web Services refers to a family of cloud computing products. The most relevant to PaaS is Elastic Compute Cloud (EC2). EC2 is a general-purpose computing platform. You can provision virtual instances of Windows or Linux machines at will, loading them with your own custom operating-system image or one prebuilt by Amazon or the community. These instances run until you shut them down, and you are billed for usage of resources such as CPU, disk, and network.
A raw machine with an OS on it is a great start, but to build a business application requires you to install, manage access to, maintain, monitor, patch and upgrade, back up, plan to scale, and generally care and feed in perpetuity an application platform on the EC2 instance. If your organization has the skills to build on .NET, J2EE, LAMP, or other application stacks, plus the OS, database administration, and IT operations experience, EC2's virtual servers in the cloud could be a strong alternative to running your own servers in-house.
Amazon provides various other products that compliment EC2. These include Simple Queue Service (SQS) for publish-and-subscribe-style integration between applications, Simple DB for managing schemaless data, and Simple Storage Service (S3), a content repository.
Microsoft Azure Services Platform
At the time of writing this book, Azure is not yet commercially available. Microsoft's entrance into the PaaS world will likely offer some unique value, particularly for companies seeking to leverage the cost savings of cloud computing but preserve their existing investments in .NET, SQL Server, SharePoint, and other Microsoft products. Azure is marketed as a blend of on-premise software and services in the cloud. It consists of two parts. The first part is Windows Azure, a new operating system that can utilize Microsoft's data centers for general computation and storage. The second part encompasses three categories of cloud services: .NET Services, SQL Services, and SharePoint Services. These services map to existing Microsoft products for computing, database, and collaboration. The intent is presumably to enable Microsoft's existing development community to pick and choose how their applications are partitioned between local and hosted resources without costly rewrites or redeployment. Pricing is not yet available, but Microsoft says it will charge for resource consumption, defined as some combination of CPU, network bandwidth, storage, and number of transactions.
Google App Engine
App Engine is a platform designed for hosting Web applications. App Engine is like having an unlimited number of EC2 instances working for you, preconfigured with a distributed data store and Python or Java-based application server, but without the IT operations effort required by EC2. App Engine includes tools for managing the data store, monitoring your site and its resource consumption, and debugging and logging.
App Engine is free for up to 500MB of storage and five million page views per month. Applications requiring more storage or bandwidth can purchase it by setting a maximum daily dollar amount they're willing to spend, divided into five buckets: CPU time, bandwidth in, bandwidth out, storage, and email.
Force.com is targeted toward corporate application developers and independent software vendors. Unlike the other PaaS offerings, it does not expose developers directly to its own infrastructure. Developers do not provision CPU time, disk, or instances of running operating systems. Instead, Force.com provides a custom application platform centered around the relational database, one resembling an application server stack you might be familiar with from working with .NET, J2EE, or LAMP.
Although it integrates with other technologies using open standards such as SOAP and REST, the programming languages and metadata representations used to build applications are proprietary to Force.com. This is unique among the PaaS products but not unreasonable when examined in depth. Force.com operates at a significantly higher level of abstraction than the other PaaS products, promising dramatically higher productivity to developers in return for their investment and trust in a single-vendor solution.
Force.com is free for developers. Production applications are priced primarily by storage used and number of unique users.
Facebook is a Web site for connecting with your friends, but it also provides developers with ways to build their own socially aware applications. These applications leverage the Facebook service to create new ways for users to interact while online. The Facebook platform is also accessible to applications not built inside Facebook, exposing the "social graph" (the network of relationships between users) where permitted.
Much of the value of Facebook as a platform stems from its large user base and consistent yet extensible user experience. It is a set of services for adding social context to applications. Unlike Force.com and App Engine, for example, Facebook has no facility to host custom applications.
Force.com as a Platform
Force.com is different from other PaaS solutions in its focus on business applications. Force.com is a part of Salesforce.com, which started as a SaaS Customer Relationship Management (CRM) vendor. But Force.com is unrelated to CRM. It provides the infrastructure commonly needed for any business application, customizable for the unique requirements of each business through a combination of code and configuration. This infrastructure is delivered to you as a service on the Internet.
