ENBL stock: Second quarter 2020 Financial and Operating results

August 5, 2020

Introduction

It was my mistake since I sold ENBL 800 shares this morning. I was so surprised to see the gains and sold it. Now I just noticed that price went up another 40 cents in less than 3 hours. I found out that second quarter result of 2020 is coming out today. 

Enable midstream partners

I like to go over the reports quickly. 

• Contracted or extended over 950,000 dekatherms per day (Dth/d) of transportation capacity during second quarter 2020
• Received a firm, 80,000 Dth/d commitment for Enable Mississippi River Transmission, LLC’s (MRT) Southbound Expansion project
• Achieved record quarterly Ark-La-Tex Basin natural gas gathered volumes
• On track to achieve the capital and cost reductions announced earlier this year
• Reaffirming 2020 financial outlook
• Declared a quarterly cash distribution of $0.16525 per unit on all outstanding common units and $0.625 on all outstanding Series A Preferred Units

Enable Midstream Partners, LP (NYSE: ENBL) today announced financial and operating results for second quarter 2020.

Net income attributable to limited partners was $44 million for second quarter 2020, a decrease of $80 million compared to $124 million for second quarter 2019. Net income attributable to common units was $35 million for second quarter 2020, a decrease of $80 million compared to $115 million for second quarter 2019. Net cash provided by operating activities was $111 million for second quarter 2020, a decrease of $101 million compared to $212 million for second quarter 2019. Adjusted EBITDA was $224 million for second quarter 2020, a decrease of $57 million compared to $281 million for second quarter 2019. Distributable cash flow (DCF) was $148 million for second quarter 2020, a decrease of $49 million compared to $197 million for second quarter 2019.

Enable uses derivatives to manage commodity price risk, and the gain or loss associated with these derivatives is recognized in earnings. Enable’s net income attributable to limited partners and net income attributable to common units for second quarter 2020 included a $5 million loss on commodity derivative activity, compared to a $16 million gain on commodity derivative activity for second quarter 2019, resulting in a decrease in net income of $21 million. The decrease of $21 million is comprised of a decrease related to the change in fair value of commodity derivatives of $23 million, partially offset by an increase in realized gain on commodity derivatives of $2 million.

For second quarter 2020, DCF exceeded declared distributions to common unitholders by $76 million, resulting in a distribution coverage ratio of 2.06x.

For additional information regarding the non-GAAP financial measures Gross margin, Adjusted EBITDA, DCF, Adjusted interest expense and distribution coverage ratio, please see "Non-GAAP Financial Measures."

MANAGEMENT PERSPECTIVE

"With producers bringing shut-in wells in oilier plays back to our gathering systems earlier than anticipated, we saw less than expected curtailment of crude-focused production during the second quarter," said Rod Sailor, president and CEO. "Highlighting the strength of the Haynesville Shale play, the second quarter also saw the highest quarter of natural gas gathered volumes in the Ark-La-Tex Basin since the partnership’s inception. Enable continues to operate at a high level of safety and reliability through these uncertain times, and we remain on track to achieve the capital and cost reductions announced in April of this year."

BUSINESS AND FINANCIAL HIGHLIGHTS

During second quarter 2020, Enable contracted or extended over 950,000 Dth/d of firm transportation capacity, including previously announced recontracted capacity with Enable Gas Transmission, LLC’s (EGT) largest customer, CenterPoint Energy Resources Corp (CERC). The contract term for most of the renewed CERC capacity is nine years, and the effective date of the new contracts will be April 1, 2021.

On July 7, 2020, Federal Energy Regulatory Commission (FERC) staff issued a revised schedule for the completion of the environmental assessment for the Gulf Run Pipeline project. The FERC’s current schedule anticipates an environmental assessment will be issued by Oct. 29, 2020. The project is proceeding on schedule and is expected to be placed into service in late 2022, subject to FERC approval. EGT’s MASS project, a supply-driven project designed to deliver gas from the Anadarko and Arkoma basins to delivery points with access to emerging Gulf Coast markets and growing demand markets in the Southeast, also remains on schedule and is expected to be placed into service in the second quarter of 2021.

MRT recently received a five-year commitment for 80,000 Dth/d of firm capacity for the pipeline’s Southbound Expansion project. The project will provide transportation capacity from various receipt points on MRT’s East Line to various delivery points in MRT’s Market and Field Zones and is scheduled to go into service in the fourth quarter of 2020.

As of July 29, 2020, there were seven rigs across Enable’s footprint that were drilling wells expected to be connected to Enable’s gathering systems. Three of those rigs were in the Anadarko Basin, three were in the Ark-La-Tex Basin and one was in the Williston Basin. The partnership’s Ark-La-Tex Basin natural gas gathering system gathered record quarterly volumes for second quarter 2020, driven by continued producer investment in the Haynesville Shale play. Producers continue to bring shut-in natural gas, crude oil and condensate volumes back online, and Enable has not experienced a degradation in production from these wells.

