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We have written a software package for a particular niche industry. This package has been pretty successful, to the extent that we have signed up several different clients in the industry, who use us as a hosted solution provider, and many others are knocking on our doors. If we achieve the kind of success that we're aiming for, we will have literally hundreds of clients, each with their own web site hosted on our servers.
Trouble is, each client comes in with their own little customizations and tweaks that they need for their own local circumstances and conditions, often (but not always) based on local state or even county legislation or bureaucracy. So while probably 90-95% of the system is the same across all clients, we're going to have to build and support these little customizations.
Moreover, the system is still very much a work in progress. There are enhancements and bug fixes happening continually on the core system that need to be applied across all clients.
We are writing code in .NET (ASP, C#), MS-SQL 2005 is our DB server, and we're using SourceGear Vault as our source control system. I have worked with branching in Vault before, and it's great if you only need to keep 2 or 3 branches synchronized - but we're looking at maintaining hundreds of branches, which is just unthinkable.
My question is: How do you recommend we manage all this?
I expect answers will be addressing things like object architecture, web server architecture, source control management, developer teams etc. I have a few ideas of my own, but I have no real experience in managing something like this, and I'd really appreciate hearing from people who have done this sort of thing before.
Thanks!
I would recommend against maintaining separate code branches per customer. This is a nightmare to maintain working code against your Core.
I do recommend you do implement the Strategy Pattern and cover your "customer customizations" with automated tests (e.g. Unit & Functional) whenever you are changing your Core.
UPDATE:
I recommend that before you get too many customers, you need to establish a system of creating and updating each of their websites. How involved you get is going to be balanced by your current revenue stream of course, but you should have an end in mind.
For example, when you just signed up Customer X (hopefully all via the web), their website will be created in XX minutes and send the customer an email stating it's ready.
You definitely want to setup a Continuous Integration (CI) environment. TeamCity is a great tool, and free.
With this in place, you'll be able to check your updates in a staging environment and can then apply those patches across your production instances.
Bottom Line: Once you get over a handful of customers, you need to start thinking about automating your operations and your deployment as yet another application to itself.
UPDATE: This post highlights the negative effects of branching per customer.
Our software has very similar requirements and I've picked up a few things over the years.
First of all, such customizations will cost you both in the short and long-term. If you have control over it, place some checks and balances such that sales & marketing do not over-zealously sell customizations.
I agree with the other posters that say NOT to use source control to manage this. It should be built into the project architecture wherever possible. When I first began working for my current employer, source control was being used for this and it quickly became a nightmare.
We use a separate database for each client, mainly because for many of our clients, the law or the client themselves require it due to privacy concerns, etc...
I would say that the business logic differences have probably been the least difficult part of the experience for us (your mileage may vary depending on the nature of the customizations required). For us, most variations in business logic can be broken down into a set of configuration values which we store in an xml file that is modified upon deployment (if machine specific) or stored in a client-specific folder and kept in source control (explained below). The business logic obtains these values at runtime and adjusts its execution appropriately. You can use this in concert with various strategy and factory patterns as well -- config fields can contain names of strategies etc... . Also, unit testing can be used to verify that you haven't broken things for other clients when you make changes. Currently, adding most new clients to the system involves simply mixing/matching the appropriate config values (as far as business logic is concerned).
More of a problem for us is managing the content of the site itself including the pages/style sheets/text strings/images, all of which our clients often want customized. The current approach that I've taken for this is to create a folder tree for each client that mirrors the main site - this tree is rooted at a folder named "custom" that is located in the main site folder and deployed with the site. Content placed in the client-specific set of folders either overrides or merges with the default content (depending on file type). At runtime the correct file is chosen based on the current context (user, language, etc...). The site can be made to serve multiple clients this way. Efficiency may also be a concern - you can use caching, etc... to make it faster (I use a custom VirtualPathProvider). The largest problem we run into is the burden of visually testing all of these pages when we need to make changes. Basically, to be 100% sure you haven't broken something in a client's custom setup when you have changed a shared stylesheet, image, etc... you would have to visually inspect every single page after any significant design change. I've developed some "feel" over time as to what changes can be comfortably made without breaking things, but it's still not a foolproof system by any means.
In my case I also have no control other than offering my opinion over which visual/code customizations are sold so MANY more of them than I would like have been sold and implemented.
This is not something that you want to solve with source control management, but within the architecture of your application.
I would come up with some sort of plugin like architecture. Which plugins to use for which website would then become a configuration issue and not a source control issue.