Since you are reading this book, you have probably developed a few business applications in your time. Consider the features you implemented and reimplemented in multiple applications, the unglamorous plumbing, wiring, and foundation work. Some examples are security, user identity, logging, profiling, integration, data storage, transactions, workflow, and reporting. This infrastructure is essential to your applications but expensive to develop and maintain. Business application developers do not code their own relational database kernels, windowing systems, or operating systems. This is basic infrastructure, acquired from software vendors or the open-source community and then configured to meet user requirements. What if you could do the same for your application infrastructure? This is the premise of the Force.com.
The following subsections list differentiating architectural features of Force.com with brief descriptions.
Multitenancy is an abstract concept, an implementation detail of Force.com, but one with tangible benefits for developers. Figure 1-1 shows a conceptual view of multitenancy. Customers access shared infrastructure, with metadata and data stored in the same logical database.
Figure 1-1 Multitenant architecture
The multitenant architecture of Force.com consists of the following features.
- Shared infrastructure: Every customer (or tenant) of Force.com shares the same infrastructure. You are assigned a logical environment within the Force.com infrastructure.At first some might be uncomfortable with the thought of handing their data to a third-party where it is co-mingled with that of competitors. Salesforce's whitepaper on its multitenant technology includes the technical details of how it works and why your data is safe from loss or spontaneous appearance to unauthorized parties.
- Single version: There is only one version of the Force.com platform in production. The same platform is used to deliver applications of all sizes and shapes, used by 1 to 100,000 users, running everything from dog-grooming businesses to the Japanese national post office.
- Continuous, zero-cost improvements: When Force.com is upgraded to include new features or bug fixes, the upgrade is enabled in every customer's logical environment with zero to minimal effort required.
Salesforce can roll out new releases with confidence because it maintains a single version of its infrastructure and can achieve broad test coverage by leveraging tests, code, and configurations from their production environment. You, the customer, are helping maintain and improve Force.com in a systematic, measurable way as a side effect of simply using it. This deep feedback loop between the Force.com and its users is something impractical to achieve with on-premise software.
The heart of Force.com is the relational database provided as a service. The relational database is the most well-understood and widely used way to store and manage business data. Business applications typically require reporting, transactional integrity, summarization, and structured search, and implementing those on nonrelational data stores requires significant effort. Force.com provides a relational database to each tenant, one that is tightly integrated with every other feature of the platform. There are no Oracle licenses to purchase, no tablespaces to configure, no JDBC drivers to install, no ORM to wrangle, no DDL to write, no queries to optimize, and no replication and backup strategies to implement. Force.com takes care of all of this for you.
Force.com provides many of the common services needed for modern business application development. These are the services you might have built or integrated repeatedly in your past development projects. They include logging, transaction processing, validation, workflow, email, integration, testing, reporting, and user interface.
These services are highly customizable with and without writing code. Although each service can be valued as an individual unit of functionality, there is tremendous value from their unification. All the features of Force.com are designed, built, and maintained by a single responsible party, Salesforce. Salesforce provides documentation for these features as well as support staff on-call, training and certification classes, and accountability to its customers for keeping things running smoothly. This is in contrast to many software projects that end up as a patchwork of open-source, best-of-breed tools and libraries glued together by you, the developer, asked to do more with fewer people, shorter timelines, and cheaper, often unsupported tools.
Almost every customization configured or coded within Force.com is readily available as simple XML with a documented schema. At any point in time, you can ask Force.com for this metadata via a set of Web services. The metadata can be used to configure an identical environment or integrate with a source control system. It is also helpful for troubleshooting, allowing you to visually compare the state of two environments. Although there are a few features of Force.com not available in this declarative metadata form, Salesforce's stated product direction is to provide full coverage.
Force.com has its own programming language, called Apex. It allows developers to script interactions with other platform features, including the user interface. Its syntax is a blend of Java and database stored procedure languages like T/SQL and can be written using a Web browser or a plug-in to the Eclipse IDE.
Other platforms take a different approach. Google's App Engine simultaneously restricts and extends existing languages such as Python so that they play nicely in a PaaS sandbox. There are obvious benefits, such as leveraging the development community, ease of migration, and skills preservation. One way to understand Apex is as a domain-specific language. Force.com is not a general-purpose computing platform to run any Java or C# program you want to run. Apex is kept intentionally minimalistic, designed with only the needs of Force.com developers in mind, built within the controlled environment of Salesforce R&D. Although it won't solve every programming problem, Apex's specialized nature leads to some advantages in learning curve, code conciseness, ease of refactoring, and ongoing maintenance costs.