During second quarter 2020, the partnership repurchased approximately $22 million aggregate principal amount of senior notes in the open market for approximately $17 million plus accrued interest. These repurchases resulted in a $5 million gain on extinguishment of debt. The partnership will continue to evaluate opportunistic note repurchases based on market conditions and available liquidity.

QUARTERLY DISTRIBUTIONS

On Aug. 4, 2020, the board of directors of Enable’s general partner declared a quarterly cash distribution of $0.16525 per unit on all outstanding common units for the quarter ended June 30, 2020. The distribution is unchanged from the previous quarter. The quarterly cash distribution of $0.16525 per unit on all outstanding common units will be paid Aug. 25, 2020, to unitholders of record at the close of business Aug. 18, 2020.

The board declared a quarterly cash distribution of $0.625 per unit on all outstanding Series A Preferred Units for the quarter ended June 30, 2020. The quarterly cash distribution of $0.625 per unit on all outstanding Series A Preferred Units will be paid Aug. 14, 2020, to unitholders of record at the close of business Aug. 4, 2020.

KEY OPERATING STATISTICS

Natural gas gathered volumes were 4.14 trillion British thermal units per day (TBtu/d) for second quarter 2020, a decrease of 10% compared to 4.62 TBtu/d for second quarter 2019. The decrease was primarily due to shut-in production in the Anadarko Basin, partially offset by higher gathered volumes in the Ark-La-Tex Basin.

Natural gas processed volumes were 2.04 TBtu/d for second quarter 2020, a decrease of 20% compared to 2.54 TBtu/d for second quarter 2019. The decrease was due to lower processed volumes across all basins.

Crude oil and condensate gathered volumes were 84.68 thousand barrels per day (MBbl/d) for second quarter 2020, a decrease of 29% compared to 119.34 MBbl/d for second quarter 2019. The decrease was primarily due to a decrease in crude oil and condensate gathered volumes as a result of shut-in production in the Anadarko and Williston Basins.

Transported volumes were 5.40 TBtu/d for second quarter 2020, a decrease of 11% compared to 6.04 TBtu/d for second quarter 2019. The decrease was primarily due to lower transported volumes due to decreased production in the Anadarko Basin.

Interstate transportation firm contracted capacity was 5.78 billion cubic feet per day (Bcf/d) for second quarter 2020, a decrease of 9% compared to 6.38 Bcf/d for second quarter 2019. The decrease was primarily related to contract expirations, including lower recontracted capacity on the MRT system.

Intrastate transportation average deliveries were 1.67 TBtu/d for second quarter 2020, a decrease of 19% compared to 2.06 TBtu/d for second quarter 2019. The decrease was primarily due to decreased production in the Anadarko Basin.

SECOND QUARTER FINANCIAL PERFORMANCE

Revenues were $515 million for second quarter 2020, a decrease of $220 million compared to $735 million for second quarter 2019. Revenues are net of $59 million of intercompany eliminations for second quarter 2020 and $104 million of intercompany eliminations for second quarter 2019.

Gathering and processing segment revenues were $391 million for second quarter 2020, a decrease of $196 million compared to $587 million for second quarter 2019. The decrease in gathering and processing segment revenues was primarily due to:

• a decrease in revenues from natural gas liquids (NGL) sales primarily due to lower average market prices for NGL products and lower processed volumes as well as a decrease in revenues from natural gas sales due to lower average sales prices and lower sales volumes,
• a decrease in processing service revenues due to lower processed volumes under fee-based arrangements, partially offset by the recognition of certain annual minimum processing fees,
• a decrease in changes in the fair value of natural gas, condensate and NGL derivatives,
• a decrease in crude oil, condensate and produced water gathering revenues primarily due to a decrease in gathered volumes,
• a decrease in natural gas gathering revenues due to lower gathered volumes in the Anadarko and Arkoma Basins and lower shortfall payments associated with the expiration of certain minimum volume commitment contracts in the Ark-La-Tex and Arkoma Basins, partially offset by higher revenue associated with the third quarter 2019 amendment of certain minimum volume commitment contracts in the Arkoma Basin and
• a decrease in intercompany management fees.

These decreases were partially offset by an increase in realized gains on natural gas, condensate and NGL derivatives.

Transportation and storage segment revenues were $183 million for second quarter 2020, a decrease of $69 million compared to $252 million for second quarter 2019. The decrease in transportation and storage segment revenues was primarily due to:

• a decrease in revenues from natural gas sales primarily due to lower sales volumes and lower average sales prices,
• a decrease in firm transportation and storage services due to lower interstate contracted capacity and lower rates on certain contracts for intrastate service with power generators, partially offset by higher recognized rates subsequent to the settlement of the MRT rate cases,
• a decrease in volume-dependent transportation and storage revenues due to lower off-system intrastate transportation rates and lower transported volumes due to decreased production activity in the Anadarko Basin,
• a decrease in revenues from NGL sales due to lower average sales prices and lower volumes, and
• a decrease due to realized losses on natural gas derivatives.