This allows you to use branches, etc. for the stuff that they are intended for: parallel development of code between (or maybe even over) releases. Each plugin becomes a seperate project (or subproject) within your source code system. This also allows you to combine all plugins and your main application into one visual studio solution to help with dependency analisys etc.
Loosely coupling the various components in your application is the best way to go.
As mention before, source control does not sound like a good solution for your problem. To me it sounds that is better yo have a single code base using a multi-tenant architecture. This way you get a lot of benefits in terms of managing your application, load on the service, scalability, etc.
Our product using this approach and what we have is some (a lot) of core functionality that is the same for all clients, custom modules that are used by one or more clients and at the core a the "customization" is a simple workflow engine that uses different workflows for different clients, so each clients gets the core functionality, its own workflow(s) and some extended set of modules that are either client specific or generalized for more that one client.
Here's something to get you started on multi-tenancy architecture:
Multi-Tenant Data Architecture
SaaS database tenancy patterns
Without more info, such as types of client specific customization, one can only guess how deep or superficial the changes are. Some simple/standard approaches to consider:
If you can keep a central config specifying the uniqueness from client to client
If you can centralize the business rules to one class or group of classes
If you can store the business rules in the database and pull out based on client
If the business rules can all be DB/SQL based (each client having their own DB
Overall hard coding differences based on client name/id is very problematic, keeping different code bases per client is costly (think of the complete testing/retesting time required for the 90% that doesn't change)...I think more info is required to properly answer (give some specifics)
Layer the application. One of those layers contains customizations and should be able to be pulled out at any time without affect on the rest of the system. Application- and DB-level "triggers" (quoted because they may or many not employ actual DB triggers) that call customer-specific code or are parametrized with customer keys) are very helpful.
Core should never be customized, but you must layer it in somewhere, even if it is simplistic web filtering.
What we have is a a core datbase that has the functionality that all clients get. Then each client has a separate database that contains the customizations for that client. This is expensive in terms of maintenance. The other problem is that when two clients ask for a simliar functionality, it is often done differnetly by the two separate teams. There is currently little done to share custiomizations between clients and make common ones become part of the core application. Each client has their own application portal, so we don't have the worry about a change to one client affecting some other client.
Right now we are looking at changing to a process using a rules engine, but there is some concern that the perfomance won't be there for the number of records we need to be able to process. However, in your circumstances, this might be a viable alternative.
I've used some applications that offered the following customizations:
Web pages were configurable - we could drag fields out of view, position them where we wanted with our own name for the field label.
Add our own views or stored procedures and use them in: data grids (along with an update proc) and reports. Each client would need their own database.
Custom mapping of Excel files to import data into system.
Add our own calculated fields.
Ability to run custom scripts on forms during various events.
Identify our own custom fields.
If you clients are larger companies, you're almost going to need your own SDK, API's, etc.
Related
We're an SME with SAP implemented. We're trying to use the transactional data in SAP to build another system in PHP for our trucking division for graphical reports, etc. This is because we don't have in-house expertise ABAP development and any SAP modifications are expensive.
Presently, I've managed to achieve our objectives with read-only access to our Quality DB2 server and any writes go to another DB2 server. We've found the CPU usage on the SELECT statements to be acceptable and the user is granted access only to specific tables/views.
SAP's Quality DB2 -> PHP -> Different DB2 client
Would like your opinion on whether it is safe to read from production the same way? Implementing all of this again via the RFC connector seems very painful. Master-Slave config is an option for us but again will involve external consultancy.
EDIT
Forgot to mention that our SAP guys don't want to build even reports for another 6-months - they want to leave the system intact. Which is why we're building this in PHP on the top.
If you don't have ABAP expertise, get it - it's not that hard, and you'll get a lot of stuff "for granted" (as in "provided by the platform") that you'll have to implement manually otherwise - like user authentication and authority management and software logistics (moving stuff from the development to the production repository). See these articles for a short (although biased) introduction. If you still need an external PHP application, fine - but you really should give ABAP a try first. For web applications, you might want to look into Web Dynpro ABAP. Using the IGS built'in chart engine with the BusinessGraphics element, you'll get a ton of the most custom chart types for free. You can also integrate PDF forms created with Adobe Livecycle Designer.
Second, while "any SAP modifications are expensive" might be a good approach, what you're suggesting isn't a modification. That's add-on development, and it's neither expensive nor more complex than any other programming language and/or environment out there. If you can't or don't want to implement your own application entirely using the existing infrastructure, at least use a decent interface - web services, RFC, whatever. From an ABAP point of view, RFC is always the easiest option, but you can use SOAP or REST as well, although you'll have to implement the latter manually. It's not that hard either.