Force.com can be divided into four major services: database, business logic, user interface, and integration. Technically there are many more services provided by Force.com, but these are the high-level categories that are most relevant to new Force.com developers.
Force.com is built around a relational database. It allows the definition of custom tables containing up to 500 fields. Fields contain strongly typed data using any of the standard data types, plus rich types such as currency amounts, picklists, and phone numbers. Fields can contain validation rules to keep data clean before it is committed and formulas to derive values like cells in a spreadsheet. Field history tracking provides an audit log of changes to chosen fields.
Custom tables can be related to each other, allowing the definition of complex data schemas. Tables, rows, and columns can be configured with security constraints. Data and metadata is protected against accidental deletion through a "recycling bin" metaphor. The database schema is often modifiable instantly, without manual migration. Data is imported from files or other sources with free tools, and APIs are provided for custom data loading solutions.
Data is queried via a SQL-like language called SOQL (Salesforce Object Query Language). Full-text search is available through SOSL (Salesforce Object Search Language).
Apex is the language used to implement business logic on Force.com. It allows code to be structured into classes and interfaces, and it supports object-oriented behaviors. It has strongly typed collection objects and arrays modeled after Java.
Data binding is a first-class concept in Apex, with the database schema automatically imported as language constructs. Data manipulation statements, trigger semantics, and transaction boundaries are also part of the language.
The philosophy of test-driven development is hard-wired into the Force.com platform. Methods are annotated as tests and run from a provided test harness or test API calls. Test methods are automatically instrumented by Force.com and output timing information for performance tuning. Force.com prevents code from being deployed into production that does not have adequate unit test coverage.
Force.com provides two approaches for the development of user interfaces: Page Layouts and Visualforce. Page Layouts are inferred from the data model, including validation rules, and then customized using a WYSIWYG editor. Page Layouts feature the standard Salesforce look-and-feel. For many applications, Page Layouts can deliver some or all of the user interface with no development effort.
Visualforce allows developers to build custom user interfaces. It consists of a series of XML markup tags called components with their own namespace. As with JSP, ASP.NET, Velocity, and other template processing technologies, the components serve as containers to structure data returned by the Controller, a class written in Apex. To the user, the resulting Web pages might look nothing like Salesforce, or adopt its standard look-and-feel. There are Visualforce components to express the many types and styles of UIs, including basic entry forms, lists, multistep wizards, Ajax, Flex, mobile applications, and content management systems. Developers can create their own components to reuse across applications.
User interfaces in Visualforce are public, private, or some blend of the two. Private user interfaces require a user to log in before gaining access. Public user interfaces, called Sites, can be made available to anonymous users on the Internet.
In the world of integration, more options are usually better, and standards support is essential. Force.com supports a wide array of integration technologies, almost all of them based on industry-standard protocols and message formats. You can integrate other technologies with Force.com using the standard recipe of configuration plus code. Here are some examples.
- Business logic developed in Apex can be exposed as a Web service, accessible with or without a Force.com user identity. Force.com generates the WSDL from your Apex code. Additionally, Force.com converts WSDL to Apex bindings to allow access to external Web services from within the platform.
- You can create virtual email inboxes on Force.com and write code to process the incoming email. Sending email from Force.com is also supported.
- Force.com provides an API for making HTTP requests, including support for client-side certificates, SSL, proxies, and HTTP authentication. With this you can integrate with Web-based resources, such as Representational State Transfer (REST) or JSON services.
- Salesforce-to-Salesforce (S2S) is a publish-and-subscribe model of data sharing between multiple Force.com environments. If the company you need to integrate with already uses Force.com and the data is supported by S2S, integration becomes a relatively simple configuration exercise. There is no code or message formats to maintain. Your data is transported within the Force.com environment from one tenant to another.
If your requirements dictate a higher-level approach to integration, integration software vendors like Cast Iron Systems and Informatica offer adapters to Force.com to read and write data and orchestrate complex transactions spanning disparate systems.