Gross margin was $338 million for second quarter 2020, a decrease of $80 million compared to $418 million for second quarter 2019.

Gathering and processing segment gross margin was $215 million for second quarter 2020, a decrease of $75 million compared to $290 million for second quarter 2019. The decrease in gathering and processing segment gross margin was primarily due to:

• a decrease in revenues from natural gas sales due to lower average sales prices and lower sales volumes,
• a decrease in changes in the fair value of natural gas, condensate and NGL derivatives,
• a decrease in revenues from NGL sales due to lower average sales prices for NGL products,
• a decrease in crude, condensate and produced water gathering revenues primarily due to a decrease in gathered volumes,
• a decrease in natural gas gathering fees due to lower gathered volumes in the Anadarko and Arkoma Basins and lower shortfall payments associated with the expiration of certain minimum volume commitment contracts in the Ark-La-Tex and Arkoma Basins, partially offset by higher revenue associated with the third quarter 2019 amendment of certain minimum volume commitment contracts in the Arkoma Basin and
• a decrease in intercompany management fees.

These decreases were partially offset by an increase in realized gains on natural gas, condensate and NGL derivatives.

Transportation and storage segment gross margin was $124 million for second quarter 2020, a decrease of $5 million compared to $129 million for second quarter 2019. The decrease in transportation and storage segment gross margin was primarily due to:

• a decrease in firm transportation and storage services due to lower interstate contracted capacity and lower rates on certain contracts for intrastate service with power generators, partially offset by higher recognized rates subsequent to the settlement of the MRT rate case,
• a decrease in volume-dependent transportation and storage revenues due to lower off-system intrastate transportation rates and lower transported volumes due to decreased production activity in the Anadarko Basin,
• an increase in realized losses on natural gas derivatives, and
• a decrease in revenues from NGL sales due to lower average sales prices and lower volumes.

These decreases were partially offset by an increase in system management activities and a reduction in lower of cost or net realizable value adjustments related to natural gas storage inventories.

Operation and maintenance and general and administrative expenses were $136 million for second quarter 2020, an increase of $12 million compared to $124 million for second quarter 2019. The increase in operation and maintenance and general and administrative expenses was primarily due to a loss on retirement of an Ark-La-Tex gathering system in 2020, partially offset by a decrease in compressor rentals and a decrease in materials and supplies due to the timing of operation and maintenance activities and lower maintenance on treating plants as compared to the prior year.

Depreciation and amortization expense was $105 million for second quarter 2020, a decrease of $5 million compared to $110 million for second quarter 2019. The decrease in depreciation and amortization expense was primarily related to new depreciation rates implemented in the prior year, which resulted in higher depreciation expense in 2019 for certain assets with shorter remaining useful lives, as compared to 2020.

Interest expense was $46 million for second quarter 2020, a decrease of $2 million compared to $48 million for second quarter 2019. The decrease was primarily due to lower interest rates on the partnership’s short-term borrowings.

Capital expenditures were $48 million for second quarter 2020, compared to $109 million for second quarter 2019. Expansion capital expenditures were $26 million for second quarter 2020, compared to $83 million for second quarter 2019. Maintenance capital expenditures were $22 million for second quarter 2020, compared to $26 million for second quarter 2019.

2020 OUTLOOK

Enable reaffirms the 2020 outlook presented in its first quarter 2020 financial results press release dated May 6, 2020.

EARNINGS CONFERENCE CALL AND WEBCAST

A conference call discussing second quarter results is scheduled today at 10 a.m. EDT (9 a.m. CDT). The toll-free dial-in number to access the conference call is 833-968-1938, and the international dial-in number is 778-560-2726. The conference call ID is 7684665. Investors may also listen to the call via Enable’s website at https://investors.enablemidstream.com. Replays of the conference call will be available on Enable’s website.

TFSA closed P&L: August 5, 2020

August 5, 2020

Introduction

It is hard for me to learn how to invest even though I keep all the documents how I think and learn; What I learn most is to from people in my wechat investment small group. I learn so many things from each of them. 

My TFSA closed P& L

TFSA oil stocks: Oil stock sold

August 5, 2020

Introduction

It takes me some time to learn how to work with market swing. I do think that it is good investment of time to trade short terms. As a Christian, I do believe that it is hard for me to figure out if I am a gambler or an investor at the beginning. I do choose to start the learning process after March 27 crash. 

Oil stock investment

I made purchase of oil stocks and Air Canada stocks on July 31 $35,337.00. And I sold all oil stocks except Air Canada stocks. 

I should purchase $25,000 dollars more since the fund is in my account. I like to review the transactions. 

I tried to figure out why the oil stocks rebounded so quickly today. I have not checked the news yet. 

Recall my purchase:

Here is my blog about the purchase on July 31, 2020. 