NEVER EVER access the SAP database directly. Just don't. You'll have to implement all the constraints like client dependency or checks for validity dates and cancellation flags for yourself - that's hardly less complex than writing a decent interface, and it's prone to break every time the structure is changed. And if at some point you need to read some of the more complex contents like long texts, you're screwed - period. Not to mention that most internal or external auditors (if that happens to be an issue with your company and/or legal requirements) don't like direct database access to a system as critical as this one, which again can cause lots of trouble from people you really don't want to mess with. It's just not worth it.
My current project involves using LDAP (Active Directory) and I'm using issue tracking for all of my projects, so the idea of combining both of them crossed my mind. In order to fit the requirements of StackOverflow I'll try to formulate this as question but I admit, this is more about just getting some opinions, please forgive me :):
I think that issue-tracking and SCM (software configuration management) in general would be a good application for LDAP because of the following reasons:
Easy to integrate into existing infrastructure (no need for additional user management)
Fine-grained access control for projects/issues etc.
Ready-To-Use hierarchical, property-oriented storage (which is typically needed for SCM/issue trackers)
Standard-API with bindings for almost all languages/technologies
Searching/Indexing, Backup/replication functionality already present in most LDAP solutions
Extensible schema already part of the LDAP technology (it would be easy to add properties to issues/projects etc.)
So my questions are:
Are you aware of any existing attempts to define a (standard) schema for issue-tracking resp. SCM (i.e. class definitions for issues, projects, versions, releases, revisions etc)
LDAP usually manage relatively slowly-changing data. How well would current implementations (OpenLDAP, ActiveDirectory) handle data (mainly in terms of performance and amount of data) that typically changes very frequently?
Are there any other drawbacks of such a solution you can think of?
and of course
Who would like to try to start such a project :) ...
The OP precises:
The question is not about using an existing issue tracker with LDAP authentication (redmine can do this for example),
but about storing tickets/issues/etc. directly within the LDAP tree...
Currently, each issue tracker has it's own API for accessing data, having all data accesible via LDAP could make writing tools (e.g. integration into IDEs etc.) much easier
To which the answer is easy.
Don't.
LDAP is not (repeat, not) made for that, and there is much more to an SCM or an Issue Tracker than just a bunch of hierarchical data.
An SCM has to come up with a way to store/reference efficiently deltas, entire tree, branches, labels.
an Issue Tracker is all about multiple relationship between one item and several other (several parents/children, related, duplicated, ...), plus has to manage somehow a tight reference with the code (or rather the changeset, set of version modified)
While it is true than by adding a all lot of new objectClass types, you could end up with a similar structure, you would essentially take what it is a Lightweight Directory (ie optimized for reading only) and transform it into a huge referential (with lots of read/write operations and complex data structures).
If you are looking about an unifying API, one generic one (not just for SCM or Bug Tracking) is OSLC (Open Services for Lifecycle Collaboration), an open-sourced protocol currently used for Change Management by RTC (Rational Team Concert).
I'm currently working with a tool that over the years has evolved naturally from a number of perl scripts accessed through an apache web server, to a huge collection of tools using a common database and web site (still running apache, but using catalyst instead of CGI).
The problem we're having is that different departments have done local branches from the common main branch for implementing their own new functionality and adaptations.
We're now charged with the task of deciding how a common platform can be made available where certain base functionality is made one track instead of having all these different branches.
These kind of problems must spring up all the time so I'm hoping someone have a good strategy to offer as to how we should continue from here. Any thoughts would be appreciated.
In general, make sure you have buy in from everybody involved. Trying to do this kind of project without having people on board will just make your life more difficult.
Look for the quick wins. What functionality, if it changed, would have the fastest and clearest beneficial effect across all departments. If it takes you three months to get some good out of it, people won't rate the good results very highly.
Break functionality down as far as you can. One of the biggest problems in forked legacy systems is that a seemingly innocuous change in one place can have huge ramifications elsewhere because of the assumptions made about state. Isolating state in different features should help you out there.
Basically my project is product based.
Once we developed a project and catch the multiple client and deploy the application based on their needs.
But We decided to put the new features and project dependent modules are as component.
Now my application got many number of customer.
Every customer needs a different features based on the component.
But we have centralized component for all client . we move the components additional feature to client specific folder and deploy.
My problem is , I am unable maintain the components features for multiple client.
My component feature code is increased and I am unable to track the client features.
Is there any solution for maintaining the multiple component features for multiple client ?