University of waterloo: CS 454/654 Distributed Systems

Here is the link. 

Lecture slides:

Introduction

Architecture and models

Computer networks

Distributed objects & Remote invocation

Distributed naming

Distributed filesystems

Synchronization

Replication

Fault tolerance

Security

IMO stock: One business day 5% gains

Bank of America believes AMD will be the next $100 billion chip company

Save stock: How to help a friend in my wechat investment group

Beginner investor: Canada oil stock

My oil stocks

A stock market correction may be imminent, JPMorgan says. Here’s why you shouldn’t panic

Here is the article. 

The typically muted month of August is upon us but there’s still a lot for investors to digest.

Talks over another coronavirus stimulus package that would restore jobless benefits to millions of Americans continued into the weekend and will remain in focus this week. However, lawmakers reportedly remain far apart in the negotiations. U.S.-China tensions are also back in the spotlight after President Trump said he would ban Chinese videosharing app TikTok. Technology company Microsoft MSFT, -2.18% confirmed talks on Sunday to buy TikTok, owned by Chinese company ByteDance, after a call between Chief Executive Satya Nadella and Trump.

It is also another big week of earnings, with 130 members of the S&P 500 — including ridesharing app Uber UBER, 4.47%, entertainment company Disney DIS, 0.32% and plant-based-food producer Beyond Meat BYND, 2.93% — set to report second-quarter results.

In our call of the day, JPMorgan strategists say a modest stock market correction could occur in the next few weeks but doesn’t justify bearish targets or even a defensive investment strategy.

They say key coming data releases, such as payrolls on Thursday and retail sales on Aug. 14 could “undershoot expectations” and drive the modest correction.

BitTiger: 顶尖架构师：如何设计一个Uber

Here is the link. 

BitTiger: 如何设计一个推荐系统

Here is the link. 

CVE stock: SimplyWall.st analysis

Here is the link. 

Husky energy stock: wallstreet.io analysis

Here is the page. I like to spend at least 20 minutes to review the content. 

System design: How to prepare and learn starting from CS fundamental

Path to SV Engineer

Step 1: CS Fundamental

computer architecture

operating system

Computer network

Software engineering

Step 2:

System design

Design by yourself

Step 3: 

Open source projects

Kafka

Spark

MongoDB

Redis

Step 4: Hands on

code by yourself

SimpleWall.st: Suncor energy stock

August 3, 2020

Introduction

As an investor, I have to watch myself to go through learning process to chase high price, and then sell when the price is low. I have to play with greedy and fear, also I like to build connections with other JTU alumni on my wechat group. I have to take it seriously. One thing is so good to learn from today - SimpleWall.St.

Suncor stock

I need to learn from my investment position: Suncor energy stock. And I do think that it is smart for me to learn from SimpleWall.st. 

Here is the link. 

SimpleWall.st: What if I am the product manager of SimpleWall.st?

August 3, 2020

Introduction

I came cross this website again through the article related to Intel stock research. I like to explore all the features of the website using a free account. I like to talk about product features on this website. It is challenging for me to be an intelligent investor, through the website, I do think that I can be much better one. 

My research

Compared to the owner of a small investor group on wechat, I do think that it is also a good investment to find a best website to pay for, and then I can evaluate how good the website will be. 

There are a few choices: Yahoo finance, Fenviz, MarketBeat, SimpleWall.st. 

BitTiger: 【面试中】系统设计怎么考？系统设计题怎么答？

Here is the link. 

System design common questions:

Uber

LinkedIn

Monitor System

Dashboard

Dropbox

Twitch

Google Doc

Google Sheet

Google File System

BigTable

MapReduce

Restful service

WhatsApp

WeChat

User System

SQL database

KV database

Netflix

Crawler

TineyURL

Task scheduler

RateLimitor

Flickr

Recommender System

Message broker

Elevator

Chess

ATM

Facebook

Twitter

Typeahead

Yelp

Template: SNAKE

• Scenairo: case/interface
• Necessary: constrain/hypothesis
• Application: service/algorithm
• Kilobit: data
• Evolve

BigTiger: 系统设计的基本方法SNAKE原则

Here is the link. 

The process of defining the architecture, components, modules, interfaces, and data for a system to satisfy specified requirements. 

How to design NetFlix? 

Top level design:

Scenario:

Necessary: requirement/ assumptions

First step: ask how many users

  5,000,000 daily users

Second step: prediction

  2 - 10 times more - future, 3 months, Netflix - twice more users

125 users

3MBps -> peak bandwidth 3.75 Tb/s 

Storage 

  10KB

3 months later storage 5,000,000 * 2 * 10 = 100GB

Hard disk

14,000 movies

Total storage:

Application: 

service/ algorithms

Step 1: 

Step 2: 

Kilobit (Data)

First step:   

Evolve (How to advance system design?)

Step 1: analysis

  directions:

   Better: limitation

   Broad: scenarios

   Depth: small details

Angles:

  . Property

  

SNAKE:

Scenario

Necessary

Application

Kilobit

Evolve 

Micro: 

recommendations: 

u1 = {m3, m5, m7, m11)

Class Recommender{

}

Necessary (limitation)

prediction

Algorithm & Kilobit 

For movie liked by u1

   

Questrade.com: MY TFSA account

NYSE stock market:

August 3, 2020 11:05 AM

SU stock: 2.54% gain on August 3, 2020

IMO stock: 2.11% gain 

CNQ stock: 0.68%

HUSKF:   -3.43%

CVE: 2.91%

PPL: -0.15%

So those positions should have gain: $500 dollars

Ameritrade.com: My key largo update

August 3, 2020

Introduction

It is a holiday in British Columbia. I like to take some time to thank my employer and also I have luxury to play with stock market, as a beginner, I lost $3000 to $4000 in the stock market since June 5, but I learned to hold valuable stocks. 

My key largo

Here's What We Like About Intel's (NASDAQ:INTC) Upcoming Dividend

Here is the article. 

Here are highlights:

1. Intel's next dividend payment will be US$0.33 per share
2. Last year, in total, the company distributed US$1.32 to shareholders.
3. Calculating the last year's worth of payments shows that Intel has a trailing yield of 2.8% on the current share price of $47.73.
4. Intel has a low and conservative payout ratio of just 23% of its income after tax.
5.  Thankfully its dividend payments took up just 25% of the free cash flow it generated, which is a comfortable payout ratio.
6. Intel's earnings per share have risen 18% per annum over the last five years.
7. It's encouraging to see the company lifting dividends while earnings are growing, suggesting at least some corporate interest in rewarding shareholders.

Things I learn to read the article:

1. How to calculate trailing yield
2. Gather all financial information about Intel

Intel Corporation (NASDAQ:INTC) stock is about to trade ex-dividend in three days. Ex-dividend means that investors that purchase the stock on or after the 6th of August will not receive this dividend, which will be paid on the 1st of September.

Intel's next dividend payment will be US$0.33 per share. Last year, in total, the company distributed US$1.32 to shareholders. Calculating the last year's worth of payments shows that Intel has a trailing yield of 2.8% on the current share price of $47.73. Dividends are a major contributor to investment returns for long term holders, but only if the dividend continues to be paid. So we need to check whether the dividend payments are covered, and if earnings are growing.

Check out our latest analysis for Intel

Dividends are typically paid out of company income, so if a company pays out more than it earned, its dividend is usually at a higher risk of being cut. Intel has a low and conservative payout ratio of just 23% of its income after tax. A useful secondary check can be to evaluate whether Intel generated enough free cash flow to afford its dividend. Thankfully its dividend payments took up just 25% of the free cash flow it generated, which is a comfortable payout ratio.

It's encouraging to see that the dividend is covered by both profit and cash flow. This generally suggests the dividend is sustainable, as long as earnings don't drop precipitously.

Click here to see the company's payout ratio, plus analyst estimates of its future dividends.

Have Earnings And Dividends Been Growing?

Businesses with strong growth prospects usually make the best dividend payers, because it's easier to grow dividends when earnings per share are improving. Investors love dividends, so if earnings fall and the dividend is reduced, expect a stock to be sold off heavily at the same time. For this reason, we're glad to see Intel's earnings per share have risen 18% per annum over the last five years. Earnings per share have been growing rapidly and the company is retaining a majority of its earnings within the business. This will make it easier to fund future growth efforts and we think this is an attractive combination - plus the dividend can always be increased later.

Many investors will assess a company's dividend performance by evaluating how much the dividend payments have changed over time. Since the start of our data, 10 years ago, Intel has lifted its dividend by approximately 9.0% a year on average. It's encouraging to see the company lifting dividends while earnings are growing, suggesting at least some corporate interest in rewarding shareholders.

Final Takeaway

From a dividend perspective, should investors buy or avoid Intel? Intel has been growing earnings at a rapid rate, and has a conservatively low payout ratio, implying that it is reinvesting heavily in its business; a sterling combination. It's a promising combination that should mark this company worthy of closer attention.

With that in mind, a critical part of thorough stock research is being aware of any risks that stock currently faces. To help with this, we've discovered 2 warning signs for Intel that you should be aware of before investing in their shares.

A common investment mistake is buying the first interesting stock you see. Here you can find a list of promising dividend stocks with a greater than 2% yield and an upcoming dividend.

Facebook／LinkedIn面试官亲授：硅谷“两大巨头”，究竟如何面试？

Here is the link. 

在Facebook面试超过50人的Jim老师，在LinkedIn面试超80人的Jeff老师，拥有“面人”超级丰富的经验。他们逐条分析，两大“硅谷巨头”如何面试？添加微信（orangechaser）加入BitTiger求职内推群。

1:20/ 2:17

Linkedin system design interview tips

Time range: 1:12 - 1:14 /2:17

How to prepare for interview from hiring manager? Based on how the report is written by hiring manager. 