I've worked for a couple of companies in a similar space - product software but very heavily customised.
Essentially there is a decision the company needs to make - are you a product company (that is you ship broadly the same to every client) or are you a bespoke company. At the moment it sounds like they're between two stools and wanting the economies of being a product company with the ability to meet specific client demands the way a bespoke software company can.
Assuming the company wants to be a product software company, unless there are specific technical reasons why you can't, you need to move to a single code base with the modifications for each customer being handled through customisable options (i.e. flags saying how this particular situation is being handled, whether this feature is available and so on).
These can be set at run time (so they can be changed as the client wants - think options in Word or Excel), or build time (so code is included / excluded when you do the build), but the key things is that every client has to be pulled from the same code base.
But this needs to be agreed with the business as it limits what they can sell - every change they sell has to fit into an overall vision which can be accommodated by the single product.
The alternative is that you're essentially producing bespoke software for each client (that is coded specifically for what they want) but using many common libraries. That's fine and allows you to produce something which is exactly what they want but in the end it is going to be more work and the business needs to understand and cost for that.
We actually do a bit of both - there is a server product which is identical for all clients, and then web and mobile clients which are specific to them (in the case of mobile you can't have lots of dead code on the device - the web stuff is historic and will be moving to a standard product for all clients).
Good luck though, it's a difficult problem with no easy solution.
You are essentially talking about software product lines (SPLs): variations from a common base. Since you already package your features as components, you need a specialized tool to manage such variations.
You can then build a complete custom application based on a configuration that is unique to any given customer. Easier said than done, of course.
A model-driven software development(MDSD) approach can help a lot on this task. One such system that can support this development setup is ABSE, an emerging MDSD approach that among other things, can implement a software product line (info at http://www.abse.info - Disclaimer: I am the ABSE project lead). There is no product yet though. An alpha preview is coming.
Again, I know some companies that, using an MDSD coupled with code generation, have achieved what I understand you want: products that are half pre-packaged, half custom.
We have a web application which contains a bunch of content that the system operator can change (e.g. news and events). Occasionally we publish new versions of the software. The software is being tagged and stored in subversion. However, I'm a bit torn on how to best version control the content that may be changed independently. What are some mechanisms that people use to make sure that content is stored and versioned in a way that the site can be recreated or at the very least version controlled?
When you identify two set of files which have their own life cycle (software files on one side, "news and events" on the other, you know that:
you can not versionned them together at the same time
you should not put the same label
You need to save the "news and event" files separatly (either in the VCS or in a DB like Ian Jacobs suggests, or in a CMS - Content Management system), and find a way to link the tow together (an id, a timestamp, a meta-label, ...)
Do not forget you are not only talking about two different set of files in term of life cycle, but also about different set of files in term of their very natures:
Consider the terminology introduced in this SO question "Is asset management a superset of source control" by S.Lott
software files: Infrastructure information, that is "representing the processing of the enterprise information asset". Your code is part of that asset and is managed by a VCS (Version Control System), as part of the Configuration management discipline.
"news and events": Enterprise Information, that is data (not processing); this is often split between Content Managers and Relational Databases.
So not everything should end up in Subversion.
Keep everything in the DB, and give every transaction to the DB a timestamp. that way you can keep standard DB backups and load the site content at whatever date you want if the worst happens.
I suppose part of the answer depends on what CMS you're using, and how your web app is designed, but in general, I'd regard data such as news items or events as "content". In other words, it's not part of your application - it's the data which your application processes.
Of course, there will be versioning issues between your CMS code and your application code. You could manage this by defining the interface between the two. Personally, I'd publish the data to the web app as XML, which gives you the possibility of using XML schema to define exactly what the CMS is required to produce, and what the web app should expect to process.
This ought to mean that most changes in the web app can be made without a corresponding alteration in the rendering of the data. When functionality changes require this, you can create a new version of the schema and continue to make progress. In this scenario, I'd check the schema in with the web app code, but YMMV.
It isn't easy, and it gets more complicated again if you need additional data fields in your CMS. Expect to plan for a fairly complex release process (also depending on how complex your Dev-Test-Acceptance-Production scenario is.)
If you aren't using a CMS, then you should consider it. (Of course, if the operation is very small, it may still fall into the category where doing it by hand is acceptable.) Simply putting raw data into a versioning system doesn't solve the problem - you need to be able to control the format in which your data is published to the web app. Almost certainly this format should be something intended for consumption by software, and therefore not usually suitable for hand-editing by the kind of people who write news items or events.