How to present the talent to manage projects at work? 

How do you manage those problems at project? 

Time estimation, coordination, ...

a problem, present a solution - how to manage the project? 

Life cycle of project, how users will use, and then have a product manager thinking as an engineer. 

How to design product feature to enhance competitions? 

BitTiger: Lyft Manager袁林：如何高效准备软件工程师（Software Engineer)面试？

Here is the link. 

-看中求职者身上什么能力？ -面试中怎么present自己的项目最“吸睛”？ -Behaviro question怎么答？ -面试中遇到不会回答的问题，怎么答不丢分？ -对转专业的面试者有Bias吗？

Behavior questions:

Projects:

Project design:

bitTiger: Load balancer - presentation in Chinese

Here is the link. 

OSI Layer - Protocol data unit (PDU)

Data

TCP/UDP

IP

Mac

Bit

Load balancer: 

Application Delivery Controller/ Network (ADC/ ADN)

Load balancing algorithm:  round robin 

My study notes:

I just could not believe how good the presentation is, and I learned a few things. It is interesting to see how load balancer is configured in a small program. 

 

System design: Websocket and REST

August, 2020

Introduction

It is a very good topic for me to learn quickly. I do think that the comparison between websocket and REST is the start for me to ask questions, and build strong curiosity in learning networking, HTTP protocol, application layer. 

Ten difference

I just copy the content from the article here. 

Both  are popular choices in the market; let us discuss some of the major difference :

1. WebSocket is a low-level protocol, based on the concept of socket and port, which are the underlying transport mechanism whereas REST is based on CRUD operation.
2. WebSocket require the use of IP address and Port details, which are lower level details for any application whereas RESTful application needs to design operation based on verbs, and HTTP based.
3. WebSocket is bi-directional in nature i.e. both way operation from client to server and vice versa is possible whereas REST follows a uni-directional approach.
4. WebSocket approach is ideal for real-time scalable application, whereas REST is better suited for the scenario with lots of getting request.
5. WebSocket is a stateful protocol whereas REST is based on stateless protocol i.e. client does not need to know about the server and same hold true for the server.
6. WebSocket connection can scale vertically on a single server whereas REST, which is HTTP based can scale horizontally.
7. WebSocket is ideal for a scenario where high loads are a part of game i.e. real-time scalable chat application whereas REST is better fitted for occasional communication, in a typical GET request scenario to call RESTful APIs.
8. WebSocket works better, where client-server communicates over the same TCP connection for the life of web socket connection whereas, for HTTP request, a new TCP connection is initiated.
9. WebSocket communication allows client and server to talk independently of each other whereas with the REST based approach, either client is talking to the client or server is talking to the client at any given time.
10. WebSocket communication cost is lower whereas REST-based communication is comparatively higher end on the cost.

Websockets vs REST API

The idea behind a socket, is that it is a “port” through which data goes in and out of. Much like a real trading port for data, the socket itself is like the dock, it’s where exchanges are happening from the application standpoint. The socket itself is abstract and low level, and staying with the metaphor, many different ships, trains, and equipment can use it. We can call all of these Protocols.

On the Internet there are hundreds of protocols, but a few stand out as the most common, like HTTP, FTP, SMTP, POP3, etc. and lower level transport protocols like TCP and UDP. In essence, Protocols determine how to interpret the data going to and from the socket and the machines that are communicating with each other.

What are WebSockets?

WebSockets are really just an extension of the socket idea. While HTTP was invented for the World Wide Web, and has been used by browsers since then, it had limitations. It was a particular protocol that worked in a particular way, and wasn’t well suited for every need. In particular was how HTTP handled connections. Whenever you made a request, say to download html, or an image, a port/socket was opened, data was transferred, and then it was closed.

The opening and closing creates overhead, and for certain applications, especially those that want rapid responses or real time interactions or display streams of data, this just doesn’t work.

Case study: mock interview - construct binary tree from post order and inorder traversal lists

Here is the link of transcript. 

Start of transcript

End of transcript

Actionable items

I tried to write the same idea, here is my discussion post. 

System design: From a novice to an expert in less than 10 days

August 2, 2020

Introduction

It is the interviewee's dilemma, if I cannot pass the phone screen, then I should focus on algorithm and data structure; After the phone screen, there is less than 2 - 3 weeks to prepare system design, and also algorithm practice. How should I make myself an expert on system design interview? Can I make transition from a novice to an expert. 

Domain sharding on the modern web

Here is the article. 

Another interesting limit is that browsers have a total limit of concurrent connections regardless of the number of different hostnames used. This can be a major reason against domain sharding, if you consider that some browsers only support 10–17 requests max in any case.

Domain sharding is not as useful for sites with mostly static assets that do not change often, because they will get cached in the browser’s cache. The user will still feel the impact on the first load. You will get further by pushing down less Javascript, CSS and other assets to your users by making use of techniques like code-splitting, but that is a topic for another post.

Investigate where in your web app or site you are actually running into assets which are being queued because of the browser’s concurrent call limitation. It might not actually be a problem. Then, first try to reduce the number of assets before deciding on using domain sharding.

Study notes:

browser’s concurrent call limitation

reduce the number of assets before deciding on using domain sharding ...

being queued - app or site 

static assets - browser's cache 

impact on first load 

code-splitting vs domain sharing on the modern web - Spend 10 minutes to look into code-splitting

Introduction to HTTP/2

Here is the article. 

I plan to read the article when I have 10 minutes to spend. 

Comet, Ajax Push, Reverse Ajax, Two-way-web, HTTP Streaming and HTTP server push

Here is the wiki article. 

Google added web-based chat to Gmail; 

JotSpot, a startup since acquired by Google, built Comet-based real-time collaborative document editing.^[23] 

New Comet variants were created, such as the Java-based ICEfaces JSF framework (although they prefer the term "Ajax Push"^[5]). 

Others that had previously used Java-applet based transports switched instead to pure-JavaScript implementations.^[24]

Google Docs? - HTTP server push?

Google added web-based chat to Gmail; JotSpot, a startup since acquired by Google, built Comet-based real-time collaborative document editing.^[23] New Comet variants were created, such as the Java-based ICEfaces JSF framework (although they prefer the term "Ajax Push"^[5]). Others that had previously used Java-applet based transports switched instead to pure-JavaScript implementations.^[24]

My notes:

Polling - two-way sustained interaction, persistent or long-lasting HTTP connection

page-by-page web model? 

Comet applications attempt to eliminate the limitations of the page-by-page web model and traditional polling by offering two-way sustained interaction, using a persistent or long-lasting HTTP connection between the server and the client.

traditional polling? 

two-way sustained interaction? 

persistent or long-lasting HTTP connection? 

many Comet applications use long polling, which is easier to implement on the browser side, and works, at minimum, in every browser that supports XHR.

XMLHttpRequest long polling

Streaming and long polling

Streaming - hidden iframe

XMLHttpRequest 

Ajax with long polling 

Actionable Items

Ask more questions first. And then go back to read networking lecture notes related to application layer and network layer

Push technology, server push - internet based communication

Push technology, or server push, is a style of Internet-based communication where the request for a given transaction is initiated by the publisher or central server. It is contrasted with pull/get, where the request for the transmission of information is initiated by the receiver or client.

Push services are often based on information preferences expressed in advance. This is called a publish/subscribe model. A client "subscribes" to various information "channels" provided by a server; whenever new content is available on one of those channels, the server pushes that information out to the client.

Push is sometimes emulated with a polling technique, particularly under circumstances where a real push is not possible, such as sites with security policies that require rejection of incoming HTTP/S requests.

Traders: Millions by the Minute - BBC Two

Movie and investor CNBC hostess - Karen Finerman

I like to look into those keywords:

1. 厌恶损失的人类天性并没有在交易年岁上或者补偿
2. 三类典型的交易特征：交易量过少，无法获得盘感，出局；交易量过大，交易冲动过多，没有慎重思考，出局；管理自己的钱和代理别人的钱，承担风险的欲望不同。

在网上看ichimoku指标晕头转向时，发现了《交易员》视频，本着放松的初衷看了一集。真是真实生活的写照啊。那些人，没有笑脸的，除了盈利时露出一丝会意的笑容——“我对了！”。大多数时候，他们是严肃的、紧张的、面无表情的、甚至沮丧的。是的，亏损时，自然很沮丧。盈利时，如果跑的比别人慢，也没有那么的愉快啊~~

但这些不是重点，重点是不同交易**赋予**的生活模式。对，《我生活的种种模式》。他不是西蒙有目的的每隔几年切换工作方向的模式。而是反过来，几十年市场变动后，让交易员将自己的生活模式与交易模式相契合的结果。

片中的对冲基金经理，那个**双**双胞胎妈妈，她是一个价值投资者，换言之，她buy low，and sell high。她并不**很**在乎每天市场的波动，而更关注那些长期影响股票价值，以及突发事件对股票的影响。她辨别价值和噪音，从而将精力从每日的波动中解放出来。她大概是几个人中生活得比较有质量的人。可以去参加慈善party，可以有空享受孩子和老公的环抱。不过看到她走过彩打出不同孩子time schedule的区域，坐在凳子上微微皱起眉头，烦恼地看着家里的宠物狗时，我真的想开怀大笑。就连她的喜好也和我同出一辙，烦躁时唯有看看书，才能有所收获。她的想法，家里要宽敞一点儿，也是我的偏好。毕竟工作时考虑那么多，回家后如果脑子不能放空，屋子里空一些也好......

我真的跟她很有共鸣。

日内交易者的痛苦就很明显了。片中的老交易员，也会失手。在前一个交易损失后，明明知道后一个交易在获利，也会急于close掉，以获得对前一个损失补偿的心理效果。厌恶损失的人类天性并没有在交易年岁上或者补偿。他们可以很明确的说出三类典型的交易特征：交易量过少，无法获得盘感，出局；交易量过大，交易冲动过多，没有慎重思考，出局；管理自己的钱和代理别人的钱，承担风险的欲望不同。但除此之外，10个人入局的6个人，还有其他一些什么特征，就没有再接着阐述了。

高频交易商一脸苦相的出现在镜头里，他知道自己不受人待见，所以很诚恳地站在一大排服务器前，说出了一项事实。如果我把这些我珍爱的，每个都起了名字的服务器关掉，明天你们买卖的价格很可能不会更好。

是的，高频交易/算法交易现在是最受争议和发展最快的领域。散单无疑创造了一些流动性，但闪单则是截胡策略。在以百万分之一秒为单位交易的世界里，人类没有办法超过机器的执行能力。片中两个场内交易商选择黯然退场，去找寻其他轻脑力劳动的工作。

但是，人类不是适应性动物吗？为什么西蒙可以转换自如？但是在金融这个行业里，转换单一子类工种都那么困难呢？世界变化了，我们为什么不能选择适应它？

不是绝对不能，但属于相对不能。

我们都是被时空局限的人类。一个人高度注意的时间是有限的。在高度运转的世界里呆久了，没有时间没有**心流**去学习更新自己。片中可以看到，在这个领域里，每个人都定型了。连最有时间思考，闭市后脑海里没那么多心思考虑自己头寸压力的女对冲基金经理，看到家里的宠物狗时，都不是一种放松的心情。那种表情，是一种忧虑、烦躁、恨不得get rid of that的样子。不是我们选择了生活方式，而是这个行情选择了我们自己。

所以每个人都在他初始设定的轨道下进行下去。路径依赖越来越明显。

或迟或早，你总会找到属于自己的pattern。但这个pattern不完全是由你自己的意愿决定的。交易者要形成2个系统。一个系统是处理你的注意力系统。在集中大量脑力之后，能不能有更多的精力用来跟踪市场的科技发展，让你从场内做市商，成功转换到高频做市商呢？没有那么容易的事情。另一个系统是你的情绪系统。你要学会热爱你的职业。如果你不热爱它，你就不能自觉自愿地从一个生手转换为熟手。你还不能太热爱它。让你丧失为人的另一大乐趣：家庭生活。

如果你意识到这两个系统，在已经很忙碌的交易时间驱动后，找到自己的创造者时间，你就能用它平衡自己的心理局限，找到更为舒适的人生。

Individual investor - most important is sentimental management

心态比技术更重要

1、大多数散户犯的最大的错误之一，就是缺乏纪律性，你必须有条不紊，提前做好方案，然后等待市场的考验，那么多交易员不幸亏钱，原因就在于此。

2、很多散户一直在看多，认为它会涨涨涨，所以他们会因为看错方向而被套牢，他们总是站在市场错误的一边，而我想站在另一边，因为大众通常都是错的。

3、大多数新手总是想着他们能赚多少钱，而专业的交易员，会着眼于可能会亏多少钱，这是一个简单的成功法门，但令人惊讶的是，既然有那么多人会犯这个错误。

4、我虽然在外面，但是我已经做好了分析，并做好了执行方案，单子已经提交了，让他们自动执行就行了，这就是风险与回报的问题了，我要么亏2个点，要么赚6个点，就这么简单。

5、说到交易，你要么赚钱要么赔钱，那为什么很多人赚不到钱呢，这并不是技术能力的问题，随着时间的推移，你会逐渐获得技术能力。但你还要面对回吐的问题，交易中会遭遇巨额的回吐，很多人会觉得自己没办法承受而选择放弃，大多数选择放弃的人，可能并没有付出自己最大的努力吧.

Long polling -> system design -> networking course -> go back to long polling article

August 2, 2020

Introduction

It is the first time I realize that it is so powerful tool I should master last 10 years. What I did miss is to review those networking and distribute system courses on the internet regularly. It will make me an excellent engineer and learner any where and any time. 

My system design reading task

I have to focus on the basics this time.  I do believe those course lecture notes are so good for me to learn and review basics, and then get back to those topics like long polling I worked on before. The article I read should be perfect match to examine how good I learn through those lecture notes. 

Long polling article is here. 

Camila Cabello - Easy (Live on SNL)

Here is the link. 

Forbes: #39 Shawn Mendes

• The singer-songwriter grossed $87 million on tour in 2019, slightly more than the Jonas Brothers and a bit less than Post Malone.
• Mendes is barely old enough to buy a beer and has endorsement deals with the likes of Calvin Klein.
• His music moved over 1 million album-equivalent units during our 12-month scoring period.

24 Hours With Hailee Steinfeld | Vogue

Here is the link.